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Boiler Boiler maintenancemaintenance
And And inspectioninspection
Pre-Boiler water Pre-Boiler water treatmenttreatment
bull The quality of the water used The quality of the water used within the boiler cycle is very within the boiler cycle is very important Higher pressure boilers important Higher pressure boilers require higher quality water require higher quality water Maintaining the recommended Maintaining the recommended feed water and boiler water feed water and boiler water quality limits will insure more quality limits will insure more reliable and increase unit reliable and increase unit availabilityavailability
Typical arrangement of the Typical arrangement of the pre-boiler water treatment pre-boiler water treatment equipment-equipment-bull 1pre-boiler water treatment-1pre-boiler water treatment-used to used to
remove the contaminates in the raw feed remove the contaminates in the raw feed waterwater
bull 2clarification-2clarification-the addition of chemicals to the addition of chemicals to assist in the setting out of suspended solidsassist in the setting out of suspended solids
bull 3filtration-3filtration-used to kill the organics in the used to kill the organics in the water and to remove the finer suspended water and to remove the finer suspended materialmaterial
bull 4demineralization-4demineralization-used to remove the used to remove the dissolved solids (various cations and anions) dissolved solids (various cations and anions) in the feed waterin the feed water
bull 5dearation-5dearation-to remove the bulk of free to remove the bulk of free oxygen in the feed wateroxygen in the feed water
bull 6addition of hydrazine-6addition of hydrazine-an oxygen an oxygen scavenger used for additional free oxygen scavenger used for additional free oxygen removalremoval
bull 7addition of ammonia-7addition of ammonia-to increase the PH to increase the PH of the feed water between 85 and 95of the feed water between 85 and 95
bull 8condensate treatment-8condensate treatment-to purify the to purify the condensate returns for boiler feed water condensate returns for boiler feed water usageusage
bull 9condensate polishing-9condensate polishing-to remove the to remove the bulk of the contaminates such as metal bulk of the contaminates such as metal oxides which have been entrained in the oxides which have been entrained in the condensatecondensate
Chemical cleaning-Chemical cleaning-
bull The purpose of chemical cleaning The purpose of chemical cleaning is to remove any internal deposits is to remove any internal deposits within the boiler and therefore within the boiler and therefore reduce the possibility of down reduce the possibility of down time due to tube failures Periodic time due to tube failures Periodic chemical cleaning should become chemical cleaning should become a part of a preventive a part of a preventive maintenance program maintenance program
Methods of determining Methods of determining when chemical cleaning is when chemical cleaning is necessary-necessary-bull 1Tube failure-1Tube failure-an analysis of the cause an analysis of the cause
for the tube failure could indicate the for the tube failure could indicate the need for chemical cleaning This is a need for chemical cleaning This is a highly undesirable method of highly undesirable method of determinationdetermination
bull 2Periodic tube sample analysis-2Periodic tube sample analysis-the the analysis could indicate the need for analysis could indicate the need for chemical cleaning prior to tube failureschemical cleaning prior to tube failures
bull 3Chordal thermocouples-3Chordal thermocouples- the increase the increase in external surface metal temperature in external surface metal temperature during operation could be used to gauge during operation could be used to gauge the build-up of internal depositionthe build-up of internal deposition
Energy loss-Energy loss-
bull Loss in external depositsLoss in external deposits
bull Loss in internal depositsLoss in internal deposits
1Remove externaldepositsby sootblowing
2avoid internal deposits by chemical cleaning (by acidcleaning)
Corrosion due to Corrosion due to combustion product-combustion product-bull 1- High temperature corrosion in superheaters
andbull Reheaters-bull ndash promoted by sodium and vanadium
compoundsbull ndash sensitive if metal temp above 600degCbull 2- Medium temp Corrosion in evaporatorsbull ndash fixed through combustion system adjustmentbull 3- Low temp Corrosion in cold areasbull ndash promoted by sulfur which turns into sulfuric
acidbull below dew point keep temperature above
150degC
Basic principles for design Basic principles for design material-material-
bull 1-Carbon steel1-Carbon steelbull 2-Low alloy steel (Crlt25)2-Low alloy steel (Crlt25)bull 3-Medium alloy steel (Crgt25)3-Medium alloy steel (Crgt25)bull 4-High alloy steel (Crgt9)4-High alloy steel (Crgt9)bull 5-Stainless steel (Crgt11)5-Stainless steel (Crgt11)bull Note-Note- increase Ni improve low increase Ni improve low
temperature resistancetemperature resistancebull Increase Cr improve high Increase Cr improve high
temperature resistancetemperature resistance
Metals of steam boilers-Metals of steam boilers-
bull The main materials for boilers are carbon The main materials for boilers are carbon steels and alloy steelssteels and alloy steels
bull 1-carbon steel-1-carbon steel-steels are used for making steels are used for making steam boiler elements which operate under steam boiler elements which operate under no-creep conditions at temperatures not no-creep conditions at temperatures not higher than 450 higher than 450 degC
bull 2-alloy steel- used for making boiler elements for operation under creep condition like superheater elements
bull Note-the principle alloying elements in steels are Mo Cr Si and Al Molybdenum increase the long term strength and creep strength Chromium Silicon and Aluminum increase scale resistance
An application for boiler An application for boiler material and design material and design temperature-temperature-Material (ASTM)Material (ASTM) Design Design
temperaturetemperature
A 209 GR P1A 209 GR P1 16 to 412 16 to 412 degC
A 335 GR P11A 335 GR P11 496 to 538 496 to 538 degC
A 335 GR P12A 335 GR P12 496 to 538 496 to 538 degC
A 335 GR p22A 335 GR p22 539 to 593 539 to 593 degC
Tube failure Tube failure mechanisms-mechanisms-bull 1-Short term over heating failure-1-Short term over heating failure-
bull The cause of short term over heat is a rapid The cause of short term over heat is a rapid elevation of temperature of the tube metal elevation of temperature of the tube metal caused by restriction of the water steam caused by restriction of the water steam mixture to the tube and resulting in a wide mixture to the tube and resulting in a wide mouth rupture The edges of the rupture are mouth rupture The edges of the rupture are thin and sharp in the super heater A short term thin and sharp in the super heater A short term over heat could result from a blockage of steam over heat could result from a blockage of steam flowflow
Short time overheating failure
Failures due to scale and Failures due to scale and long term creep failure-long term creep failure-
bull The cause of this type of failure is build-up of The cause of this type of failure is build-up of internal scale that leads to gradual increase in internal scale that leads to gradual increase in temperature of the tube metal The tube may temperature of the tube metal The tube may appear swollen with blisters or bulges The out appear swollen with blisters or bulges The out side surface may have an elephant hide side surface may have an elephant hide appearance Rupture are a thin opening a long appearance Rupture are a thin opening a long the longitudinal axis of the tube The edges of the longitudinal axis of the tube The edges of the failure do not generally experience thinning the failure do not generally experience thinning
Long time overheating failure
Ash corrosion -Ash corrosion -
bull Ash corrosion result in a thinning of Ash corrosion result in a thinning of super heater and reheater tubing super heater and reheater tubing External wastage of the metal occurs External wastage of the metal occurs where ash deposits accumulate When where ash deposits accumulate When ash deposits on the tube and ash deposits on the tube and experiences high temperatures It experiences high temperatures It becomes semi-molten and corrodes becomes semi-molten and corrodes most alloy steels that might be used in most alloy steels that might be used in super heater constructionsuper heater construction
Corrosion by molten ashCorrosion by molten ash
Oxygen pitting Oxygen pitting (Economizer)-(Economizer)-bull In-service oxygen pitting appears as random In-service oxygen pitting appears as random
Round bottomed pits on the water side of Round bottomed pits on the water side of tubes in the economizer If there is no tubes in the economizer If there is no economizer similar pitting may be present at economizer similar pitting may be present at or above normal water level in the steam or above normal water level in the steam drum Proper mechanical deaeration of feed drum Proper mechanical deaeration of feed water is absolutely essential for protection of water is absolutely essential for protection of the pre-boiler equipment ( feed water heater the pre-boiler equipment ( feed water heater piping) and the economizer The addition of piping) and the economizer The addition of an oxygen scavenger such as hydrazine to an oxygen scavenger such as hydrazine to the deaerator storage tank will permit the deaerator storage tank will permit removal of minute quantities of dissolved removal of minute quantities of dissolved oxygenoxygen
Oxygen pitting Oxygen pitting (superheater)-(superheater)-
bull Out-of-service oxygen pitting is Out-of-service oxygen pitting is usually found in the bottom loops usually found in the bottom loops of the superheater and is result of of the superheater and is result of the exposure of water or the exposure of water or condensate that forms in the bends condensate that forms in the bends after shutdown in contact with air after shutdown in contact with air The distress is seen as pitting and The distress is seen as pitting and corrosion of the wetted internal corrosion of the wetted internal surfacessurfaces
Carry over-Carry over-
bull The cause for carry over is an The cause for carry over is an incomplete separation of the steam incomplete separation of the steam from the steamwater mixture in the from the steamwater mixture in the boiler Possible causes of carry over boiler Possible causes of carry over are high water level high total are high water level high total dissolved solids concentration in the dissolved solids concentration in the boiler water excessive alkalinity and boiler water excessive alkalinity and the presence of oil andor organics the presence of oil andor organics The result of carry over is a build up of The result of carry over is a build up of contaminates on the inner surface of contaminates on the inner surface of the super heater tubesthe super heater tubes
Steam blanketing-Steam blanketing-
bull The cause for steam blanketing is an The cause for steam blanketing is an improper mass flow in the boiler tube improper mass flow in the boiler tube in relation to the heat input and in relation to the heat input and pressure Causing localized thinning in pressure Causing localized thinning in the tube This type of attack is the tube This type of attack is sometimes accompanied by a gross sometimes accompanied by a gross accumulation of corrosive product accumulation of corrosive product Steam blanketing is also referred to as Steam blanketing is also referred to as DNB (departure from nucleate boiling)DNB (departure from nucleate boiling)
Thinning of tube due to Thinning of tube due to steam blanketing-steam blanketing-
Hydrogen attack or Hydrogen attack or damage-damage-
bull This type of failure is found in high pressure units This type of failure is found in high pressure units A situation occurs when excessive deposits are A situation occurs when excessive deposits are present on the tube water side surface that permit present on the tube water side surface that permit boiler chemicals to concentrate under the deposit boiler chemicals to concentrate under the deposit and corrode the metal Hydrogen is formed which and corrode the metal Hydrogen is formed which permeates the metal structure and reacts with the permeates the metal structure and reacts with the carbon of the metal to form methane The methane carbon of the metal to form methane The methane molecule which is much larger than the carbon molecule which is much larger than the carbon atom Exerts pressure and causes the metal to atom Exerts pressure and causes the metal to rupture along the grain boundaries Ruptures are rupture along the grain boundaries Ruptures are violent sudden and can be disastrousviolent sudden and can be disastrous
bull 4H+C=CH44H+C=CH4
The effect of hydrogen The effect of hydrogen attack in tubes-attack in tubes-
Cold end corrosion-Cold end corrosion-
bull Cold-end corrosion will occur Cold-end corrosion will occur wherever the temperature of metal wherever the temperature of metal drops below the sulfuric acid dew drops below the sulfuric acid dew point of the flue gas It occurs in point of the flue gas It occurs in economizer air preheater economizer air preheater induced draft fan and stackinduced draft fan and stack
Soot blowers erosion-Soot blowers erosion-
bull A misdirected blower allows a high A misdirected blower allows a high velocity jet of steam or air carrying velocity jet of steam or air carrying condensed water droplets to condensed water droplets to impinge directed upon tube impinge directed upon tube surfaces rather than to be directed surfaces rather than to be directed between tubes Physical abrasion between tubes Physical abrasion and acceleration oxidation cause and acceleration oxidation cause metal loss Erosive thinning often metal loss Erosive thinning often leads to tube ruptureleads to tube rupture
Foaming-Foaming-
bull It is a condition in which It is a condition in which concentration of soluble salts create concentration of soluble salts create frothy bubbles in the steam space of frothy bubbles in the steam space of the boiler Foaming can form slugs the boiler Foaming can form slugs of water that can carried over into of water that can carried over into the steam systemthe steam system
How to remove a tube How to remove a tube sample for inspectionsample for inspection
When removing a tube When removing a tube sample-sample-
bull 1-the tube section should be dry saw 1-the tube section should be dry saw cut to prevent any slag andor cutting cut to prevent any slag andor cutting oil from contaminating the internal oil from contaminating the internal depositdeposit
bull 2-the sample should be cut 2-the sample should be cut approximately 8-10 inches above and approximately 8-10 inches above and below the affected areabelow the affected area
bull 3-the exact location should be 3-the exact location should be documented as follows-documented as follows-
bull A-tubes should be numbered and A-tubes should be numbered and counted from east to west and north counted from east to west and north to southto south
bull B-the wall (front rear right hand B-the wall (front rear right hand side left hand side) and elevation side left hand side) and elevation should be noted and marked on the should be noted and marked on the tubetube
bull C-an arrow should be marked to C-an arrow should be marked to indicate which end of sample is upindicate which end of sample is up
bull D-on a universal pressure unit the D-on a universal pressure unit the sample should be identified as sample should be identified as removed from the first second or removed from the first second or third passthird pass
Troubles associated to drums-
bull1048698 Loss of level gauges
bull1048698 water level controllers out of service
bull1048698 corrosion
bull1048698 moisture carry-over in the steam
bull1048698 safety valves leaking
bull1048698 leaks of roll-expanded evaporator
bullTubes
bull1048698 plugging of evaporator tubes
Trouble associated to air Trouble associated to air heaters-heaters-
bull1048698 Leakages due to damaged axial or circumferential seals
bull1048698 Cold end baskets damaged by acid corrosion
bull1048698 Poor sootblowing
bull1048698 Standby pneumatic or DC motor not working or absent
New application in air New application in air heater-heater-
The modification-The modification-
bull We used to manufacture the air We used to manufacture the air heater basket material from heater basket material from carbon steel or Corten steel now carbon steel or Corten steel now they add a new material called they add a new material called enamel to improve quality reduce enamel to improve quality reduce cost and extend service life for air cost and extend service life for air and gas heater which increase the and gas heater which increase the existing of elementexisting of element
The material composition of The material composition of enamel-enamel-
bull The enamel layer is basically The enamel layer is basically composed by a borosilicate glass plus composed by a borosilicate glass plus cobalt fluorine sodium potassium cobalt fluorine sodium potassium quartz titanium borax helliphellipquartz titanium borax helliphellip
The benefits of enamel The benefits of enamel coating include-coating include-
bull 1-greater resistance to the attack of 1-greater resistance to the attack of acidsacids
bull 2-abrasive and wear resistance2-abrasive and wear resistance
bull 3-high mechanical and thermal shock 3-high mechanical and thermal shock resistanceresistance
bull 4-high resistance to erosion by fly ash4-high resistance to erosion by fly ash
bull 5-smooth and vitreous surface reduces 5-smooth and vitreous surface reduces adhesion of solidsadhesion of solids
The EndThe End
bullGood luckGood luck
Pre-Boiler water Pre-Boiler water treatmenttreatment
bull The quality of the water used The quality of the water used within the boiler cycle is very within the boiler cycle is very important Higher pressure boilers important Higher pressure boilers require higher quality water require higher quality water Maintaining the recommended Maintaining the recommended feed water and boiler water feed water and boiler water quality limits will insure more quality limits will insure more reliable and increase unit reliable and increase unit availabilityavailability
Typical arrangement of the Typical arrangement of the pre-boiler water treatment pre-boiler water treatment equipment-equipment-bull 1pre-boiler water treatment-1pre-boiler water treatment-used to used to
remove the contaminates in the raw feed remove the contaminates in the raw feed waterwater
bull 2clarification-2clarification-the addition of chemicals to the addition of chemicals to assist in the setting out of suspended solidsassist in the setting out of suspended solids
bull 3filtration-3filtration-used to kill the organics in the used to kill the organics in the water and to remove the finer suspended water and to remove the finer suspended materialmaterial
bull 4demineralization-4demineralization-used to remove the used to remove the dissolved solids (various cations and anions) dissolved solids (various cations and anions) in the feed waterin the feed water
bull 5dearation-5dearation-to remove the bulk of free to remove the bulk of free oxygen in the feed wateroxygen in the feed water
bull 6addition of hydrazine-6addition of hydrazine-an oxygen an oxygen scavenger used for additional free oxygen scavenger used for additional free oxygen removalremoval
bull 7addition of ammonia-7addition of ammonia-to increase the PH to increase the PH of the feed water between 85 and 95of the feed water between 85 and 95
bull 8condensate treatment-8condensate treatment-to purify the to purify the condensate returns for boiler feed water condensate returns for boiler feed water usageusage
bull 9condensate polishing-9condensate polishing-to remove the to remove the bulk of the contaminates such as metal bulk of the contaminates such as metal oxides which have been entrained in the oxides which have been entrained in the condensatecondensate
Chemical cleaning-Chemical cleaning-
bull The purpose of chemical cleaning The purpose of chemical cleaning is to remove any internal deposits is to remove any internal deposits within the boiler and therefore within the boiler and therefore reduce the possibility of down reduce the possibility of down time due to tube failures Periodic time due to tube failures Periodic chemical cleaning should become chemical cleaning should become a part of a preventive a part of a preventive maintenance program maintenance program
Methods of determining Methods of determining when chemical cleaning is when chemical cleaning is necessary-necessary-bull 1Tube failure-1Tube failure-an analysis of the cause an analysis of the cause
for the tube failure could indicate the for the tube failure could indicate the need for chemical cleaning This is a need for chemical cleaning This is a highly undesirable method of highly undesirable method of determinationdetermination
bull 2Periodic tube sample analysis-2Periodic tube sample analysis-the the analysis could indicate the need for analysis could indicate the need for chemical cleaning prior to tube failureschemical cleaning prior to tube failures
bull 3Chordal thermocouples-3Chordal thermocouples- the increase the increase in external surface metal temperature in external surface metal temperature during operation could be used to gauge during operation could be used to gauge the build-up of internal depositionthe build-up of internal deposition
Energy loss-Energy loss-
bull Loss in external depositsLoss in external deposits
bull Loss in internal depositsLoss in internal deposits
1Remove externaldepositsby sootblowing
2avoid internal deposits by chemical cleaning (by acidcleaning)
Corrosion due to Corrosion due to combustion product-combustion product-bull 1- High temperature corrosion in superheaters
andbull Reheaters-bull ndash promoted by sodium and vanadium
compoundsbull ndash sensitive if metal temp above 600degCbull 2- Medium temp Corrosion in evaporatorsbull ndash fixed through combustion system adjustmentbull 3- Low temp Corrosion in cold areasbull ndash promoted by sulfur which turns into sulfuric
acidbull below dew point keep temperature above
150degC
Basic principles for design Basic principles for design material-material-
bull 1-Carbon steel1-Carbon steelbull 2-Low alloy steel (Crlt25)2-Low alloy steel (Crlt25)bull 3-Medium alloy steel (Crgt25)3-Medium alloy steel (Crgt25)bull 4-High alloy steel (Crgt9)4-High alloy steel (Crgt9)bull 5-Stainless steel (Crgt11)5-Stainless steel (Crgt11)bull Note-Note- increase Ni improve low increase Ni improve low
temperature resistancetemperature resistancebull Increase Cr improve high Increase Cr improve high
temperature resistancetemperature resistance
Metals of steam boilers-Metals of steam boilers-
bull The main materials for boilers are carbon The main materials for boilers are carbon steels and alloy steelssteels and alloy steels
bull 1-carbon steel-1-carbon steel-steels are used for making steels are used for making steam boiler elements which operate under steam boiler elements which operate under no-creep conditions at temperatures not no-creep conditions at temperatures not higher than 450 higher than 450 degC
bull 2-alloy steel- used for making boiler elements for operation under creep condition like superheater elements
bull Note-the principle alloying elements in steels are Mo Cr Si and Al Molybdenum increase the long term strength and creep strength Chromium Silicon and Aluminum increase scale resistance
An application for boiler An application for boiler material and design material and design temperature-temperature-Material (ASTM)Material (ASTM) Design Design
temperaturetemperature
A 209 GR P1A 209 GR P1 16 to 412 16 to 412 degC
A 335 GR P11A 335 GR P11 496 to 538 496 to 538 degC
A 335 GR P12A 335 GR P12 496 to 538 496 to 538 degC
A 335 GR p22A 335 GR p22 539 to 593 539 to 593 degC
Tube failure Tube failure mechanisms-mechanisms-bull 1-Short term over heating failure-1-Short term over heating failure-
bull The cause of short term over heat is a rapid The cause of short term over heat is a rapid elevation of temperature of the tube metal elevation of temperature of the tube metal caused by restriction of the water steam caused by restriction of the water steam mixture to the tube and resulting in a wide mixture to the tube and resulting in a wide mouth rupture The edges of the rupture are mouth rupture The edges of the rupture are thin and sharp in the super heater A short term thin and sharp in the super heater A short term over heat could result from a blockage of steam over heat could result from a blockage of steam flowflow
Short time overheating failure
Failures due to scale and Failures due to scale and long term creep failure-long term creep failure-
bull The cause of this type of failure is build-up of The cause of this type of failure is build-up of internal scale that leads to gradual increase in internal scale that leads to gradual increase in temperature of the tube metal The tube may temperature of the tube metal The tube may appear swollen with blisters or bulges The out appear swollen with blisters or bulges The out side surface may have an elephant hide side surface may have an elephant hide appearance Rupture are a thin opening a long appearance Rupture are a thin opening a long the longitudinal axis of the tube The edges of the longitudinal axis of the tube The edges of the failure do not generally experience thinning the failure do not generally experience thinning
Long time overheating failure
Ash corrosion -Ash corrosion -
bull Ash corrosion result in a thinning of Ash corrosion result in a thinning of super heater and reheater tubing super heater and reheater tubing External wastage of the metal occurs External wastage of the metal occurs where ash deposits accumulate When where ash deposits accumulate When ash deposits on the tube and ash deposits on the tube and experiences high temperatures It experiences high temperatures It becomes semi-molten and corrodes becomes semi-molten and corrodes most alloy steels that might be used in most alloy steels that might be used in super heater constructionsuper heater construction
Corrosion by molten ashCorrosion by molten ash
Oxygen pitting Oxygen pitting (Economizer)-(Economizer)-bull In-service oxygen pitting appears as random In-service oxygen pitting appears as random
Round bottomed pits on the water side of Round bottomed pits on the water side of tubes in the economizer If there is no tubes in the economizer If there is no economizer similar pitting may be present at economizer similar pitting may be present at or above normal water level in the steam or above normal water level in the steam drum Proper mechanical deaeration of feed drum Proper mechanical deaeration of feed water is absolutely essential for protection of water is absolutely essential for protection of the pre-boiler equipment ( feed water heater the pre-boiler equipment ( feed water heater piping) and the economizer The addition of piping) and the economizer The addition of an oxygen scavenger such as hydrazine to an oxygen scavenger such as hydrazine to the deaerator storage tank will permit the deaerator storage tank will permit removal of minute quantities of dissolved removal of minute quantities of dissolved oxygenoxygen
Oxygen pitting Oxygen pitting (superheater)-(superheater)-
bull Out-of-service oxygen pitting is Out-of-service oxygen pitting is usually found in the bottom loops usually found in the bottom loops of the superheater and is result of of the superheater and is result of the exposure of water or the exposure of water or condensate that forms in the bends condensate that forms in the bends after shutdown in contact with air after shutdown in contact with air The distress is seen as pitting and The distress is seen as pitting and corrosion of the wetted internal corrosion of the wetted internal surfacessurfaces
Carry over-Carry over-
bull The cause for carry over is an The cause for carry over is an incomplete separation of the steam incomplete separation of the steam from the steamwater mixture in the from the steamwater mixture in the boiler Possible causes of carry over boiler Possible causes of carry over are high water level high total are high water level high total dissolved solids concentration in the dissolved solids concentration in the boiler water excessive alkalinity and boiler water excessive alkalinity and the presence of oil andor organics the presence of oil andor organics The result of carry over is a build up of The result of carry over is a build up of contaminates on the inner surface of contaminates on the inner surface of the super heater tubesthe super heater tubes
Steam blanketing-Steam blanketing-
bull The cause for steam blanketing is an The cause for steam blanketing is an improper mass flow in the boiler tube improper mass flow in the boiler tube in relation to the heat input and in relation to the heat input and pressure Causing localized thinning in pressure Causing localized thinning in the tube This type of attack is the tube This type of attack is sometimes accompanied by a gross sometimes accompanied by a gross accumulation of corrosive product accumulation of corrosive product Steam blanketing is also referred to as Steam blanketing is also referred to as DNB (departure from nucleate boiling)DNB (departure from nucleate boiling)
Thinning of tube due to Thinning of tube due to steam blanketing-steam blanketing-
Hydrogen attack or Hydrogen attack or damage-damage-
bull This type of failure is found in high pressure units This type of failure is found in high pressure units A situation occurs when excessive deposits are A situation occurs when excessive deposits are present on the tube water side surface that permit present on the tube water side surface that permit boiler chemicals to concentrate under the deposit boiler chemicals to concentrate under the deposit and corrode the metal Hydrogen is formed which and corrode the metal Hydrogen is formed which permeates the metal structure and reacts with the permeates the metal structure and reacts with the carbon of the metal to form methane The methane carbon of the metal to form methane The methane molecule which is much larger than the carbon molecule which is much larger than the carbon atom Exerts pressure and causes the metal to atom Exerts pressure and causes the metal to rupture along the grain boundaries Ruptures are rupture along the grain boundaries Ruptures are violent sudden and can be disastrousviolent sudden and can be disastrous
bull 4H+C=CH44H+C=CH4
The effect of hydrogen The effect of hydrogen attack in tubes-attack in tubes-
Cold end corrosion-Cold end corrosion-
bull Cold-end corrosion will occur Cold-end corrosion will occur wherever the temperature of metal wherever the temperature of metal drops below the sulfuric acid dew drops below the sulfuric acid dew point of the flue gas It occurs in point of the flue gas It occurs in economizer air preheater economizer air preheater induced draft fan and stackinduced draft fan and stack
Soot blowers erosion-Soot blowers erosion-
bull A misdirected blower allows a high A misdirected blower allows a high velocity jet of steam or air carrying velocity jet of steam or air carrying condensed water droplets to condensed water droplets to impinge directed upon tube impinge directed upon tube surfaces rather than to be directed surfaces rather than to be directed between tubes Physical abrasion between tubes Physical abrasion and acceleration oxidation cause and acceleration oxidation cause metal loss Erosive thinning often metal loss Erosive thinning often leads to tube ruptureleads to tube rupture
Foaming-Foaming-
bull It is a condition in which It is a condition in which concentration of soluble salts create concentration of soluble salts create frothy bubbles in the steam space of frothy bubbles in the steam space of the boiler Foaming can form slugs the boiler Foaming can form slugs of water that can carried over into of water that can carried over into the steam systemthe steam system
How to remove a tube How to remove a tube sample for inspectionsample for inspection
When removing a tube When removing a tube sample-sample-
bull 1-the tube section should be dry saw 1-the tube section should be dry saw cut to prevent any slag andor cutting cut to prevent any slag andor cutting oil from contaminating the internal oil from contaminating the internal depositdeposit
bull 2-the sample should be cut 2-the sample should be cut approximately 8-10 inches above and approximately 8-10 inches above and below the affected areabelow the affected area
bull 3-the exact location should be 3-the exact location should be documented as follows-documented as follows-
bull A-tubes should be numbered and A-tubes should be numbered and counted from east to west and north counted from east to west and north to southto south
bull B-the wall (front rear right hand B-the wall (front rear right hand side left hand side) and elevation side left hand side) and elevation should be noted and marked on the should be noted and marked on the tubetube
bull C-an arrow should be marked to C-an arrow should be marked to indicate which end of sample is upindicate which end of sample is up
bull D-on a universal pressure unit the D-on a universal pressure unit the sample should be identified as sample should be identified as removed from the first second or removed from the first second or third passthird pass
Troubles associated to drums-
bull1048698 Loss of level gauges
bull1048698 water level controllers out of service
bull1048698 corrosion
bull1048698 moisture carry-over in the steam
bull1048698 safety valves leaking
bull1048698 leaks of roll-expanded evaporator
bullTubes
bull1048698 plugging of evaporator tubes
Trouble associated to air Trouble associated to air heaters-heaters-
bull1048698 Leakages due to damaged axial or circumferential seals
bull1048698 Cold end baskets damaged by acid corrosion
bull1048698 Poor sootblowing
bull1048698 Standby pneumatic or DC motor not working or absent
New application in air New application in air heater-heater-
The modification-The modification-
bull We used to manufacture the air We used to manufacture the air heater basket material from heater basket material from carbon steel or Corten steel now carbon steel or Corten steel now they add a new material called they add a new material called enamel to improve quality reduce enamel to improve quality reduce cost and extend service life for air cost and extend service life for air and gas heater which increase the and gas heater which increase the existing of elementexisting of element
The material composition of The material composition of enamel-enamel-
bull The enamel layer is basically The enamel layer is basically composed by a borosilicate glass plus composed by a borosilicate glass plus cobalt fluorine sodium potassium cobalt fluorine sodium potassium quartz titanium borax helliphellipquartz titanium borax helliphellip
The benefits of enamel The benefits of enamel coating include-coating include-
bull 1-greater resistance to the attack of 1-greater resistance to the attack of acidsacids
bull 2-abrasive and wear resistance2-abrasive and wear resistance
bull 3-high mechanical and thermal shock 3-high mechanical and thermal shock resistanceresistance
bull 4-high resistance to erosion by fly ash4-high resistance to erosion by fly ash
bull 5-smooth and vitreous surface reduces 5-smooth and vitreous surface reduces adhesion of solidsadhesion of solids
The EndThe End
bullGood luckGood luck
Typical arrangement of the Typical arrangement of the pre-boiler water treatment pre-boiler water treatment equipment-equipment-bull 1pre-boiler water treatment-1pre-boiler water treatment-used to used to
remove the contaminates in the raw feed remove the contaminates in the raw feed waterwater
bull 2clarification-2clarification-the addition of chemicals to the addition of chemicals to assist in the setting out of suspended solidsassist in the setting out of suspended solids
bull 3filtration-3filtration-used to kill the organics in the used to kill the organics in the water and to remove the finer suspended water and to remove the finer suspended materialmaterial
bull 4demineralization-4demineralization-used to remove the used to remove the dissolved solids (various cations and anions) dissolved solids (various cations and anions) in the feed waterin the feed water
bull 5dearation-5dearation-to remove the bulk of free to remove the bulk of free oxygen in the feed wateroxygen in the feed water
bull 6addition of hydrazine-6addition of hydrazine-an oxygen an oxygen scavenger used for additional free oxygen scavenger used for additional free oxygen removalremoval
bull 7addition of ammonia-7addition of ammonia-to increase the PH to increase the PH of the feed water between 85 and 95of the feed water between 85 and 95
bull 8condensate treatment-8condensate treatment-to purify the to purify the condensate returns for boiler feed water condensate returns for boiler feed water usageusage
bull 9condensate polishing-9condensate polishing-to remove the to remove the bulk of the contaminates such as metal bulk of the contaminates such as metal oxides which have been entrained in the oxides which have been entrained in the condensatecondensate
Chemical cleaning-Chemical cleaning-
bull The purpose of chemical cleaning The purpose of chemical cleaning is to remove any internal deposits is to remove any internal deposits within the boiler and therefore within the boiler and therefore reduce the possibility of down reduce the possibility of down time due to tube failures Periodic time due to tube failures Periodic chemical cleaning should become chemical cleaning should become a part of a preventive a part of a preventive maintenance program maintenance program
Methods of determining Methods of determining when chemical cleaning is when chemical cleaning is necessary-necessary-bull 1Tube failure-1Tube failure-an analysis of the cause an analysis of the cause
for the tube failure could indicate the for the tube failure could indicate the need for chemical cleaning This is a need for chemical cleaning This is a highly undesirable method of highly undesirable method of determinationdetermination
bull 2Periodic tube sample analysis-2Periodic tube sample analysis-the the analysis could indicate the need for analysis could indicate the need for chemical cleaning prior to tube failureschemical cleaning prior to tube failures
bull 3Chordal thermocouples-3Chordal thermocouples- the increase the increase in external surface metal temperature in external surface metal temperature during operation could be used to gauge during operation could be used to gauge the build-up of internal depositionthe build-up of internal deposition
Energy loss-Energy loss-
bull Loss in external depositsLoss in external deposits
bull Loss in internal depositsLoss in internal deposits
1Remove externaldepositsby sootblowing
2avoid internal deposits by chemical cleaning (by acidcleaning)
Corrosion due to Corrosion due to combustion product-combustion product-bull 1- High temperature corrosion in superheaters
andbull Reheaters-bull ndash promoted by sodium and vanadium
compoundsbull ndash sensitive if metal temp above 600degCbull 2- Medium temp Corrosion in evaporatorsbull ndash fixed through combustion system adjustmentbull 3- Low temp Corrosion in cold areasbull ndash promoted by sulfur which turns into sulfuric
acidbull below dew point keep temperature above
150degC
Basic principles for design Basic principles for design material-material-
bull 1-Carbon steel1-Carbon steelbull 2-Low alloy steel (Crlt25)2-Low alloy steel (Crlt25)bull 3-Medium alloy steel (Crgt25)3-Medium alloy steel (Crgt25)bull 4-High alloy steel (Crgt9)4-High alloy steel (Crgt9)bull 5-Stainless steel (Crgt11)5-Stainless steel (Crgt11)bull Note-Note- increase Ni improve low increase Ni improve low
temperature resistancetemperature resistancebull Increase Cr improve high Increase Cr improve high
temperature resistancetemperature resistance
Metals of steam boilers-Metals of steam boilers-
bull The main materials for boilers are carbon The main materials for boilers are carbon steels and alloy steelssteels and alloy steels
bull 1-carbon steel-1-carbon steel-steels are used for making steels are used for making steam boiler elements which operate under steam boiler elements which operate under no-creep conditions at temperatures not no-creep conditions at temperatures not higher than 450 higher than 450 degC
bull 2-alloy steel- used for making boiler elements for operation under creep condition like superheater elements
