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Marine Engineering Maintenance and Repair at Operational Level <MROL> 1. What does 3/8” or ¾” means in thread nomenclature? 3/8” or ¾” means the nominal OD of the bolt. For Course threads the TPI will be 16 and for fine threads the TPI will be 20. Actually that’s according to the American standards. Metric standards define it in eg. M10 * 1.5 where, 10 is the nominal diameter and 1.5 is the pitch. If Pitch is not mentioned, then we take it as that thread is belonging to the course group. 2. What does 15W40 denote? Here 40 is SAE number. SAE number like SAE 10, SAE 20 corresponds to that having kinematic viscousity at 100°C. Likewise W denotes the winter grade for cold start. Thus SAE 15W40 denotes that the lube oil of this grade has kinematic viscosity of 40 cst at 100°C and its winter grade is 15W ie, the cranking and pump ability of this lube oil grade has passed tests of 20W and 15W but failed test of 10W at below zero temperatures. 3. Actions to be taken during boiler uptake fire? Boiler uptake fire is because of wet soot deposited during low steaming and also during uptakefire do not carry out soot blow reduce the load and stop the engine , cover the m/e t/c with thecanvas so that no air is supplied 4.How much is Needle vv lift? Generally 1mm maximum for 320 bar lifting pressure. 5. Boiler corrosion how it happens and how to prevent? The most common causes of corrosion are dissolved gases (primarily oxygen and carbon di oxide), under-deposit attack, low pH, and attack of areas weakened by mechanical stress, leading to stress and fatigue cracking and pitting corrosion: scales such as calcium and magnesium salts.Many corrosion problems occur in the hottest areas of the boiler-the water wall,screen, and superheater tubes. Other common problem areas include deaerators, feedwater heaters, and economizers. Prevention : 1 Anoop Vijayakumar

MEO CLASS IV orals

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Page 1: MEO CLASS IV orals

Marine Engineering Maintenance and Repair at Operational Level <MROL>

1. What does 3/8” or ¾” means in thread nomenclature?3/8” or ¾” means the nominal OD of the bolt. For Course threads the TPI will be 16 and for fine threads the TPI will be 20. Actually that’s according to the American standards. Metric standards define it in eg. M10 * 1.5 where, 10 is the nominal diameter and 1.5 is the pitch. If Pitch is not mentioned, then we take it as that thread is belonging to the course group.

2. What does 15W40 denote?

Here 40 is SAE number. SAE number like SAE 10, SAE 20 corresponds to that having kinematic viscousity at 100°C. Likewise W denotes the winter grade for cold start. Thus SAE 15W40 denotes that the lube oil of this grade has kinematic viscosity of 40 cst at 100°C and its winter grade is 15W ie, the cranking and pump ability of this lube oil grade has passed tests of 20W and 15W but failed test of 10W at below zero temperatures.

3. Actions to be taken during boiler uptake fire?Boiler uptake fire is because of wet soot deposited during low steaming and also during uptakefire do not carry out soot blow reduce the load and stop the engine , cover the m/e t/c with thecanvas so that no air is supplied

4.How much is Needle vv lift? Generally 1mm maximum for 320 bar lifting pressure.

5. Boiler corrosion how it happens and how to prevent?

The most common causes of corrosion are dissolved gases (primarily oxygen and carbon di oxide), under-deposit attack, low pH, and attack of areas weakened by mechanical stress, leading to stress and fatigue cracking and pitting corrosion: scales such as calcium and magnesium salts.Many corrosion problems occur in the hottest areas of the boiler-the water wall,screen, and superheater tubes. Other common problem areas include deaerators, feedwater heaters, and economizers.

Prevention:Maintenance of proper pH and alkalinity levels between 8.5 and 9.5control of oxygen and boiler feedwater contamination (less than 7 ppb oxygen for a 900 psig boiler)Reduction of mechanical stressesOperation within design specifications, especially for temperature and pressureproper precautions during start-up and shutdown effective monitoring and control

24. Accumulation of pressure test in boiler?

Classification Societies require that that when initially fitted to boilers safety valves must be subjected to an accumulation of pressure test to ensure the valves are of the correct discharge capacity for the boiler.

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To conduct such a test, all feed inlets and steam outlets to and from theboiler must be closed and maximum firing load achieved. Accumulation of pressure must then notexceed 10% of working pressure. Duration of test is not to exceed 15 minutes for cylindricalboilers and 7 minutes for water tube boilers.

25. How to reduce maintenance in exhaust valve?Good quality fuel usage, VIT adjustment, avoid running engine on low load, check fuel injection system, good scavenging, maintaining cooling water temp, check rotation of exhaust v/v. 26.Refrigeration gases how it’s classified according to environment hazard?Ozone depletion potential max R11, for R22 is 0.05 and global warming potential- max is R11….and R22 is 0.365 27

27 Contactors maintenance on starter what is the material of contactor?

Check for loose, missing, broken contactorsCleaning and checking contact surfaces for improper wear or discolorationRemove oxides from faces using fine filesMain contacts are high conductivity copper because they will not heat up due to lower resistance and arcing contacts are made of sintered silver tungsten or other materials which don’t weld at high temperatures.Crane jib is cracked how u r going to weld? Arrest crack by drilling holes at both ends and weld supporting plate at the back and then carry out welding on the crack.

28 Junior engineer boxed back the purifier after cleaning then its found vibrating probable causes?

Bowl may not be cleaned properly,Lock ring not tightening properly,Bowled assembled with wrong parts,Gear can be in damaged condition,Bowl springs not fitted correctly,Top bearing springs damaged,Discs not properly assembled or tightened,Some external tool left inside

32. Insulation of motor is found to be 0.5 mega ohms what we can do to bring back the insulation?

Disconnect motorClean windingsDry the motor by heating lampCheck visually for any wires brokenPut fast drying varnish Test insulation

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40. How aluminum is welded? TIG (Tungsten Inert Gas) welding, also called a GTAW (Gas Tungsten Arc Welding), is the best method of welding aluminum. Spray the aluminum with acetone Rinse the aluminum in water, just in case there’s any nasty residue. The aluminum should be completely dry before welding. Use a stainless steel brush to scrub the aluminum shiny clean around the area to be welded in one direction Clamp your work to a heat sink made of copper or aluminum Preheat before welding upto 275 deg to 500 deg but optimum temp. is 350 deg. If the tungsten gets contaminated, stop welding and fix it. When the tungsten gets touches the weld pool or the filler, the arc becomes unstable and the weld quality goes way down. The best method for fixing this is to remove the tungsten, lay it on a flat surface with the contaminated part hanging over the edge, hit the contaminated part of the tungsten (it will snap right off),reinstall the tungsten, change the polarity to DCEP (direct current electrode positive), strike an arc on some scrap metal to re-ball the tungsten, switch back to AC high, and you're ready to weld again. Fit the parts together as tightly as possible leaving no gaps. The tighter the pieces are pressed together and the fewer the gaps, the easier the welding is. Use one amp per .001" of material thickness. Set the amperage a higher than the maximum you expect to use and use the foot pedal to back it down. Use pure tungsten for aluminum. Use a 1/16" pure tungsten for 30 to 80 amps Use a 3/32" pure tungsten for 60 to 130 amps Use a 1/8" pure tungsten for 100 to 180 amp Use 15 to 20 CFH Argon flow. Use a filler rod size equal to the tungsten size. Adjust the tungsten to project from the hood a distance roughly equal to the diameter of the tungsten. Thearc length should be roughly equal to the diameter of the tungsten.

46. What is setting for safety valves? One safety v/v is to be set at 3% of working pressure and other v/v slightly more (0.5bar) and superheater safety v/v at lesser pressure (sup v/v= blr v/v – 0.35bar – pr drop across superheater)

CRANK CASE INSPECTION (20 points)

1. Firstly check the oil condition for any smell,discolouration or degradation.

2. Turn the Engine to BDC & start checking from under

stuffing box area for any signs of black oil, if so indication of stuffing box leaking.

3. Check piston rod surface for scoring marks & roughness.

4. Check Piston palm bolts & locking device for slackness & fretting.

5. Check guide & guide shoe bearing general condition & area around frame

where guide is attached for any visible cracks.

6. Check guide shoe end cover bolts in place & notslack.

7. Check cross head general bearing condition.

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8. Top & Bottom end of the con rod bolt, nut & locking devices for slackness, sign of

fretting etc.

9. Check sliding of bottom end bearing(floating of con rod).

10. Check for slip of web & journal by checking the reference mark.

11.Check the web in the area of stress concentration & check tie bolts (bottom side).

12. Check cross girder, area around main bearing & bearing keep for signs of cracks &

check the main bearing.

13. All bearings to be checked for silvery colour, (indicates bearing wiping)

14. Check all the surrounding oil pan area of all units for any sludge deposits, bearing

metal pieces etc.

15. Check crankcase relief door (wire mesh should be wet, spring tension sealing

condition etc.)

16. Check the teeth of transmission gears for signs of wear.

17. Check chain drive for tightness.

18. Oil mist detector sampling pipe to be checked for clear passage.

19. Clear all foreign materials

from the C.C. & tools accounted for.

20. Start L.O.p/p & X-Hd p/p & check oil flow & distribution.

21Check C.C.door sealing condition & close the door.

60. How to remove broken tie rod?

Take out upper part as with clamp provided by maker wd clinging bolts after loosening top nut then see wd withdrawn piece how deep is breaking part...then there cut a window in tie rod casing put a rod down from top weld it loose the bottom nut and take out..later on grind burn metal take a template and close the window in casing

63. What is blowdown ring in boiler?

Blow down rings are fitted in consolidated type safety valves and cross by safety valves only. It is a ring which is fitted to the valve seat, and this can be rotated to change the height. Now the inner surface of the valve has an angular cut. This ring serves two purposes. Firstly it gives the valve rapid and more lift and secondly, when the valve is sitting back, it cushions its seating preventing damage to the valve and seat.

52. What is lantern ring? Where it is located?

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Lantern ring are the split rings. They are provided in centrifugal pump between the packing ring so as to direct the clean fluid between gland packingand seal and lubricate the gland.

53. Why do we use compound gauge for refer system?Compound gauge is to see the system is not going into vacuum anyway. If goes to vacuum then any leak in system will take air in and that is not good for the system in any condition. Bringing suction pressure below one bar gauge is itself not good. To prevent this we have low press cut out too to prevent it from vacuum.