bull Note-the principle alloying elements in steels are Mo Cr Si and Al Molybdenum increase the long term strength and creep strength Chromium Silicon and Aluminum increase scale resistance
An application for boiler An application for boiler material and design material and design temperature-temperature-Material (ASTM)Material (ASTM) Design Design
temperaturetemperature
A 209 GR P1A 209 GR P1 16 to 412 16 to 412 degC
A 335 GR P11A 335 GR P11 496 to 538 496 to 538 degC
A 335 GR P12A 335 GR P12 496 to 538 496 to 538 degC
A 335 GR p22A 335 GR p22 539 to 593 539 to 593 degC
Tube failure Tube failure mechanisms-mechanisms-bull 1-Short term over heating failure-1-Short term over heating failure-
bull The cause of short term over heat is a rapid The cause of short term over heat is a rapid elevation of temperature of the tube metal elevation of temperature of the tube metal caused by restriction of the water steam caused by restriction of the water steam mixture to the tube and resulting in a wide mixture to the tube and resulting in a wide mouth rupture The edges of the rupture are mouth rupture The edges of the rupture are thin and sharp in the super heater A short term thin and sharp in the super heater A short term over heat could result from a blockage of steam over heat could result from a blockage of steam flowflow
Short time overheating failure
Failures due to scale and Failures due to scale and long term creep failure-long term creep failure-
bull The cause of this type of failure is build-up of The cause of this type of failure is build-up of internal scale that leads to gradual increase in internal scale that leads to gradual increase in temperature of the tube metal The tube may temperature of the tube metal The tube may appear swollen with blisters or bulges The out appear swollen with blisters or bulges The out side surface may have an elephant hide side surface may have an elephant hide appearance Rupture are a thin opening a long appearance Rupture are a thin opening a long the longitudinal axis of the tube The edges of the longitudinal axis of the tube The edges of the failure do not generally experience thinning the failure do not generally experience thinning
Long time overheating failure
Ash corrosion -Ash corrosion -
bull Ash corrosion result in a thinning of Ash corrosion result in a thinning of super heater and reheater tubing super heater and reheater tubing External wastage of the metal occurs External wastage of the metal occurs where ash deposits accumulate When where ash deposits accumulate When ash deposits on the tube and ash deposits on the tube and experiences high temperatures It experiences high temperatures It becomes semi-molten and corrodes becomes semi-molten and corrodes most alloy steels that might be used in most alloy steels that might be used in super heater constructionsuper heater construction
Corrosion by molten ashCorrosion by molten ash
Oxygen pitting Oxygen pitting (Economizer)-(Economizer)-bull In-service oxygen pitting appears as random In-service oxygen pitting appears as random
Round bottomed pits on the water side of Round bottomed pits on the water side of tubes in the economizer If there is no tubes in the economizer If there is no economizer similar pitting may be present at economizer similar pitting may be present at or above normal water level in the steam or above normal water level in the steam drum Proper mechanical deaeration of feed drum Proper mechanical deaeration of feed water is absolutely essential for protection of water is absolutely essential for protection of the pre-boiler equipment ( feed water heater the pre-boiler equipment ( feed water heater piping) and the economizer The addition of piping) and the economizer The addition of an oxygen scavenger such as hydrazine to an oxygen scavenger such as hydrazine to the deaerator storage tank will permit the deaerator storage tank will permit removal of minute quantities of dissolved removal of minute quantities of dissolved oxygenoxygen
Oxygen pitting Oxygen pitting (superheater)-(superheater)-
bull Out-of-service oxygen pitting is Out-of-service oxygen pitting is usually found in the bottom loops usually found in the bottom loops of the superheater and is result of of the superheater and is result of the exposure of water or the exposure of water or condensate that forms in the bends condensate that forms in the bends after shutdown in contact with air after shutdown in contact with air The distress is seen as pitting and The distress is seen as pitting and corrosion of the wetted internal corrosion of the wetted internal surfacessurfaces
Carry over-Carry over-
bull The cause for carry over is an The cause for carry over is an incomplete separation of the steam incomplete separation of the steam from the steamwater mixture in the from the steamwater mixture in the boiler Possible causes of carry over boiler Possible causes of carry over are high water level high total are high water level high total dissolved solids concentration in the dissolved solids concentration in the boiler water excessive alkalinity and boiler water excessive alkalinity and the presence of oil andor organics the presence of oil andor organics The result of carry over is a build up of The result of carry over is a build up of contaminates on the inner surface of contaminates on the inner surface of the super heater tubesthe super heater tubes
Steam blanketing-Steam blanketing-
bull The cause for steam blanketing is an The cause for steam blanketing is an improper mass flow in the boiler tube improper mass flow in the boiler tube in relation to the heat input and in relation to the heat input and pressure Causing localized thinning in pressure Causing localized thinning in the tube This type of attack is the tube This type of attack is sometimes accompanied by a gross sometimes accompanied by a gross accumulation of corrosive product accumulation of corrosive product Steam blanketing is also referred to as Steam blanketing is also referred to as DNB (departure from nucleate boiling)DNB (departure from nucleate boiling)
Thinning of tube due to Thinning of tube due to steam blanketing-steam blanketing-
Hydrogen attack or Hydrogen attack or damage-damage-
bull This type of failure is found in high pressure units This type of failure is found in high pressure units A situation occurs when excessive deposits are A situation occurs when excessive deposits are present on the tube water side surface that permit present on the tube water side surface that permit boiler chemicals to concentrate under the deposit boiler chemicals to concentrate under the deposit and corrode the metal Hydrogen is formed which and corrode the metal Hydrogen is formed which permeates the metal structure and reacts with the permeates the metal structure and reacts with the carbon of the metal to form methane The methane carbon of the metal to form methane The methane molecule which is much larger than the carbon molecule which is much larger than the carbon atom Exerts pressure and causes the metal to atom Exerts pressure and causes the metal to rupture along the grain boundaries Ruptures are rupture along the grain boundaries Ruptures are violent sudden and can be disastrousviolent sudden and can be disastrous
bull 4H+C=CH44H+C=CH4
The effect of hydrogen The effect of hydrogen attack in tubes-attack in tubes-
Cold end corrosion-Cold end corrosion-
bull Cold-end corrosion will occur Cold-end corrosion will occur wherever the temperature of metal wherever the temperature of metal drops below the sulfuric acid dew drops below the sulfuric acid dew point of the flue gas It occurs in point of the flue gas It occurs in economizer air preheater economizer air preheater induced draft fan and stackinduced draft fan and stack
Soot blowers erosion-Soot blowers erosion-
bull A misdirected blower allows a high A misdirected blower allows a high velocity jet of steam or air carrying velocity jet of steam or air carrying condensed water droplets to condensed water droplets to impinge directed upon tube impinge directed upon tube surfaces rather than to be directed surfaces rather than to be directed between tubes Physical abrasion between tubes Physical abrasion and acceleration oxidation cause and acceleration oxidation cause metal loss Erosive thinning often metal loss Erosive thinning often leads to tube ruptureleads to tube rupture
Foaming-Foaming-
bull It is a condition in which It is a condition in which concentration of soluble salts create concentration of soluble salts create frothy bubbles in the steam space of frothy bubbles in the steam space of the boiler Foaming can form slugs the boiler Foaming can form slugs of water that can carried over into of water that can carried over into the steam systemthe steam system
How to remove a tube How to remove a tube sample for inspectionsample for inspection
When removing a tube When removing a tube sample-sample-
bull 1-the tube section should be dry saw 1-the tube section should be dry saw cut to prevent any slag andor cutting cut to prevent any slag andor cutting oil from contaminating the internal oil from contaminating the internal depositdeposit
bull 2-the sample should be cut 2-the sample should be cut approximately 8-10 inches above and approximately 8-10 inches above and below the affected areabelow the affected area
bull 3-the exact location should be 3-the exact location should be documented as follows-documented as follows-
bull A-tubes should be numbered and A-tubes should be numbered and counted from east to west and north counted from east to west and north to southto south
bull B-the wall (front rear right hand B-the wall (front rear right hand side left hand side) and elevation side left hand side) and elevation should be noted and marked on the should be noted and marked on the tubetube
bull C-an arrow should be marked to C-an arrow should be marked to indicate which end of sample is upindicate which end of sample is up
bull D-on a universal pressure unit the D-on a universal pressure unit the sample should be identified as sample should be identified as removed from the first second or removed from the first second or third passthird pass
Troubles associated to drums-
bull1048698 Loss of level gauges
bull1048698 water level controllers out of service
bull1048698 corrosion
bull1048698 moisture carry-over in the steam
bull1048698 safety valves leaking
bull1048698 leaks of roll-expanded evaporator
bullTubes
bull1048698 plugging of evaporator tubes
Trouble associated to air Trouble associated to air heaters-heaters-
bull1048698 Leakages due to damaged axial or circumferential seals
bull1048698 Cold end baskets damaged by acid corrosion
bull1048698 Poor sootblowing
bull1048698 Standby pneumatic or DC motor not working or absent
New application in air New application in air heater-heater-
The modification-The modification-
bull We used to manufacture the air We used to manufacture the air heater basket material from heater basket material from carbon steel or Corten steel now carbon steel or Corten steel now they add a new material called they add a new material called enamel to improve quality reduce enamel to improve quality reduce cost and extend service life for air cost and extend service life for air and gas heater which increase the and gas heater which increase the existing of elementexisting of element
The material composition of The material composition of enamel-enamel-
bull The enamel layer is basically The enamel layer is basically composed by a borosilicate glass plus composed by a borosilicate glass plus cobalt fluorine sodium potassium cobalt fluorine sodium potassium quartz titanium borax helliphellipquartz titanium borax helliphellip
The benefits of enamel The benefits of enamel coating include-coating include-
bull 1-greater resistance to the attack of 1-greater resistance to the attack of acidsacids
bull 2-abrasive and wear resistance2-abrasive and wear resistance
bull 3-high mechanical and thermal shock 3-high mechanical and thermal shock resistanceresistance
bull 4-high resistance to erosion by fly ash4-high resistance to erosion by fly ash
bull 5-smooth and vitreous surface reduces 5-smooth and vitreous surface reduces adhesion of solidsadhesion of solids
The EndThe End
bullGood luckGood luck
bull 5dearation-5dearation-to remove the bulk of free to remove the bulk of free oxygen in the feed wateroxygen in the feed water
bull 6addition of hydrazine-6addition of hydrazine-an oxygen an oxygen scavenger used for additional free oxygen scavenger used for additional free oxygen removalremoval
bull 7addition of ammonia-7addition of ammonia-to increase the PH to increase the PH of the feed water between 85 and 95of the feed water between 85 and 95
bull 8condensate treatment-8condensate treatment-to purify the to purify the condensate returns for boiler feed water condensate returns for boiler feed water usageusage
bull 9condensate polishing-9condensate polishing-to remove the to remove the bulk of the contaminates such as metal bulk of the contaminates such as metal oxides which have been entrained in the oxides which have been entrained in the condensatecondensate
Chemical cleaning-Chemical cleaning-
bull The purpose of chemical cleaning The purpose of chemical cleaning is to remove any internal deposits is to remove any internal deposits within the boiler and therefore within the boiler and therefore reduce the possibility of down reduce the possibility of down time due to tube failures Periodic time due to tube failures Periodic chemical cleaning should become chemical cleaning should become a part of a preventive a part of a preventive maintenance program maintenance program
Methods of determining Methods of determining when chemical cleaning is when chemical cleaning is necessary-necessary-bull 1Tube failure-1Tube failure-an analysis of the cause an analysis of the cause
for the tube failure could indicate the for the tube failure could indicate the need for chemical cleaning This is a need for chemical cleaning This is a highly undesirable method of highly undesirable method of determinationdetermination
bull 2Periodic tube sample analysis-2Periodic tube sample analysis-the the analysis could indicate the need for analysis could indicate the need for chemical cleaning prior to tube failureschemical cleaning prior to tube failures
bull 3Chordal thermocouples-3Chordal thermocouples- the increase the increase in external surface metal temperature in external surface metal temperature during operation could be used to gauge during operation could be used to gauge the build-up of internal depositionthe build-up of internal deposition
Energy loss-Energy loss-
bull Loss in external depositsLoss in external deposits
bull Loss in internal depositsLoss in internal deposits
1Remove externaldepositsby sootblowing
2avoid internal deposits by chemical cleaning (by acidcleaning)
Corrosion due to Corrosion due to combustion product-combustion product-bull 1- High temperature corrosion in superheaters
andbull Reheaters-bull ndash promoted by sodium and vanadium
compoundsbull ndash sensitive if metal temp above 600degCbull 2- Medium temp Corrosion in evaporatorsbull ndash fixed through combustion system adjustmentbull 3- Low temp Corrosion in cold areasbull ndash promoted by sulfur which turns into sulfuric
acidbull below dew point keep temperature above
150degC
Basic principles for design Basic principles for design material-material-
bull 1-Carbon steel1-Carbon steelbull 2-Low alloy steel (Crlt25)2-Low alloy steel (Crlt25)bull 3-Medium alloy steel (Crgt25)3-Medium alloy steel (Crgt25)bull 4-High alloy steel (Crgt9)4-High alloy steel (Crgt9)bull 5-Stainless steel (Crgt11)5-Stainless steel (Crgt11)bull Note-Note- increase Ni improve low increase Ni improve low
temperature resistancetemperature resistancebull Increase Cr improve high Increase Cr improve high
temperature resistancetemperature resistance
Metals of steam boilers-Metals of steam boilers-
bull The main materials for boilers are carbon The main materials for boilers are carbon steels and alloy steelssteels and alloy steels
bull 1-carbon steel-1-carbon steel-steels are used for making steels are used for making steam boiler elements which operate under steam boiler elements which operate under no-creep conditions at temperatures not no-creep conditions at temperatures not higher than 450 higher than 450 degC
bull 2-alloy steel- used for making boiler elements for operation under creep condition like superheater elements
bull Note-the principle alloying elements in steels are Mo Cr Si and Al Molybdenum increase the long term strength and creep strength Chromium Silicon and Aluminum increase scale resistance
An application for boiler An application for boiler material and design material and design temperature-temperature-Material (ASTM)Material (ASTM) Design Design
temperaturetemperature
A 209 GR P1A 209 GR P1 16 to 412 16 to 412 degC
A 335 GR P11A 335 GR P11 496 to 538 496 to 538 degC
A 335 GR P12A 335 GR P12 496 to 538 496 to 538 degC
A 335 GR p22A 335 GR p22 539 to 593 539 to 593 degC
Tube failure Tube failure mechanisms-mechanisms-bull 1-Short term over heating failure-1-Short term over heating failure-
bull The cause of short term over heat is a rapid The cause of short term over heat is a rapid elevation of temperature of the tube metal elevation of temperature of the tube metal caused by restriction of the water steam caused by restriction of the water steam mixture to the tube and resulting in a wide mixture to the tube and resulting in a wide mouth rupture The edges of the rupture are mouth rupture The edges of the rupture are thin and sharp in the super heater A short term thin and sharp in the super heater A short term over heat could result from a blockage of steam over heat could result from a blockage of steam flowflow
Short time overheating failure
Failures due to scale and Failures due to scale and long term creep failure-long term creep failure-
bull The cause of this type of failure is build-up of The cause of this type of failure is build-up of internal scale that leads to gradual increase in internal scale that leads to gradual increase in temperature of the tube metal The tube may temperature of the tube metal The tube may appear swollen with blisters or bulges The out appear swollen with blisters or bulges The out side surface may have an elephant hide side surface may have an elephant hide appearance Rupture are a thin opening a long appearance Rupture are a thin opening a long the longitudinal axis of the tube The edges of the longitudinal axis of the tube The edges of the failure do not generally experience thinning the failure do not generally experience thinning
Long time overheating failure
Ash corrosion -Ash corrosion -
bull Ash corrosion result in a thinning of Ash corrosion result in a thinning of super heater and reheater tubing super heater and reheater tubing External wastage of the metal occurs External wastage of the metal occurs where ash deposits accumulate When where ash deposits accumulate When ash deposits on the tube and ash deposits on the tube and experiences high temperatures It experiences high temperatures It becomes semi-molten and corrodes becomes semi-molten and corrodes most alloy steels that might be used in most alloy steels that might be used in super heater constructionsuper heater construction
Corrosion by molten ashCorrosion by molten ash
Oxygen pitting Oxygen pitting (Economizer)-(Economizer)-bull In-service oxygen pitting appears as random In-service oxygen pitting appears as random
Round bottomed pits on the water side of Round bottomed pits on the water side of tubes in the economizer If there is no tubes in the economizer If there is no economizer similar pitting may be present at economizer similar pitting may be present at or above normal water level in the steam or above normal water level in the steam drum Proper mechanical deaeration of feed drum Proper mechanical deaeration of feed water is absolutely essential for protection of water is absolutely essential for protection of the pre-boiler equipment ( feed water heater the pre-boiler equipment ( feed water heater piping) and the economizer The addition of piping) and the economizer The addition of an oxygen scavenger such as hydrazine to an oxygen scavenger such as hydrazine to the deaerator storage tank will permit the deaerator storage tank will permit removal of minute quantities of dissolved removal of minute quantities of dissolved oxygenoxygen
Oxygen pitting Oxygen pitting (superheater)-(superheater)-
bull Out-of-service oxygen pitting is Out-of-service oxygen pitting is usually found in the bottom loops usually found in the bottom loops of the superheater and is result of of the superheater and is result of the exposure of water or the exposure of water or condensate that forms in the bends condensate that forms in the bends after shutdown in contact with air after shutdown in contact with air The distress is seen as pitting and The distress is seen as pitting and corrosion of the wetted internal corrosion of the wetted internal surfacessurfaces
Carry over-Carry over-
bull The cause for carry over is an The cause for carry over is an incomplete separation of the steam incomplete separation of the steam from the steamwater mixture in the from the steamwater mixture in the boiler Possible causes of carry over boiler Possible causes of carry over are high water level high total are high water level high total dissolved solids concentration in the dissolved solids concentration in the boiler water excessive alkalinity and boiler water excessive alkalinity and the presence of oil andor organics the presence of oil andor organics The result of carry over is a build up of The result of carry over is a build up of contaminates on the inner surface of contaminates on the inner surface of the super heater tubesthe super heater tubes
Steam blanketing-Steam blanketing-
bull The cause for steam blanketing is an The cause for steam blanketing is an improper mass flow in the boiler tube improper mass flow in the boiler tube in relation to the heat input and in relation to the heat input and pressure Causing localized thinning in pressure Causing localized thinning in the tube This type of attack is the tube This type of attack is sometimes accompanied by a gross sometimes accompanied by a gross accumulation of corrosive product accumulation of corrosive product Steam blanketing is also referred to as Steam blanketing is also referred to as DNB (departure from nucleate boiling)DNB (departure from nucleate boiling)
Thinning of tube due to Thinning of tube due to steam blanketing-steam blanketing-
Hydrogen attack or Hydrogen attack or damage-damage-
bull This type of failure is found in high pressure units This type of failure is found in high pressure units A situation occurs when excessive deposits are A situation occurs when excessive deposits are present on the tube water side surface that permit present on the tube water side surface that permit boiler chemicals to concentrate under the deposit boiler chemicals to concentrate under the deposit and corrode the metal Hydrogen is formed which and corrode the metal Hydrogen is formed which permeates the metal structure and reacts with the permeates the metal structure and reacts with the carbon of the metal to form methane The methane carbon of the metal to form methane The methane molecule which is much larger than the carbon molecule which is much larger than the carbon atom Exerts pressure and causes the metal to atom Exerts pressure and causes the metal to rupture along the grain boundaries Ruptures are rupture along the grain boundaries Ruptures are violent sudden and can be disastrousviolent sudden and can be disastrous
bull 4H+C=CH44H+C=CH4
The effect of hydrogen The effect of hydrogen attack in tubes-attack in tubes-
Cold end corrosion-Cold end corrosion-
bull Cold-end corrosion will occur Cold-end corrosion will occur wherever the temperature of metal wherever the temperature of metal drops below the sulfuric acid dew drops below the sulfuric acid dew point of the flue gas It occurs in point of the flue gas It occurs in economizer air preheater economizer air preheater induced draft fan and stackinduced draft fan and stack
Soot blowers erosion-Soot blowers erosion-
bull A misdirected blower allows a high A misdirected blower allows a high velocity jet of steam or air carrying velocity jet of steam or air carrying condensed water droplets to condensed water droplets to impinge directed upon tube impinge directed upon tube surfaces rather than to be directed surfaces rather than to be directed between tubes Physical abrasion between tubes Physical abrasion and acceleration oxidation cause and acceleration oxidation cause metal loss Erosive thinning often metal loss Erosive thinning often leads to tube ruptureleads to tube rupture
Foaming-Foaming-
bull It is a condition in which It is a condition in which concentration of soluble salts create concentration of soluble salts create frothy bubbles in the steam space of frothy bubbles in the steam space of the boiler Foaming can form slugs the boiler Foaming can form slugs of water that can carried over into of water that can carried over into the steam systemthe steam system
How to remove a tube How to remove a tube sample for inspectionsample for inspection
When removing a tube When removing a tube sample-sample-
bull 1-the tube section should be dry saw 1-the tube section should be dry saw cut to prevent any slag andor cutting cut to prevent any slag andor cutting oil from contaminating the internal oil from contaminating the internal depositdeposit
bull 2-the sample should be cut 2-the sample should be cut approximately 8-10 inches above and approximately 8-10 inches above and below the affected areabelow the affected area
bull 3-the exact location should be 3-the exact location should be documented as follows-documented as follows-
bull A-tubes should be numbered and A-tubes should be numbered and counted from east to west and north counted from east to west and north to southto south
bull B-the wall (front rear right hand B-the wall (front rear right hand side left hand side) and elevation side left hand side) and elevation should be noted and marked on the should be noted and marked on the tubetube
bull C-an arrow should be marked to C-an arrow should be marked to indicate which end of sample is upindicate which end of sample is up
bull D-on a universal pressure unit the D-on a universal pressure unit the sample should be identified as sample should be identified as removed from the first second or removed from the first second or third passthird pass
Troubles associated to drums-
bull1048698 Loss of level gauges
bull1048698 water level controllers out of service
bull1048698 corrosion
bull1048698 moisture carry-over in the steam
bull1048698 safety valves leaking
bull1048698 leaks of roll-expanded evaporator
bullTubes
bull1048698 plugging of evaporator tubes
Trouble associated to air Trouble associated to air heaters-heaters-
bull1048698 Leakages due to damaged axial or circumferential seals
bull1048698 Cold end baskets damaged by acid corrosion
bull1048698 Poor sootblowing
bull1048698 Standby pneumatic or DC motor not working or absent
New application in air New application in air heater-heater-
The modification-The modification-
bull We used to manufacture the air We used to manufacture the air heater basket material from heater basket material from carbon steel or Corten steel now carbon steel or Corten steel now they add a new material called they add a new material called enamel to improve quality reduce enamel to improve quality reduce cost and extend service life for air cost and extend service life for air and gas heater which increase the and gas heater which increase the existing of elementexisting of element
The material composition of The material composition of enamel-enamel-
bull The enamel layer is basically The enamel layer is basically composed by a borosilicate glass plus composed by a borosilicate glass plus cobalt fluorine sodium potassium cobalt fluorine sodium potassium quartz titanium borax helliphellipquartz titanium borax helliphellip
The benefits of enamel The benefits of enamel coating include-coating include-
bull 1-greater resistance to the attack of 1-greater resistance to the attack of acidsacids
bull 2-abrasive and wear resistance2-abrasive and wear resistance
bull 3-high mechanical and thermal shock 3-high mechanical and thermal shock resistanceresistance
bull 4-high resistance to erosion by fly ash4-high resistance to erosion by fly ash
bull 5-smooth and vitreous surface reduces 5-smooth and vitreous surface reduces adhesion of solidsadhesion of solids
The EndThe End
bullGood luckGood luck
Chemical cleaning-Chemical cleaning-
bull The purpose of chemical cleaning The purpose of chemical cleaning is to remove any internal deposits is to remove any internal deposits within the boiler and therefore within the boiler and therefore reduce the possibility of down reduce the possibility of down time due to tube failures Periodic time due to tube failures Periodic chemical cleaning should become chemical cleaning should become a part of a preventive a part of a preventive maintenance program maintenance program
Methods of determining Methods of determining when chemical cleaning is when chemical cleaning is necessary-necessary-bull 1Tube failure-1Tube failure-an analysis of the cause an analysis of the cause
for the tube failure could indicate the for the tube failure could indicate the need for chemical cleaning This is a need for chemical cleaning This is a highly undesirable method of highly undesirable method of determinationdetermination
bull 2Periodic tube sample analysis-2Periodic tube sample analysis-the the analysis could indicate the need for analysis could indicate the need for chemical cleaning prior to tube failureschemical cleaning prior to tube failures
bull 3Chordal thermocouples-3Chordal thermocouples- the increase the increase in external surface metal temperature in external surface metal temperature during operation could be used to gauge during operation could be used to gauge the build-up of internal depositionthe build-up of internal deposition
Energy loss-Energy loss-
bull Loss in external depositsLoss in external deposits
bull Loss in internal depositsLoss in internal deposits
1Remove externaldepositsby sootblowing
2avoid internal deposits by chemical cleaning (by acidcleaning)
Corrosion due to Corrosion due to combustion product-combustion product-bull 1- High temperature corrosion in superheaters
andbull Reheaters-bull ndash promoted by sodium and vanadium
compoundsbull ndash sensitive if metal temp above 600degCbull 2- Medium temp Corrosion in evaporatorsbull ndash fixed through combustion system adjustmentbull 3- Low temp Corrosion in cold areasbull ndash promoted by sulfur which turns into sulfuric
acidbull below dew point keep temperature above
150degC
Basic principles for design Basic principles for design material-material-
bull 1-Carbon steel1-Carbon steelbull 2-Low alloy steel (Crlt25)2-Low alloy steel (Crlt25)bull 3-Medium alloy steel (Crgt25)3-Medium alloy steel (Crgt25)bull 4-High alloy steel (Crgt9)4-High alloy steel (Crgt9)bull 5-Stainless steel (Crgt11)5-Stainless steel (Crgt11)bull Note-Note- increase Ni improve low increase Ni improve low
temperature resistancetemperature resistancebull Increase Cr improve high Increase Cr improve high
temperature resistancetemperature resistance
Metals of steam boilers-Metals of steam boilers-
bull The main materials for boilers are carbon The main materials for boilers are carbon steels and alloy steelssteels and alloy steels
bull 1-carbon steel-1-carbon steel-steels are used for making steels are used for making steam boiler elements which operate under steam boiler elements which operate under no-creep conditions at temperatures not no-creep conditions at temperatures not higher than 450 higher than 450 degC
bull 2-alloy steel- used for making boiler elements for operation under creep condition like superheater elements
bull Note-the principle alloying elements in steels are Mo Cr Si and Al Molybdenum increase the long term strength and creep strength Chromium Silicon and Aluminum increase scale resistance
An application for boiler An application for boiler material and design material and design temperature-temperature-Material (ASTM)Material (ASTM) Design Design
temperaturetemperature
A 209 GR P1A 209 GR P1 16 to 412 16 to 412 degC
A 335 GR P11A 335 GR P11 496 to 538 496 to 538 degC
A 335 GR P12A 335 GR P12 496 to 538 496 to 538 degC
A 335 GR p22A 335 GR p22 539 to 593 539 to 593 degC
Tube failure Tube failure mechanisms-mechanisms-bull 1-Short term over heating failure-1-Short term over heating failure-
bull The cause of short term over heat is a rapid The cause of short term over heat is a rapid elevation of temperature of the tube metal elevation of temperature of the tube metal caused by restriction of the water steam caused by restriction of the water steam mixture to the tube and resulting in a wide mixture to the tube and resulting in a wide mouth rupture The edges of the rupture are mouth rupture The edges of the rupture are thin and sharp in the super heater A short term thin and sharp in the super heater A short term over heat could result from a blockage of steam over heat could result from a blockage of steam flowflow
Short time overheating failure
Failures due to scale and Failures due to scale and long term creep failure-long term creep failure-
bull The cause of this type of failure is build-up of The cause of this type of failure is build-up of internal scale that leads to gradual increase in internal scale that leads to gradual increase in temperature of the tube metal The tube may temperature of the tube metal The tube may appear swollen with blisters or bulges The out appear swollen with blisters or bulges The out side surface may have an elephant hide side surface may have an elephant hide appearance Rupture are a thin opening a long appearance Rupture are a thin opening a long the longitudinal axis of the tube The edges of the longitudinal axis of the tube The edges of the failure do not generally experience thinning the failure do not generally experience thinning
Long time overheating failure
Ash corrosion -Ash corrosion -
bull Ash corrosion result in a thinning of Ash corrosion result in a thinning of super heater and reheater tubing super heater and reheater tubing External wastage of the metal occurs External wastage of the metal occurs where ash deposits accumulate When where ash deposits accumulate When ash deposits on the tube and ash deposits on the tube and experiences high temperatures It experiences high temperatures It becomes semi-molten and corrodes becomes semi-molten and corrodes most alloy steels that might be used in most alloy steels that might be used in super heater constructionsuper heater construction
Corrosion by molten ashCorrosion by molten ash
Oxygen pitting Oxygen pitting (Economizer)-(Economizer)-bull In-service oxygen pitting appears as random In-service oxygen pitting appears as random
Round bottomed pits on the water side of Round bottomed pits on the water side of tubes in the economizer If there is no tubes in the economizer If there is no economizer similar pitting may be present at economizer similar pitting may be present at or above normal water level in the steam or above normal water level in the steam drum Proper mechanical deaeration of feed drum Proper mechanical deaeration of feed water is absolutely essential for protection of water is absolutely essential for protection of the pre-boiler equipment ( feed water heater the pre-boiler equipment ( feed water heater piping) and the economizer The addition of piping) and the economizer The addition of an oxygen scavenger such as hydrazine to an oxygen scavenger such as hydrazine to the deaerator storage tank will permit the deaerator storage tank will permit removal of minute quantities of dissolved removal of minute quantities of dissolved oxygenoxygen
Oxygen pitting Oxygen pitting (superheater)-(superheater)-
bull Out-of-service oxygen pitting is Out-of-service oxygen pitting is usually found in the bottom loops usually found in the bottom loops of the superheater and is result of of the superheater and is result of the exposure of water or the exposure of water or condensate that forms in the bends condensate that forms in the bends after shutdown in contact with air after shutdown in contact with air The distress is seen as pitting and The distress is seen as pitting and corrosion of the wetted internal corrosion of the wetted internal surfacessurfaces
Carry over-Carry over-
bull The cause for carry over is an The cause for carry over is an incomplete separation of the steam incomplete separation of the steam from the steamwater mixture in the from the steamwater mixture in the boiler Possible causes of carry over boiler Possible causes of carry over are high water level high total are high water level high total dissolved solids concentration in the dissolved solids concentration in the boiler water excessive alkalinity and boiler water excessive alkalinity and the presence of oil andor organics the presence of oil andor organics The result of carry over is a build up of The result of carry over is a build up of contaminates on the inner surface of contaminates on the inner surface of the super heater tubesthe super heater tubes
Steam blanketing-Steam blanketing-
bull The cause for steam blanketing is an The cause for steam blanketing is an improper mass flow in the boiler tube improper mass flow in the boiler tube in relation to the heat input and in relation to the heat input and pressure Causing localized thinning in pressure Causing localized thinning in the tube This type of attack is the tube This type of attack is sometimes accompanied by a gross sometimes accompanied by a gross accumulation of corrosive product accumulation of corrosive product Steam blanketing is also referred to as Steam blanketing is also referred to as DNB (departure from nucleate boiling)DNB (departure from nucleate boiling)
Thinning of tube due to Thinning of tube due to steam blanketing-steam blanketing-
Hydrogen attack or Hydrogen attack or damage-damage-
bull This type of failure is found in high pressure units This type of failure is found in high pressure units A situation occurs when excessive deposits are A situation occurs when excessive deposits are present on the tube water side surface that permit present on the tube water side surface that permit boiler chemicals to concentrate under the deposit boiler chemicals to concentrate under the deposit and corrode the metal Hydrogen is formed which and corrode the metal Hydrogen is formed which permeates the metal structure and reacts with the permeates the metal structure and reacts with the carbon of the metal to form methane The methane carbon of the metal to form methane The methane molecule which is much larger than the carbon molecule which is much larger than the carbon atom Exerts pressure and causes the metal to atom Exerts pressure and causes the metal to rupture along the grain boundaries Ruptures are rupture along the grain boundaries Ruptures are violent sudden and can be disastrousviolent sudden and can be disastrous
bull 4H+C=CH44H+C=CH4
The effect of hydrogen The effect of hydrogen attack in tubes-attack in tubes-
Cold end corrosion-Cold end corrosion-
bull Cold-end corrosion will occur Cold-end corrosion will occur wherever the temperature of metal wherever the temperature of metal drops below the sulfuric acid dew drops below the sulfuric acid dew point of the flue gas It occurs in point of the flue gas It occurs in economizer air preheater economizer air preheater induced draft fan and stackinduced draft fan and stack
Soot blowers erosion-Soot blowers erosion-
bull A misdirected blower allows a high A misdirected blower allows a high velocity jet of steam or air carrying velocity jet of steam or air carrying condensed water droplets to condensed water droplets to impinge directed upon tube impinge directed upon tube surfaces rather than to be directed surfaces rather than to be directed between tubes Physical abrasion between tubes Physical abrasion and acceleration oxidation cause and acceleration oxidation cause metal loss Erosive thinning often metal loss Erosive thinning often leads to tube ruptureleads to tube rupture
Foaming-Foaming-
bull It is a condition in which It is a condition in which concentration of soluble salts create concentration of soluble salts create frothy bubbles in the steam space of frothy bubbles in the steam space of the boiler Foaming can form slugs the boiler Foaming can form slugs of water that can carried over into of water that can carried over into the steam systemthe steam system
How to remove a tube How to remove a tube sample for inspectionsample for inspection
When removing a tube When removing a tube sample-sample-