54 After you have detected air ingress in a refrigeration system how do you purge it out?

Collect all the gas in the receiver and let it cool and note the temp of the receiver, then check the pressure of the receiver and the corresponding temp on the gauge. Then purge the receiver till both the temp are equal. Every refrigerant will have a saturation pressure corresponding to a particular temp. Air ingress in the system will show a higher pressure on the gauge. Purging has to be carried out till it both the pressures are same on the gauge. As per regulation never purge the air and gas in open atmosphere, always collect it into gas recovery cylinder

55 How to remove thrust pads?

Remove the spray pipes, take out the nuts holding the stopperand remove the stoppers on both side, then remove each shoe, (generally there are eight) by sliding them around the holding panel. The shoe pads have a tilt and are to be mounted taking care of it. Before removal of pads, it is important to take out the temperature sensors, which are located on engine entablature, just forward side of the fly wheel. There are two sensors fitted, one in working condition, and other one remains on standby.

60. How to remove broken tie rod?Take out upper part as with clamp provided by maker wd clinging bolts after loosening top nut then see wd withdrawn piece how deep is breaking part...then there cut a window in tie rod casing put a rod down from top weld it loose the bottom nut and take out..later on grind burn metal take a template and close the window in casing

.

70. Welding of Cast Iron?

Gray cast iron can usually be welded without loss of essentialproperties. For fusion welding, preheating of the casting is absolutely essential. Since a higher level of preheat is required for oxy-acetylene welding then for arc welding, arc welding is likely to be chosen where fusion welding is essential (as it is whenever good color match is desired). For many repair jobs, however, oxy-acetylene braze welding is

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the ideal method. Much less preheating is required; in many cases, preheating can be done with the torch. If the work is properly done, the braze-welded joint will have a strength equal to that of the base metal, and excellent machinability. Welding of gray iron castings which have chilled white iron surfaces is seldom attempted, since the desirable properties of white iron will always be affected by welding temperatures. Welding of white iron generally is limited to malleable iron foundries, wherecastings may be reclaimed by welding before conversion to malleable iron takes place.

72. Why ME foundation bolts have long sleeve?

Long sleeve bolts have high resilience. Also they have higher value of elastic strain when in tension. Owing to the length bending moment is reduced in the bolt because radius of curvature of the bolt will be much larger when bend.

73. ME main bearing removal?

Top Main bearing clearance: max- 0.58mm, min- 0.40mm.

The procedure for opening of the main bearing is as follows:

1) Inform company and take permission.

2) Take immobilization certificate from port state Authority stating that the main engine

will not be available for a particular period of time.

3) Read the manual and have a toll box meeting with everyone involved in the job.

Discuss the procedure.

4) Prepare important tools and spares to be used in operation.

5) Prepare risk assessment with the personnel involved in operation.

6) Shut starting air valve for main engine.

7) Open indicator cocks of all the units.

8) Engage turning gear and put it in remote control. The remote control switch to be

operated by in charge of the operation.

9) Stop main lube oil pump.

10) Open crank case doors.

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11) Put blower and ventilate it thoroughly.

12) Prepare enclosed space entry checklist.

13) After sufficient ventilation, wearing proper PPE enter the C/C.

14) Make sure that the main bearing measuring tool (depth gauge) is calibrate and set

to ’0′.

15) Open the screws of lube oil pipe connection and insert the depth gauge and

measure the clearance between upper bearing keep and journal.

16) Compare this reading with the earlier reading in the record or the new bearing

reading.

17) Now disconnect the lube oil pipe line.

18) Turn the crank throw so that it is towards the exhaust side.

19) Now mount the hydraulic jacks

and loosen the main bearing stud nuts.

20) Mount the lifting tool for main bearing keep and lift the keep using a pulley and a

wire rope.

21) Note the marking on the main bearing keep before lifting for correct direction of the

keep.

22) Guide the keep safely outside with a help of another chain block and place it on a

wooden base once it is out.

23) Mount the tool for lifting the upper bearing shell and place it safely outside.

24) Place the strong back (cross piece) support on the bed plate so that its ends rest

on the cross girders.

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25) Mount the hydraulic jack on the cross piece placing it such that it lies beneath the

crank webs

. 26) Mount a dial gauge on the adjacent main bearing so that the lift of the crank shaft

can be recorded.

27) Now with hydraulic pressure (1500-1650 bar) lift the crankshaft corresponding to

the main bearing clearance to the adjacent main bearing, and check the lift with the help

of a dial gauge.

28) Remove the lock screws from the lower shell.

29) Place the dismantling tool on the lower bearing shell such that the flap enters the oil

groove.

30) Pull the bearing shell round and up so that it lies on the journal and take it out safely

75. How to order hydraulic pipes?

For ordering hydraulic pipe, we need working pressure, symbol of standard ( ost1/ost2). Schedule 80120, manufacturing process s-c, e-c, outside diameter, thickness and length is optional because standard length is 4 metres and sold by weight, and made of carbon steel

76. Difference between ship side v/v and overboard v/v?SHIP SIDE VALVE IS A BUTTERFLY VALVE I.E, sea suction valve, where as overboard valve is a screw down non return globe valve, as per the classification society requirements and overhauling procedure is same like checking for corrosion and pitting marks and checking the rubber lining in case of butterfly valve. Material is copper nickel alloy or monel metal for disc andseat and body is nickel alloy.

.110. Reefer system meat room solenoid coil burnt... no spares...how to maintain meat room temp?

There will be a bypass v/v, if it is there then bypass the v/v, if not then close the main v/v before that and open the solenoid v/v and take out v/v assembly with the spring, put back the cover and open the main v/v,after achieving the desired temp close the main v/v, after some hours when the temp. is up again open the v/v and regain the temp

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111. One unit liner ovality is more – reasons?Reasons for liner ovality can be less lubrication, improper matching of lub oil with fuel oil, worn out piston rings or rings wrongly fitted, Overloading/unbalanced engine, clover leafing, injector malfunction causing the oil to spread on d liner walls and burn on it. The reason can also be the clearance of the crosshead sliding guides of the particular unit is more disrupting the centering of piston

117. How to carry out brake testing of e/r crane, procedure and load?

Load test of the engine room crane is carried out by actually loading the crane by dynamometer spring loaded balance which is attached between the hook & strong point on the e/r floor or deck.The tension reading is noted down. Load test is carried out once in 5 years. Lifting gear is tested at 1.5 times the safe working load. Lift a load through lifting gear which is 1.5 times the safe working load & then switch off the power, crane hook should not come down. This confirms the brake test of e/r crane.

10. What are the reasons for foaming in refrigeration compressor crankcase?

Due to rapid boiling out of the refrigerant dissolved in the oil when the pressure is suddenly reduced.When the compressor starts operating, if a large quantity of refrigerant has been dissolved,larger quantity of refrigerant boils out and can be carried through the refrigeration lines.Reasons:a. Liquid in the suction line (viz. TEV stuck open, incorrect super heat setting, sensingbulb not closing, overcharge etc.,)b. Crankcase heater not working.c. Compressor capacity too high at the start.d. Expansion valve giving too small superheate. Oil charge is less.

90. How will you know the presence of air in the refrigeration system? Explainthe procedure for purging air?

a. High condenser pressureb. Small bubbles in the sight glassc. Compressor discharge pressure high/running hotd. More superheate. Pressure fluctuationsf. Inefficient working

PROCEDURE FOR PURGING AIR

a. In the normal operation of the system, measure the liquid refrigerant pressure,

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temperature at the outlet of the condenser/reservoirb. Check the corresponding saturation temperature for the recorded pressure of theliquid refrigerant from the P-T chart for the same refrigerantc. Compare the measured temperature with the determined saturation temperature forany sub-cooling and adjust the flow of the cooling water through the condenser toachieve near saturation condition inside the condenser, Then,d. With the condenser liquid refrigerant outlet valve closed, circulate cooling water, startthe compressor and pump down the liquid to the condenser/reservoir, checking thepressure in the suction line. If this pressure is allowed to drop down below theatmospheric pressure then there could be chances of air ingress into the systeme. Circulate the cooling water till the cooling water outlet and the inlet temperaturesequal, a check to ensure complete pump down operationf. Check the condenser sea water out let temperature, check the refrigerant pressurecorresponding to its temperature from the P-T chart of same refrigerant g. Due to the presence of air they don’t agreeh. Release air from the condenser, through the vent cock until the pressure of therefrigerant in the condenser corresponds to the saturation pressure at the sea wateroutlet temperature

102. What are the liner wear rates? And how is it achieved?

Old engines: 0.1mm/1000hrsModern engines(2S): 0.03mm/1000hrsModern engines(4S): 0.12mm/1000hrsThis is achieved by:a. Highly alkaline lube oilb. Load dependant jacket cooling water temperature controlc. Good quality of cast iron with a hard faced. Careful design of the piston ring profilee. Improvement in lube oilf. Multilevel cylinder lubricationg. Condensate separation from the scavenging airh. By use of the anti-polishing ring or the piston cleaning

Quote some important clearances in the rudder system

Jumping clearance: 6mmClearance at raphson slide mechanism: 16~19mmPropeller drop: 1mm/160mm diameter of the tail shaftPintle clearance: 1.1mm~3.3mm

107. What are the usual pressures to which the boilers are tested?

New boilers, if > 6.9bar working pressure, 1.5xdesign pressureIf < 6.9bar working pressure, 2.0xdesign pressureAfter major repair, 1.25~1.5x working pressure, duration of the testing: 30Min.

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112. What is the course of action after finding that a bottom end bolt isslackened?

a. Check the length of the boltb. Check whether it is within the limitsc. Check for cracks / surface finish. Check the threadsd. The tie rod can be rolled over a flat surface coated with Prussian blue. Any twists inthe rod are revealed by the Prussian blue lines on the tie rod which get adhered alongthe twisted planee. If found alright, tighten the bolt and check the remaining bolts

Gear pump suitable for operating up to 25bar and can achieve displacement volume of0.35~1.0 liters/revolutionClearances between the gear teeth and the housing are of the order 0.02~0.03mm

119. What are the reasons for short cycling of a refrigerant compressor?a. Refrigerant charge is too lowb. Frosting or clogging of the evaporatorc. Dirty suction strainerd. Low pressure control differential too smalle. Wrongly adjusted capacity regulatorf. Refrigerant vapor in the liquid lineg. Too much cooling waterh. TEV faultyi. Too high compressor capacity

What actions do you take incase of an EGB Soot fire?

The oxygen levels in the EG Boiler/Economizer is about 14~16%, so this can supportcombustion. The nature of combustible deposits include soot from the combustion of fuel in the plant as well as some amount of unburnt oil (fuel and lube oil), particularly at low loads.Ignition of soot may arise at sufficient high temperature of the layer of the soot whosesurface temperature may go up to 300~400°C, but presence of unburnt oil may lower this temperature to about 150°C and under favorable conditions to about 120°C.