bull 1-the tube section should be dry saw 1-the tube section should be dry saw cut to prevent any slag andor cutting cut to prevent any slag andor cutting oil from contaminating the internal oil from contaminating the internal depositdeposit
bull 2-the sample should be cut 2-the sample should be cut approximately 8-10 inches above and approximately 8-10 inches above and below the affected areabelow the affected area
bull 3-the exact location should be 3-the exact location should be documented as follows-documented as follows-
bull A-tubes should be numbered and A-tubes should be numbered and counted from east to west and north counted from east to west and north to southto south
bull B-the wall (front rear right hand B-the wall (front rear right hand side left hand side) and elevation side left hand side) and elevation should be noted and marked on the should be noted and marked on the tubetube
bull C-an arrow should be marked to C-an arrow should be marked to indicate which end of sample is upindicate which end of sample is up
bull D-on a universal pressure unit the D-on a universal pressure unit the sample should be identified as sample should be identified as removed from the first second or removed from the first second or third passthird pass
Troubles associated to drums-
bull1048698 Loss of level gauges
bull1048698 water level controllers out of service
bull1048698 corrosion
bull1048698 moisture carry-over in the steam
bull1048698 safety valves leaking
bull1048698 leaks of roll-expanded evaporator
bullTubes
bull1048698 plugging of evaporator tubes
Trouble associated to air Trouble associated to air heaters-heaters-
bull1048698 Leakages due to damaged axial or circumferential seals
bull1048698 Cold end baskets damaged by acid corrosion
bull1048698 Poor sootblowing
bull1048698 Standby pneumatic or DC motor not working or absent
New application in air New application in air heater-heater-
The modification-The modification-
bull We used to manufacture the air We used to manufacture the air heater basket material from heater basket material from carbon steel or Corten steel now carbon steel or Corten steel now they add a new material called they add a new material called enamel to improve quality reduce enamel to improve quality reduce cost and extend service life for air cost and extend service life for air and gas heater which increase the and gas heater which increase the existing of elementexisting of element
The material composition of The material composition of enamel-enamel-
bull The enamel layer is basically The enamel layer is basically composed by a borosilicate glass plus composed by a borosilicate glass plus cobalt fluorine sodium potassium cobalt fluorine sodium potassium quartz titanium borax helliphellipquartz titanium borax helliphellip
The benefits of enamel The benefits of enamel coating include-coating include-
bull 1-greater resistance to the attack of 1-greater resistance to the attack of acidsacids
bull 2-abrasive and wear resistance2-abrasive and wear resistance
bull 3-high mechanical and thermal shock 3-high mechanical and thermal shock resistanceresistance
bull 4-high resistance to erosion by fly ash4-high resistance to erosion by fly ash
bull 5-smooth and vitreous surface reduces 5-smooth and vitreous surface reduces adhesion of solidsadhesion of solids
The EndThe End
bullGood luckGood luck
Methods of determining Methods of determining when chemical cleaning is when chemical cleaning is necessary-necessary-bull 1Tube failure-1Tube failure-an analysis of the cause an analysis of the cause
for the tube failure could indicate the for the tube failure could indicate the need for chemical cleaning This is a need for chemical cleaning This is a highly undesirable method of highly undesirable method of determinationdetermination
bull 2Periodic tube sample analysis-2Periodic tube sample analysis-the the analysis could indicate the need for analysis could indicate the need for chemical cleaning prior to tube failureschemical cleaning prior to tube failures
bull 3Chordal thermocouples-3Chordal thermocouples- the increase the increase in external surface metal temperature in external surface metal temperature during operation could be used to gauge during operation could be used to gauge the build-up of internal depositionthe build-up of internal deposition
Energy loss-Energy loss-
bull Loss in external depositsLoss in external deposits
bull Loss in internal depositsLoss in internal deposits
1Remove externaldepositsby sootblowing
2avoid internal deposits by chemical cleaning (by acidcleaning)
Corrosion due to Corrosion due to combustion product-combustion product-bull 1- High temperature corrosion in superheaters
andbull Reheaters-bull ndash promoted by sodium and vanadium
compoundsbull ndash sensitive if metal temp above 600degCbull 2- Medium temp Corrosion in evaporatorsbull ndash fixed through combustion system adjustmentbull 3- Low temp Corrosion in cold areasbull ndash promoted by sulfur which turns into sulfuric
acidbull below dew point keep temperature above
150degC
Basic principles for design Basic principles for design material-material-
bull 1-Carbon steel1-Carbon steelbull 2-Low alloy steel (Crlt25)2-Low alloy steel (Crlt25)bull 3-Medium alloy steel (Crgt25)3-Medium alloy steel (Crgt25)bull 4-High alloy steel (Crgt9)4-High alloy steel (Crgt9)bull 5-Stainless steel (Crgt11)5-Stainless steel (Crgt11)bull Note-Note- increase Ni improve low increase Ni improve low
temperature resistancetemperature resistancebull Increase Cr improve high Increase Cr improve high
temperature resistancetemperature resistance
Metals of steam boilers-Metals of steam boilers-
bull The main materials for boilers are carbon The main materials for boilers are carbon steels and alloy steelssteels and alloy steels
bull 1-carbon steel-1-carbon steel-steels are used for making steels are used for making steam boiler elements which operate under steam boiler elements which operate under no-creep conditions at temperatures not no-creep conditions at temperatures not higher than 450 higher than 450 degC
bull 2-alloy steel- used for making boiler elements for operation under creep condition like superheater elements
bull Note-the principle alloying elements in steels are Mo Cr Si and Al Molybdenum increase the long term strength and creep strength Chromium Silicon and Aluminum increase scale resistance
An application for boiler An application for boiler material and design material and design temperature-temperature-Material (ASTM)Material (ASTM) Design Design
temperaturetemperature
A 209 GR P1A 209 GR P1 16 to 412 16 to 412 degC
A 335 GR P11A 335 GR P11 496 to 538 496 to 538 degC
A 335 GR P12A 335 GR P12 496 to 538 496 to 538 degC
A 335 GR p22A 335 GR p22 539 to 593 539 to 593 degC
Tube failure Tube failure mechanisms-mechanisms-bull 1-Short term over heating failure-1-Short term over heating failure-
bull The cause of short term over heat is a rapid The cause of short term over heat is a rapid elevation of temperature of the tube metal elevation of temperature of the tube metal caused by restriction of the water steam caused by restriction of the water steam mixture to the tube and resulting in a wide mixture to the tube and resulting in a wide mouth rupture The edges of the rupture are mouth rupture The edges of the rupture are thin and sharp in the super heater A short term thin and sharp in the super heater A short term over heat could result from a blockage of steam over heat could result from a blockage of steam flowflow
Short time overheating failure
Failures due to scale and Failures due to scale and long term creep failure-long term creep failure-
bull The cause of this type of failure is build-up of The cause of this type of failure is build-up of internal scale that leads to gradual increase in internal scale that leads to gradual increase in temperature of the tube metal The tube may temperature of the tube metal The tube may appear swollen with blisters or bulges The out appear swollen with blisters or bulges The out side surface may have an elephant hide side surface may have an elephant hide appearance Rupture are a thin opening a long appearance Rupture are a thin opening a long the longitudinal axis of the tube The edges of the longitudinal axis of the tube The edges of the failure do not generally experience thinning the failure do not generally experience thinning
Long time overheating failure
Ash corrosion -Ash corrosion -
bull Ash corrosion result in a thinning of Ash corrosion result in a thinning of super heater and reheater tubing super heater and reheater tubing External wastage of the metal occurs External wastage of the metal occurs where ash deposits accumulate When where ash deposits accumulate When ash deposits on the tube and ash deposits on the tube and experiences high temperatures It experiences high temperatures It becomes semi-molten and corrodes becomes semi-molten and corrodes most alloy steels that might be used in most alloy steels that might be used in super heater constructionsuper heater construction
Corrosion by molten ashCorrosion by molten ash
Oxygen pitting Oxygen pitting (Economizer)-(Economizer)-bull In-service oxygen pitting appears as random In-service oxygen pitting appears as random
Round bottomed pits on the water side of Round bottomed pits on the water side of tubes in the economizer If there is no tubes in the economizer If there is no economizer similar pitting may be present at economizer similar pitting may be present at or above normal water level in the steam or above normal water level in the steam drum Proper mechanical deaeration of feed drum Proper mechanical deaeration of feed water is absolutely essential for protection of water is absolutely essential for protection of the pre-boiler equipment ( feed water heater the pre-boiler equipment ( feed water heater piping) and the economizer The addition of piping) and the economizer The addition of an oxygen scavenger such as hydrazine to an oxygen scavenger such as hydrazine to the deaerator storage tank will permit the deaerator storage tank will permit removal of minute quantities of dissolved removal of minute quantities of dissolved oxygenoxygen
Oxygen pitting Oxygen pitting (superheater)-(superheater)-
bull Out-of-service oxygen pitting is Out-of-service oxygen pitting is usually found in the bottom loops usually found in the bottom loops of the superheater and is result of of the superheater and is result of the exposure of water or the exposure of water or condensate that forms in the bends condensate that forms in the bends after shutdown in contact with air after shutdown in contact with air The distress is seen as pitting and The distress is seen as pitting and corrosion of the wetted internal corrosion of the wetted internal surfacessurfaces
Carry over-Carry over-
bull The cause for carry over is an The cause for carry over is an incomplete separation of the steam incomplete separation of the steam from the steamwater mixture in the from the steamwater mixture in the boiler Possible causes of carry over boiler Possible causes of carry over are high water level high total are high water level high total dissolved solids concentration in the dissolved solids concentration in the boiler water excessive alkalinity and boiler water excessive alkalinity and the presence of oil andor organics the presence of oil andor organics The result of carry over is a build up of The result of carry over is a build up of contaminates on the inner surface of contaminates on the inner surface of the super heater tubesthe super heater tubes
Steam blanketing-Steam blanketing-
bull The cause for steam blanketing is an The cause for steam blanketing is an improper mass flow in the boiler tube improper mass flow in the boiler tube in relation to the heat input and in relation to the heat input and pressure Causing localized thinning in pressure Causing localized thinning in the tube This type of attack is the tube This type of attack is sometimes accompanied by a gross sometimes accompanied by a gross accumulation of corrosive product accumulation of corrosive product Steam blanketing is also referred to as Steam blanketing is also referred to as DNB (departure from nucleate boiling)DNB (departure from nucleate boiling)
Thinning of tube due to Thinning of tube due to steam blanketing-steam blanketing-
Hydrogen attack or Hydrogen attack or damage-damage-
bull This type of failure is found in high pressure units This type of failure is found in high pressure units A situation occurs when excessive deposits are A situation occurs when excessive deposits are present on the tube water side surface that permit present on the tube water side surface that permit boiler chemicals to concentrate under the deposit boiler chemicals to concentrate under the deposit and corrode the metal Hydrogen is formed which and corrode the metal Hydrogen is formed which permeates the metal structure and reacts with the permeates the metal structure and reacts with the carbon of the metal to form methane The methane carbon of the metal to form methane The methane molecule which is much larger than the carbon molecule which is much larger than the carbon atom Exerts pressure and causes the metal to atom Exerts pressure and causes the metal to rupture along the grain boundaries Ruptures are rupture along the grain boundaries Ruptures are violent sudden and can be disastrousviolent sudden and can be disastrous
bull 4H+C=CH44H+C=CH4
The effect of hydrogen The effect of hydrogen attack in tubes-attack in tubes-
Cold end corrosion-Cold end corrosion-
bull Cold-end corrosion will occur Cold-end corrosion will occur wherever the temperature of metal wherever the temperature of metal drops below the sulfuric acid dew drops below the sulfuric acid dew point of the flue gas It occurs in point of the flue gas It occurs in economizer air preheater economizer air preheater induced draft fan and stackinduced draft fan and stack
Soot blowers erosion-Soot blowers erosion-
bull A misdirected blower allows a high A misdirected blower allows a high velocity jet of steam or air carrying velocity jet of steam or air carrying condensed water droplets to condensed water droplets to impinge directed upon tube impinge directed upon tube surfaces rather than to be directed surfaces rather than to be directed between tubes Physical abrasion between tubes Physical abrasion and acceleration oxidation cause and acceleration oxidation cause metal loss Erosive thinning often metal loss Erosive thinning often leads to tube ruptureleads to tube rupture
Foaming-Foaming-
bull It is a condition in which It is a condition in which concentration of soluble salts create concentration of soluble salts create frothy bubbles in the steam space of frothy bubbles in the steam space of the boiler Foaming can form slugs the boiler Foaming can form slugs of water that can carried over into of water that can carried over into the steam systemthe steam system
How to remove a tube How to remove a tube sample for inspectionsample for inspection
When removing a tube When removing a tube sample-sample-
bull 1-the tube section should be dry saw 1-the tube section should be dry saw cut to prevent any slag andor cutting cut to prevent any slag andor cutting oil from contaminating the internal oil from contaminating the internal depositdeposit
bull 2-the sample should be cut 2-the sample should be cut approximately 8-10 inches above and approximately 8-10 inches above and below the affected areabelow the affected area
bull 3-the exact location should be 3-the exact location should be documented as follows-documented as follows-
bull A-tubes should be numbered and A-tubes should be numbered and counted from east to west and north counted from east to west and north to southto south
bull B-the wall (front rear right hand B-the wall (front rear right hand side left hand side) and elevation side left hand side) and elevation should be noted and marked on the should be noted and marked on the tubetube
bull C-an arrow should be marked to C-an arrow should be marked to indicate which end of sample is upindicate which end of sample is up
bull D-on a universal pressure unit the D-on a universal pressure unit the sample should be identified as sample should be identified as removed from the first second or removed from the first second or third passthird pass
Troubles associated to drums-
bull1048698 Loss of level gauges
bull1048698 water level controllers out of service
bull1048698 corrosion
bull1048698 moisture carry-over in the steam
bull1048698 safety valves leaking
bull1048698 leaks of roll-expanded evaporator
bullTubes
bull1048698 plugging of evaporator tubes
Trouble associated to air Trouble associated to air heaters-heaters-
bull1048698 Leakages due to damaged axial or circumferential seals
bull1048698 Cold end baskets damaged by acid corrosion
bull1048698 Poor sootblowing
bull1048698 Standby pneumatic or DC motor not working or absent
New application in air New application in air heater-heater-
The modification-The modification-
bull We used to manufacture the air We used to manufacture the air heater basket material from heater basket material from carbon steel or Corten steel now carbon steel or Corten steel now they add a new material called they add a new material called enamel to improve quality reduce enamel to improve quality reduce cost and extend service life for air cost and extend service life for air and gas heater which increase the and gas heater which increase the existing of elementexisting of element
The material composition of The material composition of enamel-enamel-
bull The enamel layer is basically The enamel layer is basically composed by a borosilicate glass plus composed by a borosilicate glass plus cobalt fluorine sodium potassium cobalt fluorine sodium potassium quartz titanium borax helliphellipquartz titanium borax helliphellip
The benefits of enamel The benefits of enamel coating include-coating include-
bull 1-greater resistance to the attack of 1-greater resistance to the attack of acidsacids
bull 2-abrasive and wear resistance2-abrasive and wear resistance
bull 3-high mechanical and thermal shock 3-high mechanical and thermal shock resistanceresistance
bull 4-high resistance to erosion by fly ash4-high resistance to erosion by fly ash
bull 5-smooth and vitreous surface reduces 5-smooth and vitreous surface reduces adhesion of solidsadhesion of solids
The EndThe End
bullGood luckGood luck
Energy loss-Energy loss-
bull Loss in external depositsLoss in external deposits
bull Loss in internal depositsLoss in internal deposits
1Remove externaldepositsby sootblowing
2avoid internal deposits by chemical cleaning (by acidcleaning)
Corrosion due to Corrosion due to combustion product-combustion product-bull 1- High temperature corrosion in superheaters
andbull Reheaters-bull ndash promoted by sodium and vanadium
compoundsbull ndash sensitive if metal temp above 600degCbull 2- Medium temp Corrosion in evaporatorsbull ndash fixed through combustion system adjustmentbull 3- Low temp Corrosion in cold areasbull ndash promoted by sulfur which turns into sulfuric
acidbull below dew point keep temperature above
150degC
Basic principles for design Basic principles for design material-material-
bull 1-Carbon steel1-Carbon steelbull 2-Low alloy steel (Crlt25)2-Low alloy steel (Crlt25)bull 3-Medium alloy steel (Crgt25)3-Medium alloy steel (Crgt25)bull 4-High alloy steel (Crgt9)4-High alloy steel (Crgt9)bull 5-Stainless steel (Crgt11)5-Stainless steel (Crgt11)bull Note-Note- increase Ni improve low increase Ni improve low
temperature resistancetemperature resistancebull Increase Cr improve high Increase Cr improve high
temperature resistancetemperature resistance
Metals of steam boilers-Metals of steam boilers-
bull The main materials for boilers are carbon The main materials for boilers are carbon steels and alloy steelssteels and alloy steels
bull 1-carbon steel-1-carbon steel-steels are used for making steels are used for making steam boiler elements which operate under steam boiler elements which operate under no-creep conditions at temperatures not no-creep conditions at temperatures not higher than 450 higher than 450 degC
bull 2-alloy steel- used for making boiler elements for operation under creep condition like superheater elements
bull Note-the principle alloying elements in steels are Mo Cr Si and Al Molybdenum increase the long term strength and creep strength Chromium Silicon and Aluminum increase scale resistance
An application for boiler An application for boiler material and design material and design temperature-temperature-Material (ASTM)Material (ASTM) Design Design
temperaturetemperature
A 209 GR P1A 209 GR P1 16 to 412 16 to 412 degC
A 335 GR P11A 335 GR P11 496 to 538 496 to 538 degC
A 335 GR P12A 335 GR P12 496 to 538 496 to 538 degC
A 335 GR p22A 335 GR p22 539 to 593 539 to 593 degC
Tube failure Tube failure mechanisms-mechanisms-bull 1-Short term over heating failure-1-Short term over heating failure-
bull The cause of short term over heat is a rapid The cause of short term over heat is a rapid elevation of temperature of the tube metal elevation of temperature of the tube metal caused by restriction of the water steam caused by restriction of the water steam mixture to the tube and resulting in a wide mixture to the tube and resulting in a wide mouth rupture The edges of the rupture are mouth rupture The edges of the rupture are thin and sharp in the super heater A short term thin and sharp in the super heater A short term over heat could result from a blockage of steam over heat could result from a blockage of steam flowflow
Short time overheating failure
Failures due to scale and Failures due to scale and long term creep failure-long term creep failure-
bull The cause of this type of failure is build-up of The cause of this type of failure is build-up of internal scale that leads to gradual increase in internal scale that leads to gradual increase in temperature of the tube metal The tube may temperature of the tube metal The tube may appear swollen with blisters or bulges The out appear swollen with blisters or bulges The out side surface may have an elephant hide side surface may have an elephant hide appearance Rupture are a thin opening a long appearance Rupture are a thin opening a long the longitudinal axis of the tube The edges of the longitudinal axis of the tube The edges of the failure do not generally experience thinning the failure do not generally experience thinning
Long time overheating failure
Ash corrosion -Ash corrosion -
bull Ash corrosion result in a thinning of Ash corrosion result in a thinning of super heater and reheater tubing super heater and reheater tubing External wastage of the metal occurs External wastage of the metal occurs where ash deposits accumulate When where ash deposits accumulate When ash deposits on the tube and ash deposits on the tube and experiences high temperatures It experiences high temperatures It becomes semi-molten and corrodes becomes semi-molten and corrodes most alloy steels that might be used in most alloy steels that might be used in super heater constructionsuper heater construction
Corrosion by molten ashCorrosion by molten ash
Oxygen pitting Oxygen pitting (Economizer)-(Economizer)-bull In-service oxygen pitting appears as random In-service oxygen pitting appears as random
Round bottomed pits on the water side of Round bottomed pits on the water side of tubes in the economizer If there is no tubes in the economizer If there is no economizer similar pitting may be present at economizer similar pitting may be present at or above normal water level in the steam or above normal water level in the steam drum Proper mechanical deaeration of feed drum Proper mechanical deaeration of feed water is absolutely essential for protection of water is absolutely essential for protection of the pre-boiler equipment ( feed water heater the pre-boiler equipment ( feed water heater piping) and the economizer The addition of piping) and the economizer The addition of an oxygen scavenger such as hydrazine to an oxygen scavenger such as hydrazine to the deaerator storage tank will permit the deaerator storage tank will permit removal of minute quantities of dissolved removal of minute quantities of dissolved oxygenoxygen
Oxygen pitting Oxygen pitting (superheater)-(superheater)-
bull Out-of-service oxygen pitting is Out-of-service oxygen pitting is usually found in the bottom loops usually found in the bottom loops of the superheater and is result of of the superheater and is result of the exposure of water or the exposure of water or condensate that forms in the bends condensate that forms in the bends after shutdown in contact with air after shutdown in contact with air The distress is seen as pitting and The distress is seen as pitting and corrosion of the wetted internal corrosion of the wetted internal surfacessurfaces
Carry over-Carry over-
bull The cause for carry over is an The cause for carry over is an incomplete separation of the steam incomplete separation of the steam from the steamwater mixture in the from the steamwater mixture in the boiler Possible causes of carry over boiler Possible causes of carry over are high water level high total are high water level high total dissolved solids concentration in the dissolved solids concentration in the boiler water excessive alkalinity and boiler water excessive alkalinity and the presence of oil andor organics the presence of oil andor organics The result of carry over is a build up of The result of carry over is a build up of contaminates on the inner surface of contaminates on the inner surface of the super heater tubesthe super heater tubes
Steam blanketing-Steam blanketing-
bull The cause for steam blanketing is an The cause for steam blanketing is an improper mass flow in the boiler tube improper mass flow in the boiler tube in relation to the heat input and in relation to the heat input and pressure Causing localized thinning in pressure Causing localized thinning in the tube This type of attack is the tube This type of attack is sometimes accompanied by a gross sometimes accompanied by a gross accumulation of corrosive product accumulation of corrosive product Steam blanketing is also referred to as Steam blanketing is also referred to as DNB (departure from nucleate boiling)DNB (departure from nucleate boiling)
Thinning of tube due to Thinning of tube due to steam blanketing-steam blanketing-
Hydrogen attack or Hydrogen attack or damage-damage-
bull This type of failure is found in high pressure units This type of failure is found in high pressure units A situation occurs when excessive deposits are A situation occurs when excessive deposits are present on the tube water side surface that permit present on the tube water side surface that permit boiler chemicals to concentrate under the deposit boiler chemicals to concentrate under the deposit and corrode the metal Hydrogen is formed which and corrode the metal Hydrogen is formed which permeates the metal structure and reacts with the permeates the metal structure and reacts with the carbon of the metal to form methane The methane carbon of the metal to form methane The methane molecule which is much larger than the carbon molecule which is much larger than the carbon atom Exerts pressure and causes the metal to atom Exerts pressure and causes the metal to rupture along the grain boundaries Ruptures are rupture along the grain boundaries Ruptures are violent sudden and can be disastrousviolent sudden and can be disastrous
bull 4H+C=CH44H+C=CH4
The effect of hydrogen The effect of hydrogen attack in tubes-attack in tubes-
Cold end corrosion-Cold end corrosion-
bull Cold-end corrosion will occur Cold-end corrosion will occur wherever the temperature of metal wherever the temperature of metal drops below the sulfuric acid dew drops below the sulfuric acid dew point of the flue gas It occurs in point of the flue gas It occurs in economizer air preheater economizer air preheater induced draft fan and stackinduced draft fan and stack
Soot blowers erosion-Soot blowers erosion-
bull A misdirected blower allows a high A misdirected blower allows a high velocity jet of steam or air carrying velocity jet of steam or air carrying condensed water droplets to condensed water droplets to impinge directed upon tube impinge directed upon tube surfaces rather than to be directed surfaces rather than to be directed between tubes Physical abrasion between tubes Physical abrasion and acceleration oxidation cause and acceleration oxidation cause metal loss Erosive thinning often metal loss Erosive thinning often leads to tube ruptureleads to tube rupture
Foaming-Foaming-
bull It is a condition in which It is a condition in which concentration of soluble salts create concentration of soluble salts create frothy bubbles in the steam space of frothy bubbles in the steam space of the boiler Foaming can form slugs the boiler Foaming can form slugs of water that can carried over into of water that can carried over into the steam systemthe steam system
How to remove a tube How to remove a tube sample for inspectionsample for inspection
When removing a tube When removing a tube sample-sample-
bull 1-the tube section should be dry saw 1-the tube section should be dry saw cut to prevent any slag andor cutting cut to prevent any slag andor cutting oil from contaminating the internal oil from contaminating the internal depositdeposit
bull 2-the sample should be cut 2-the sample should be cut approximately 8-10 inches above and approximately 8-10 inches above and below the affected areabelow the affected area
bull 3-the exact location should be 3-the exact location should be documented as follows-documented as follows-
bull A-tubes should be numbered and A-tubes should be numbered and counted from east to west and north counted from east to west and north to southto south
bull B-the wall (front rear right hand B-the wall (front rear right hand side left hand side) and elevation side left hand side) and elevation should be noted and marked on the should be noted and marked on the tubetube
bull C-an arrow should be marked to C-an arrow should be marked to indicate which end of sample is upindicate which end of sample is up
bull D-on a universal pressure unit the D-on a universal pressure unit the sample should be identified as sample should be identified as removed from the first second or removed from the first second or third passthird pass
Troubles associated to drums-
bull1048698 Loss of level gauges
bull1048698 water level controllers out of service
bull1048698 corrosion
bull1048698 moisture carry-over in the steam
bull1048698 safety valves leaking
bull1048698 leaks of roll-expanded evaporator
bullTubes
bull1048698 plugging of evaporator tubes
Trouble associated to air Trouble associated to air heaters-heaters-
bull1048698 Leakages due to damaged axial or circumferential seals
bull1048698 Cold end baskets damaged by acid corrosion
bull1048698 Poor sootblowing
bull1048698 Standby pneumatic or DC motor not working or absent
New application in air New application in air heater-heater-
The modification-The modification-
bull We used to manufacture the air We used to manufacture the air heater basket material from heater basket material from carbon steel or Corten steel now carbon steel or Corten steel now they add a new material called they add a new material called enamel to improve quality reduce enamel to improve quality reduce cost and extend service life for air cost and extend service life for air and gas heater which increase the and gas heater which increase the existing of elementexisting of element
The material composition of The material composition of enamel-enamel-
bull The enamel layer is basically The enamel layer is basically composed by a borosilicate glass plus composed by a borosilicate glass plus cobalt fluorine sodium potassium cobalt fluorine sodium potassium quartz titanium borax helliphellipquartz titanium borax helliphellip
The benefits of enamel The benefits of enamel coating include-coating include-
bull 1-greater resistance to the attack of 1-greater resistance to the attack of acidsacids
bull 2-abrasive and wear resistance2-abrasive and wear resistance
bull 3-high mechanical and thermal shock 3-high mechanical and thermal shock resistanceresistance
bull 4-high resistance to erosion by fly ash4-high resistance to erosion by fly ash
bull 5-smooth and vitreous surface reduces 5-smooth and vitreous surface reduces adhesion of solidsadhesion of solids
The EndThe End
bullGood luckGood luck
1Remove externaldepositsby sootblowing
2avoid internal deposits by chemical cleaning (by acidcleaning)
Corrosion due to Corrosion due to combustion product-combustion product-bull 1- High temperature corrosion in superheaters
andbull Reheaters-bull ndash promoted by sodium and vanadium
compoundsbull ndash sensitive if metal temp above 600degCbull 2- Medium temp Corrosion in evaporatorsbull ndash fixed through combustion system adjustmentbull 3- Low temp Corrosion in cold areasbull ndash promoted by sulfur which turns into sulfuric
acidbull below dew point keep temperature above
150degC
Basic principles for design Basic principles for design material-material-
bull 1-Carbon steel1-Carbon steelbull 2-Low alloy steel (Crlt25)2-Low alloy steel (Crlt25)bull 3-Medium alloy steel (Crgt25)3-Medium alloy steel (Crgt25)bull 4-High alloy steel (Crgt9)4-High alloy steel (Crgt9)bull 5-Stainless steel (Crgt11)5-Stainless steel (Crgt11)bull Note-Note- increase Ni improve low increase Ni improve low
temperature resistancetemperature resistancebull Increase Cr improve high Increase Cr improve high
temperature resistancetemperature resistance
Metals of steam boilers-Metals of steam boilers-
bull The main materials for boilers are carbon The main materials for boilers are carbon steels and alloy steelssteels and alloy steels
bull 1-carbon steel-1-carbon steel-steels are used for making steels are used for making steam boiler elements which operate under steam boiler elements which operate under no-creep conditions at temperatures not no-creep conditions at temperatures not higher than 450 higher than 450 degC
bull 2-alloy steel- used for making boiler elements for operation under creep condition like superheater elements
bull Note-the principle alloying elements in steels are Mo Cr Si and Al Molybdenum increase the long term strength and creep strength Chromium Silicon and Aluminum increase scale resistance
An application for boiler An application for boiler material and design material and design temperature-temperature-Material (ASTM)Material (ASTM) Design Design
temperaturetemperature
A 209 GR P1A 209 GR P1 16 to 412 16 to 412 degC
A 335 GR P11A 335 GR P11 496 to 538 496 to 538 degC
A 335 GR P12A 335 GR P12 496 to 538 496 to 538 degC
A 335 GR p22A 335 GR p22 539 to 593 539 to 593 degC
Tube failure Tube failure mechanisms-mechanisms-bull 1-Short term over heating failure-1-Short term over heating failure-
bull The cause of short term over heat is a rapid The cause of short term over heat is a rapid elevation of temperature of the tube metal elevation of temperature of the tube metal caused by restriction of the water steam caused by restriction of the water steam mixture to the tube and resulting in a wide mixture to the tube and resulting in a wide mouth rupture The edges of the rupture are mouth rupture The edges of the rupture are thin and sharp in the super heater A short term thin and sharp in the super heater A short term over heat could result from a blockage of steam over heat could result from a blockage of steam flowflow
Short time overheating failure
Failures due to scale and Failures due to scale and long term creep failure-long term creep failure-
bull The cause of this type of failure is build-up of The cause of this type of failure is build-up of internal scale that leads to gradual increase in internal scale that leads to gradual increase in temperature of the tube metal The tube may temperature of the tube metal The tube may appear swollen with blisters or bulges The out appear swollen with blisters or bulges The out side surface may have an elephant hide side surface may have an elephant hide appearance Rupture are a thin opening a long appearance Rupture are a thin opening a long the longitudinal axis of the tube The edges of the longitudinal axis of the tube The edges of the failure do not generally experience thinning the failure do not generally experience thinning
Long time overheating failure
Ash corrosion -Ash corrosion -
bull Ash corrosion result in a thinning of Ash corrosion result in a thinning of super heater and reheater tubing super heater and reheater tubing External wastage of the metal occurs External wastage of the metal occurs where ash deposits accumulate When where ash deposits accumulate When ash deposits on the tube and ash deposits on the tube and experiences high temperatures It experiences high temperatures It becomes semi-molten and corrodes becomes semi-molten and corrodes most alloy steels that might be used in most alloy steels that might be used in super heater constructionsuper heater construction
Corrosion by molten ashCorrosion by molten ash
Oxygen pitting Oxygen pitting (Economizer)-(Economizer)-bull In-service oxygen pitting appears as random In-service oxygen pitting appears as random
Round bottomed pits on the water side of Round bottomed pits on the water side of tubes in the economizer If there is no tubes in the economizer If there is no economizer similar pitting may be present at economizer similar pitting may be present at or above normal water level in the steam or above normal water level in the steam drum Proper mechanical deaeration of feed drum Proper mechanical deaeration of feed water is absolutely essential for protection of water is absolutely essential for protection of the pre-boiler equipment ( feed water heater the pre-boiler equipment ( feed water heater piping) and the economizer The addition of piping) and the economizer The addition of an oxygen scavenger such as hydrazine to an oxygen scavenger such as hydrazine to the deaerator storage tank will permit the deaerator storage tank will permit removal of minute quantities of dissolved removal of minute quantities of dissolved oxygenoxygen
Oxygen pitting Oxygen pitting (superheater)-(superheater)-
bull Out-of-service oxygen pitting is Out-of-service oxygen pitting is usually found in the bottom loops usually found in the bottom loops of the superheater and is result of of the superheater and is result of the exposure of water or the exposure of water or condensate that forms in the bends condensate that forms in the bends after shutdown in contact with air after shutdown in contact with air The distress is seen as pitting and The distress is seen as pitting and corrosion of the wetted internal corrosion of the wetted internal surfacessurfaces
Carry over-Carry over-
bull The cause for carry over is an The cause for carry over is an incomplete separation of the steam incomplete separation of the steam from the steamwater mixture in the from the steamwater mixture in the boiler Possible causes of carry over boiler Possible causes of carry over are high water level high total are high water level high total dissolved solids concentration in the dissolved solids concentration in the boiler water excessive alkalinity and boiler water excessive alkalinity and the presence of oil andor organics the presence of oil andor organics The result of carry over is a build up of The result of carry over is a build up of contaminates on the inner surface of contaminates on the inner surface of the super heater tubesthe super heater tubes
Steam blanketing-Steam blanketing-
bull The cause for steam blanketing is an The cause for steam blanketing is an improper mass flow in the boiler tube improper mass flow in the boiler tube in relation to the heat input and in relation to the heat input and pressure Causing localized thinning in pressure Causing localized thinning in the tube This type of attack is the tube This type of attack is sometimes accompanied by a gross sometimes accompanied by a gross accumulation of corrosive product accumulation of corrosive product Steam blanketing is also referred to as Steam blanketing is also referred to as DNB (departure from nucleate boiling)DNB (departure from nucleate boiling)
Thinning of tube due to Thinning of tube due to steam blanketing-steam blanketing-
Hydrogen attack or Hydrogen attack or damage-damage-
bull This type of failure is found in high pressure units This type of failure is found in high pressure units A situation occurs when excessive deposits are A situation occurs when excessive deposits are present on the tube water side surface that permit present on the tube water side surface that permit boiler chemicals to concentrate under the deposit boiler chemicals to concentrate under the deposit and corrode the metal Hydrogen is formed which and corrode the metal Hydrogen is formed which permeates the metal structure and reacts with the permeates the metal structure and reacts with the carbon of the metal to form methane The methane carbon of the metal to form methane The methane molecule which is much larger than the carbon molecule which is much larger than the carbon atom Exerts pressure and causes the metal to atom Exerts pressure and causes the metal to rupture along the grain boundaries Ruptures are rupture along the grain boundaries Ruptures are violent sudden and can be disastrousviolent sudden and can be disastrous