SMALL SOOT FIRES: Mainly occurs during maneuvering with the engine being operated at prolonged low loads. The situation may arise even at short low load running if the fuel is bad.Indications:a. High economizer exhaust gas outlet temperatureb. Sparks from the funnelc. Engine running parameters showing deviations due to increased exhaust back

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pressured. High steam pressure or outlet temperature from the super heater section if fitted How to deal with this situation:a. Stop the main engine so that the oxygen levels can be brought well below the firesustenance levelsb. Carry out the boundary coolingc. Fire watch to be kept on deck due to the risk of the funnel sparks, fire hoses to bekept chargedd. Continue running the circulating water pumpe. Never use the soot blowers for fire fightingf. Stop the auxiliary blowersg. Ensure that all the exhaust valves are positively closed (check the spring air pressure) If the soot fire has now turned into metal fire (identified immediately by the loss of thecirculating water of the economizer), stop the circulating water pump. Carry out theboundary cooling. If means are provided, deluging the economizer fires with copious amounts of water should be carried out to the seat of the fire. This is essential because, if lesser amount of water used the fire is additionally supported by the production of steam sourcing hydrogen for the situation to get worse.

Hydrogen fire: Occurs because of dissociation of water (steam) into hydrogen and oxygen or carbon in connection with carbon monoxide and hydrogenThis occurs only above 1000°C

Iron fire: Oxidation of the iron at high temperature occurs at a rate sufficiently high to make the amount of hest release from the reactions sustain the process. These reactions may take place at a temperature in excess of 1100°C

124. How do you identify the symptoms of a crank case explosion? What actionwould you take to minimize the hazard?

a. Engine noiseb. Oil mist detector alarmc. High bearing temperature (alarm if fitted)d. In case of minor explosions the crank case relief door releases the pressure

ACTION:

a. Slow down the engine, inform the bridgeb. Take permission from the bridge for stopping the enginec. Continue running the engine lube oil pumpsd. In severe cases, it is prudent to open the engine room skylights and other vents andabandoning the engine room. The doors from the engine room to the accommodationshould be kept shut. Return to the engine room only after carrying out riskassessmente. Turn the engine by turning gear with the indicator cock opened to prevent seizure of

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the hot spotsf. Stay clear of the crank case specially in the region of the relief door to theturbocharger suctiong. Don’t open the crank case door until sufficient time has elapsed

Reciprocating pump is getting over heated, what checks should be carriedout?

a. Inlet and outlet valves are to be examinedb. Inspect the seat and lapping should be done if requiredc. Valve lift should be checkedd. Inspect piston and piston ringse. Spring (valves should be checked for tension and springing action)f. Liner wear down should be checkedg. Driving belt should be checked for wear down or damage

A shell & tube type cooler tubes are leaking, what is the procedure to rectifythe leaks?Before jumping to any conclusions it is prudent to check where the leaks are from. It could be from the breach on the tube (a hole etc) or from the origination of small gaps between the tube plate and the expanded portion of the tube. The procedure should to be based on the findings.

A holed tube should be plugged from both the sides; the plugs can be of cork, wood, rubber, brass, or copper as supplied by the manufacturer. Care should be taken when plugging with the metal plugs, not to damage the tube plate.

If the leaks are from the gaps between the tube plate and the tubes, slight flaring of the tube may help preventing the leaks however this flaring, if excessive will damage the tube plate and also the tube itself. Alternative methods are available by carrying out surface preparation and applying metal repair putty, like Devcon’s brush able ceramic repair putty.

In the above process, if the plugging of the tubes is about 10% the tubes have to berenewed.

132. What is the routine anchor windlass maintenance?

a. Brake drum should be free of oil, grease and other deposits. The brake drum should be cleaned periodically with a solvent prescribed by the makerb. The brake drum and the disk should be checked for wearing out or damagec. Gear oil should be checked for contaminants and leveld. The direction of tensioning should correspond to the correct operation of the brake. As the reverse direction for tensioning would render the brake ineffective, check shouldbe carried out to ensure the samee. Brake test of the windlass is to be carried out to the pressure mentioned by the

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maker on the jack tool. If necessary, the spring tension adjusted. It should be done inguidance of the instructions and in the tensioning direction. The number of turns onthe drum should also be checked and should be same as to the makers quotef. The securing device of the tension spring adjust should be checked periodically forany tamperg. Anchor windlass testing should be carried out to check the efficiency of the windlass.The windlass should raise the anchor with chain from 82.5m to 27.5m at a meanspeed of 9m/minh. The foundation of the windlass should be checkedi. Other routines of the prime mover should also be carried out like for the windlasselectric motor or the hydraulic motor as the case may be