bull 4H+C=CH44H+C=CH4
The effect of hydrogen The effect of hydrogen attack in tubes-attack in tubes-
Cold end corrosion-Cold end corrosion-
bull Cold-end corrosion will occur Cold-end corrosion will occur wherever the temperature of metal wherever the temperature of metal drops below the sulfuric acid dew drops below the sulfuric acid dew point of the flue gas It occurs in point of the flue gas It occurs in economizer air preheater economizer air preheater induced draft fan and stackinduced draft fan and stack
Soot blowers erosion-Soot blowers erosion-
bull A misdirected blower allows a high A misdirected blower allows a high velocity jet of steam or air carrying velocity jet of steam or air carrying condensed water droplets to condensed water droplets to impinge directed upon tube impinge directed upon tube surfaces rather than to be directed surfaces rather than to be directed between tubes Physical abrasion between tubes Physical abrasion and acceleration oxidation cause and acceleration oxidation cause metal loss Erosive thinning often metal loss Erosive thinning often leads to tube ruptureleads to tube rupture
Foaming-Foaming-
bull It is a condition in which It is a condition in which concentration of soluble salts create concentration of soluble salts create frothy bubbles in the steam space of frothy bubbles in the steam space of the boiler Foaming can form slugs the boiler Foaming can form slugs of water that can carried over into of water that can carried over into the steam systemthe steam system
How to remove a tube How to remove a tube sample for inspectionsample for inspection
When removing a tube When removing a tube sample-sample-
bull 1-the tube section should be dry saw 1-the tube section should be dry saw cut to prevent any slag andor cutting cut to prevent any slag andor cutting oil from contaminating the internal oil from contaminating the internal depositdeposit
bull 2-the sample should be cut 2-the sample should be cut approximately 8-10 inches above and approximately 8-10 inches above and below the affected areabelow the affected area
bull 3-the exact location should be 3-the exact location should be documented as follows-documented as follows-
bull A-tubes should be numbered and A-tubes should be numbered and counted from east to west and north counted from east to west and north to southto south
bull B-the wall (front rear right hand B-the wall (front rear right hand side left hand side) and elevation side left hand side) and elevation should be noted and marked on the should be noted and marked on the tubetube
bull C-an arrow should be marked to C-an arrow should be marked to indicate which end of sample is upindicate which end of sample is up
bull D-on a universal pressure unit the D-on a universal pressure unit the sample should be identified as sample should be identified as removed from the first second or removed from the first second or third passthird pass
Troubles associated to drums-
bull1048698 Loss of level gauges
bull1048698 water level controllers out of service
bull1048698 corrosion
bull1048698 moisture carry-over in the steam
bull1048698 safety valves leaking
bull1048698 leaks of roll-expanded evaporator
bullTubes
bull1048698 plugging of evaporator tubes
Trouble associated to air Trouble associated to air heaters-heaters-
bull1048698 Leakages due to damaged axial or circumferential seals
bull1048698 Cold end baskets damaged by acid corrosion
bull1048698 Poor sootblowing
bull1048698 Standby pneumatic or DC motor not working or absent
New application in air New application in air heater-heater-
The modification-The modification-
bull We used to manufacture the air We used to manufacture the air heater basket material from heater basket material from carbon steel or Corten steel now carbon steel or Corten steel now they add a new material called they add a new material called enamel to improve quality reduce enamel to improve quality reduce cost and extend service life for air cost and extend service life for air and gas heater which increase the and gas heater which increase the existing of elementexisting of element
The material composition of The material composition of enamel-enamel-
bull The enamel layer is basically The enamel layer is basically composed by a borosilicate glass plus composed by a borosilicate glass plus cobalt fluorine sodium potassium cobalt fluorine sodium potassium quartz titanium borax helliphellipquartz titanium borax helliphellip
The benefits of enamel The benefits of enamel coating include-coating include-
bull 1-greater resistance to the attack of 1-greater resistance to the attack of acidsacids
bull 2-abrasive and wear resistance2-abrasive and wear resistance
bull 3-high mechanical and thermal shock 3-high mechanical and thermal shock resistanceresistance
bull 4-high resistance to erosion by fly ash4-high resistance to erosion by fly ash
bull 5-smooth and vitreous surface reduces 5-smooth and vitreous surface reduces adhesion of solidsadhesion of solids
The EndThe End
bullGood luckGood luck
Corrosion due to Corrosion due to combustion product-combustion product-bull 1- High temperature corrosion in superheaters
andbull Reheaters-bull ndash promoted by sodium and vanadium
compoundsbull ndash sensitive if metal temp above 600degCbull 2- Medium temp Corrosion in evaporatorsbull ndash fixed through combustion system adjustmentbull 3- Low temp Corrosion in cold areasbull ndash promoted by sulfur which turns into sulfuric
acidbull below dew point keep temperature above
150degC
Basic principles for design Basic principles for design material-material-
bull 1-Carbon steel1-Carbon steelbull 2-Low alloy steel (Crlt25)2-Low alloy steel (Crlt25)bull 3-Medium alloy steel (Crgt25)3-Medium alloy steel (Crgt25)bull 4-High alloy steel (Crgt9)4-High alloy steel (Crgt9)bull 5-Stainless steel (Crgt11)5-Stainless steel (Crgt11)bull Note-Note- increase Ni improve low increase Ni improve low
temperature resistancetemperature resistancebull Increase Cr improve high Increase Cr improve high
temperature resistancetemperature resistance
Metals of steam boilers-Metals of steam boilers-
bull The main materials for boilers are carbon The main materials for boilers are carbon steels and alloy steelssteels and alloy steels
bull 1-carbon steel-1-carbon steel-steels are used for making steels are used for making steam boiler elements which operate under steam boiler elements which operate under no-creep conditions at temperatures not no-creep conditions at temperatures not higher than 450 higher than 450 degC
bull 2-alloy steel- used for making boiler elements for operation under creep condition like superheater elements
bull Note-the principle alloying elements in steels are Mo Cr Si and Al Molybdenum increase the long term strength and creep strength Chromium Silicon and Aluminum increase scale resistance
An application for boiler An application for boiler material and design material and design temperature-temperature-Material (ASTM)Material (ASTM) Design Design
temperaturetemperature
A 209 GR P1A 209 GR P1 16 to 412 16 to 412 degC
A 335 GR P11A 335 GR P11 496 to 538 496 to 538 degC
A 335 GR P12A 335 GR P12 496 to 538 496 to 538 degC
A 335 GR p22A 335 GR p22 539 to 593 539 to 593 degC
Tube failure Tube failure mechanisms-mechanisms-bull 1-Short term over heating failure-1-Short term over heating failure-
bull The cause of short term over heat is a rapid The cause of short term over heat is a rapid elevation of temperature of the tube metal elevation of temperature of the tube metal caused by restriction of the water steam caused by restriction of the water steam mixture to the tube and resulting in a wide mixture to the tube and resulting in a wide mouth rupture The edges of the rupture are mouth rupture The edges of the rupture are thin and sharp in the super heater A short term thin and sharp in the super heater A short term over heat could result from a blockage of steam over heat could result from a blockage of steam flowflow
Short time overheating failure
Failures due to scale and Failures due to scale and long term creep failure-long term creep failure-
bull The cause of this type of failure is build-up of The cause of this type of failure is build-up of internal scale that leads to gradual increase in internal scale that leads to gradual increase in temperature of the tube metal The tube may temperature of the tube metal The tube may appear swollen with blisters or bulges The out appear swollen with blisters or bulges The out side surface may have an elephant hide side surface may have an elephant hide appearance Rupture are a thin opening a long appearance Rupture are a thin opening a long the longitudinal axis of the tube The edges of the longitudinal axis of the tube The edges of the failure do not generally experience thinning the failure do not generally experience thinning
Long time overheating failure
Ash corrosion -Ash corrosion -
bull Ash corrosion result in a thinning of Ash corrosion result in a thinning of super heater and reheater tubing super heater and reheater tubing External wastage of the metal occurs External wastage of the metal occurs where ash deposits accumulate When where ash deposits accumulate When ash deposits on the tube and ash deposits on the tube and experiences high temperatures It experiences high temperatures It becomes semi-molten and corrodes becomes semi-molten and corrodes most alloy steels that might be used in most alloy steels that might be used in super heater constructionsuper heater construction
Corrosion by molten ashCorrosion by molten ash
Oxygen pitting Oxygen pitting (Economizer)-(Economizer)-bull In-service oxygen pitting appears as random In-service oxygen pitting appears as random
Round bottomed pits on the water side of Round bottomed pits on the water side of tubes in the economizer If there is no tubes in the economizer If there is no economizer similar pitting may be present at economizer similar pitting may be present at or above normal water level in the steam or above normal water level in the steam drum Proper mechanical deaeration of feed drum Proper mechanical deaeration of feed water is absolutely essential for protection of water is absolutely essential for protection of the pre-boiler equipment ( feed water heater the pre-boiler equipment ( feed water heater piping) and the economizer The addition of piping) and the economizer The addition of an oxygen scavenger such as hydrazine to an oxygen scavenger such as hydrazine to the deaerator storage tank will permit the deaerator storage tank will permit removal of minute quantities of dissolved removal of minute quantities of dissolved oxygenoxygen
Oxygen pitting Oxygen pitting (superheater)-(superheater)-
bull Out-of-service oxygen pitting is Out-of-service oxygen pitting is usually found in the bottom loops usually found in the bottom loops of the superheater and is result of of the superheater and is result of the exposure of water or the exposure of water or condensate that forms in the bends condensate that forms in the bends after shutdown in contact with air after shutdown in contact with air The distress is seen as pitting and The distress is seen as pitting and corrosion of the wetted internal corrosion of the wetted internal surfacessurfaces
Carry over-Carry over-
bull The cause for carry over is an The cause for carry over is an incomplete separation of the steam incomplete separation of the steam from the steamwater mixture in the from the steamwater mixture in the boiler Possible causes of carry over boiler Possible causes of carry over are high water level high total are high water level high total dissolved solids concentration in the dissolved solids concentration in the boiler water excessive alkalinity and boiler water excessive alkalinity and the presence of oil andor organics the presence of oil andor organics The result of carry over is a build up of The result of carry over is a build up of contaminates on the inner surface of contaminates on the inner surface of the super heater tubesthe super heater tubes
Steam blanketing-Steam blanketing-
bull The cause for steam blanketing is an The cause for steam blanketing is an improper mass flow in the boiler tube improper mass flow in the boiler tube in relation to the heat input and in relation to the heat input and pressure Causing localized thinning in pressure Causing localized thinning in the tube This type of attack is the tube This type of attack is sometimes accompanied by a gross sometimes accompanied by a gross accumulation of corrosive product accumulation of corrosive product Steam blanketing is also referred to as Steam blanketing is also referred to as DNB (departure from nucleate boiling)DNB (departure from nucleate boiling)
Thinning of tube due to Thinning of tube due to steam blanketing-steam blanketing-
Hydrogen attack or Hydrogen attack or damage-damage-
bull This type of failure is found in high pressure units This type of failure is found in high pressure units A situation occurs when excessive deposits are A situation occurs when excessive deposits are present on the tube water side surface that permit present on the tube water side surface that permit boiler chemicals to concentrate under the deposit boiler chemicals to concentrate under the deposit and corrode the metal Hydrogen is formed which and corrode the metal Hydrogen is formed which permeates the metal structure and reacts with the permeates the metal structure and reacts with the carbon of the metal to form methane The methane carbon of the metal to form methane The methane molecule which is much larger than the carbon molecule which is much larger than the carbon atom Exerts pressure and causes the metal to atom Exerts pressure and causes the metal to rupture along the grain boundaries Ruptures are rupture along the grain boundaries Ruptures are violent sudden and can be disastrousviolent sudden and can be disastrous
bull 4H+C=CH44H+C=CH4
The effect of hydrogen The effect of hydrogen attack in tubes-attack in tubes-
Cold end corrosion-Cold end corrosion-
bull Cold-end corrosion will occur Cold-end corrosion will occur wherever the temperature of metal wherever the temperature of metal drops below the sulfuric acid dew drops below the sulfuric acid dew point of the flue gas It occurs in point of the flue gas It occurs in economizer air preheater economizer air preheater induced draft fan and stackinduced draft fan and stack
Soot blowers erosion-Soot blowers erosion-
bull A misdirected blower allows a high A misdirected blower allows a high velocity jet of steam or air carrying velocity jet of steam or air carrying condensed water droplets to condensed water droplets to impinge directed upon tube impinge directed upon tube surfaces rather than to be directed surfaces rather than to be directed between tubes Physical abrasion between tubes Physical abrasion and acceleration oxidation cause and acceleration oxidation cause metal loss Erosive thinning often metal loss Erosive thinning often leads to tube ruptureleads to tube rupture
Foaming-Foaming-
bull It is a condition in which It is a condition in which concentration of soluble salts create concentration of soluble salts create frothy bubbles in the steam space of frothy bubbles in the steam space of the boiler Foaming can form slugs the boiler Foaming can form slugs of water that can carried over into of water that can carried over into the steam systemthe steam system
How to remove a tube How to remove a tube sample for inspectionsample for inspection
When removing a tube When removing a tube sample-sample-
bull 1-the tube section should be dry saw 1-the tube section should be dry saw cut to prevent any slag andor cutting cut to prevent any slag andor cutting oil from contaminating the internal oil from contaminating the internal depositdeposit
bull 2-the sample should be cut 2-the sample should be cut approximately 8-10 inches above and approximately 8-10 inches above and below the affected areabelow the affected area
bull 3-the exact location should be 3-the exact location should be documented as follows-documented as follows-
bull A-tubes should be numbered and A-tubes should be numbered and counted from east to west and north counted from east to west and north to southto south
bull B-the wall (front rear right hand B-the wall (front rear right hand side left hand side) and elevation side left hand side) and elevation should be noted and marked on the should be noted and marked on the tubetube
bull C-an arrow should be marked to C-an arrow should be marked to indicate which end of sample is upindicate which end of sample is up
bull D-on a universal pressure unit the D-on a universal pressure unit the sample should be identified as sample should be identified as removed from the first second or removed from the first second or third passthird pass
Troubles associated to drums-
bull1048698 Loss of level gauges
bull1048698 water level controllers out of service
bull1048698 corrosion
bull1048698 moisture carry-over in the steam
bull1048698 safety valves leaking
bull1048698 leaks of roll-expanded evaporator
bullTubes
bull1048698 plugging of evaporator tubes
Trouble associated to air Trouble associated to air heaters-heaters-
bull1048698 Leakages due to damaged axial or circumferential seals
bull1048698 Cold end baskets damaged by acid corrosion
bull1048698 Poor sootblowing
bull1048698 Standby pneumatic or DC motor not working or absent
New application in air New application in air heater-heater-
The modification-The modification-
bull We used to manufacture the air We used to manufacture the air heater basket material from heater basket material from carbon steel or Corten steel now carbon steel or Corten steel now they add a new material called they add a new material called enamel to improve quality reduce enamel to improve quality reduce cost and extend service life for air cost and extend service life for air and gas heater which increase the and gas heater which increase the existing of elementexisting of element
The material composition of The material composition of enamel-enamel-
bull The enamel layer is basically The enamel layer is basically composed by a borosilicate glass plus composed by a borosilicate glass plus cobalt fluorine sodium potassium cobalt fluorine sodium potassium quartz titanium borax helliphellipquartz titanium borax helliphellip
The benefits of enamel The benefits of enamel coating include-coating include-
bull 1-greater resistance to the attack of 1-greater resistance to the attack of acidsacids
bull 2-abrasive and wear resistance2-abrasive and wear resistance
bull 3-high mechanical and thermal shock 3-high mechanical and thermal shock resistanceresistance
bull 4-high resistance to erosion by fly ash4-high resistance to erosion by fly ash
bull 5-smooth and vitreous surface reduces 5-smooth and vitreous surface reduces adhesion of solidsadhesion of solids
The EndThe End
bullGood luckGood luck
Basic principles for design Basic principles for design material-material-
bull 1-Carbon steel1-Carbon steelbull 2-Low alloy steel (Crlt25)2-Low alloy steel (Crlt25)bull 3-Medium alloy steel (Crgt25)3-Medium alloy steel (Crgt25)bull 4-High alloy steel (Crgt9)4-High alloy steel (Crgt9)bull 5-Stainless steel (Crgt11)5-Stainless steel (Crgt11)bull Note-Note- increase Ni improve low increase Ni improve low
temperature resistancetemperature resistancebull Increase Cr improve high Increase Cr improve high
temperature resistancetemperature resistance
Metals of steam boilers-Metals of steam boilers-
bull The main materials for boilers are carbon The main materials for boilers are carbon steels and alloy steelssteels and alloy steels
bull 1-carbon steel-1-carbon steel-steels are used for making steels are used for making steam boiler elements which operate under steam boiler elements which operate under no-creep conditions at temperatures not no-creep conditions at temperatures not higher than 450 higher than 450 degC
bull 2-alloy steel- used for making boiler elements for operation under creep condition like superheater elements
bull Note-the principle alloying elements in steels are Mo Cr Si and Al Molybdenum increase the long term strength and creep strength Chromium Silicon and Aluminum increase scale resistance
An application for boiler An application for boiler material and design material and design temperature-temperature-Material (ASTM)Material (ASTM) Design Design
temperaturetemperature
A 209 GR P1A 209 GR P1 16 to 412 16 to 412 degC
A 335 GR P11A 335 GR P11 496 to 538 496 to 538 degC
A 335 GR P12A 335 GR P12 496 to 538 496 to 538 degC
A 335 GR p22A 335 GR p22 539 to 593 539 to 593 degC
Tube failure Tube failure mechanisms-mechanisms-bull 1-Short term over heating failure-1-Short term over heating failure-
bull The cause of short term over heat is a rapid The cause of short term over heat is a rapid elevation of temperature of the tube metal elevation of temperature of the tube metal caused by restriction of the water steam caused by restriction of the water steam mixture to the tube and resulting in a wide mixture to the tube and resulting in a wide mouth rupture The edges of the rupture are mouth rupture The edges of the rupture are thin and sharp in the super heater A short term thin and sharp in the super heater A short term over heat could result from a blockage of steam over heat could result from a blockage of steam flowflow
Short time overheating failure
Failures due to scale and Failures due to scale and long term creep failure-long term creep failure-
bull The cause of this type of failure is build-up of The cause of this type of failure is build-up of internal scale that leads to gradual increase in internal scale that leads to gradual increase in temperature of the tube metal The tube may temperature of the tube metal The tube may appear swollen with blisters or bulges The out appear swollen with blisters or bulges The out side surface may have an elephant hide side surface may have an elephant hide appearance Rupture are a thin opening a long appearance Rupture are a thin opening a long the longitudinal axis of the tube The edges of the longitudinal axis of the tube The edges of the failure do not generally experience thinning the failure do not generally experience thinning
Long time overheating failure
Ash corrosion -Ash corrosion -
bull Ash corrosion result in a thinning of Ash corrosion result in a thinning of super heater and reheater tubing super heater and reheater tubing External wastage of the metal occurs External wastage of the metal occurs where ash deposits accumulate When where ash deposits accumulate When ash deposits on the tube and ash deposits on the tube and experiences high temperatures It experiences high temperatures It becomes semi-molten and corrodes becomes semi-molten and corrodes most alloy steels that might be used in most alloy steels that might be used in super heater constructionsuper heater construction
Corrosion by molten ashCorrosion by molten ash
Oxygen pitting Oxygen pitting (Economizer)-(Economizer)-bull In-service oxygen pitting appears as random In-service oxygen pitting appears as random
Round bottomed pits on the water side of Round bottomed pits on the water side of tubes in the economizer If there is no tubes in the economizer If there is no economizer similar pitting may be present at economizer similar pitting may be present at or above normal water level in the steam or above normal water level in the steam drum Proper mechanical deaeration of feed drum Proper mechanical deaeration of feed water is absolutely essential for protection of water is absolutely essential for protection of the pre-boiler equipment ( feed water heater the pre-boiler equipment ( feed water heater piping) and the economizer The addition of piping) and the economizer The addition of an oxygen scavenger such as hydrazine to an oxygen scavenger such as hydrazine to the deaerator storage tank will permit the deaerator storage tank will permit removal of minute quantities of dissolved removal of minute quantities of dissolved oxygenoxygen
Oxygen pitting Oxygen pitting (superheater)-(superheater)-
bull Out-of-service oxygen pitting is Out-of-service oxygen pitting is usually found in the bottom loops usually found in the bottom loops of the superheater and is result of of the superheater and is result of the exposure of water or the exposure of water or condensate that forms in the bends condensate that forms in the bends after shutdown in contact with air after shutdown in contact with air The distress is seen as pitting and The distress is seen as pitting and corrosion of the wetted internal corrosion of the wetted internal surfacessurfaces
Carry over-Carry over-
bull The cause for carry over is an The cause for carry over is an incomplete separation of the steam incomplete separation of the steam from the steamwater mixture in the from the steamwater mixture in the boiler Possible causes of carry over boiler Possible causes of carry over are high water level high total are high water level high total dissolved solids concentration in the dissolved solids concentration in the boiler water excessive alkalinity and boiler water excessive alkalinity and the presence of oil andor organics the presence of oil andor organics The result of carry over is a build up of The result of carry over is a build up of contaminates on the inner surface of contaminates on the inner surface of the super heater tubesthe super heater tubes
Steam blanketing-Steam blanketing-
bull The cause for steam blanketing is an The cause for steam blanketing is an improper mass flow in the boiler tube improper mass flow in the boiler tube in relation to the heat input and in relation to the heat input and pressure Causing localized thinning in pressure Causing localized thinning in the tube This type of attack is the tube This type of attack is sometimes accompanied by a gross sometimes accompanied by a gross accumulation of corrosive product accumulation of corrosive product Steam blanketing is also referred to as Steam blanketing is also referred to as DNB (departure from nucleate boiling)DNB (departure from nucleate boiling)
Thinning of tube due to Thinning of tube due to steam blanketing-steam blanketing-
Hydrogen attack or Hydrogen attack or damage-damage-
bull This type of failure is found in high pressure units This type of failure is found in high pressure units A situation occurs when excessive deposits are A situation occurs when excessive deposits are present on the tube water side surface that permit present on the tube water side surface that permit boiler chemicals to concentrate under the deposit boiler chemicals to concentrate under the deposit and corrode the metal Hydrogen is formed which and corrode the metal Hydrogen is formed which permeates the metal structure and reacts with the permeates the metal structure and reacts with the carbon of the metal to form methane The methane carbon of the metal to form methane The methane molecule which is much larger than the carbon molecule which is much larger than the carbon atom Exerts pressure and causes the metal to atom Exerts pressure and causes the metal to rupture along the grain boundaries Ruptures are rupture along the grain boundaries Ruptures are violent sudden and can be disastrousviolent sudden and can be disastrous
bull 4H+C=CH44H+C=CH4
The effect of hydrogen The effect of hydrogen attack in tubes-attack in tubes-
Cold end corrosion-Cold end corrosion-
bull Cold-end corrosion will occur Cold-end corrosion will occur wherever the temperature of metal wherever the temperature of metal drops below the sulfuric acid dew drops below the sulfuric acid dew point of the flue gas It occurs in point of the flue gas It occurs in economizer air preheater economizer air preheater induced draft fan and stackinduced draft fan and stack
Soot blowers erosion-Soot blowers erosion-
bull A misdirected blower allows a high A misdirected blower allows a high velocity jet of steam or air carrying velocity jet of steam or air carrying condensed water droplets to condensed water droplets to impinge directed upon tube impinge directed upon tube surfaces rather than to be directed surfaces rather than to be directed between tubes Physical abrasion between tubes Physical abrasion and acceleration oxidation cause and acceleration oxidation cause metal loss Erosive thinning often metal loss Erosive thinning often leads to tube ruptureleads to tube rupture
Foaming-Foaming-
bull It is a condition in which It is a condition in which concentration of soluble salts create concentration of soluble salts create frothy bubbles in the steam space of frothy bubbles in the steam space of the boiler Foaming can form slugs the boiler Foaming can form slugs of water that can carried over into of water that can carried over into the steam systemthe steam system
How to remove a tube How to remove a tube sample for inspectionsample for inspection
When removing a tube When removing a tube sample-sample-
bull 1-the tube section should be dry saw 1-the tube section should be dry saw cut to prevent any slag andor cutting cut to prevent any slag andor cutting oil from contaminating the internal oil from contaminating the internal depositdeposit
bull 2-the sample should be cut 2-the sample should be cut approximately 8-10 inches above and approximately 8-10 inches above and below the affected areabelow the affected area
bull 3-the exact location should be 3-the exact location should be documented as follows-documented as follows-
bull A-tubes should be numbered and A-tubes should be numbered and counted from east to west and north counted from east to west and north to southto south
bull B-the wall (front rear right hand B-the wall (front rear right hand side left hand side) and elevation side left hand side) and elevation should be noted and marked on the should be noted and marked on the tubetube
bull C-an arrow should be marked to C-an arrow should be marked to indicate which end of sample is upindicate which end of sample is up
bull D-on a universal pressure unit the D-on a universal pressure unit the sample should be identified as sample should be identified as removed from the first second or removed from the first second or third passthird pass
Troubles associated to drums-
bull1048698 Loss of level gauges
bull1048698 water level controllers out of service
bull1048698 corrosion
bull1048698 moisture carry-over in the steam
bull1048698 safety valves leaking
bull1048698 leaks of roll-expanded evaporator
bullTubes
bull1048698 plugging of evaporator tubes
Trouble associated to air Trouble associated to air heaters-heaters-
bull1048698 Leakages due to damaged axial or circumferential seals
bull1048698 Cold end baskets damaged by acid corrosion
bull1048698 Poor sootblowing
bull1048698 Standby pneumatic or DC motor not working or absent
New application in air New application in air heater-heater-
The modification-The modification-
bull We used to manufacture the air We used to manufacture the air heater basket material from heater basket material from carbon steel or Corten steel now carbon steel or Corten steel now they add a new material called they add a new material called enamel to improve quality reduce enamel to improve quality reduce cost and extend service life for air cost and extend service life for air and gas heater which increase the and gas heater which increase the existing of elementexisting of element
The material composition of The material composition of enamel-enamel-
bull The enamel layer is basically The enamel layer is basically composed by a borosilicate glass plus composed by a borosilicate glass plus cobalt fluorine sodium potassium cobalt fluorine sodium potassium quartz titanium borax helliphellipquartz titanium borax helliphellip
The benefits of enamel The benefits of enamel coating include-coating include-
bull 1-greater resistance to the attack of 1-greater resistance to the attack of acidsacids
bull 2-abrasive and wear resistance2-abrasive and wear resistance
bull 3-high mechanical and thermal shock 3-high mechanical and thermal shock resistanceresistance
bull 4-high resistance to erosion by fly ash4-high resistance to erosion by fly ash
bull 5-smooth and vitreous surface reduces 5-smooth and vitreous surface reduces adhesion of solidsadhesion of solids
The EndThe End
bullGood luckGood luck
Metals of steam boilers-Metals of steam boilers-
bull The main materials for boilers are carbon The main materials for boilers are carbon steels and alloy steelssteels and alloy steels
bull 1-carbon steel-1-carbon steel-steels are used for making steels are used for making steam boiler elements which operate under steam boiler elements which operate under no-creep conditions at temperatures not no-creep conditions at temperatures not higher than 450 higher than 450 degC
bull 2-alloy steel- used for making boiler elements for operation under creep condition like superheater elements
bull Note-the principle alloying elements in steels are Mo Cr Si and Al Molybdenum increase the long term strength and creep strength Chromium Silicon and Aluminum increase scale resistance
An application for boiler An application for boiler material and design material and design temperature-temperature-Material (ASTM)Material (ASTM) Design Design
temperaturetemperature
A 209 GR P1A 209 GR P1 16 to 412 16 to 412 degC
A 335 GR P11A 335 GR P11 496 to 538 496 to 538 degC
A 335 GR P12A 335 GR P12 496 to 538 496 to 538 degC
A 335 GR p22A 335 GR p22 539 to 593 539 to 593 degC
Tube failure Tube failure mechanisms-mechanisms-bull 1-Short term over heating failure-1-Short term over heating failure-
bull The cause of short term over heat is a rapid The cause of short term over heat is a rapid elevation of temperature of the tube metal elevation of temperature of the tube metal caused by restriction of the water steam caused by restriction of the water steam mixture to the tube and resulting in a wide mixture to the tube and resulting in a wide mouth rupture The edges of the rupture are mouth rupture The edges of the rupture are thin and sharp in the super heater A short term thin and sharp in the super heater A short term over heat could result from a blockage of steam over heat could result from a blockage of steam flowflow
Short time overheating failure
Failures due to scale and Failures due to scale and long term creep failure-long term creep failure-
bull The cause of this type of failure is build-up of The cause of this type of failure is build-up of internal scale that leads to gradual increase in internal scale that leads to gradual increase in temperature of the tube metal The tube may temperature of the tube metal The tube may appear swollen with blisters or bulges The out appear swollen with blisters or bulges The out side surface may have an elephant hide side surface may have an elephant hide appearance Rupture are a thin opening a long appearance Rupture are a thin opening a long the longitudinal axis of the tube The edges of the longitudinal axis of the tube The edges of the failure do not generally experience thinning the failure do not generally experience thinning
Long time overheating failure
Ash corrosion -Ash corrosion -
bull Ash corrosion result in a thinning of Ash corrosion result in a thinning of super heater and reheater tubing super heater and reheater tubing External wastage of the metal occurs External wastage of the metal occurs where ash deposits accumulate When where ash deposits accumulate When ash deposits on the tube and ash deposits on the tube and experiences high temperatures It experiences high temperatures It becomes semi-molten and corrodes becomes semi-molten and corrodes most alloy steels that might be used in most alloy steels that might be used in super heater constructionsuper heater construction
Corrosion by molten ashCorrosion by molten ash
Oxygen pitting Oxygen pitting (Economizer)-(Economizer)-bull In-service oxygen pitting appears as random In-service oxygen pitting appears as random
Round bottomed pits on the water side of Round bottomed pits on the water side of tubes in the economizer If there is no tubes in the economizer If there is no economizer similar pitting may be present at economizer similar pitting may be present at or above normal water level in the steam or above normal water level in the steam drum Proper mechanical deaeration of feed drum Proper mechanical deaeration of feed water is absolutely essential for protection of water is absolutely essential for protection of the pre-boiler equipment ( feed water heater the pre-boiler equipment ( feed water heater piping) and the economizer The addition of piping) and the economizer The addition of an oxygen scavenger such as hydrazine to an oxygen scavenger such as hydrazine to the deaerator storage tank will permit the deaerator storage tank will permit removal of minute quantities of dissolved removal of minute quantities of dissolved oxygenoxygen
Oxygen pitting Oxygen pitting (superheater)-(superheater)-
bull Out-of-service oxygen pitting is Out-of-service oxygen pitting is usually found in the bottom loops usually found in the bottom loops of the superheater and is result of of the superheater and is result of the exposure of water or the exposure of water or condensate that forms in the bends condensate that forms in the bends after shutdown in contact with air after shutdown in contact with air The distress is seen as pitting and The distress is seen as pitting and corrosion of the wetted internal corrosion of the wetted internal surfacessurfaces
Carry over-Carry over-
bull The cause for carry over is an The cause for carry over is an incomplete separation of the steam incomplete separation of the steam from the steamwater mixture in the from the steamwater mixture in the boiler Possible causes of carry over boiler Possible causes of carry over are high water level high total are high water level high total dissolved solids concentration in the dissolved solids concentration in the boiler water excessive alkalinity and boiler water excessive alkalinity and the presence of oil andor organics the presence of oil andor organics The result of carry over is a build up of The result of carry over is a build up of contaminates on the inner surface of contaminates on the inner surface of the super heater tubesthe super heater tubes
Steam blanketing-Steam blanketing-
bull The cause for steam blanketing is an The cause for steam blanketing is an improper mass flow in the boiler tube improper mass flow in the boiler tube in relation to the heat input and in relation to the heat input and pressure Causing localized thinning in pressure Causing localized thinning in the tube This type of attack is the tube This type of attack is sometimes accompanied by a gross sometimes accompanied by a gross accumulation of corrosive product accumulation of corrosive product Steam blanketing is also referred to as Steam blanketing is also referred to as DNB (departure from nucleate boiling)DNB (departure from nucleate boiling)
Thinning of tube due to Thinning of tube due to steam blanketing-steam blanketing-
Hydrogen attack or Hydrogen attack or damage-damage-
bull This type of failure is found in high pressure units This type of failure is found in high pressure units A situation occurs when excessive deposits are A situation occurs when excessive deposits are present on the tube water side surface that permit present on the tube water side surface that permit boiler chemicals to concentrate under the deposit boiler chemicals to concentrate under the deposit and corrode the metal Hydrogen is formed which and corrode the metal Hydrogen is formed which permeates the metal structure and reacts with the permeates the metal structure and reacts with the carbon of the metal to form methane The methane carbon of the metal to form methane The methane molecule which is much larger than the carbon molecule which is much larger than the carbon atom Exerts pressure and causes the metal to atom Exerts pressure and causes the metal to rupture along the grain boundaries Ruptures are rupture along the grain boundaries Ruptures are violent sudden and can be disastrousviolent sudden and can be disastrous
bull 4H+C=CH44H+C=CH4
The effect of hydrogen The effect of hydrogen attack in tubes-attack in tubes-
Cold end corrosion-Cold end corrosion-
bull Cold-end corrosion will occur Cold-end corrosion will occur wherever the temperature of metal wherever the temperature of metal drops below the sulfuric acid dew drops below the sulfuric acid dew point of the flue gas It occurs in point of the flue gas It occurs in economizer air preheater economizer air preheater induced draft fan and stackinduced draft fan and stack
Soot blowers erosion-Soot blowers erosion-
bull A misdirected blower allows a high A misdirected blower allows a high velocity jet of steam or air carrying velocity jet of steam or air carrying condensed water droplets to condensed water droplets to impinge directed upon tube impinge directed upon tube surfaces rather than to be directed surfaces rather than to be directed between tubes Physical abrasion between tubes Physical abrasion and acceleration oxidation cause and acceleration oxidation cause metal loss Erosive thinning often metal loss Erosive thinning often leads to tube ruptureleads to tube rupture
Foaming-Foaming-
bull It is a condition in which It is a condition in which concentration of soluble salts create concentration of soluble salts create frothy bubbles in the steam space of frothy bubbles in the steam space of the boiler Foaming can form slugs the boiler Foaming can form slugs of water that can carried over into of water that can carried over into the steam systemthe steam system
How to remove a tube How to remove a tube sample for inspectionsample for inspection
When removing a tube When removing a tube sample-sample-
bull 1-the tube section should be dry saw 1-the tube section should be dry saw cut to prevent any slag andor cutting cut to prevent any slag andor cutting oil from contaminating the internal oil from contaminating the internal depositdeposit
bull 2-the sample should be cut 2-the sample should be cut approximately 8-10 inches above and approximately 8-10 inches above and below the affected areabelow the affected area
bull 3-the exact location should be 3-the exact location should be documented as follows-documented as follows-
bull A-tubes should be numbered and A-tubes should be numbered and counted from east to west and north counted from east to west and north to southto south
bull B-the wall (front rear right hand B-the wall (front rear right hand side left hand side) and elevation side left hand side) and elevation should be noted and marked on the should be noted and marked on the tubetube
bull C-an arrow should be marked to C-an arrow should be marked to indicate which end of sample is upindicate which end of sample is up
bull D-on a universal pressure unit the D-on a universal pressure unit the sample should be identified as sample should be identified as removed from the first second or removed from the first second or third passthird pass
Troubles associated to drums-
bull1048698 Loss of level gauges
bull1048698 water level controllers out of service
bull1048698 corrosion
bull1048698 moisture carry-over in the steam
bull1048698 safety valves leaking
bull1048698 leaks of roll-expanded evaporator
bullTubes
bull1048698 plugging of evaporator tubes
Trouble associated to air Trouble associated to air heaters-heaters-
bull1048698 Leakages due to damaged axial or circumferential seals
bull1048698 Cold end baskets damaged by acid corrosion
bull1048698 Poor sootblowing
bull1048698 Standby pneumatic or DC motor not working or absent
New application in air New application in air heater-heater-
The modification-The modification-
bull We used to manufacture the air We used to manufacture the air heater basket material from heater basket material from carbon steel or Corten steel now carbon steel or Corten steel now they add a new material called they add a new material called enamel to improve quality reduce enamel to improve quality reduce cost and extend service life for air cost and extend service life for air and gas heater which increase the and gas heater which increase the existing of elementexisting of element
The material composition of The material composition of enamel-enamel-
bull The enamel layer is basically The enamel layer is basically composed by a borosilicate glass plus composed by a borosilicate glass plus cobalt fluorine sodium potassium cobalt fluorine sodium potassium quartz titanium borax helliphellipquartz titanium borax helliphellip
The benefits of enamel The benefits of enamel coating include-coating include-
bull 1-greater resistance to the attack of 1-greater resistance to the attack of acidsacids
bull 2-abrasive and wear resistance2-abrasive and wear resistance
bull 3-high mechanical and thermal shock 3-high mechanical and thermal shock resistanceresistance
bull 4-high resistance to erosion by fly ash4-high resistance to erosion by fly ash
bull 5-smooth and vitreous surface reduces 5-smooth and vitreous surface reduces adhesion of solidsadhesion of solids
The EndThe End
bullGood luckGood luck
An application for boiler An application for boiler material and design material and design temperature-temperature-Material (ASTM)Material (ASTM) Design Design
temperaturetemperature
A 209 GR P1A 209 GR P1 16 to 412 16 to 412 degC
A 335 GR P11A 335 GR P11 496 to 538 496 to 538 degC
A 335 GR P12A 335 GR P12 496 to 538 496 to 538 degC
A 335 GR p22A 335 GR p22 539 to 593 539 to 593 degC
Tube failure Tube failure mechanisms-mechanisms-bull 1-Short term over heating failure-1-Short term over heating failure-
bull The cause of short term over heat is a rapid The cause of short term over heat is a rapid elevation of temperature of the tube metal elevation of temperature of the tube metal caused by restriction of the water steam caused by restriction of the water steam mixture to the tube and resulting in a wide mixture to the tube and resulting in a wide mouth rupture The edges of the rupture are mouth rupture The edges of the rupture are thin and sharp in the super heater A short term thin and sharp in the super heater A short term over heat could result from a blockage of steam over heat could result from a blockage of steam flowflow
Short time overheating failure
Failures due to scale and Failures due to scale and long term creep failure-long term creep failure-
bull The cause of this type of failure is build-up of The cause of this type of failure is build-up of internal scale that leads to gradual increase in internal scale that leads to gradual increase in temperature of the tube metal The tube may temperature of the tube metal The tube may appear swollen with blisters or bulges The out appear swollen with blisters or bulges The out side surface may have an elephant hide side surface may have an elephant hide appearance Rupture are a thin opening a long appearance Rupture are a thin opening a long the longitudinal axis of the tube The edges of the longitudinal axis of the tube The edges of the failure do not generally experience thinning the failure do not generally experience thinning
Long time overheating failure
Ash corrosion -Ash corrosion -
bull Ash corrosion result in a thinning of Ash corrosion result in a thinning of super heater and reheater tubing super heater and reheater tubing External wastage of the metal occurs External wastage of the metal occurs where ash deposits accumulate When where ash deposits accumulate When ash deposits on the tube and ash deposits on the tube and experiences high temperatures It experiences high temperatures It becomes semi-molten and corrodes becomes semi-molten and corrodes most alloy steels that might be used in most alloy steels that might be used in super heater constructionsuper heater construction
Corrosion by molten ashCorrosion by molten ash
Oxygen pitting Oxygen pitting (Economizer)-(Economizer)-bull In-service oxygen pitting appears as random In-service oxygen pitting appears as random
Round bottomed pits on the water side of Round bottomed pits on the water side of tubes in the economizer If there is no tubes in the economizer If there is no economizer similar pitting may be present at economizer similar pitting may be present at or above normal water level in the steam or above normal water level in the steam drum Proper mechanical deaeration of feed drum Proper mechanical deaeration of feed water is absolutely essential for protection of water is absolutely essential for protection of the pre-boiler equipment ( feed water heater the pre-boiler equipment ( feed water heater piping) and the economizer The addition of piping) and the economizer The addition of an oxygen scavenger such as hydrazine to an oxygen scavenger such as hydrazine to the deaerator storage tank will permit the deaerator storage tank will permit removal of minute quantities of dissolved removal of minute quantities of dissolved oxygenoxygen
Oxygen pitting Oxygen pitting (superheater)-(superheater)-
bull Out-of-service oxygen pitting is Out-of-service oxygen pitting is usually found in the bottom loops usually found in the bottom loops of the superheater and is result of of the superheater and is result of the exposure of water or the exposure of water or condensate that forms in the bends condensate that forms in the bends after shutdown in contact with air after shutdown in contact with air The distress is seen as pitting and The distress is seen as pitting and corrosion of the wetted internal corrosion of the wetted internal surfacessurfaces
Carry over-Carry over-
bull The cause for carry over is an The cause for carry over is an incomplete separation of the steam incomplete separation of the steam from the steamwater mixture in the from the steamwater mixture in the boiler Possible causes of carry over boiler Possible causes of carry over are high water level high total are high water level high total dissolved solids concentration in the dissolved solids concentration in the boiler water excessive alkalinity and boiler water excessive alkalinity and the presence of oil andor organics the presence of oil andor organics The result of carry over is a build up of The result of carry over is a build up of contaminates on the inner surface of contaminates on the inner surface of the super heater tubesthe super heater tubes
Steam blanketing-Steam blanketing-
bull The cause for steam blanketing is an The cause for steam blanketing is an improper mass flow in the boiler tube improper mass flow in the boiler tube in relation to the heat input and in relation to the heat input and pressure Causing localized thinning in pressure Causing localized thinning in the tube This type of attack is the tube This type of attack is sometimes accompanied by a gross sometimes accompanied by a gross accumulation of corrosive product accumulation of corrosive product Steam blanketing is also referred to as Steam blanketing is also referred to as DNB (departure from nucleate boiling)DNB (departure from nucleate boiling)
Thinning of tube due to Thinning of tube due to steam blanketing-steam blanketing-
Hydrogen attack or Hydrogen attack or damage-damage-
bull This type of failure is found in high pressure units This type of failure is found in high pressure units A situation occurs when excessive deposits are A situation occurs when excessive deposits are present on the tube water side surface that permit present on the tube water side surface that permit boiler chemicals to concentrate under the deposit boiler chemicals to concentrate under the deposit and corrode the metal Hydrogen is formed which and corrode the metal Hydrogen is formed which permeates the metal structure and reacts with the permeates the metal structure and reacts with the carbon of the metal to form methane The methane carbon of the metal to form methane The methane molecule which is much larger than the carbon molecule which is much larger than the carbon atom Exerts pressure and causes the metal to atom Exerts pressure and causes the metal to rupture along the grain boundaries Ruptures are rupture along the grain boundaries Ruptures are violent sudden and can be disastrousviolent sudden and can be disastrous
bull 4H+C=CH44H+C=CH4
The effect of hydrogen The effect of hydrogen attack in tubes-attack in tubes-
Cold end corrosion-Cold end corrosion-
bull Cold-end corrosion will occur Cold-end corrosion will occur wherever the temperature of metal wherever the temperature of metal drops below the sulfuric acid dew drops below the sulfuric acid dew point of the flue gas It occurs in point of the flue gas It occurs in economizer air preheater economizer air preheater induced draft fan and stackinduced draft fan and stack
Soot blowers erosion-Soot blowers erosion-
bull A misdirected blower allows a high A misdirected blower allows a high velocity jet of steam or air carrying velocity jet of steam or air carrying condensed water droplets to condensed water droplets to impinge directed upon tube impinge directed upon tube surfaces rather than to be directed surfaces rather than to be directed between tubes Physical abrasion between tubes Physical abrasion and acceleration oxidation cause and acceleration oxidation cause metal loss Erosive thinning often metal loss Erosive thinning often leads to tube ruptureleads to tube rupture
Foaming-Foaming-
bull It is a condition in which It is a condition in which concentration of soluble salts create concentration of soluble salts create frothy bubbles in the steam space of frothy bubbles in the steam space of the boiler Foaming can form slugs the boiler Foaming can form slugs of water that can carried over into of water that can carried over into the steam systemthe steam system
How to remove a tube How to remove a tube sample for inspectionsample for inspection
When removing a tube When removing a tube sample-sample-
bull 1-the tube section should be dry saw 1-the tube section should be dry saw cut to prevent any slag andor cutting cut to prevent any slag andor cutting oil from contaminating the internal oil from contaminating the internal depositdeposit
bull 2-the sample should be cut 2-the sample should be cut approximately 8-10 inches above and approximately 8-10 inches above and below the affected areabelow the affected area
bull 3-the exact location should be 3-the exact location should be documented as follows-documented as follows-
bull A-tubes should be numbered and A-tubes should be numbered and counted from east to west and north counted from east to west and north to southto south
bull B-the wall (front rear right hand B-the wall (front rear right hand side left hand side) and elevation side left hand side) and elevation should be noted and marked on the should be noted and marked on the tubetube
bull C-an arrow should be marked to C-an arrow should be marked to indicate which end of sample is upindicate which end of sample is up
bull D-on a universal pressure unit the D-on a universal pressure unit the sample should be identified as sample should be identified as removed from the first second or removed from the first second or third passthird pass
Troubles associated to drums-
bull1048698 Loss of level gauges
bull1048698 water level controllers out of service
bull1048698 corrosion
bull1048698 moisture carry-over in the steam
bull1048698 safety valves leaking
bull1048698 leaks of roll-expanded evaporator
bullTubes
bull1048698 plugging of evaporator tubes
Trouble associated to air Trouble associated to air heaters-heaters-
bull1048698 Leakages due to damaged axial or circumferential seals
bull1048698 Cold end baskets damaged by acid corrosion
bull1048698 Poor sootblowing
bull1048698 Standby pneumatic or DC motor not working or absent
New application in air New application in air heater-heater-
The modification-The modification-
bull We used to manufacture the air We used to manufacture the air heater basket material from heater basket material from carbon steel or Corten steel now carbon steel or Corten steel now they add a new material called they add a new material called enamel to improve quality reduce enamel to improve quality reduce cost and extend service life for air cost and extend service life for air and gas heater which increase the and gas heater which increase the existing of elementexisting of element
The material composition of The material composition of enamel-enamel-
bull The enamel layer is basically The enamel layer is basically composed by a borosilicate glass plus composed by a borosilicate glass plus cobalt fluorine sodium potassium cobalt fluorine sodium potassium quartz titanium borax helliphellipquartz titanium borax helliphellip
The benefits of enamel The benefits of enamel coating include-coating include-
bull 1-greater resistance to the attack of 1-greater resistance to the attack of acidsacids
bull 2-abrasive and wear resistance2-abrasive and wear resistance
bull 3-high mechanical and thermal shock 3-high mechanical and thermal shock resistanceresistance
bull 4-high resistance to erosion by fly ash4-high resistance to erosion by fly ash
bull 5-smooth and vitreous surface reduces 5-smooth and vitreous surface reduces adhesion of solidsadhesion of solids
The EndThe End
bullGood luckGood luck
Tube failure Tube failure mechanisms-mechanisms-bull 1-Short term over heating failure-1-Short term over heating failure-
bull The cause of short term over heat is a rapid The cause of short term over heat is a rapid elevation of temperature of the tube metal elevation of temperature of the tube metal caused by restriction of the water steam caused by restriction of the water steam mixture to the tube and resulting in a wide mixture to the tube and resulting in a wide mouth rupture The edges of the rupture are mouth rupture The edges of the rupture are thin and sharp in the super heater A short term thin and sharp in the super heater A short term over heat could result from a blockage of steam over heat could result from a blockage of steam flowflow
Short time overheating failure
Failures due to scale and Failures due to scale and long term creep failure-long term creep failure-
bull The cause of this type of failure is build-up of The cause of this type of failure is build-up of internal scale that leads to gradual increase in internal scale that leads to gradual increase in temperature of the tube metal The tube may temperature of the tube metal The tube may appear swollen with blisters or bulges The out appear swollen with blisters or bulges The out side surface may have an elephant hide side surface may have an elephant hide appearance Rupture are a thin opening a long appearance Rupture are a thin opening a long the longitudinal axis of the tube The edges of the longitudinal axis of the tube The edges of the failure do not generally experience thinning the failure do not generally experience thinning
Long time overheating failure
Ash corrosion -Ash corrosion -
bull Ash corrosion result in a thinning of Ash corrosion result in a thinning of super heater and reheater tubing super heater and reheater tubing External wastage of the metal occurs External wastage of the metal occurs where ash deposits accumulate When where ash deposits accumulate When ash deposits on the tube and ash deposits on the tube and experiences high temperatures It experiences high temperatures It becomes semi-molten and corrodes becomes semi-molten and corrodes most alloy steels that might be used in most alloy steels that might be used in super heater constructionsuper heater construction
Corrosion by molten ashCorrosion by molten ash
Oxygen pitting Oxygen pitting (Economizer)-(Economizer)-bull In-service oxygen pitting appears as random In-service oxygen pitting appears as random
Round bottomed pits on the water side of Round bottomed pits on the water side of tubes in the economizer If there is no tubes in the economizer If there is no economizer similar pitting may be present at economizer similar pitting may be present at or above normal water level in the steam or above normal water level in the steam drum Proper mechanical deaeration of feed drum Proper mechanical deaeration of feed water is absolutely essential for protection of water is absolutely essential for protection of the pre-boiler equipment ( feed water heater the pre-boiler equipment ( feed water heater piping) and the economizer The addition of piping) and the economizer The addition of an oxygen scavenger such as hydrazine to an oxygen scavenger such as hydrazine to the deaerator storage tank will permit the deaerator storage tank will permit removal of minute quantities of dissolved removal of minute quantities of dissolved oxygenoxygen
Oxygen pitting Oxygen pitting (superheater)-(superheater)-
bull Out-of-service oxygen pitting is Out-of-service oxygen pitting is usually found in the bottom loops usually found in the bottom loops of the superheater and is result of of the superheater and is result of the exposure of water or the exposure of water or condensate that forms in the bends condensate that forms in the bends after shutdown in contact with air after shutdown in contact with air The distress is seen as pitting and The distress is seen as pitting and corrosion of the wetted internal corrosion of the wetted internal surfacessurfaces
Carry over-Carry over-
bull The cause for carry over is an The cause for carry over is an incomplete separation of the steam incomplete separation of the steam from the steamwater mixture in the from the steamwater mixture in the boiler Possible causes of carry over boiler Possible causes of carry over are high water level high total are high water level high total dissolved solids concentration in the dissolved solids concentration in the boiler water excessive alkalinity and boiler water excessive alkalinity and the presence of oil andor organics the presence of oil andor organics The result of carry over is a build up of The result of carry over is a build up of contaminates on the inner surface of contaminates on the inner surface of the super heater tubesthe super heater tubes
Steam blanketing-Steam blanketing-
bull The cause for steam blanketing is an The cause for steam blanketing is an improper mass flow in the boiler tube improper mass flow in the boiler tube in relation to the heat input and in relation to the heat input and pressure Causing localized thinning in pressure Causing localized thinning in the tube This type of attack is the tube This type of attack is sometimes accompanied by a gross sometimes accompanied by a gross accumulation of corrosive product accumulation of corrosive product Steam blanketing is also referred to as Steam blanketing is also referred to as DNB (departure from nucleate boiling)DNB (departure from nucleate boiling)
Thinning of tube due to Thinning of tube due to steam blanketing-steam blanketing-
Hydrogen attack or Hydrogen attack or damage-damage-
bull This type of failure is found in high pressure units This type of failure is found in high pressure units A situation occurs when excessive deposits are A situation occurs when excessive deposits are present on the tube water side surface that permit present on the tube water side surface that permit boiler chemicals to concentrate under the deposit boiler chemicals to concentrate under the deposit and corrode the metal Hydrogen is formed which and corrode the metal Hydrogen is formed which permeates the metal structure and reacts with the permeates the metal structure and reacts with the carbon of the metal to form methane The methane carbon of the metal to form methane The methane molecule which is much larger than the carbon molecule which is much larger than the carbon atom Exerts pressure and causes the metal to atom Exerts pressure and causes the metal to rupture along the grain boundaries Ruptures are rupture along the grain boundaries Ruptures are violent sudden and can be disastrousviolent sudden and can be disastrous
bull 4H+C=CH44H+C=CH4
The effect of hydrogen The effect of hydrogen attack in tubes-attack in tubes-
Cold end corrosion-Cold end corrosion-
bull Cold-end corrosion will occur Cold-end corrosion will occur wherever the temperature of metal wherever the temperature of metal drops below the sulfuric acid dew drops below the sulfuric acid dew point of the flue gas It occurs in point of the flue gas It occurs in economizer air preheater economizer air preheater induced draft fan and stackinduced draft fan and stack
Soot blowers erosion-Soot blowers erosion-
bull A misdirected blower allows a high A misdirected blower allows a high velocity jet of steam or air carrying velocity jet of steam or air carrying condensed water droplets to condensed water droplets to impinge directed upon tube impinge directed upon tube surfaces rather than to be directed surfaces rather than to be directed between tubes Physical abrasion between tubes Physical abrasion and acceleration oxidation cause and acceleration oxidation cause metal loss Erosive thinning often metal loss Erosive thinning often leads to tube ruptureleads to tube rupture
Foaming-Foaming-
bull It is a condition in which It is a condition in which concentration of soluble salts create concentration of soluble salts create frothy bubbles in the steam space of frothy bubbles in the steam space of the boiler Foaming can form slugs the boiler Foaming can form slugs of water that can carried over into of water that can carried over into the steam systemthe steam system
How to remove a tube How to remove a tube sample for inspectionsample for inspection
When removing a tube When removing a tube sample-sample-
bull 1-the tube section should be dry saw 1-the tube section should be dry saw cut to prevent any slag andor cutting cut to prevent any slag andor cutting oil from contaminating the internal oil from contaminating the internal depositdeposit
bull 2-the sample should be cut 2-the sample should be cut approximately 8-10 inches above and approximately 8-10 inches above and below the affected areabelow the affected area
bull 3-the exact location should be 3-the exact location should be documented as follows-documented as follows-
bull A-tubes should be numbered and A-tubes should be numbered and counted from east to west and north counted from east to west and north to southto south
bull B-the wall (front rear right hand B-the wall (front rear right hand side left hand side) and elevation side left hand side) and elevation should be noted and marked on the should be noted and marked on the tubetube
bull C-an arrow should be marked to C-an arrow should be marked to indicate which end of sample is upindicate which end of sample is up
bull D-on a universal pressure unit the D-on a universal pressure unit the sample should be identified as sample should be identified as removed from the first second or removed from the first second or third passthird pass
Troubles associated to drums-
bull1048698 Loss of level gauges
bull1048698 water level controllers out of service
bull1048698 corrosion
bull1048698 moisture carry-over in the steam
bull1048698 safety valves leaking
bull1048698 leaks of roll-expanded evaporator
bullTubes
bull1048698 plugging of evaporator tubes
Trouble associated to air Trouble associated to air heaters-heaters-
bull1048698 Leakages due to damaged axial or circumferential seals
bull1048698 Cold end baskets damaged by acid corrosion
bull1048698 Poor sootblowing
bull1048698 Standby pneumatic or DC motor not working or absent
New application in air New application in air heater-heater-
The modification-The modification-
bull We used to manufacture the air We used to manufacture the air heater basket material from heater basket material from carbon steel or Corten steel now carbon steel or Corten steel now they add a new material called they add a new material called enamel to improve quality reduce enamel to improve quality reduce cost and extend service life for air cost and extend service life for air and gas heater which increase the and gas heater which increase the existing of elementexisting of element
The material composition of The material composition of enamel-enamel-
bull The enamel layer is basically The enamel layer is basically composed by a borosilicate glass plus composed by a borosilicate glass plus cobalt fluorine sodium potassium cobalt fluorine sodium potassium quartz titanium borax helliphellipquartz titanium borax helliphellip
The benefits of enamel The benefits of enamel coating include-coating include-
bull 1-greater resistance to the attack of 1-greater resistance to the attack of acidsacids
bull 2-abrasive and wear resistance2-abrasive and wear resistance
bull 3-high mechanical and thermal shock 3-high mechanical and thermal shock resistanceresistance
bull 4-high resistance to erosion by fly ash4-high resistance to erosion by fly ash
bull 5-smooth and vitreous surface reduces 5-smooth and vitreous surface reduces adhesion of solidsadhesion of solids
The EndThe End
bullGood luckGood luck
Short time overheating failure
Failures due to scale and Failures due to scale and long term creep failure-long term creep failure-
bull The cause of this type of failure is build-up of The cause of this type of failure is build-up of internal scale that leads to gradual increase in internal scale that leads to gradual increase in temperature of the tube metal The tube may temperature of the tube metal The tube may appear swollen with blisters or bulges The out appear swollen with blisters or bulges The out side surface may have an elephant hide side surface may have an elephant hide appearance Rupture are a thin opening a long appearance Rupture are a thin opening a long the longitudinal axis of the tube The edges of the longitudinal axis of the tube The edges of the failure do not generally experience thinning the failure do not generally experience thinning
Long time overheating failure
Ash corrosion -Ash corrosion -
bull Ash corrosion result in a thinning of Ash corrosion result in a thinning of super heater and reheater tubing super heater and reheater tubing External wastage of the metal occurs External wastage of the metal occurs where ash deposits accumulate When where ash deposits accumulate When ash deposits on the tube and ash deposits on the tube and experiences high temperatures It experiences high temperatures It becomes semi-molten and corrodes becomes semi-molten and corrodes most alloy steels that might be used in most alloy steels that might be used in super heater constructionsuper heater construction
Corrosion by molten ashCorrosion by molten ash
Oxygen pitting Oxygen pitting (Economizer)-(Economizer)-bull In-service oxygen pitting appears as random In-service oxygen pitting appears as random
Round bottomed pits on the water side of Round bottomed pits on the water side of tubes in the economizer If there is no tubes in the economizer If there is no economizer similar pitting may be present at economizer similar pitting may be present at or above normal water level in the steam or above normal water level in the steam drum Proper mechanical deaeration of feed drum Proper mechanical deaeration of feed water is absolutely essential for protection of water is absolutely essential for protection of the pre-boiler equipment ( feed water heater the pre-boiler equipment ( feed water heater piping) and the economizer The addition of piping) and the economizer The addition of an oxygen scavenger such as hydrazine to an oxygen scavenger such as hydrazine to the deaerator storage tank will permit the deaerator storage tank will permit removal of minute quantities of dissolved removal of minute quantities of dissolved oxygenoxygen
Oxygen pitting Oxygen pitting (superheater)-(superheater)-
bull Out-of-service oxygen pitting is Out-of-service oxygen pitting is usually found in the bottom loops usually found in the bottom loops of the superheater and is result of of the superheater and is result of the exposure of water or the exposure of water or condensate that forms in the bends condensate that forms in the bends after shutdown in contact with air after shutdown in contact with air The distress is seen as pitting and The distress is seen as pitting and corrosion of the wetted internal corrosion of the wetted internal surfacessurfaces
Carry over-Carry over-
bull The cause for carry over is an The cause for carry over is an incomplete separation of the steam incomplete separation of the steam from the steamwater mixture in the from the steamwater mixture in the boiler Possible causes of carry over boiler Possible causes of carry over are high water level high total are high water level high total dissolved solids concentration in the dissolved solids concentration in the boiler water excessive alkalinity and boiler water excessive alkalinity and the presence of oil andor organics the presence of oil andor organics The result of carry over is a build up of The result of carry over is a build up of contaminates on the inner surface of contaminates on the inner surface of the super heater tubesthe super heater tubes
Steam blanketing-Steam blanketing-
bull The cause for steam blanketing is an The cause for steam blanketing is an improper mass flow in the boiler tube improper mass flow in the boiler tube in relation to the heat input and in relation to the heat input and pressure Causing localized thinning in pressure Causing localized thinning in the tube This type of attack is the tube This type of attack is sometimes accompanied by a gross sometimes accompanied by a gross accumulation of corrosive product accumulation of corrosive product Steam blanketing is also referred to as Steam blanketing is also referred to as DNB (departure from nucleate boiling)DNB (departure from nucleate boiling)
Thinning of tube due to Thinning of tube due to steam blanketing-steam blanketing-
Hydrogen attack or Hydrogen attack or damage-damage-
bull This type of failure is found in high pressure units This type of failure is found in high pressure units A situation occurs when excessive deposits are A situation occurs when excessive deposits are present on the tube water side surface that permit present on the tube water side surface that permit boiler chemicals to concentrate under the deposit boiler chemicals to concentrate under the deposit and corrode the metal Hydrogen is formed which and corrode the metal Hydrogen is formed which permeates the metal structure and reacts with the permeates the metal structure and reacts with the carbon of the metal to form methane The methane carbon of the metal to form methane The methane molecule which is much larger than the carbon molecule which is much larger than the carbon atom Exerts pressure and causes the metal to atom Exerts pressure and causes the metal to rupture along the grain boundaries Ruptures are rupture along the grain boundaries Ruptures are violent sudden and can be disastrousviolent sudden and can be disastrous
bull 4H+C=CH44H+C=CH4
The effect of hydrogen The effect of hydrogen attack in tubes-attack in tubes-
Cold end corrosion-Cold end corrosion-
bull Cold-end corrosion will occur Cold-end corrosion will occur wherever the temperature of metal wherever the temperature of metal drops below the sulfuric acid dew drops below the sulfuric acid dew point of the flue gas It occurs in point of the flue gas It occurs in economizer air preheater economizer air preheater induced draft fan and stackinduced draft fan and stack
Soot blowers erosion-Soot blowers erosion-
bull A misdirected blower allows a high A misdirected blower allows a high velocity jet of steam or air carrying velocity jet of steam or air carrying condensed water droplets to condensed water droplets to impinge directed upon tube impinge directed upon tube surfaces rather than to be directed surfaces rather than to be directed between tubes Physical abrasion between tubes Physical abrasion and acceleration oxidation cause and acceleration oxidation cause metal loss Erosive thinning often metal loss Erosive thinning often leads to tube ruptureleads to tube rupture
Foaming-Foaming-
bull It is a condition in which It is a condition in which concentration of soluble salts create concentration of soluble salts create frothy bubbles in the steam space of frothy bubbles in the steam space of the boiler Foaming can form slugs the boiler Foaming can form slugs of water that can carried over into of water that can carried over into the steam systemthe steam system
How to remove a tube How to remove a tube sample for inspectionsample for inspection
When removing a tube When removing a tube sample-sample-
bull 1-the tube section should be dry saw 1-the tube section should be dry saw cut to prevent any slag andor cutting cut to prevent any slag andor cutting oil from contaminating the internal oil from contaminating the internal depositdeposit
bull 2-the sample should be cut 2-the sample should be cut approximately 8-10 inches above and approximately 8-10 inches above and below the affected areabelow the affected area
bull 3-the exact location should be 3-the exact location should be documented as follows-documented as follows-
bull A-tubes should be numbered and A-tubes should be numbered and counted from east to west and north counted from east to west and north to southto south
bull B-the wall (front rear right hand B-the wall (front rear right hand side left hand side) and elevation side left hand side) and elevation should be noted and marked on the should be noted and marked on the tubetube
bull C-an arrow should be marked to C-an arrow should be marked to indicate which end of sample is upindicate which end of sample is up
bull D-on a universal pressure unit the D-on a universal pressure unit the sample should be identified as sample should be identified as removed from the first second or removed from the first second or third passthird pass
Troubles associated to drums-
bull1048698 Loss of level gauges
bull1048698 water level controllers out of service
bull1048698 corrosion
bull1048698 moisture carry-over in the steam
bull1048698 safety valves leaking
bull1048698 leaks of roll-expanded evaporator
bullTubes
bull1048698 plugging of evaporator tubes
Trouble associated to air Trouble associated to air heaters-heaters-
bull1048698 Leakages due to damaged axial or circumferential seals
bull1048698 Cold end baskets damaged by acid corrosion
bull1048698 Poor sootblowing
bull1048698 Standby pneumatic or DC motor not working or absent
New application in air New application in air heater-heater-
The modification-The modification-
bull We used to manufacture the air We used to manufacture the air heater basket material from heater basket material from carbon steel or Corten steel now carbon steel or Corten steel now they add a new material called they add a new material called enamel to improve quality reduce enamel to improve quality reduce cost and extend service life for air cost and extend service life for air and gas heater which increase the and gas heater which increase the existing of elementexisting of element
The material composition of The material composition of enamel-enamel-
bull The enamel layer is basically The enamel layer is basically composed by a borosilicate glass plus composed by a borosilicate glass plus cobalt fluorine sodium potassium cobalt fluorine sodium potassium quartz titanium borax helliphellipquartz titanium borax helliphellip
The benefits of enamel The benefits of enamel coating include-coating include-
bull 1-greater resistance to the attack of 1-greater resistance to the attack of acidsacids
bull 2-abrasive and wear resistance2-abrasive and wear resistance
bull 3-high mechanical and thermal shock 3-high mechanical and thermal shock resistanceresistance
bull 4-high resistance to erosion by fly ash4-high resistance to erosion by fly ash
bull 5-smooth and vitreous surface reduces 5-smooth and vitreous surface reduces adhesion of solidsadhesion of solids
The EndThe End
bullGood luckGood luck
Failures due to scale and Failures due to scale and long term creep failure-long term creep failure-
bull The cause of this type of failure is build-up of The cause of this type of failure is build-up of internal scale that leads to gradual increase in internal scale that leads to gradual increase in temperature of the tube metal The tube may temperature of the tube metal The tube may appear swollen with blisters or bulges The out appear swollen with blisters or bulges The out side surface may have an elephant hide side surface may have an elephant hide appearance Rupture are a thin opening a long appearance Rupture are a thin opening a long the longitudinal axis of the tube The edges of the longitudinal axis of the tube The edges of the failure do not generally experience thinning the failure do not generally experience thinning
Long time overheating failure
Ash corrosion -Ash corrosion -
bull Ash corrosion result in a thinning of Ash corrosion result in a thinning of super heater and reheater tubing super heater and reheater tubing External wastage of the metal occurs External wastage of the metal occurs where ash deposits accumulate When where ash deposits accumulate When ash deposits on the tube and ash deposits on the tube and experiences high temperatures It experiences high temperatures It becomes semi-molten and corrodes becomes semi-molten and corrodes most alloy steels that might be used in most alloy steels that might be used in super heater constructionsuper heater construction
Corrosion by molten ashCorrosion by molten ash
Oxygen pitting Oxygen pitting (Economizer)-(Economizer)-bull In-service oxygen pitting appears as random In-service oxygen pitting appears as random