136. Air bottle maintenance and inspection

a. Regularly drain the bottle of water and oilb. Regular inspection to ensure that the internal condition of the bottle is goodc. Check for corrosion both externally and internallyd. Inside coating, COPAL varnish condition to be checked to ensure that it is unbrokenand no peeling is taking placee. Welding seam to be checked, carry out dye-penetrant test at suspected areasf. The tell tale hole between the lap welding seams of the doubler plate / ring to bechecked for leaks in service to ensure that the internal welding is intactg. Face of the man hole is to be checked for pitting marksh. Drain should be cleari. All points of high stress and corrosion are to be thoroughly checked viz. welds,supports braces, the bottom of the bottle where water/oil is collected. Pay attentionto the zone of water line.j. Check for leaks at the mounted valve glands/flanges, carry out inspection of the valveface and seat for wire drawing effectk. A timing check with the air bottle completely charged and isolated will give a goodidea of the intactness of the pressure vessell. The safety/relief valve setting to be inspected as per the class requirementm. Regularly check the alarms and monitoring equipment for proper functioning

137. Explain the air bottle entry procedure

a. Inspection is to be carried out when the receiver capacity is not required formaneuveringb. Receiver properly isolated, depressurized and notice pastedc. The internal pressure is to be checked by the pressure gauge and by opening thedrain valved. Open the manhole door carefully and ventilate the air bottlee. Obtain an enclosed space permit and comply with itf. Ventilation is to be maintained during the entire time of enclosed space entry

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138. What action should be taken in case of corrosion/wasting observed on airbottle?

MINOR: clean the site of corrosion, observe the varnish manufacturer instructions for surface finishing prior applying the coat. Apply new coat of the varnish.MAJOR: The site has to be cleaned and revarnished as above. The air bottle has to bederated.

Incase of excessive the entire bottle has to be replaced.The derating procedure should be carried out as follows:

a. The extent of the derating is determined by the class surveyor to a value whichensures the safe limit of the hoop stress at this reduced thickness of the shell platingb. The derating should not violate the starting air requirements for consecutive starts ofthe main propulsion engine

c. The setting of the safety/relief valve, should be set not exceeding 10% of themaximum working pressure after deratingd. The cut in and cut out pressure switches for compressor automation should bereadjustedFor these reasons the air pressure vessels on board ship are fabricated to allow for deratingin future still complying with the consecutive start requirements of the propulsion engine

140. What is the routine maintenance, checks on the PV breaker?

CHECKS:a. Check the seal liquid periodically and replenish the liquid in case• Liquid levels of inner and outer pipes do not coincide• “0” points of inner and outer pipes do not coincide when the pressure insidethe cargo tanks is atmospheric pressureb. Clean the flame screen in the cover at the top when the ships makes a dock-in

CHECKING PROCEDURE:a. Checking the liquid level of the inner pipe (open the vent cock located at most top ofthe gauge, close the upper gauge cock and open the lower gauge cock) this is alsotermed as “bigger range”b. Checking the liquid level of the outer pipe (close the vent cock, open the upper gaugecock also open the lower gauge cock) this is also termed as “smaller range”Two distinct scales are provided for the liquid gauge one “higher” and other “lower” therespective readings (as in ‘a’ and ‘b’) should match numerically

144. Soon after complete overhauling a generator engine, its lube oil consumption increases. What checks do you carry out in this regard?

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a. Check that the lube oil system valves are set back to normal, and that the concernedvalves are correctly holdingb. Verify dip stick bottom for any blockage which can give erroneous resultsc. Check for normal operation of the purifierd. Ensure that the piston scraper ring is set correctly, if this ring is boxed back upsidedown, the oil scraping action of the ring is lost and uncontrolled lube oil enters thecombustion chamber. This presents a significant oil losse. Ensure that the cylinder head valves are correctly boxed back. Misalignment of thevalve spindle with their guide also causes lube oil to enter the combustion chambercausing oil loss

145. Generator lube oil sump level increases, what are the checks you wouldcarry out?a. Check that the generator lube oil systems valves are correctly positioned and that thesump filling valve is holdingb. Ask the personnel for if they have carried out any transfers just before, related to thesump oil of the generatorc. Check the purifier for correct operation and that no water is being discharged with thepurified oild. Change over the generator concerned, isolate it and check the sump for anycontamination like water. Basing on the findings further inspections can be carriedout, like checking the cylinder liner jacket cooling water sealing O-ring etc.,

148. How is the chain drive of a main engine inspected?

Chain inspection is to be carried out as follows:a. Make a general inspection for loose screws and boltsb. Inspect lube oil pipes for damage, and check oil jet nozzles for possible stoppages ordeformationsc. Examine the rubber track of the guideways for cracks or other damage, replace theguideway bits if they have started to be plucked out of the rubber stackd. Check the teeth of the chain wheels. If abnormal wear is found, take a measurementby placing a straight edge over the wear edges and measure the length of the wearalong the straight edge and the gap between the straight edge and the wear troughe. Check the chains for cracks on possibly defective rollers and side platesf. Check that for each chain link, chain rollers can run freely and that the chain links canfreely move on the pin and bushingg. Check the chain wear by measuring the length of 10 chain links and compare theresult with the value in the data provided by the maker. If the parameter showsabnormality then adjust the chain tightener

151. What is the difference between a safety valve and a relief valve?

A safety valve is a pressure relief valve actuated by inlet static pressure and characterized by rapid opening or pop action.A relief valve is a pressure-relieving valve actuated by inlet static pressure and opens in

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proportion to the increase in pressure over the opening pressure.

The terms ‘safety’ and ‘relief’ are synonymous; the safety valve is generally applied to valves protecting any vessel, which could explode and endanger life whereas the relief valve is more appropriate to the valve protecting system containing non-expansible liquid a burst causing no violent explosion.

Another notable difference between these valves is that the vent of a safety valve is led to a ‘safe’ place (harmless to the working personnel) whereas a relief valve vents just outside thevalve.

157. What checks do you make if a compressor trips on low lube oil pressure?

Incase of reciprocating compressora. Direction of rotation, in case the motor is overhauled or some maintenance carried onthe motorb. Suction filter should be cleanedc. Check the pressure switchd. Inspect the lube oil pumpe. Check if any lube oil pipe is holedf. Check for excessive foamingIncase of rotary compressor,a. Check whether the lube oil pump is rotating with the compressorb. Check the condition of vanes and the elliptical casing for scoring damagec. Check the compressor is free to turn, no seizure of rotor, no wear on the vanes andthe casing

What is the purpose of steam traps?

Steam traps are automatic valves that release condensed steam (condensate) from a steam space while preventing the loss of live steam. They also remove air and non-condensable gases from the steam space. Steam traps are designed to maintain steam energy efficiency by performing specific tasks such as maintaining heat for process.Once steam has transferred its energy, it becomes hot water and is removed by the trapfrom the steam side as condensate and either returned to the boiler via condensate return lines or discharged to atmosphere (a wasteful practice).

179. How do you operate the main engine after a Turbocharger breakdown?

Some points are to be taken into consideration for engine operation with turbocharger out of operation:a. Air supply for amount of fuel injectedb. Adequate flow path of the exhaust gas producedc. Cooling of the turbocharger casing, rotor or bearingsd. Isolation of air/gas/lubricating spaces in the event of no sealing air availablee. Securing damaged parts

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The method of turbocharger isolation may be done in a number of ways depending on the nature of damage.

Bypass arrangement: Turbocharger is bypassed of exhaust gases by a suitable bypass pipe. Turbine inlet and outlet are isolated by fitting blanks and by pass pipe is fitted to give a suitable gas path. The compressor side also requires isolation to prevent loss of scavenge air due to back flow from the receiver. Cooling water and lubricating oil systems may also require isolation if casing and or seal is damaged.

Rotor removal: If the rotor is damaged it should be removed for repairs. The openings of the casings should be blanked to prevent internal and external leaks of exhaust gas or air.

Cooling of the casing should be effected as exhaust gases still pass through the casing.Locking of rotor: If requirement of propulsion is of concern and time is limited, rotor islocked into position by attaching the appropriate fixtures provided by the maker. An orifice plate should be inserted on the compressor side to allow a controlled amount of scavenge air to effect cooling.

Cooling water to the casing should also be continued since exhaust gases pass through the casing. Isolation of the lubrication system may be necessary due to lack of sealing air.

The limits of engine load depend on the actual configuration of the system and how many turbochargers remain in operation.

A broad consideration of the following points should be made:

a. The actual operating temperatures should be taken into account and limits should notbe exceededb. Condition of the exhaust should be monitored to ensure acceptable combustion insidethe cylinderc. Allowance should be given for rate of change of air supply during acceleration of theengined. Remaining turbochargers should be also monitored for abnormal operation due toaltered gas flowe. Auxiliary air supply should be provided where possible, but this may be effected byremaining turbochargers in operationInternal water leaks: In the event of a holed water jacket it is possible to operate theturbocharger as an air cooled unit by supplying compressed air as the coolant after isolatingthe water supply. Attention must be paid to the operating temperatures of the casing, andbearings especially turbine end.

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Four stroke engines with turbochargers out of service and no alternative air supply may beoperated as a naturally aspirated engine with suitable attention being paid to the operatingtemperaturesIn any case the engine load is to be limited a value specified by the engine maker for theconditions of operation and usually for a two-stroke engine its value is about 15%MCR

180. What is the procedure of plugging boiler of boiler tubes?Procedure of plugging water tubesa. Clean the face of leaky tube remove all the scales and dirt both in steam and waterdrumb. Plug with brass plug, hammer tight and weldc. Cover this tube on the furnace side with heat resisting materialProcedure of plugging smoke tubes

a. Brass plug with stud and tightened by nut at both the ends

182. How do you detect a leakage in a bilge pump suction line?

b. With the main suction of the pump closed, start the pump with discharge open. Monitor the

c. vacuum in the pump suction, if the vacuum is maintained for sometime the pump is in good

d. condition.e. Proceed for checking the integrity of the suction lines as follows:f. With the discharge of the pump opened for delivery,g. a. Set the pump to draw bilge from each particular well closing other suction lines

valvesh. b. Start the pump and note the build up of vacuumi. c. Repeat the operation for all other suction lines individually, closing other

remainingj. linesk. Now conclusion can be drawn with above observations.l. The pump does not achieve good vacuum for any well, in this casem. The manifold intactness by opening the sea water valve on the suction side and

check it forn. the seawater leaking. Repair the line after identifying the locationo. Identify for the leaks on the suction lines for which the pump does not achieve

good vacuump. This can be done by pressure testing the line by opening the seawater valve on

the pumpq. suction. The non-return valve on the line has to be dismantled and the valve put

back afterr. removing the valve disc.s. The sealings on the strainers have to be checked, like renewing gaskets.