Round bottomed pits on the water side of Round bottomed pits on the water side of tubes in the economizer If there is no tubes in the economizer If there is no economizer similar pitting may be present at economizer similar pitting may be present at or above normal water level in the steam or above normal water level in the steam drum Proper mechanical deaeration of feed drum Proper mechanical deaeration of feed water is absolutely essential for protection of water is absolutely essential for protection of the pre-boiler equipment ( feed water heater the pre-boiler equipment ( feed water heater piping) and the economizer The addition of piping) and the economizer The addition of an oxygen scavenger such as hydrazine to an oxygen scavenger such as hydrazine to the deaerator storage tank will permit the deaerator storage tank will permit removal of minute quantities of dissolved removal of minute quantities of dissolved oxygenoxygen
Oxygen pitting Oxygen pitting (superheater)-(superheater)-
bull Out-of-service oxygen pitting is Out-of-service oxygen pitting is usually found in the bottom loops usually found in the bottom loops of the superheater and is result of of the superheater and is result of the exposure of water or the exposure of water or condensate that forms in the bends condensate that forms in the bends after shutdown in contact with air after shutdown in contact with air The distress is seen as pitting and The distress is seen as pitting and corrosion of the wetted internal corrosion of the wetted internal surfacessurfaces
Carry over-Carry over-
bull The cause for carry over is an The cause for carry over is an incomplete separation of the steam incomplete separation of the steam from the steamwater mixture in the from the steamwater mixture in the boiler Possible causes of carry over boiler Possible causes of carry over are high water level high total are high water level high total dissolved solids concentration in the dissolved solids concentration in the boiler water excessive alkalinity and boiler water excessive alkalinity and the presence of oil andor organics the presence of oil andor organics The result of carry over is a build up of The result of carry over is a build up of contaminates on the inner surface of contaminates on the inner surface of the super heater tubesthe super heater tubes
Steam blanketing-Steam blanketing-
bull The cause for steam blanketing is an The cause for steam blanketing is an improper mass flow in the boiler tube improper mass flow in the boiler tube in relation to the heat input and in relation to the heat input and pressure Causing localized thinning in pressure Causing localized thinning in the tube This type of attack is the tube This type of attack is sometimes accompanied by a gross sometimes accompanied by a gross accumulation of corrosive product accumulation of corrosive product Steam blanketing is also referred to as Steam blanketing is also referred to as DNB (departure from nucleate boiling)DNB (departure from nucleate boiling)
Thinning of tube due to Thinning of tube due to steam blanketing-steam blanketing-
Hydrogen attack or Hydrogen attack or damage-damage-
bull This type of failure is found in high pressure units This type of failure is found in high pressure units A situation occurs when excessive deposits are A situation occurs when excessive deposits are present on the tube water side surface that permit present on the tube water side surface that permit boiler chemicals to concentrate under the deposit boiler chemicals to concentrate under the deposit and corrode the metal Hydrogen is formed which and corrode the metal Hydrogen is formed which permeates the metal structure and reacts with the permeates the metal structure and reacts with the carbon of the metal to form methane The methane carbon of the metal to form methane The methane molecule which is much larger than the carbon molecule which is much larger than the carbon atom Exerts pressure and causes the metal to atom Exerts pressure and causes the metal to rupture along the grain boundaries Ruptures are rupture along the grain boundaries Ruptures are violent sudden and can be disastrousviolent sudden and can be disastrous
bull 4H+C=CH44H+C=CH4
The effect of hydrogen The effect of hydrogen attack in tubes-attack in tubes-
Cold end corrosion-Cold end corrosion-
bull Cold-end corrosion will occur Cold-end corrosion will occur wherever the temperature of metal wherever the temperature of metal drops below the sulfuric acid dew drops below the sulfuric acid dew point of the flue gas It occurs in point of the flue gas It occurs in economizer air preheater economizer air preheater induced draft fan and stackinduced draft fan and stack
Soot blowers erosion-Soot blowers erosion-
bull A misdirected blower allows a high A misdirected blower allows a high velocity jet of steam or air carrying velocity jet of steam or air carrying condensed water droplets to condensed water droplets to impinge directed upon tube impinge directed upon tube surfaces rather than to be directed surfaces rather than to be directed between tubes Physical abrasion between tubes Physical abrasion and acceleration oxidation cause and acceleration oxidation cause metal loss Erosive thinning often metal loss Erosive thinning often leads to tube ruptureleads to tube rupture
Foaming-Foaming-
bull It is a condition in which It is a condition in which concentration of soluble salts create concentration of soluble salts create frothy bubbles in the steam space of frothy bubbles in the steam space of the boiler Foaming can form slugs the boiler Foaming can form slugs of water that can carried over into of water that can carried over into the steam systemthe steam system
How to remove a tube How to remove a tube sample for inspectionsample for inspection
When removing a tube When removing a tube sample-sample-
bull 1-the tube section should be dry saw 1-the tube section should be dry saw cut to prevent any slag andor cutting cut to prevent any slag andor cutting oil from contaminating the internal oil from contaminating the internal depositdeposit
bull 2-the sample should be cut 2-the sample should be cut approximately 8-10 inches above and approximately 8-10 inches above and below the affected areabelow the affected area
bull 3-the exact location should be 3-the exact location should be documented as follows-documented as follows-
bull A-tubes should be numbered and A-tubes should be numbered and counted from east to west and north counted from east to west and north to southto south
bull B-the wall (front rear right hand B-the wall (front rear right hand side left hand side) and elevation side left hand side) and elevation should be noted and marked on the should be noted and marked on the tubetube
bull C-an arrow should be marked to C-an arrow should be marked to indicate which end of sample is upindicate which end of sample is up
bull D-on a universal pressure unit the D-on a universal pressure unit the sample should be identified as sample should be identified as removed from the first second or removed from the first second or third passthird pass
Troubles associated to drums-
bull1048698 Loss of level gauges
bull1048698 water level controllers out of service
bull1048698 corrosion
bull1048698 moisture carry-over in the steam
bull1048698 safety valves leaking
bull1048698 leaks of roll-expanded evaporator
bullTubes
bull1048698 plugging of evaporator tubes
Trouble associated to air Trouble associated to air heaters-heaters-
bull1048698 Leakages due to damaged axial or circumferential seals
bull1048698 Cold end baskets damaged by acid corrosion
bull1048698 Poor sootblowing
bull1048698 Standby pneumatic or DC motor not working or absent
New application in air New application in air heater-heater-
The modification-The modification-
bull We used to manufacture the air We used to manufacture the air heater basket material from heater basket material from carbon steel or Corten steel now carbon steel or Corten steel now they add a new material called they add a new material called enamel to improve quality reduce enamel to improve quality reduce cost and extend service life for air cost and extend service life for air and gas heater which increase the and gas heater which increase the existing of elementexisting of element
The material composition of The material composition of enamel-enamel-
bull The enamel layer is basically The enamel layer is basically composed by a borosilicate glass plus composed by a borosilicate glass plus cobalt fluorine sodium potassium cobalt fluorine sodium potassium quartz titanium borax helliphellipquartz titanium borax helliphellip
The benefits of enamel The benefits of enamel coating include-coating include-
bull 1-greater resistance to the attack of 1-greater resistance to the attack of acidsacids
bull 2-abrasive and wear resistance2-abrasive and wear resistance
bull 3-high mechanical and thermal shock 3-high mechanical and thermal shock resistanceresistance
bull 4-high resistance to erosion by fly ash4-high resistance to erosion by fly ash
bull 5-smooth and vitreous surface reduces 5-smooth and vitreous surface reduces adhesion of solidsadhesion of solids
The EndThe End
bullGood luckGood luck
Long time overheating failure
Ash corrosion -Ash corrosion -
bull Ash corrosion result in a thinning of Ash corrosion result in a thinning of super heater and reheater tubing super heater and reheater tubing External wastage of the metal occurs External wastage of the metal occurs where ash deposits accumulate When where ash deposits accumulate When ash deposits on the tube and ash deposits on the tube and experiences high temperatures It experiences high temperatures It becomes semi-molten and corrodes becomes semi-molten and corrodes most alloy steels that might be used in most alloy steels that might be used in super heater constructionsuper heater construction
Corrosion by molten ashCorrosion by molten ash
Oxygen pitting Oxygen pitting (Economizer)-(Economizer)-bull In-service oxygen pitting appears as random In-service oxygen pitting appears as random
Round bottomed pits on the water side of Round bottomed pits on the water side of tubes in the economizer If there is no tubes in the economizer If there is no economizer similar pitting may be present at economizer similar pitting may be present at or above normal water level in the steam or above normal water level in the steam drum Proper mechanical deaeration of feed drum Proper mechanical deaeration of feed water is absolutely essential for protection of water is absolutely essential for protection of the pre-boiler equipment ( feed water heater the pre-boiler equipment ( feed water heater piping) and the economizer The addition of piping) and the economizer The addition of an oxygen scavenger such as hydrazine to an oxygen scavenger such as hydrazine to the deaerator storage tank will permit the deaerator storage tank will permit removal of minute quantities of dissolved removal of minute quantities of dissolved oxygenoxygen
Oxygen pitting Oxygen pitting (superheater)-(superheater)-
bull Out-of-service oxygen pitting is Out-of-service oxygen pitting is usually found in the bottom loops usually found in the bottom loops of the superheater and is result of of the superheater and is result of the exposure of water or the exposure of water or condensate that forms in the bends condensate that forms in the bends after shutdown in contact with air after shutdown in contact with air The distress is seen as pitting and The distress is seen as pitting and corrosion of the wetted internal corrosion of the wetted internal surfacessurfaces
Carry over-Carry over-
bull The cause for carry over is an The cause for carry over is an incomplete separation of the steam incomplete separation of the steam from the steamwater mixture in the from the steamwater mixture in the boiler Possible causes of carry over boiler Possible causes of carry over are high water level high total are high water level high total dissolved solids concentration in the dissolved solids concentration in the boiler water excessive alkalinity and boiler water excessive alkalinity and the presence of oil andor organics the presence of oil andor organics The result of carry over is a build up of The result of carry over is a build up of contaminates on the inner surface of contaminates on the inner surface of the super heater tubesthe super heater tubes
Steam blanketing-Steam blanketing-
bull The cause for steam blanketing is an The cause for steam blanketing is an improper mass flow in the boiler tube improper mass flow in the boiler tube in relation to the heat input and in relation to the heat input and pressure Causing localized thinning in pressure Causing localized thinning in the tube This type of attack is the tube This type of attack is sometimes accompanied by a gross sometimes accompanied by a gross accumulation of corrosive product accumulation of corrosive product Steam blanketing is also referred to as Steam blanketing is also referred to as DNB (departure from nucleate boiling)DNB (departure from nucleate boiling)
Thinning of tube due to Thinning of tube due to steam blanketing-steam blanketing-
Hydrogen attack or Hydrogen attack or damage-damage-
bull This type of failure is found in high pressure units This type of failure is found in high pressure units A situation occurs when excessive deposits are A situation occurs when excessive deposits are present on the tube water side surface that permit present on the tube water side surface that permit boiler chemicals to concentrate under the deposit boiler chemicals to concentrate under the deposit and corrode the metal Hydrogen is formed which and corrode the metal Hydrogen is formed which permeates the metal structure and reacts with the permeates the metal structure and reacts with the carbon of the metal to form methane The methane carbon of the metal to form methane The methane molecule which is much larger than the carbon molecule which is much larger than the carbon atom Exerts pressure and causes the metal to atom Exerts pressure and causes the metal to rupture along the grain boundaries Ruptures are rupture along the grain boundaries Ruptures are violent sudden and can be disastrousviolent sudden and can be disastrous
bull 4H+C=CH44H+C=CH4
The effect of hydrogen The effect of hydrogen attack in tubes-attack in tubes-
Cold end corrosion-Cold end corrosion-
bull Cold-end corrosion will occur Cold-end corrosion will occur wherever the temperature of metal wherever the temperature of metal drops below the sulfuric acid dew drops below the sulfuric acid dew point of the flue gas It occurs in point of the flue gas It occurs in economizer air preheater economizer air preheater induced draft fan and stackinduced draft fan and stack
Soot blowers erosion-Soot blowers erosion-
bull A misdirected blower allows a high A misdirected blower allows a high velocity jet of steam or air carrying velocity jet of steam or air carrying condensed water droplets to condensed water droplets to impinge directed upon tube impinge directed upon tube surfaces rather than to be directed surfaces rather than to be directed between tubes Physical abrasion between tubes Physical abrasion and acceleration oxidation cause and acceleration oxidation cause metal loss Erosive thinning often metal loss Erosive thinning often leads to tube ruptureleads to tube rupture
Foaming-Foaming-
bull It is a condition in which It is a condition in which concentration of soluble salts create concentration of soluble salts create frothy bubbles in the steam space of frothy bubbles in the steam space of the boiler Foaming can form slugs the boiler Foaming can form slugs of water that can carried over into of water that can carried over into the steam systemthe steam system
How to remove a tube How to remove a tube sample for inspectionsample for inspection
When removing a tube When removing a tube sample-sample-
bull 1-the tube section should be dry saw 1-the tube section should be dry saw cut to prevent any slag andor cutting cut to prevent any slag andor cutting oil from contaminating the internal oil from contaminating the internal depositdeposit
bull 2-the sample should be cut 2-the sample should be cut approximately 8-10 inches above and approximately 8-10 inches above and below the affected areabelow the affected area
bull 3-the exact location should be 3-the exact location should be documented as follows-documented as follows-
bull A-tubes should be numbered and A-tubes should be numbered and counted from east to west and north counted from east to west and north to southto south
bull B-the wall (front rear right hand B-the wall (front rear right hand side left hand side) and elevation side left hand side) and elevation should be noted and marked on the should be noted and marked on the tubetube
bull C-an arrow should be marked to C-an arrow should be marked to indicate which end of sample is upindicate which end of sample is up
bull D-on a universal pressure unit the D-on a universal pressure unit the sample should be identified as sample should be identified as removed from the first second or removed from the first second or third passthird pass
Troubles associated to drums-
bull1048698 Loss of level gauges
bull1048698 water level controllers out of service
bull1048698 corrosion
bull1048698 moisture carry-over in the steam
bull1048698 safety valves leaking
bull1048698 leaks of roll-expanded evaporator
bullTubes
bull1048698 plugging of evaporator tubes
Trouble associated to air Trouble associated to air heaters-heaters-
bull1048698 Leakages due to damaged axial or circumferential seals
bull1048698 Cold end baskets damaged by acid corrosion
bull1048698 Poor sootblowing
bull1048698 Standby pneumatic or DC motor not working or absent
New application in air New application in air heater-heater-
The modification-The modification-
bull We used to manufacture the air We used to manufacture the air heater basket material from heater basket material from carbon steel or Corten steel now carbon steel or Corten steel now they add a new material called they add a new material called enamel to improve quality reduce enamel to improve quality reduce cost and extend service life for air cost and extend service life for air and gas heater which increase the and gas heater which increase the existing of elementexisting of element
The material composition of The material composition of enamel-enamel-
bull The enamel layer is basically The enamel layer is basically composed by a borosilicate glass plus composed by a borosilicate glass plus cobalt fluorine sodium potassium cobalt fluorine sodium potassium quartz titanium borax helliphellipquartz titanium borax helliphellip
The benefits of enamel The benefits of enamel coating include-coating include-
bull 1-greater resistance to the attack of 1-greater resistance to the attack of acidsacids
bull 2-abrasive and wear resistance2-abrasive and wear resistance
bull 3-high mechanical and thermal shock 3-high mechanical and thermal shock resistanceresistance
bull 4-high resistance to erosion by fly ash4-high resistance to erosion by fly ash
bull 5-smooth and vitreous surface reduces 5-smooth and vitreous surface reduces adhesion of solidsadhesion of solids
The EndThe End
bullGood luckGood luck
Ash corrosion -Ash corrosion -
bull Ash corrosion result in a thinning of Ash corrosion result in a thinning of super heater and reheater tubing super heater and reheater tubing External wastage of the metal occurs External wastage of the metal occurs where ash deposits accumulate When where ash deposits accumulate When ash deposits on the tube and ash deposits on the tube and experiences high temperatures It experiences high temperatures It becomes semi-molten and corrodes becomes semi-molten and corrodes most alloy steels that might be used in most alloy steels that might be used in super heater constructionsuper heater construction
Corrosion by molten ashCorrosion by molten ash
Oxygen pitting Oxygen pitting (Economizer)-(Economizer)-bull In-service oxygen pitting appears as random In-service oxygen pitting appears as random
Round bottomed pits on the water side of Round bottomed pits on the water side of tubes in the economizer If there is no tubes in the economizer If there is no economizer similar pitting may be present at economizer similar pitting may be present at or above normal water level in the steam or above normal water level in the steam drum Proper mechanical deaeration of feed drum Proper mechanical deaeration of feed water is absolutely essential for protection of water is absolutely essential for protection of the pre-boiler equipment ( feed water heater the pre-boiler equipment ( feed water heater piping) and the economizer The addition of piping) and the economizer The addition of an oxygen scavenger such as hydrazine to an oxygen scavenger such as hydrazine to the deaerator storage tank will permit the deaerator storage tank will permit removal of minute quantities of dissolved removal of minute quantities of dissolved oxygenoxygen
Oxygen pitting Oxygen pitting (superheater)-(superheater)-
bull Out-of-service oxygen pitting is Out-of-service oxygen pitting is usually found in the bottom loops usually found in the bottom loops of the superheater and is result of of the superheater and is result of the exposure of water or the exposure of water or condensate that forms in the bends condensate that forms in the bends after shutdown in contact with air after shutdown in contact with air The distress is seen as pitting and The distress is seen as pitting and corrosion of the wetted internal corrosion of the wetted internal surfacessurfaces
Carry over-Carry over-
bull The cause for carry over is an The cause for carry over is an incomplete separation of the steam incomplete separation of the steam from the steamwater mixture in the from the steamwater mixture in the boiler Possible causes of carry over boiler Possible causes of carry over are high water level high total are high water level high total dissolved solids concentration in the dissolved solids concentration in the boiler water excessive alkalinity and boiler water excessive alkalinity and the presence of oil andor organics the presence of oil andor organics The result of carry over is a build up of The result of carry over is a build up of contaminates on the inner surface of contaminates on the inner surface of the super heater tubesthe super heater tubes
Steam blanketing-Steam blanketing-
bull The cause for steam blanketing is an The cause for steam blanketing is an improper mass flow in the boiler tube improper mass flow in the boiler tube in relation to the heat input and in relation to the heat input and pressure Causing localized thinning in pressure Causing localized thinning in the tube This type of attack is the tube This type of attack is sometimes accompanied by a gross sometimes accompanied by a gross accumulation of corrosive product accumulation of corrosive product Steam blanketing is also referred to as Steam blanketing is also referred to as DNB (departure from nucleate boiling)DNB (departure from nucleate boiling)
Thinning of tube due to Thinning of tube due to steam blanketing-steam blanketing-
Hydrogen attack or Hydrogen attack or damage-damage-
bull This type of failure is found in high pressure units This type of failure is found in high pressure units A situation occurs when excessive deposits are A situation occurs when excessive deposits are present on the tube water side surface that permit present on the tube water side surface that permit boiler chemicals to concentrate under the deposit boiler chemicals to concentrate under the deposit and corrode the metal Hydrogen is formed which and corrode the metal Hydrogen is formed which permeates the metal structure and reacts with the permeates the metal structure and reacts with the carbon of the metal to form methane The methane carbon of the metal to form methane The methane molecule which is much larger than the carbon molecule which is much larger than the carbon atom Exerts pressure and causes the metal to atom Exerts pressure and causes the metal to rupture along the grain boundaries Ruptures are rupture along the grain boundaries Ruptures are violent sudden and can be disastrousviolent sudden and can be disastrous
bull 4H+C=CH44H+C=CH4
The effect of hydrogen The effect of hydrogen attack in tubes-attack in tubes-
Cold end corrosion-Cold end corrosion-
bull Cold-end corrosion will occur Cold-end corrosion will occur wherever the temperature of metal wherever the temperature of metal drops below the sulfuric acid dew drops below the sulfuric acid dew point of the flue gas It occurs in point of the flue gas It occurs in economizer air preheater economizer air preheater induced draft fan and stackinduced draft fan and stack
Soot blowers erosion-Soot blowers erosion-
bull A misdirected blower allows a high A misdirected blower allows a high velocity jet of steam or air carrying velocity jet of steam or air carrying condensed water droplets to condensed water droplets to impinge directed upon tube impinge directed upon tube surfaces rather than to be directed surfaces rather than to be directed between tubes Physical abrasion between tubes Physical abrasion and acceleration oxidation cause and acceleration oxidation cause metal loss Erosive thinning often metal loss Erosive thinning often leads to tube ruptureleads to tube rupture
Foaming-Foaming-
bull It is a condition in which It is a condition in which concentration of soluble salts create concentration of soluble salts create frothy bubbles in the steam space of frothy bubbles in the steam space of the boiler Foaming can form slugs the boiler Foaming can form slugs of water that can carried over into of water that can carried over into the steam systemthe steam system
How to remove a tube How to remove a tube sample for inspectionsample for inspection
When removing a tube When removing a tube sample-sample-
bull 1-the tube section should be dry saw 1-the tube section should be dry saw cut to prevent any slag andor cutting cut to prevent any slag andor cutting oil from contaminating the internal oil from contaminating the internal depositdeposit
bull 2-the sample should be cut 2-the sample should be cut approximately 8-10 inches above and approximately 8-10 inches above and below the affected areabelow the affected area
bull 3-the exact location should be 3-the exact location should be documented as follows-documented as follows-
bull A-tubes should be numbered and A-tubes should be numbered and counted from east to west and north counted from east to west and north to southto south
bull B-the wall (front rear right hand B-the wall (front rear right hand side left hand side) and elevation side left hand side) and elevation should be noted and marked on the should be noted and marked on the tubetube
bull C-an arrow should be marked to C-an arrow should be marked to indicate which end of sample is upindicate which end of sample is up
bull D-on a universal pressure unit the D-on a universal pressure unit the sample should be identified as sample should be identified as removed from the first second or removed from the first second or third passthird pass
Troubles associated to drums-
bull1048698 Loss of level gauges
bull1048698 water level controllers out of service
bull1048698 corrosion
bull1048698 moisture carry-over in the steam
bull1048698 safety valves leaking
bull1048698 leaks of roll-expanded evaporator
bullTubes
bull1048698 plugging of evaporator tubes
Trouble associated to air Trouble associated to air heaters-heaters-
bull1048698 Leakages due to damaged axial or circumferential seals
bull1048698 Cold end baskets damaged by acid corrosion
bull1048698 Poor sootblowing
bull1048698 Standby pneumatic or DC motor not working or absent
New application in air New application in air heater-heater-
The modification-The modification-
bull We used to manufacture the air We used to manufacture the air heater basket material from heater basket material from carbon steel or Corten steel now carbon steel or Corten steel now they add a new material called they add a new material called enamel to improve quality reduce enamel to improve quality reduce cost and extend service life for air cost and extend service life for air and gas heater which increase the and gas heater which increase the existing of elementexisting of element
The material composition of The material composition of enamel-enamel-
bull The enamel layer is basically The enamel layer is basically composed by a borosilicate glass plus composed by a borosilicate glass plus cobalt fluorine sodium potassium cobalt fluorine sodium potassium quartz titanium borax helliphellipquartz titanium borax helliphellip
The benefits of enamel The benefits of enamel coating include-coating include-
bull 1-greater resistance to the attack of 1-greater resistance to the attack of acidsacids
bull 2-abrasive and wear resistance2-abrasive and wear resistance
bull 3-high mechanical and thermal shock 3-high mechanical and thermal shock resistanceresistance
bull 4-high resistance to erosion by fly ash4-high resistance to erosion by fly ash
bull 5-smooth and vitreous surface reduces 5-smooth and vitreous surface reduces adhesion of solidsadhesion of solids
The EndThe End
bullGood luckGood luck
Corrosion by molten ashCorrosion by molten ash
Oxygen pitting Oxygen pitting (Economizer)-(Economizer)-bull In-service oxygen pitting appears as random In-service oxygen pitting appears as random
Round bottomed pits on the water side of Round bottomed pits on the water side of tubes in the economizer If there is no tubes in the economizer If there is no economizer similar pitting may be present at economizer similar pitting may be present at or above normal water level in the steam or above normal water level in the steam drum Proper mechanical deaeration of feed drum Proper mechanical deaeration of feed water is absolutely essential for protection of water is absolutely essential for protection of the pre-boiler equipment ( feed water heater the pre-boiler equipment ( feed water heater piping) and the economizer The addition of piping) and the economizer The addition of an oxygen scavenger such as hydrazine to an oxygen scavenger such as hydrazine to the deaerator storage tank will permit the deaerator storage tank will permit removal of minute quantities of dissolved removal of minute quantities of dissolved oxygenoxygen
Oxygen pitting Oxygen pitting (superheater)-(superheater)-
bull Out-of-service oxygen pitting is Out-of-service oxygen pitting is usually found in the bottom loops usually found in the bottom loops of the superheater and is result of of the superheater and is result of the exposure of water or the exposure of water or condensate that forms in the bends condensate that forms in the bends after shutdown in contact with air after shutdown in contact with air The distress is seen as pitting and The distress is seen as pitting and corrosion of the wetted internal corrosion of the wetted internal surfacessurfaces
Carry over-Carry over-
bull The cause for carry over is an The cause for carry over is an incomplete separation of the steam incomplete separation of the steam from the steamwater mixture in the from the steamwater mixture in the boiler Possible causes of carry over boiler Possible causes of carry over are high water level high total are high water level high total dissolved solids concentration in the dissolved solids concentration in the boiler water excessive alkalinity and boiler water excessive alkalinity and the presence of oil andor organics the presence of oil andor organics The result of carry over is a build up of The result of carry over is a build up of contaminates on the inner surface of contaminates on the inner surface of the super heater tubesthe super heater tubes
Steam blanketing-Steam blanketing-
bull The cause for steam blanketing is an The cause for steam blanketing is an improper mass flow in the boiler tube improper mass flow in the boiler tube in relation to the heat input and in relation to the heat input and pressure Causing localized thinning in pressure Causing localized thinning in the tube This type of attack is the tube This type of attack is sometimes accompanied by a gross sometimes accompanied by a gross accumulation of corrosive product accumulation of corrosive product Steam blanketing is also referred to as Steam blanketing is also referred to as DNB (departure from nucleate boiling)DNB (departure from nucleate boiling)
Thinning of tube due to Thinning of tube due to steam blanketing-steam blanketing-
Hydrogen attack or Hydrogen attack or damage-damage-
bull This type of failure is found in high pressure units This type of failure is found in high pressure units A situation occurs when excessive deposits are A situation occurs when excessive deposits are present on the tube water side surface that permit present on the tube water side surface that permit boiler chemicals to concentrate under the deposit boiler chemicals to concentrate under the deposit and corrode the metal Hydrogen is formed which and corrode the metal Hydrogen is formed which permeates the metal structure and reacts with the permeates the metal structure and reacts with the carbon of the metal to form methane The methane carbon of the metal to form methane The methane molecule which is much larger than the carbon molecule which is much larger than the carbon atom Exerts pressure and causes the metal to atom Exerts pressure and causes the metal to rupture along the grain boundaries Ruptures are rupture along the grain boundaries Ruptures are violent sudden and can be disastrousviolent sudden and can be disastrous
bull 4H+C=CH44H+C=CH4
The effect of hydrogen The effect of hydrogen attack in tubes-attack in tubes-
Cold end corrosion-Cold end corrosion-
bull Cold-end corrosion will occur Cold-end corrosion will occur wherever the temperature of metal wherever the temperature of metal drops below the sulfuric acid dew drops below the sulfuric acid dew point of the flue gas It occurs in point of the flue gas It occurs in economizer air preheater economizer air preheater induced draft fan and stackinduced draft fan and stack
Soot blowers erosion-Soot blowers erosion-
bull A misdirected blower allows a high A misdirected blower allows a high velocity jet of steam or air carrying velocity jet of steam or air carrying condensed water droplets to condensed water droplets to impinge directed upon tube impinge directed upon tube surfaces rather than to be directed surfaces rather than to be directed between tubes Physical abrasion between tubes Physical abrasion and acceleration oxidation cause and acceleration oxidation cause metal loss Erosive thinning often metal loss Erosive thinning often leads to tube ruptureleads to tube rupture
Foaming-Foaming-
bull It is a condition in which It is a condition in which concentration of soluble salts create concentration of soluble salts create frothy bubbles in the steam space of frothy bubbles in the steam space of the boiler Foaming can form slugs the boiler Foaming can form slugs of water that can carried over into of water that can carried over into the steam systemthe steam system
How to remove a tube How to remove a tube sample for inspectionsample for inspection
When removing a tube When removing a tube sample-sample-
bull 1-the tube section should be dry saw 1-the tube section should be dry saw cut to prevent any slag andor cutting cut to prevent any slag andor cutting oil from contaminating the internal oil from contaminating the internal depositdeposit
bull 2-the sample should be cut 2-the sample should be cut approximately 8-10 inches above and approximately 8-10 inches above and below the affected areabelow the affected area
bull 3-the exact location should be 3-the exact location should be documented as follows-documented as follows-
bull A-tubes should be numbered and A-tubes should be numbered and counted from east to west and north counted from east to west and north to southto south
bull B-the wall (front rear right hand B-the wall (front rear right hand side left hand side) and elevation side left hand side) and elevation should be noted and marked on the should be noted and marked on the tubetube
bull C-an arrow should be marked to C-an arrow should be marked to indicate which end of sample is upindicate which end of sample is up
bull D-on a universal pressure unit the D-on a universal pressure unit the sample should be identified as sample should be identified as removed from the first second or removed from the first second or third passthird pass
Troubles associated to drums-
bull1048698 Loss of level gauges
bull1048698 water level controllers out of service
bull1048698 corrosion
bull1048698 moisture carry-over in the steam
bull1048698 safety valves leaking
bull1048698 leaks of roll-expanded evaporator
bullTubes
bull1048698 plugging of evaporator tubes
Trouble associated to air Trouble associated to air heaters-heaters-
bull1048698 Leakages due to damaged axial or circumferential seals
bull1048698 Cold end baskets damaged by acid corrosion
bull1048698 Poor sootblowing
bull1048698 Standby pneumatic or DC motor not working or absent
New application in air New application in air heater-heater-
The modification-The modification-
bull We used to manufacture the air We used to manufacture the air heater basket material from heater basket material from carbon steel or Corten steel now carbon steel or Corten steel now they add a new material called they add a new material called enamel to improve quality reduce enamel to improve quality reduce cost and extend service life for air cost and extend service life for air and gas heater which increase the and gas heater which increase the existing of elementexisting of element
The material composition of The material composition of enamel-enamel-
bull The enamel layer is basically The enamel layer is basically composed by a borosilicate glass plus composed by a borosilicate glass plus cobalt fluorine sodium potassium cobalt fluorine sodium potassium quartz titanium borax helliphellipquartz titanium borax helliphellip
The benefits of enamel The benefits of enamel coating include-coating include-
bull 1-greater resistance to the attack of 1-greater resistance to the attack of acidsacids
bull 2-abrasive and wear resistance2-abrasive and wear resistance
bull 3-high mechanical and thermal shock 3-high mechanical and thermal shock resistanceresistance
bull 4-high resistance to erosion by fly ash4-high resistance to erosion by fly ash
bull 5-smooth and vitreous surface reduces 5-smooth and vitreous surface reduces adhesion of solidsadhesion of solids
The EndThe End
bullGood luckGood luck
Oxygen pitting Oxygen pitting (Economizer)-(Economizer)-bull In-service oxygen pitting appears as random In-service oxygen pitting appears as random
Round bottomed pits on the water side of Round bottomed pits on the water side of tubes in the economizer If there is no tubes in the economizer If there is no economizer similar pitting may be present at economizer similar pitting may be present at or above normal water level in the steam or above normal water level in the steam drum Proper mechanical deaeration of feed drum Proper mechanical deaeration of feed water is absolutely essential for protection of water is absolutely essential for protection of the pre-boiler equipment ( feed water heater the pre-boiler equipment ( feed water heater piping) and the economizer The addition of piping) and the economizer The addition of an oxygen scavenger such as hydrazine to an oxygen scavenger such as hydrazine to the deaerator storage tank will permit the deaerator storage tank will permit removal of minute quantities of dissolved removal of minute quantities of dissolved oxygenoxygen
Oxygen pitting Oxygen pitting (superheater)-(superheater)-
bull Out-of-service oxygen pitting is Out-of-service oxygen pitting is usually found in the bottom loops usually found in the bottom loops of the superheater and is result of of the superheater and is result of the exposure of water or the exposure of water or condensate that forms in the bends condensate that forms in the bends after shutdown in contact with air after shutdown in contact with air The distress is seen as pitting and The distress is seen as pitting and corrosion of the wetted internal corrosion of the wetted internal surfacessurfaces
Carry over-Carry over-
bull The cause for carry over is an The cause for carry over is an incomplete separation of the steam incomplete separation of the steam from the steamwater mixture in the from the steamwater mixture in the boiler Possible causes of carry over boiler Possible causes of carry over are high water level high total are high water level high total dissolved solids concentration in the dissolved solids concentration in the boiler water excessive alkalinity and boiler water excessive alkalinity and the presence of oil andor organics the presence of oil andor organics The result of carry over is a build up of The result of carry over is a build up of contaminates on the inner surface of contaminates on the inner surface of the super heater tubesthe super heater tubes
Steam blanketing-Steam blanketing-
bull The cause for steam blanketing is an The cause for steam blanketing is an improper mass flow in the boiler tube improper mass flow in the boiler tube in relation to the heat input and in relation to the heat input and pressure Causing localized thinning in pressure Causing localized thinning in the tube This type of attack is the tube This type of attack is sometimes accompanied by a gross sometimes accompanied by a gross accumulation of corrosive product accumulation of corrosive product Steam blanketing is also referred to as Steam blanketing is also referred to as DNB (departure from nucleate boiling)DNB (departure from nucleate boiling)
Thinning of tube due to Thinning of tube due to steam blanketing-steam blanketing-
Hydrogen attack or Hydrogen attack or damage-damage-
bull This type of failure is found in high pressure units This type of failure is found in high pressure units A situation occurs when excessive deposits are A situation occurs when excessive deposits are present on the tube water side surface that permit present on the tube water side surface that permit boiler chemicals to concentrate under the deposit boiler chemicals to concentrate under the deposit and corrode the metal Hydrogen is formed which and corrode the metal Hydrogen is formed which permeates the metal structure and reacts with the permeates the metal structure and reacts with the carbon of the metal to form methane The methane carbon of the metal to form methane The methane molecule which is much larger than the carbon molecule which is much larger than the carbon atom Exerts pressure and causes the metal to atom Exerts pressure and causes the metal to rupture along the grain boundaries Ruptures are rupture along the grain boundaries Ruptures are violent sudden and can be disastrousviolent sudden and can be disastrous
bull 4H+C=CH44H+C=CH4
The effect of hydrogen The effect of hydrogen attack in tubes-attack in tubes-
Cold end corrosion-Cold end corrosion-
bull Cold-end corrosion will occur Cold-end corrosion will occur wherever the temperature of metal wherever the temperature of metal drops below the sulfuric acid dew drops below the sulfuric acid dew point of the flue gas It occurs in point of the flue gas It occurs in economizer air preheater economizer air preheater induced draft fan and stackinduced draft fan and stack
Soot blowers erosion-Soot blowers erosion-
bull A misdirected blower allows a high A misdirected blower allows a high velocity jet of steam or air carrying velocity jet of steam or air carrying condensed water droplets to condensed water droplets to impinge directed upon tube impinge directed upon tube surfaces rather than to be directed surfaces rather than to be directed between tubes Physical abrasion between tubes Physical abrasion and acceleration oxidation cause and acceleration oxidation cause metal loss Erosive thinning often metal loss Erosive thinning often leads to tube ruptureleads to tube rupture
Foaming-Foaming-
bull It is a condition in which It is a condition in which concentration of soluble salts create concentration of soluble salts create frothy bubbles in the steam space of frothy bubbles in the steam space of the boiler Foaming can form slugs the boiler Foaming can form slugs of water that can carried over into of water that can carried over into the steam systemthe steam system
How to remove a tube How to remove a tube sample for inspectionsample for inspection
When removing a tube When removing a tube sample-sample-
bull 1-the tube section should be dry saw 1-the tube section should be dry saw cut to prevent any slag andor cutting cut to prevent any slag andor cutting oil from contaminating the internal oil from contaminating the internal depositdeposit
bull 2-the sample should be cut 2-the sample should be cut approximately 8-10 inches above and approximately 8-10 inches above and below the affected areabelow the affected area
bull 3-the exact location should be 3-the exact location should be documented as follows-documented as follows-
bull A-tubes should be numbered and A-tubes should be numbered and counted from east to west and north counted from east to west and north to southto south
bull B-the wall (front rear right hand B-the wall (front rear right hand side left hand side) and elevation side left hand side) and elevation should be noted and marked on the should be noted and marked on the tubetube
bull C-an arrow should be marked to C-an arrow should be marked to indicate which end of sample is upindicate which end of sample is up
bull D-on a universal pressure unit the D-on a universal pressure unit the sample should be identified as sample should be identified as removed from the first second or removed from the first second or third passthird pass
Troubles associated to drums-
bull1048698 Loss of level gauges
bull1048698 water level controllers out of service
bull1048698 corrosion
bull1048698 moisture carry-over in the steam
bull1048698 safety valves leaking
bull1048698 leaks of roll-expanded evaporator
bullTubes
bull1048698 plugging of evaporator tubes
Trouble associated to air Trouble associated to air heaters-heaters-
bull1048698 Leakages due to damaged axial or circumferential seals
bull1048698 Cold end baskets damaged by acid corrosion
bull1048698 Poor sootblowing
bull1048698 Standby pneumatic or DC motor not working or absent
New application in air New application in air heater-heater-
The modification-The modification-
bull We used to manufacture the air We used to manufacture the air heater basket material from heater basket material from carbon steel or Corten steel now carbon steel or Corten steel now they add a new material called they add a new material called enamel to improve quality reduce enamel to improve quality reduce cost and extend service life for air cost and extend service life for air and gas heater which increase the and gas heater which increase the existing of elementexisting of element
The material composition of The material composition of enamel-enamel-
bull The enamel layer is basically The enamel layer is basically composed by a borosilicate glass plus composed by a borosilicate glass plus cobalt fluorine sodium potassium cobalt fluorine sodium potassium quartz titanium borax helliphellipquartz titanium borax helliphellip
The benefits of enamel The benefits of enamel coating include-coating include-
bull 1-greater resistance to the attack of 1-greater resistance to the attack of acidsacids
bull 2-abrasive and wear resistance2-abrasive and wear resistance
bull 3-high mechanical and thermal shock 3-high mechanical and thermal shock resistanceresistance
bull 4-high resistance to erosion by fly ash4-high resistance to erosion by fly ash
bull 5-smooth and vitreous surface reduces 5-smooth and vitreous surface reduces adhesion of solidsadhesion of solids
The EndThe End
bullGood luckGood luck
Oxygen pitting Oxygen pitting (superheater)-(superheater)-
bull Out-of-service oxygen pitting is Out-of-service oxygen pitting is usually found in the bottom loops usually found in the bottom loops of the superheater and is result of of the superheater and is result of the exposure of water or the exposure of water or condensate that forms in the bends condensate that forms in the bends after shutdown in contact with air after shutdown in contact with air The distress is seen as pitting and The distress is seen as pitting and corrosion of the wetted internal corrosion of the wetted internal surfacessurfaces
Carry over-Carry over-
bull The cause for carry over is an The cause for carry over is an incomplete separation of the steam incomplete separation of the steam from the steamwater mixture in the from the steamwater mixture in the boiler Possible causes of carry over boiler Possible causes of carry over are high water level high total are high water level high total dissolved solids concentration in the dissolved solids concentration in the boiler water excessive alkalinity and boiler water excessive alkalinity and the presence of oil andor organics the presence of oil andor organics The result of carry over is a build up of The result of carry over is a build up of contaminates on the inner surface of contaminates on the inner surface of the super heater tubesthe super heater tubes
Steam blanketing-Steam blanketing-
bull The cause for steam blanketing is an The cause for steam blanketing is an improper mass flow in the boiler tube improper mass flow in the boiler tube in relation to the heat input and in relation to the heat input and pressure Causing localized thinning in pressure Causing localized thinning in the tube This type of attack is the tube This type of attack is sometimes accompanied by a gross sometimes accompanied by a gross accumulation of corrosive product accumulation of corrosive product Steam blanketing is also referred to as Steam blanketing is also referred to as DNB (departure from nucleate boiling)DNB (departure from nucleate boiling)
Thinning of tube due to Thinning of tube due to steam blanketing-steam blanketing-
Hydrogen attack or Hydrogen attack or damage-damage-
bull This type of failure is found in high pressure units This type of failure is found in high pressure units A situation occurs when excessive deposits are A situation occurs when excessive deposits are present on the tube water side surface that permit present on the tube water side surface that permit boiler chemicals to concentrate under the deposit boiler chemicals to concentrate under the deposit and corrode the metal Hydrogen is formed which and corrode the metal Hydrogen is formed which permeates the metal structure and reacts with the permeates the metal structure and reacts with the carbon of the metal to form methane The methane carbon of the metal to form methane The methane molecule which is much larger than the carbon molecule which is much larger than the carbon atom Exerts pressure and causes the metal to atom Exerts pressure and causes the metal to rupture along the grain boundaries Ruptures are rupture along the grain boundaries Ruptures are violent sudden and can be disastrousviolent sudden and can be disastrous
bull 4H+C=CH44H+C=CH4
The effect of hydrogen The effect of hydrogen attack in tubes-attack in tubes-
Cold end corrosion-Cold end corrosion-
bull Cold-end corrosion will occur Cold-end corrosion will occur wherever the temperature of metal wherever the temperature of metal drops below the sulfuric acid dew drops below the sulfuric acid dew point of the flue gas It occurs in point of the flue gas It occurs in economizer air preheater economizer air preheater induced draft fan and stackinduced draft fan and stack
Soot blowers erosion-Soot blowers erosion-
bull A misdirected blower allows a high A misdirected blower allows a high velocity jet of steam or air carrying velocity jet of steam or air carrying condensed water droplets to condensed water droplets to impinge directed upon tube impinge directed upon tube surfaces rather than to be directed surfaces rather than to be directed between tubes Physical abrasion between tubes Physical abrasion and acceleration oxidation cause and acceleration oxidation cause metal loss Erosive thinning often metal loss Erosive thinning often leads to tube ruptureleads to tube rupture
Foaming-Foaming-
bull It is a condition in which It is a condition in which concentration of soluble salts create concentration of soluble salts create frothy bubbles in the steam space of frothy bubbles in the steam space of the boiler Foaming can form slugs the boiler Foaming can form slugs of water that can carried over into of water that can carried over into the steam systemthe steam system
How to remove a tube How to remove a tube sample for inspectionsample for inspection
When removing a tube When removing a tube sample-sample-
bull 1-the tube section should be dry saw 1-the tube section should be dry saw cut to prevent any slag andor cutting cut to prevent any slag andor cutting oil from contaminating the internal oil from contaminating the internal depositdeposit
bull 2-the sample should be cut 2-the sample should be cut approximately 8-10 inches above and approximately 8-10 inches above and below the affected areabelow the affected area
bull 3-the exact location should be 3-the exact location should be documented as follows-documented as follows-
bull A-tubes should be numbered and A-tubes should be numbered and counted from east to west and north counted from east to west and north to southto south
bull B-the wall (front rear right hand B-the wall (front rear right hand side left hand side) and elevation side left hand side) and elevation should be noted and marked on the should be noted and marked on the tubetube
bull C-an arrow should be marked to C-an arrow should be marked to indicate which end of sample is upindicate which end of sample is up
bull D-on a universal pressure unit the D-on a universal pressure unit the sample should be identified as sample should be identified as removed from the first second or removed from the first second or third passthird pass
Troubles associated to drums-
bull1048698 Loss of level gauges
bull1048698 water level controllers out of service
bull1048698 corrosion
bull1048698 moisture carry-over in the steam
bull1048698 safety valves leaking
bull1048698 leaks of roll-expanded evaporator
bullTubes
bull1048698 plugging of evaporator tubes
Trouble associated to air Trouble associated to air heaters-heaters-
bull1048698 Leakages due to damaged axial or circumferential seals
bull1048698 Cold end baskets damaged by acid corrosion
bull1048698 Poor sootblowing
bull1048698 Standby pneumatic or DC motor not working or absent
New application in air New application in air heater-heater-
The modification-The modification-
bull We used to manufacture the air We used to manufacture the air heater basket material from heater basket material from carbon steel or Corten steel now carbon steel or Corten steel now they add a new material called they add a new material called enamel to improve quality reduce enamel to improve quality reduce cost and extend service life for air cost and extend service life for air and gas heater which increase the and gas heater which increase the existing of elementexisting of element
The material composition of The material composition of enamel-enamel-
bull The enamel layer is basically The enamel layer is basically composed by a borosilicate glass plus composed by a borosilicate glass plus cobalt fluorine sodium potassium cobalt fluorine sodium potassium quartz titanium borax helliphellipquartz titanium borax helliphellip
The benefits of enamel The benefits of enamel coating include-coating include-
bull 1-greater resistance to the attack of 1-greater resistance to the attack of acidsacids
bull 2-abrasive and wear resistance2-abrasive and wear resistance
bull 3-high mechanical and thermal shock 3-high mechanical and thermal shock resistanceresistance
bull 4-high resistance to erosion by fly ash4-high resistance to erosion by fly ash
bull 5-smooth and vitreous surface reduces 5-smooth and vitreous surface reduces adhesion of solidsadhesion of solids
The EndThe End
bullGood luckGood luck
Carry over-Carry over-
bull The cause for carry over is an The cause for carry over is an incomplete separation of the steam incomplete separation of the steam from the steamwater mixture in the from the steamwater mixture in the boiler Possible causes of carry over boiler Possible causes of carry over are high water level high total are high water level high total dissolved solids concentration in the dissolved solids concentration in the boiler water excessive alkalinity and boiler water excessive alkalinity and the presence of oil andor organics the presence of oil andor organics The result of carry over is a build up of The result of carry over is a build up of contaminates on the inner surface of contaminates on the inner surface of the super heater tubesthe super heater tubes
Steam blanketing-Steam blanketing-
bull The cause for steam blanketing is an The cause for steam blanketing is an improper mass flow in the boiler tube improper mass flow in the boiler tube in relation to the heat input and in relation to the heat input and pressure Causing localized thinning in pressure Causing localized thinning in the tube This type of attack is the tube This type of attack is sometimes accompanied by a gross sometimes accompanied by a gross accumulation of corrosive product accumulation of corrosive product Steam blanketing is also referred to as Steam blanketing is also referred to as DNB (departure from nucleate boiling)DNB (departure from nucleate boiling)
Thinning of tube due to Thinning of tube due to steam blanketing-steam blanketing-
Hydrogen attack or Hydrogen attack or damage-damage-
bull This type of failure is found in high pressure units This type of failure is found in high pressure units A situation occurs when excessive deposits are A situation occurs when excessive deposits are present on the tube water side surface that permit present on the tube water side surface that permit boiler chemicals to concentrate under the deposit boiler chemicals to concentrate under the deposit and corrode the metal Hydrogen is formed which and corrode the metal Hydrogen is formed which permeates the metal structure and reacts with the permeates the metal structure and reacts with the carbon of the metal to form methane The methane carbon of the metal to form methane The methane molecule which is much larger than the carbon molecule which is much larger than the carbon atom Exerts pressure and causes the metal to atom Exerts pressure and causes the metal to rupture along the grain boundaries Ruptures are rupture along the grain boundaries Ruptures are violent sudden and can be disastrousviolent sudden and can be disastrous
bull 4H+C=CH44H+C=CH4
The effect of hydrogen The effect of hydrogen attack in tubes-attack in tubes-
Cold end corrosion-Cold end corrosion-
bull Cold-end corrosion will occur Cold-end corrosion will occur wherever the temperature of metal wherever the temperature of metal drops below the sulfuric acid dew drops below the sulfuric acid dew point of the flue gas It occurs in point of the flue gas It occurs in economizer air preheater economizer air preheater induced draft fan and stackinduced draft fan and stack
Soot blowers erosion-Soot blowers erosion-
bull A misdirected blower allows a high A misdirected blower allows a high velocity jet of steam or air carrying velocity jet of steam or air carrying condensed water droplets to condensed water droplets to impinge directed upon tube impinge directed upon tube surfaces rather than to be directed surfaces rather than to be directed between tubes Physical abrasion between tubes Physical abrasion and acceleration oxidation cause and acceleration oxidation cause metal loss Erosive thinning often metal loss Erosive thinning often leads to tube ruptureleads to tube rupture
Foaming-Foaming-
bull It is a condition in which It is a condition in which concentration of soluble salts create concentration of soluble salts create frothy bubbles in the steam space of frothy bubbles in the steam space of the boiler Foaming can form slugs the boiler Foaming can form slugs of water that can carried over into of water that can carried over into the steam systemthe steam system
How to remove a tube How to remove a tube sample for inspectionsample for inspection
When removing a tube When removing a tube sample-sample-
bull 1-the tube section should be dry saw 1-the tube section should be dry saw cut to prevent any slag andor cutting cut to prevent any slag andor cutting oil from contaminating the internal oil from contaminating the internal depositdeposit
bull 2-the sample should be cut 2-the sample should be cut approximately 8-10 inches above and approximately 8-10 inches above and below the affected areabelow the affected area
bull 3-the exact location should be 3-the exact location should be documented as follows-documented as follows-
bull A-tubes should be numbered and A-tubes should be numbered and counted from east to west and north counted from east to west and north to southto south
bull B-the wall (front rear right hand B-the wall (front rear right hand side left hand side) and elevation side left hand side) and elevation should be noted and marked on the should be noted and marked on the tubetube
bull C-an arrow should be marked to C-an arrow should be marked to indicate which end of sample is upindicate which end of sample is up
bull D-on a universal pressure unit the D-on a universal pressure unit the sample should be identified as sample should be identified as removed from the first second or removed from the first second or third passthird pass
Troubles associated to drums-
bull1048698 Loss of level gauges
bull1048698 water level controllers out of service
bull1048698 corrosion
bull1048698 moisture carry-over in the steam
bull1048698 safety valves leaking
bull1048698 leaks of roll-expanded evaporator
bullTubes
bull1048698 plugging of evaporator tubes
Trouble associated to air Trouble associated to air heaters-heaters-
bull1048698 Leakages due to damaged axial or circumferential seals
bull1048698 Cold end baskets damaged by acid corrosion
bull1048698 Poor sootblowing
bull1048698 Standby pneumatic or DC motor not working or absent
New application in air New application in air heater-heater-
The modification-The modification-
bull We used to manufacture the air We used to manufacture the air heater basket material from heater basket material from carbon steel or Corten steel now carbon steel or Corten steel now they add a new material called they add a new material called enamel to improve quality reduce enamel to improve quality reduce cost and extend service life for air cost and extend service life for air and gas heater which increase the and gas heater which increase the existing of elementexisting of element
The material composition of The material composition of enamel-enamel-
bull The enamel layer is basically The enamel layer is basically composed by a borosilicate glass plus composed by a borosilicate glass plus cobalt fluorine sodium potassium cobalt fluorine sodium potassium quartz titanium borax helliphellipquartz titanium borax helliphellip
The benefits of enamel The benefits of enamel coating include-coating include-
bull 1-greater resistance to the attack of 1-greater resistance to the attack of acidsacids
bull 2-abrasive and wear resistance2-abrasive and wear resistance
bull 3-high mechanical and thermal shock 3-high mechanical and thermal shock resistanceresistance
bull 4-high resistance to erosion by fly ash4-high resistance to erosion by fly ash
bull 5-smooth and vitreous surface reduces 5-smooth and vitreous surface reduces adhesion of solidsadhesion of solids
The EndThe End
bullGood luckGood luck
Steam blanketing-Steam blanketing-
bull The cause for steam blanketing is an The cause for steam blanketing is an improper mass flow in the boiler tube improper mass flow in the boiler tube in relation to the heat input and in relation to the heat input and pressure Causing localized thinning in pressure Causing localized thinning in the tube This type of attack is the tube This type of attack is sometimes accompanied by a gross sometimes accompanied by a gross accumulation of corrosive product accumulation of corrosive product Steam blanketing is also referred to as Steam blanketing is also referred to as DNB (departure from nucleate boiling)DNB (departure from nucleate boiling)
Thinning of tube due to Thinning of tube due to steam blanketing-steam blanketing-
Hydrogen attack or Hydrogen attack or damage-damage-
bull This type of failure is found in high pressure units This type of failure is found in high pressure units A situation occurs when excessive deposits are A situation occurs when excessive deposits are present on the tube water side surface that permit present on the tube water side surface that permit boiler chemicals to concentrate under the deposit boiler chemicals to concentrate under the deposit and corrode the metal Hydrogen is formed which and corrode the metal Hydrogen is formed which permeates the metal structure and reacts with the permeates the metal structure and reacts with the carbon of the metal to form methane The methane carbon of the metal to form methane The methane molecule which is much larger than the carbon molecule which is much larger than the carbon atom Exerts pressure and causes the metal to atom Exerts pressure and causes the metal to rupture along the grain boundaries Ruptures are rupture along the grain boundaries Ruptures are violent sudden and can be disastrousviolent sudden and can be disastrous
bull 4H+C=CH44H+C=CH4
The effect of hydrogen The effect of hydrogen attack in tubes-attack in tubes-
Cold end corrosion-Cold end corrosion-
bull Cold-end corrosion will occur Cold-end corrosion will occur wherever the temperature of metal wherever the temperature of metal drops below the sulfuric acid dew drops below the sulfuric acid dew point of the flue gas It occurs in point of the flue gas It occurs in economizer air preheater economizer air preheater induced draft fan and stackinduced draft fan and stack
Soot blowers erosion-Soot blowers erosion-
bull A misdirected blower allows a high A misdirected blower allows a high velocity jet of steam or air carrying velocity jet of steam or air carrying condensed water droplets to condensed water droplets to impinge directed upon tube impinge directed upon tube surfaces rather than to be directed surfaces rather than to be directed between tubes Physical abrasion between tubes Physical abrasion and acceleration oxidation cause and acceleration oxidation cause metal loss Erosive thinning often metal loss Erosive thinning often leads to tube ruptureleads to tube rupture
Foaming-Foaming-
bull It is a condition in which It is a condition in which concentration of soluble salts create concentration of soluble salts create frothy bubbles in the steam space of frothy bubbles in the steam space of the boiler Foaming can form slugs the boiler Foaming can form slugs of water that can carried over into of water that can carried over into the steam systemthe steam system
How to remove a tube How to remove a tube sample for inspectionsample for inspection
When removing a tube When removing a tube sample-sample-
bull 1-the tube section should be dry saw 1-the tube section should be dry saw cut to prevent any slag andor cutting cut to prevent any slag andor cutting oil from contaminating the internal oil from contaminating the internal depositdeposit
bull 2-the sample should be cut 2-the sample should be cut approximately 8-10 inches above and approximately 8-10 inches above and below the affected areabelow the affected area
bull 3-the exact location should be 3-the exact location should be documented as follows-documented as follows-
bull A-tubes should be numbered and A-tubes should be numbered and counted from east to west and north counted from east to west and north to southto south
bull B-the wall (front rear right hand B-the wall (front rear right hand side left hand side) and elevation side left hand side) and elevation should be noted and marked on the should be noted and marked on the tubetube
bull C-an arrow should be marked to C-an arrow should be marked to indicate which end of sample is upindicate which end of sample is up
bull D-on a universal pressure unit the D-on a universal pressure unit the sample should be identified as sample should be identified as removed from the first second or removed from the first second or third passthird pass
Troubles associated to drums-
bull1048698 Loss of level gauges
bull1048698 water level controllers out of service
bull1048698 corrosion
bull1048698 moisture carry-over in the steam
bull1048698 safety valves leaking
bull1048698 leaks of roll-expanded evaporator
bullTubes
bull1048698 plugging of evaporator tubes
Trouble associated to air Trouble associated to air heaters-heaters-
bull1048698 Leakages due to damaged axial or circumferential seals
bull1048698 Cold end baskets damaged by acid corrosion
bull1048698 Poor sootblowing
bull1048698 Standby pneumatic or DC motor not working or absent
New application in air New application in air heater-heater-
The modification-The modification-
bull We used to manufacture the air We used to manufacture the air heater basket material from heater basket material from carbon steel or Corten steel now carbon steel or Corten steel now they add a new material called they add a new material called enamel to improve quality reduce enamel to improve quality reduce cost and extend service life for air cost and extend service life for air and gas heater which increase the and gas heater which increase the existing of elementexisting of element
The material composition of The material composition of enamel-enamel-
bull The enamel layer is basically The enamel layer is basically composed by a borosilicate glass plus composed by a borosilicate glass plus cobalt fluorine sodium potassium cobalt fluorine sodium potassium quartz titanium borax helliphellipquartz titanium borax helliphellip
The benefits of enamel The benefits of enamel coating include-coating include-
bull 1-greater resistance to the attack of 1-greater resistance to the attack of acidsacids
bull 2-abrasive and wear resistance2-abrasive and wear resistance
bull 3-high mechanical and thermal shock 3-high mechanical and thermal shock resistanceresistance
bull 4-high resistance to erosion by fly ash4-high resistance to erosion by fly ash
bull 5-smooth and vitreous surface reduces 5-smooth and vitreous surface reduces adhesion of solidsadhesion of solids
The EndThe End
bullGood luckGood luck
Thinning of tube due to Thinning of tube due to steam blanketing-steam blanketing-
Hydrogen attack or Hydrogen attack or damage-damage-
bull This type of failure is found in high pressure units This type of failure is found in high pressure units A situation occurs when excessive deposits are A situation occurs when excessive deposits are present on the tube water side surface that permit present on the tube water side surface that permit boiler chemicals to concentrate under the deposit boiler chemicals to concentrate under the deposit and corrode the metal Hydrogen is formed which and corrode the metal Hydrogen is formed which permeates the metal structure and reacts with the permeates the metal structure and reacts with the carbon of the metal to form methane The methane carbon of the metal to form methane The methane molecule which is much larger than the carbon molecule which is much larger than the carbon atom Exerts pressure and causes the metal to atom Exerts pressure and causes the metal to rupture along the grain boundaries Ruptures are rupture along the grain boundaries Ruptures are violent sudden and can be disastrousviolent sudden and can be disastrous
bull 4H+C=CH44H+C=CH4
The effect of hydrogen The effect of hydrogen attack in tubes-attack in tubes-
Cold end corrosion-Cold end corrosion-
bull Cold-end corrosion will occur Cold-end corrosion will occur wherever the temperature of metal wherever the temperature of metal drops below the sulfuric acid dew drops below the sulfuric acid dew point of the flue gas It occurs in point of the flue gas It occurs in economizer air preheater economizer air preheater induced draft fan and stackinduced draft fan and stack
Soot blowers erosion-Soot blowers erosion-
bull A misdirected blower allows a high A misdirected blower allows a high velocity jet of steam or air carrying velocity jet of steam or air carrying condensed water droplets to condensed water droplets to impinge directed upon tube impinge directed upon tube surfaces rather than to be directed surfaces rather than to be directed between tubes Physical abrasion between tubes Physical abrasion and acceleration oxidation cause and acceleration oxidation cause metal loss Erosive thinning often metal loss Erosive thinning often leads to tube ruptureleads to tube rupture
Foaming-Foaming-
bull It is a condition in which It is a condition in which concentration of soluble salts create concentration of soluble salts create frothy bubbles in the steam space of frothy bubbles in the steam space of the boiler Foaming can form slugs the boiler Foaming can form slugs of water that can carried over into of water that can carried over into the steam systemthe steam system
How to remove a tube How to remove a tube sample for inspectionsample for inspection
When removing a tube When removing a tube sample-sample-
bull 1-the tube section should be dry saw 1-the tube section should be dry saw cut to prevent any slag andor cutting cut to prevent any slag andor cutting oil from contaminating the internal oil from contaminating the internal depositdeposit
bull 2-the sample should be cut 2-the sample should be cut approximately 8-10 inches above and approximately 8-10 inches above and below the affected areabelow the affected area
bull 3-the exact location should be 3-the exact location should be documented as follows-documented as follows-
bull A-tubes should be numbered and A-tubes should be numbered and counted from east to west and north counted from east to west and north to southto south
bull B-the wall (front rear right hand B-the wall (front rear right hand side left hand side) and elevation side left hand side) and elevation should be noted and marked on the should be noted and marked on the tubetube
bull C-an arrow should be marked to C-an arrow should be marked to indicate which end of sample is upindicate which end of sample is up
bull D-on a universal pressure unit the D-on a universal pressure unit the sample should be identified as sample should be identified as removed from the first second or removed from the first second or third passthird pass
Troubles associated to drums-
bull1048698 Loss of level gauges
bull1048698 water level controllers out of service
bull1048698 corrosion
bull1048698 moisture carry-over in the steam
bull1048698 safety valves leaking
bull1048698 leaks of roll-expanded evaporator
bullTubes
bull1048698 plugging of evaporator tubes
Trouble associated to air Trouble associated to air heaters-heaters-
bull1048698 Leakages due to damaged axial or circumferential seals
bull1048698 Cold end baskets damaged by acid corrosion
bull1048698 Poor sootblowing
bull1048698 Standby pneumatic or DC motor not working or absent
New application in air New application in air heater-heater-
The modification-The modification-
bull We used to manufacture the air We used to manufacture the air heater basket material from heater basket material from carbon steel or Corten steel now carbon steel or Corten steel now they add a new material called they add a new material called enamel to improve quality reduce enamel to improve quality reduce cost and extend service life for air cost and extend service life for air and gas heater which increase the and gas heater which increase the existing of elementexisting of element
The material composition of The material composition of enamel-enamel-
bull The enamel layer is basically The enamel layer is basically composed by a borosilicate glass plus composed by a borosilicate glass plus cobalt fluorine sodium potassium cobalt fluorine sodium potassium quartz titanium borax helliphellipquartz titanium borax helliphellip
The benefits of enamel The benefits of enamel coating include-coating include-
bull 1-greater resistance to the attack of 1-greater resistance to the attack of acidsacids
bull 2-abrasive and wear resistance2-abrasive and wear resistance
bull 3-high mechanical and thermal shock 3-high mechanical and thermal shock resistanceresistance
bull 4-high resistance to erosion by fly ash4-high resistance to erosion by fly ash
bull 5-smooth and vitreous surface reduces 5-smooth and vitreous surface reduces adhesion of solidsadhesion of solids
The EndThe End
bullGood luckGood luck
Hydrogen attack or Hydrogen attack or damage-damage-
bull This type of failure is found in high pressure units This type of failure is found in high pressure units A situation occurs when excessive deposits are A situation occurs when excessive deposits are present on the tube water side surface that permit present on the tube water side surface that permit boiler chemicals to concentrate under the deposit boiler chemicals to concentrate under the deposit and corrode the metal Hydrogen is formed which and corrode the metal Hydrogen is formed which permeates the metal structure and reacts with the permeates the metal structure and reacts with the carbon of the metal to form methane The methane carbon of the metal to form methane The methane molecule which is much larger than the carbon molecule which is much larger than the carbon atom Exerts pressure and causes the metal to atom Exerts pressure and causes the metal to rupture along the grain boundaries Ruptures are rupture along the grain boundaries Ruptures are violent sudden and can be disastrousviolent sudden and can be disastrous
bull 4H+C=CH44H+C=CH4
The effect of hydrogen The effect of hydrogen attack in tubes-attack in tubes-
Cold end corrosion-Cold end corrosion-
bull Cold-end corrosion will occur Cold-end corrosion will occur wherever the temperature of metal wherever the temperature of metal drops below the sulfuric acid dew drops below the sulfuric acid dew point of the flue gas It occurs in point of the flue gas It occurs in economizer air preheater economizer air preheater induced draft fan and stackinduced draft fan and stack
Soot blowers erosion-Soot blowers erosion-
bull A misdirected blower allows a high A misdirected blower allows a high velocity jet of steam or air carrying velocity jet of steam or air carrying condensed water droplets to condensed water droplets to impinge directed upon tube impinge directed upon tube surfaces rather than to be directed surfaces rather than to be directed between tubes Physical abrasion between tubes Physical abrasion and acceleration oxidation cause and acceleration oxidation cause metal loss Erosive thinning often metal loss Erosive thinning often leads to tube ruptureleads to tube rupture
Foaming-Foaming-
bull It is a condition in which It is a condition in which concentration of soluble salts create concentration of soluble salts create frothy bubbles in the steam space of frothy bubbles in the steam space of the boiler Foaming can form slugs the boiler Foaming can form slugs of water that can carried over into of water that can carried over into the steam systemthe steam system
How to remove a tube How to remove a tube sample for inspectionsample for inspection
When removing a tube When removing a tube sample-sample-
bull 1-the tube section should be dry saw 1-the tube section should be dry saw cut to prevent any slag andor cutting cut to prevent any slag andor cutting oil from contaminating the internal oil from contaminating the internal depositdeposit
bull 2-the sample should be cut 2-the sample should be cut approximately 8-10 inches above and approximately 8-10 inches above and below the affected areabelow the affected area
bull 3-the exact location should be 3-the exact location should be documented as follows-documented as follows-
bull A-tubes should be numbered and A-tubes should be numbered and counted from east to west and north counted from east to west and north to southto south
bull B-the wall (front rear right hand B-the wall (front rear right hand side left hand side) and elevation side left hand side) and elevation should be noted and marked on the should be noted and marked on the tubetube
bull C-an arrow should be marked to C-an arrow should be marked to indicate which end of sample is upindicate which end of sample is up
bull D-on a universal pressure unit the D-on a universal pressure unit the sample should be identified as sample should be identified as removed from the first second or removed from the first second or third passthird pass
Troubles associated to drums-
bull1048698 Loss of level gauges
bull1048698 water level controllers out of service
bull1048698 corrosion
bull1048698 moisture carry-over in the steam
bull1048698 safety valves leaking
bull1048698 leaks of roll-expanded evaporator
bullTubes
bull1048698 plugging of evaporator tubes
Trouble associated to air Trouble associated to air heaters-heaters-
bull1048698 Leakages due to damaged axial or circumferential seals
bull1048698 Cold end baskets damaged by acid corrosion
bull1048698 Poor sootblowing
bull1048698 Standby pneumatic or DC motor not working or absent
New application in air New application in air heater-heater-
The modification-The modification-
bull We used to manufacture the air We used to manufacture the air heater basket material from heater basket material from carbon steel or Corten steel now carbon steel or Corten steel now they add a new material called they add a new material called enamel to improve quality reduce enamel to improve quality reduce cost and extend service life for air cost and extend service life for air and gas heater which increase the and gas heater which increase the existing of elementexisting of element
The material composition of The material composition of enamel-enamel-
bull The enamel layer is basically The enamel layer is basically composed by a borosilicate glass plus composed by a borosilicate glass plus cobalt fluorine sodium potassium cobalt fluorine sodium potassium quartz titanium borax helliphellipquartz titanium borax helliphellip
The benefits of enamel The benefits of enamel coating include-coating include-
bull 1-greater resistance to the attack of 1-greater resistance to the attack of acidsacids
bull 2-abrasive and wear resistance2-abrasive and wear resistance
bull 3-high mechanical and thermal shock 3-high mechanical and thermal shock resistanceresistance
bull 4-high resistance to erosion by fly ash4-high resistance to erosion by fly ash
bull 5-smooth and vitreous surface reduces 5-smooth and vitreous surface reduces adhesion of solidsadhesion of solids
The EndThe End
bullGood luckGood luck
The effect of hydrogen The effect of hydrogen attack in tubes-attack in tubes-
Cold end corrosion-Cold end corrosion-
bull Cold-end corrosion will occur Cold-end corrosion will occur wherever the temperature of metal wherever the temperature of metal drops below the sulfuric acid dew drops below the sulfuric acid dew point of the flue gas It occurs in point of the flue gas It occurs in economizer air preheater economizer air preheater induced draft fan and stackinduced draft fan and stack
Soot blowers erosion-Soot blowers erosion-
bull A misdirected blower allows a high A misdirected blower allows a high velocity jet of steam or air carrying velocity jet of steam or air carrying condensed water droplets to condensed water droplets to impinge directed upon tube impinge directed upon tube surfaces rather than to be directed surfaces rather than to be directed between tubes Physical abrasion between tubes Physical abrasion and acceleration oxidation cause and acceleration oxidation cause metal loss Erosive thinning often metal loss Erosive thinning often leads to tube ruptureleads to tube rupture
Foaming-Foaming-
bull It is a condition in which It is a condition in which concentration of soluble salts create concentration of soluble salts create frothy bubbles in the steam space of frothy bubbles in the steam space of the boiler Foaming can form slugs the boiler Foaming can form slugs of water that can carried over into of water that can carried over into the steam systemthe steam system
How to remove a tube How to remove a tube sample for inspectionsample for inspection
When removing a tube When removing a tube sample-sample-
bull 1-the tube section should be dry saw 1-the tube section should be dry saw cut to prevent any slag andor cutting cut to prevent any slag andor cutting oil from contaminating the internal oil from contaminating the internal depositdeposit
bull 2-the sample should be cut 2-the sample should be cut approximately 8-10 inches above and approximately 8-10 inches above and below the affected areabelow the affected area
bull 3-the exact location should be 3-the exact location should be documented as follows-documented as follows-
bull A-tubes should be numbered and A-tubes should be numbered and counted from east to west and north counted from east to west and north to southto south
bull B-the wall (front rear right hand B-the wall (front rear right hand side left hand side) and elevation side left hand side) and elevation should be noted and marked on the should be noted and marked on the tubetube
bull C-an arrow should be marked to C-an arrow should be marked to indicate which end of sample is upindicate which end of sample is up
bull D-on a universal pressure unit the D-on a universal pressure unit the sample should be identified as sample should be identified as removed from the first second or removed from the first second or third passthird pass
Troubles associated to drums-
bull1048698 Loss of level gauges
bull1048698 water level controllers out of service
bull1048698 corrosion
bull1048698 moisture carry-over in the steam
bull1048698 safety valves leaking
bull1048698 leaks of roll-expanded evaporator
bullTubes
bull1048698 plugging of evaporator tubes
Trouble associated to air Trouble associated to air heaters-heaters-
bull1048698 Leakages due to damaged axial or circumferential seals
bull1048698 Cold end baskets damaged by acid corrosion
bull1048698 Poor sootblowing
bull1048698 Standby pneumatic or DC motor not working or absent
New application in air New application in air heater-heater-
The modification-The modification-
bull We used to manufacture the air We used to manufacture the air heater basket material from heater basket material from carbon steel or Corten steel now carbon steel or Corten steel now they add a new material called they add a new material called enamel to improve quality reduce enamel to improve quality reduce cost and extend service life for air cost and extend service life for air and gas heater which increase the and gas heater which increase the existing of elementexisting of element
The material composition of The material composition of enamel-enamel-
bull The enamel layer is basically The enamel layer is basically composed by a borosilicate glass plus composed by a borosilicate glass plus cobalt fluorine sodium potassium cobalt fluorine sodium potassium quartz titanium borax helliphellipquartz titanium borax helliphellip
The benefits of enamel The benefits of enamel coating include-coating include-
bull 1-greater resistance to the attack of 1-greater resistance to the attack of acidsacids
bull 2-abrasive and wear resistance2-abrasive and wear resistance
bull 3-high mechanical and thermal shock 3-high mechanical and thermal shock resistanceresistance
bull 4-high resistance to erosion by fly ash4-high resistance to erosion by fly ash
bull 5-smooth and vitreous surface reduces 5-smooth and vitreous surface reduces adhesion of solidsadhesion of solids
The EndThe End
bullGood luckGood luck
Cold end corrosion-Cold end corrosion-
bull Cold-end corrosion will occur Cold-end corrosion will occur wherever the temperature of metal wherever the temperature of metal drops below the sulfuric acid dew drops below the sulfuric acid dew point of the flue gas It occurs in point of the flue gas It occurs in economizer air preheater economizer air preheater induced draft fan and stackinduced draft fan and stack
Soot blowers erosion-Soot blowers erosion-
bull A misdirected blower allows a high A misdirected blower allows a high velocity jet of steam or air carrying velocity jet of steam or air carrying condensed water droplets to condensed water droplets to impinge directed upon tube impinge directed upon tube surfaces rather than to be directed surfaces rather than to be directed between tubes Physical abrasion between tubes Physical abrasion and acceleration oxidation cause and acceleration oxidation cause metal loss Erosive thinning often metal loss Erosive thinning often leads to tube ruptureleads to tube rupture
Foaming-Foaming-
bull It is a condition in which It is a condition in which concentration of soluble salts create concentration of soluble salts create frothy bubbles in the steam space of frothy bubbles in the steam space of the boiler Foaming can form slugs the boiler Foaming can form slugs of water that can carried over into of water that can carried over into the steam systemthe steam system
How to remove a tube How to remove a tube sample for inspectionsample for inspection
When removing a tube When removing a tube sample-sample-
bull 1-the tube section should be dry saw 1-the tube section should be dry saw cut to prevent any slag andor cutting cut to prevent any slag andor cutting oil from contaminating the internal oil from contaminating the internal depositdeposit
bull 2-the sample should be cut 2-the sample should be cut approximately 8-10 inches above and approximately 8-10 inches above and below the affected areabelow the affected area
bull 3-the exact location should be 3-the exact location should be documented as follows-documented as follows-
bull A-tubes should be numbered and A-tubes should be numbered and counted from east to west and north counted from east to west and north to southto south
bull B-the wall (front rear right hand B-the wall (front rear right hand side left hand side) and elevation side left hand side) and elevation should be noted and marked on the should be noted and marked on the tubetube
bull C-an arrow should be marked to C-an arrow should be marked to indicate which end of sample is upindicate which end of sample is up
bull D-on a universal pressure unit the D-on a universal pressure unit the sample should be identified as sample should be identified as removed from the first second or removed from the first second or third passthird pass
Troubles associated to drums-
bull1048698 Loss of level gauges
bull1048698 water level controllers out of service
bull1048698 corrosion
bull1048698 moisture carry-over in the steam
bull1048698 safety valves leaking
bull1048698 leaks of roll-expanded evaporator
bullTubes
bull1048698 plugging of evaporator tubes
Trouble associated to air Trouble associated to air heaters-heaters-
bull1048698 Leakages due to damaged axial or circumferential seals
bull1048698 Cold end baskets damaged by acid corrosion
bull1048698 Poor sootblowing
bull1048698 Standby pneumatic or DC motor not working or absent
New application in air New application in air heater-heater-
The modification-The modification-
bull We used to manufacture the air We used to manufacture the air heater basket material from heater basket material from carbon steel or Corten steel now carbon steel or Corten steel now they add a new material called they add a new material called enamel to improve quality reduce enamel to improve quality reduce cost and extend service life for air cost and extend service life for air and gas heater which increase the and gas heater which increase the existing of elementexisting of element
The material composition of The material composition of enamel-enamel-
bull The enamel layer is basically The enamel layer is basically composed by a borosilicate glass plus composed by a borosilicate glass plus cobalt fluorine sodium potassium cobalt fluorine sodium potassium quartz titanium borax helliphellipquartz titanium borax helliphellip
The benefits of enamel The benefits of enamel coating include-coating include-
bull 1-greater resistance to the attack of 1-greater resistance to the attack of acidsacids
bull 2-abrasive and wear resistance2-abrasive and wear resistance
bull 3-high mechanical and thermal shock 3-high mechanical and thermal shock resistanceresistance
bull 4-high resistance to erosion by fly ash4-high resistance to erosion by fly ash
bull 5-smooth and vitreous surface reduces 5-smooth and vitreous surface reduces adhesion of solidsadhesion of solids
The EndThe End
bullGood luckGood luck
Soot blowers erosion-Soot blowers erosion-
bull A misdirected blower allows a high A misdirected blower allows a high velocity jet of steam or air carrying velocity jet of steam or air carrying condensed water droplets to condensed water droplets to impinge directed upon tube impinge directed upon tube surfaces rather than to be directed surfaces rather than to be directed between tubes Physical abrasion between tubes Physical abrasion and acceleration oxidation cause and acceleration oxidation cause metal loss Erosive thinning often metal loss Erosive thinning often leads to tube ruptureleads to tube rupture
Foaming-Foaming-
bull It is a condition in which It is a condition in which concentration of soluble salts create concentration of soluble salts create frothy bubbles in the steam space of frothy bubbles in the steam space of the boiler Foaming can form slugs the boiler Foaming can form slugs of water that can carried over into of water that can carried over into the steam systemthe steam system
How to remove a tube How to remove a tube sample for inspectionsample for inspection
When removing a tube When removing a tube sample-sample-
bull 1-the tube section should be dry saw 1-the tube section should be dry saw cut to prevent any slag andor cutting cut to prevent any slag andor cutting oil from contaminating the internal oil from contaminating the internal depositdeposit
bull 2-the sample should be cut 2-the sample should be cut approximately 8-10 inches above and approximately 8-10 inches above and below the affected areabelow the affected area
bull 3-the exact location should be 3-the exact location should be documented as follows-documented as follows-
bull A-tubes should be numbered and A-tubes should be numbered and counted from east to west and north counted from east to west and north to southto south
bull B-the wall (front rear right hand B-the wall (front rear right hand side left hand side) and elevation side left hand side) and elevation should be noted and marked on the should be noted and marked on the tubetube
bull C-an arrow should be marked to C-an arrow should be marked to indicate which end of sample is upindicate which end of sample is up
bull D-on a universal pressure unit the D-on a universal pressure unit the sample should be identified as sample should be identified as removed from the first second or removed from the first second or third passthird pass
Troubles associated to drums-
bull1048698 Loss of level gauges
bull1048698 water level controllers out of service
bull1048698 corrosion
bull1048698 moisture carry-over in the steam
bull1048698 safety valves leaking
bull1048698 leaks of roll-expanded evaporator
bullTubes
bull1048698 plugging of evaporator tubes
Trouble associated to air Trouble associated to air heaters-heaters-
bull1048698 Leakages due to damaged axial or circumferential seals
bull1048698 Cold end baskets damaged by acid corrosion
bull1048698 Poor sootblowing
bull1048698 Standby pneumatic or DC motor not working or absent
New application in air New application in air heater-heater-
The modification-The modification-
bull We used to manufacture the air We used to manufacture the air heater basket material from heater basket material from carbon steel or Corten steel now carbon steel or Corten steel now they add a new material called they add a new material called enamel to improve quality reduce enamel to improve quality reduce cost and extend service life for air cost and extend service life for air and gas heater which increase the and gas heater which increase the existing of elementexisting of element
The material composition of The material composition of enamel-enamel-
bull The enamel layer is basically The enamel layer is basically composed by a borosilicate glass plus composed by a borosilicate glass plus cobalt fluorine sodium potassium cobalt fluorine sodium potassium quartz titanium borax helliphellipquartz titanium borax helliphellip
The benefits of enamel The benefits of enamel coating include-coating include-
bull 1-greater resistance to the attack of 1-greater resistance to the attack of acidsacids
bull 2-abrasive and wear resistance2-abrasive and wear resistance
bull 3-high mechanical and thermal shock 3-high mechanical and thermal shock resistanceresistance
bull 4-high resistance to erosion by fly ash4-high resistance to erosion by fly ash
bull 5-smooth and vitreous surface reduces 5-smooth and vitreous surface reduces adhesion of solidsadhesion of solids
The EndThe End
bullGood luckGood luck
Foaming-Foaming-
bull It is a condition in which It is a condition in which concentration of soluble salts create concentration of soluble salts create frothy bubbles in the steam space of frothy bubbles in the steam space of the boiler Foaming can form slugs the boiler Foaming can form slugs of water that can carried over into of water that can carried over into the steam systemthe steam system
How to remove a tube How to remove a tube sample for inspectionsample for inspection
When removing a tube When removing a tube sample-sample-
bull 1-the tube section should be dry saw 1-the tube section should be dry saw cut to prevent any slag andor cutting cut to prevent any slag andor cutting oil from contaminating the internal oil from contaminating the internal depositdeposit
bull 2-the sample should be cut 2-the sample should be cut approximately 8-10 inches above and approximately 8-10 inches above and below the affected areabelow the affected area
bull 3-the exact location should be 3-the exact location should be documented as follows-documented as follows-
bull A-tubes should be numbered and A-tubes should be numbered and counted from east to west and north counted from east to west and north to southto south
bull B-the wall (front rear right hand B-the wall (front rear right hand side left hand side) and elevation side left hand side) and elevation should be noted and marked on the should be noted and marked on the tubetube
bull C-an arrow should be marked to C-an arrow should be marked to indicate which end of sample is upindicate which end of sample is up
bull D-on a universal pressure unit the D-on a universal pressure unit the sample should be identified as sample should be identified as removed from the first second or removed from the first second or third passthird pass
Troubles associated to drums-
bull1048698 Loss of level gauges
bull1048698 water level controllers out of service
bull1048698 corrosion
bull1048698 moisture carry-over in the steam
bull1048698 safety valves leaking
bull1048698 leaks of roll-expanded evaporator
bullTubes
bull1048698 plugging of evaporator tubes
Trouble associated to air Trouble associated to air heaters-heaters-
bull1048698 Leakages due to damaged axial or circumferential seals
bull1048698 Cold end baskets damaged by acid corrosion
bull1048698 Poor sootblowing
bull1048698 Standby pneumatic or DC motor not working or absent
New application in air New application in air heater-heater-
The modification-The modification-
bull We used to manufacture the air We used to manufacture the air heater basket material from heater basket material from carbon steel or Corten steel now carbon steel or Corten steel now they add a new material called they add a new material called enamel to improve quality reduce enamel to improve quality reduce cost and extend service life for air cost and extend service life for air and gas heater which increase the and gas heater which increase the existing of elementexisting of element
The material composition of The material composition of enamel-enamel-
bull The enamel layer is basically The enamel layer is basically composed by a borosilicate glass plus composed by a borosilicate glass plus cobalt fluorine sodium potassium cobalt fluorine sodium potassium quartz titanium borax helliphellipquartz titanium borax helliphellip
The benefits of enamel The benefits of enamel coating include-coating include-
bull 1-greater resistance to the attack of 1-greater resistance to the attack of acidsacids
bull 2-abrasive and wear resistance2-abrasive and wear resistance
bull 3-high mechanical and thermal shock 3-high mechanical and thermal shock resistanceresistance
bull 4-high resistance to erosion by fly ash4-high resistance to erosion by fly ash
bull 5-smooth and vitreous surface reduces 5-smooth and vitreous surface reduces adhesion of solidsadhesion of solids
The EndThe End
bullGood luckGood luck
How to remove a tube How to remove a tube sample for inspectionsample for inspection
When removing a tube When removing a tube sample-sample-
bull 1-the tube section should be dry saw 1-the tube section should be dry saw cut to prevent any slag andor cutting cut to prevent any slag andor cutting oil from contaminating the internal oil from contaminating the internal depositdeposit
bull 2-the sample should be cut 2-the sample should be cut approximately 8-10 inches above and approximately 8-10 inches above and below the affected areabelow the affected area
bull 3-the exact location should be 3-the exact location should be documented as follows-documented as follows-
bull A-tubes should be numbered and A-tubes should be numbered and counted from east to west and north counted from east to west and north to southto south
bull B-the wall (front rear right hand B-the wall (front rear right hand side left hand side) and elevation side left hand side) and elevation should be noted and marked on the should be noted and marked on the tubetube
bull C-an arrow should be marked to C-an arrow should be marked to indicate which end of sample is upindicate which end of sample is up
bull D-on a universal pressure unit the D-on a universal pressure unit the sample should be identified as sample should be identified as removed from the first second or removed from the first second or third passthird pass
Troubles associated to drums-
bull1048698 Loss of level gauges
bull1048698 water level controllers out of service
bull1048698 corrosion
bull1048698 moisture carry-over in the steam
bull1048698 safety valves leaking
bull1048698 leaks of roll-expanded evaporator
bullTubes
bull1048698 plugging of evaporator tubes
Trouble associated to air Trouble associated to air heaters-heaters-
bull1048698 Leakages due to damaged axial or circumferential seals
bull1048698 Cold end baskets damaged by acid corrosion
bull1048698 Poor sootblowing
bull1048698 Standby pneumatic or DC motor not working or absent
New application in air New application in air heater-heater-
The modification-The modification-
bull We used to manufacture the air We used to manufacture the air heater basket material from heater basket material from carbon steel or Corten steel now carbon steel or Corten steel now they add a new material called they add a new material called enamel to improve quality reduce enamel to improve quality reduce cost and extend service life for air cost and extend service life for air and gas heater which increase the and gas heater which increase the existing of elementexisting of element
The material composition of The material composition of enamel-enamel-
bull The enamel layer is basically The enamel layer is basically composed by a borosilicate glass plus composed by a borosilicate glass plus cobalt fluorine sodium potassium cobalt fluorine sodium potassium quartz titanium borax helliphellipquartz titanium borax helliphellip
The benefits of enamel The benefits of enamel coating include-coating include-
bull 1-greater resistance to the attack of 1-greater resistance to the attack of acidsacids
bull 2-abrasive and wear resistance2-abrasive and wear resistance
bull 3-high mechanical and thermal shock 3-high mechanical and thermal shock resistanceresistance
bull 4-high resistance to erosion by fly ash4-high resistance to erosion by fly ash
bull 5-smooth and vitreous surface reduces 5-smooth and vitreous surface reduces adhesion of solidsadhesion of solids
The EndThe End
bullGood luckGood luck
When removing a tube When removing a tube sample-sample-
bull 1-the tube section should be dry saw 1-the tube section should be dry saw cut to prevent any slag andor cutting cut to prevent any slag andor cutting oil from contaminating the internal oil from contaminating the internal depositdeposit
bull 2-the sample should be cut 2-the sample should be cut approximately 8-10 inches above and approximately 8-10 inches above and below the affected areabelow the affected area
bull 3-the exact location should be 3-the exact location should be documented as follows-documented as follows-
bull A-tubes should be numbered and A-tubes should be numbered and counted from east to west and north counted from east to west and north to southto south
bull B-the wall (front rear right hand B-the wall (front rear right hand side left hand side) and elevation side left hand side) and elevation should be noted and marked on the should be noted and marked on the tubetube
bull C-an arrow should be marked to C-an arrow should be marked to indicate which end of sample is upindicate which end of sample is up
bull D-on a universal pressure unit the D-on a universal pressure unit the sample should be identified as sample should be identified as removed from the first second or removed from the first second or third passthird pass
Troubles associated to drums-
bull1048698 Loss of level gauges
bull1048698 water level controllers out of service
bull1048698 corrosion
bull1048698 moisture carry-over in the steam
bull1048698 safety valves leaking
bull1048698 leaks of roll-expanded evaporator
bullTubes
bull1048698 plugging of evaporator tubes
Trouble associated to air Trouble associated to air heaters-heaters-
bull1048698 Leakages due to damaged axial or circumferential seals
bull1048698 Cold end baskets damaged by acid corrosion
bull1048698 Poor sootblowing
bull1048698 Standby pneumatic or DC motor not working or absent
New application in air New application in air heater-heater-
The modification-The modification-
bull We used to manufacture the air We used to manufacture the air heater basket material from heater basket material from carbon steel or Corten steel now carbon steel or Corten steel now they add a new material called they add a new material called enamel to improve quality reduce enamel to improve quality reduce cost and extend service life for air cost and extend service life for air and gas heater which increase the and gas heater which increase the existing of elementexisting of element
The material composition of The material composition of enamel-enamel-
bull The enamel layer is basically The enamel layer is basically composed by a borosilicate glass plus composed by a borosilicate glass plus cobalt fluorine sodium potassium cobalt fluorine sodium potassium quartz titanium borax helliphellipquartz titanium borax helliphellip
The benefits of enamel The benefits of enamel coating include-coating include-
bull 1-greater resistance to the attack of 1-greater resistance to the attack of acidsacids
bull 2-abrasive and wear resistance2-abrasive and wear resistance
bull 3-high mechanical and thermal shock 3-high mechanical and thermal shock resistanceresistance
bull 4-high resistance to erosion by fly ash4-high resistance to erosion by fly ash
bull 5-smooth and vitreous surface reduces 5-smooth and vitreous surface reduces adhesion of solidsadhesion of solids
The EndThe End
bullGood luckGood luck
bull A-tubes should be numbered and A-tubes should be numbered and counted from east to west and north counted from east to west and north to southto south
bull B-the wall (front rear right hand B-the wall (front rear right hand side left hand side) and elevation side left hand side) and elevation should be noted and marked on the should be noted and marked on the tubetube
bull C-an arrow should be marked to C-an arrow should be marked to indicate which end of sample is upindicate which end of sample is up
bull D-on a universal pressure unit the D-on a universal pressure unit the sample should be identified as sample should be identified as removed from the first second or removed from the first second or third passthird pass
Troubles associated to drums-
bull1048698 Loss of level gauges
bull1048698 water level controllers out of service
bull1048698 corrosion
bull1048698 moisture carry-over in the steam
bull1048698 safety valves leaking
bull1048698 leaks of roll-expanded evaporator
bullTubes
bull1048698 plugging of evaporator tubes
Trouble associated to air Trouble associated to air heaters-heaters-
bull1048698 Leakages due to damaged axial or circumferential seals
bull1048698 Cold end baskets damaged by acid corrosion
bull1048698 Poor sootblowing
bull1048698 Standby pneumatic or DC motor not working or absent
New application in air New application in air heater-heater-
The modification-The modification-
bull We used to manufacture the air We used to manufacture the air heater basket material from heater basket material from carbon steel or Corten steel now carbon steel or Corten steel now they add a new material called they add a new material called enamel to improve quality reduce enamel to improve quality reduce cost and extend service life for air cost and extend service life for air and gas heater which increase the and gas heater which increase the existing of elementexisting of element
The material composition of The material composition of enamel-enamel-
bull The enamel layer is basically The enamel layer is basically composed by a borosilicate glass plus composed by a borosilicate glass plus cobalt fluorine sodium potassium cobalt fluorine sodium potassium quartz titanium borax helliphellipquartz titanium borax helliphellip
The benefits of enamel The benefits of enamel coating include-coating include-
bull 1-greater resistance to the attack of 1-greater resistance to the attack of acidsacids
bull 2-abrasive and wear resistance2-abrasive and wear resistance
bull 3-high mechanical and thermal shock 3-high mechanical and thermal shock resistanceresistance
bull 4-high resistance to erosion by fly ash4-high resistance to erosion by fly ash
bull 5-smooth and vitreous surface reduces 5-smooth and vitreous surface reduces adhesion of solidsadhesion of solids
The EndThe End
bullGood luckGood luck
Troubles associated to drums-
bull1048698 Loss of level gauges
bull1048698 water level controllers out of service
bull1048698 corrosion
bull1048698 moisture carry-over in the steam
bull1048698 safety valves leaking
bull1048698 leaks of roll-expanded evaporator
bullTubes
bull1048698 plugging of evaporator tubes
Trouble associated to air Trouble associated to air heaters-heaters-
bull1048698 Leakages due to damaged axial or circumferential seals
bull1048698 Cold end baskets damaged by acid corrosion
bull1048698 Poor sootblowing
bull1048698 Standby pneumatic or DC motor not working or absent
New application in air New application in air heater-heater-
The modification-The modification-
bull We used to manufacture the air We used to manufacture the air heater basket material from heater basket material from carbon steel or Corten steel now carbon steel or Corten steel now they add a new material called they add a new material called enamel to improve quality reduce enamel to improve quality reduce cost and extend service life for air cost and extend service life for air and gas heater which increase the and gas heater which increase the existing of elementexisting of element
The material composition of The material composition of enamel-enamel-
bull The enamel layer is basically The enamel layer is basically composed by a borosilicate glass plus composed by a borosilicate glass plus cobalt fluorine sodium potassium cobalt fluorine sodium potassium quartz titanium borax helliphellipquartz titanium borax helliphellip
The benefits of enamel The benefits of enamel coating include-coating include-
bull 1-greater resistance to the attack of 1-greater resistance to the attack of acidsacids
bull 2-abrasive and wear resistance2-abrasive and wear resistance
bull 3-high mechanical and thermal shock 3-high mechanical and thermal shock resistanceresistance
bull 4-high resistance to erosion by fly ash4-high resistance to erosion by fly ash
bull 5-smooth and vitreous surface reduces 5-smooth and vitreous surface reduces adhesion of solidsadhesion of solids
The EndThe End
bullGood luckGood luck
bull1048698 Loss of level gauges
bull1048698 water level controllers out of service
bull1048698 corrosion
bull1048698 moisture carry-over in the steam
bull1048698 safety valves leaking
bull1048698 leaks of roll-expanded evaporator
bullTubes
bull1048698 plugging of evaporator tubes
Trouble associated to air Trouble associated to air heaters-heaters-
bull1048698 Leakages due to damaged axial or circumferential seals
bull1048698 Cold end baskets damaged by acid corrosion
bull1048698 Poor sootblowing
bull1048698 Standby pneumatic or DC motor not working or absent
New application in air New application in air heater-heater-
The modification-The modification-
bull We used to manufacture the air We used to manufacture the air heater basket material from heater basket material from carbon steel or Corten steel now carbon steel or Corten steel now they add a new material called they add a new material called enamel to improve quality reduce enamel to improve quality reduce cost and extend service life for air cost and extend service life for air and gas heater which increase the and gas heater which increase the existing of elementexisting of element
The material composition of The material composition of enamel-enamel-
bull The enamel layer is basically The enamel layer is basically composed by a borosilicate glass plus composed by a borosilicate glass plus cobalt fluorine sodium potassium cobalt fluorine sodium potassium quartz titanium borax helliphellipquartz titanium borax helliphellip
The benefits of enamel The benefits of enamel coating include-coating include-
bull 1-greater resistance to the attack of 1-greater resistance to the attack of acidsacids
bull 2-abrasive and wear resistance2-abrasive and wear resistance
bull 3-high mechanical and thermal shock 3-high mechanical and thermal shock resistanceresistance
bull 4-high resistance to erosion by fly ash4-high resistance to erosion by fly ash
bull 5-smooth and vitreous surface reduces 5-smooth and vitreous surface reduces adhesion of solidsadhesion of solids
The EndThe End
bullGood luckGood luck
Trouble associated to air Trouble associated to air heaters-heaters-
bull1048698 Leakages due to damaged axial or circumferential seals
bull1048698 Cold end baskets damaged by acid corrosion
bull1048698 Poor sootblowing
bull1048698 Standby pneumatic or DC motor not working or absent
New application in air New application in air heater-heater-
The modification-The modification-
bull We used to manufacture the air We used to manufacture the air heater basket material from heater basket material from carbon steel or Corten steel now carbon steel or Corten steel now they add a new material called they add a new material called enamel to improve quality reduce enamel to improve quality reduce cost and extend service life for air cost and extend service life for air and gas heater which increase the and gas heater which increase the existing of elementexisting of element
The material composition of The material composition of enamel-enamel-
bull The enamel layer is basically The enamel layer is basically composed by a borosilicate glass plus composed by a borosilicate glass plus cobalt fluorine sodium potassium cobalt fluorine sodium potassium quartz titanium borax helliphellipquartz titanium borax helliphellip
The benefits of enamel The benefits of enamel coating include-coating include-
bull 1-greater resistance to the attack of 1-greater resistance to the attack of acidsacids
bull 2-abrasive and wear resistance2-abrasive and wear resistance
bull 3-high mechanical and thermal shock 3-high mechanical and thermal shock resistanceresistance
bull 4-high resistance to erosion by fly ash4-high resistance to erosion by fly ash
bull 5-smooth and vitreous surface reduces 5-smooth and vitreous surface reduces adhesion of solidsadhesion of solids
The EndThe End
bullGood luckGood luck
bull1048698 Leakages due to damaged axial or circumferential seals
bull1048698 Cold end baskets damaged by acid corrosion
bull1048698 Poor sootblowing
bull1048698 Standby pneumatic or DC motor not working or absent
New application in air New application in air heater-heater-
The modification-The modification-
bull We used to manufacture the air We used to manufacture the air heater basket material from heater basket material from carbon steel or Corten steel now carbon steel or Corten steel now they add a new material called they add a new material called enamel to improve quality reduce enamel to improve quality reduce cost and extend service life for air cost and extend service life for air and gas heater which increase the and gas heater which increase the existing of elementexisting of element
The material composition of The material composition of enamel-enamel-
bull The enamel layer is basically The enamel layer is basically composed by a borosilicate glass plus composed by a borosilicate glass plus cobalt fluorine sodium potassium cobalt fluorine sodium potassium quartz titanium borax helliphellipquartz titanium borax helliphellip
The benefits of enamel The benefits of enamel coating include-coating include-
bull 1-greater resistance to the attack of 1-greater resistance to the attack of acidsacids
bull 2-abrasive and wear resistance2-abrasive and wear resistance
bull 3-high mechanical and thermal shock 3-high mechanical and thermal shock resistanceresistance
bull 4-high resistance to erosion by fly ash4-high resistance to erosion by fly ash
bull 5-smooth and vitreous surface reduces 5-smooth and vitreous surface reduces adhesion of solidsadhesion of solids
The EndThe End
bullGood luckGood luck
New application in air New application in air heater-heater-
The modification-The modification-
bull We used to manufacture the air We used to manufacture the air heater basket material from heater basket material from carbon steel or Corten steel now carbon steel or Corten steel now they add a new material called they add a new material called enamel to improve quality reduce enamel to improve quality reduce cost and extend service life for air cost and extend service life for air and gas heater which increase the and gas heater which increase the existing of elementexisting of element
The material composition of The material composition of enamel-enamel-
bull The enamel layer is basically The enamel layer is basically composed by a borosilicate glass plus composed by a borosilicate glass plus cobalt fluorine sodium potassium cobalt fluorine sodium potassium quartz titanium borax helliphellipquartz titanium borax helliphellip
The benefits of enamel The benefits of enamel coating include-coating include-
bull 1-greater resistance to the attack of 1-greater resistance to the attack of acidsacids
bull 2-abrasive and wear resistance2-abrasive and wear resistance
bull 3-high mechanical and thermal shock 3-high mechanical and thermal shock resistanceresistance
bull 4-high resistance to erosion by fly ash4-high resistance to erosion by fly ash
bull 5-smooth and vitreous surface reduces 5-smooth and vitreous surface reduces adhesion of solidsadhesion of solids
The EndThe End
bullGood luckGood luck
The modification-The modification-
bull We used to manufacture the air We used to manufacture the air heater basket material from heater basket material from carbon steel or Corten steel now carbon steel or Corten steel now they add a new material called they add a new material called enamel to improve quality reduce enamel to improve quality reduce cost and extend service life for air cost and extend service life for air and gas heater which increase the and gas heater which increase the existing of elementexisting of element
The material composition of The material composition of enamel-enamel-
bull The enamel layer is basically The enamel layer is basically composed by a borosilicate glass plus composed by a borosilicate glass plus cobalt fluorine sodium potassium cobalt fluorine sodium potassium quartz titanium borax helliphellipquartz titanium borax helliphellip
The benefits of enamel The benefits of enamel coating include-coating include-
bull 1-greater resistance to the attack of 1-greater resistance to the attack of acidsacids
bull 2-abrasive and wear resistance2-abrasive and wear resistance
bull 3-high mechanical and thermal shock 3-high mechanical and thermal shock resistanceresistance
bull 4-high resistance to erosion by fly ash4-high resistance to erosion by fly ash
bull 5-smooth and vitreous surface reduces 5-smooth and vitreous surface reduces adhesion of solidsadhesion of solids
The EndThe End
bullGood luckGood luck
The material composition of The material composition of enamel-enamel-
bull The enamel layer is basically The enamel layer is basically composed by a borosilicate glass plus composed by a borosilicate glass plus cobalt fluorine sodium potassium cobalt fluorine sodium potassium quartz titanium borax helliphellipquartz titanium borax helliphellip
The benefits of enamel The benefits of enamel coating include-coating include-
bull 1-greater resistance to the attack of 1-greater resistance to the attack of acidsacids
bull 2-abrasive and wear resistance2-abrasive and wear resistance
bull 3-high mechanical and thermal shock 3-high mechanical and thermal shock resistanceresistance
bull 4-high resistance to erosion by fly ash4-high resistance to erosion by fly ash
bull 5-smooth and vitreous surface reduces 5-smooth and vitreous surface reduces adhesion of solidsadhesion of solids
The EndThe End
bullGood luckGood luck
The benefits of enamel The benefits of enamel coating include-coating include-
bull 1-greater resistance to the attack of 1-greater resistance to the attack of acidsacids
bull 2-abrasive and wear resistance2-abrasive and wear resistance
bull 3-high mechanical and thermal shock 3-high mechanical and thermal shock resistanceresistance
bull 4-high resistance to erosion by fly ash4-high resistance to erosion by fly ash
bull 5-smooth and vitreous surface reduces 5-smooth and vitreous surface reduces adhesion of solidsadhesion of solids
The EndThe End
bullGood luckGood luck
The EndThe End
bullGood luckGood luck