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183. How is an engine lube oil sample collected?Sampling points for an engine lube oil are clearly mentioned by the maker of the engine. In any case, the following points are to be adhered to

a. Sample of lube oil should be drawn from the inlet to the engineb. Before collecting a sample some amount of oil is to be drained from the samplingpoint. Later sufficient amount of oil should be collected into a clean container,decanted and collected in a clean sampling bottlec. Engine should be in operation as close as possible to the MCR for some time beforecollecting a sampled. The sampling container should be unused one specially produced for lube oil samplinge. After collecting a sample in the bottle, it should be stored in a cool dry place to let theoil cool down before securing it with cap/seal. This is essential to prevent slightcondensation in the bottlef. The sample should be fully identified with the date, vessel name, running hours of theengine, lube oil running hours, sampling point identification

g. Each time the sample should be drawn from the same point

184. Explain onboard testing of lube oilSome or all of the testing explained below is done onboard ship.1. FLASH POINT (Pensky Martin Apparatus)This method determines the flash point of the lube oil sample in a closed cup. This givesthe lowest possible ignition point of the oil.A portion of the lube oil sample is slowly heated at a constant rate, whilst continualstirring is provided. A small flame is directed through an open shutter at regulartemperature intervals, with simultaneous interruption of stirring.The flash point is the lowest point at which the application of the test flame causes thevapor above the test point to ignite. For a new oil the flash point should be above 220°C,and any reduction would indicate fuel oil contamination.2. BASE NUMBERBN tester kits are provided onboard to determine the alkaline properties of the lube oil.These testers use the chemical reaction of a reagent with the alkaline lube oil additive(calcium) to produce a pressure rise. 10ml of oil is mixed with equal volume of a reagent.10ml of another reactive reagent is placed in a plastic cup, which is floated on top of theoil and reagent. The testing unit is sealed and thoroughly mixed. The resultant pressurerise is directly read on an calibrated pressure gauge against base number.

3. KINEMATIC VISCOSITYOnboard testing lube oil for viscosity is by the use of a comparative flow stick. Thismeasures the relative flow between two oils, usually a sample of the in-use lube oil ismeasured against a fresh unused sample of the same grade of lube oil.The flow stick is filled with 3ml of each oil in each reservoir, once both the oils are at the

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same temperature, the flow stick is tilted to cause both oil grades to flow down thechannels. Once the new oil has reached the reference mark, the position of used oil in thechannel is checked. The following inferences can be drawna. If the used oil has a low viscosity, due to light fuel dilution. Then oil will havetraveled further down the channel than the new oil.b. If the used oil has a higher viscosity, due to oxidation or heavy fuel oilcontamination it would not have traveled as far as the new oil.4. DENSITYThis method uses hydrometer to test the sample oil density. It is important to keep theoil and the hydrometer at the same temperature and maintained throughout theexperiment.5. WATER CONTENTOnboard water content is tested by using a calcium carbide. The tested is carried out bymixing 5ml of oil with 15ml of a petroleum reagent (paraffin, toluene). The two liquorsare thoroughly mixed and then a measured amount of reagent (calcium carbide) is placedon floating on the oil/reagent surface. The test unit is sealed and thoroughly mixed tobring all liquids together. If water is present the carbide will produce acetylene gas, andthe resultant pressure rise will indicate the level of water contamination.

187. What are actions you would take if a purifier starts overflowing?Some or all of the following should be checked for in case the purifier overflowing:a. Sealing water lowb. Excessive fuel back pressurec. Low pressure, chocked water line (check the water filter)d. Gravity disc oversized for the density of the fuel oil in questione. Oil temperature highf. Excessive sludge deposition inside the purifier bowlg. Excessive feed rateh. Sealing ring damaged (between the Bowl and Hood)i. Check RPM and direction of rotation of bowlj. Leaking three-way valve

195. How do you select a gravity disc of a purifier?Makers nomogram is an aid to select a tentative gravity disc in purification, when thedensity of the oil at a temperature of 15°C is known.The hole diameter of the first gravity disc to be tried appears directly from the nomogram. However, in practical operation the best result is obtained by using the gravity disc with the largest hole diameter that will not cause a break of the liquid seal in the bowl or anemulsification in the water outlet.

The presence of seawater may demand the use of a gravity disc with larger hole thanindicated in the nomogram. (the nomogram is based on the properties of fresh water)

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The nomogram consists of two graphs arranged in series, one consists of density of fuel at 15°C Vs Separating temperature and the other graph is divided into different zones of disc hole diameters against through put of the purifier

202. Explain the procedure of setting a boiler safety valve

The safety valve is the sole safety device, which relieves the boiler of a dangerous excess pressure. In the majority of designs the oil fired boiler and the exhaust gas boiler have a common steam circuit, though separate heat input and flue gas paths. The oil fired section of the oil fired boiler has a fuel cut out which is operated by the steam pressure limiting device, whereas the exhaust gas boiler has to depend solely on its safety valve to protect it.

In a composite boiler as mentioned above the pair of safety valves can serve to protect thecommon steam circuit. An additional pair of safety valves is provided in the outlet header of the exhaust gas boiler, which has to be set separately.

The setting of the safety valve has to be done when the heat input and the rate of pressurerise is maximum. The setting of the exhaust gas boiler safety valve to comply with the above, shall be carried out as follows:While at sea, with the main engine running at normal service speed and when all systems are steady, the oil-fired section of the boiler can be fired to augment steam production (all precautions such as adequate water level in the boiler, operator standing by the burner quick shut off valve etc. are to be followed). With the safety valve on the steam receiver of the boiler lightly gagged. The safety valve of the exhaust gas boiler section is set at slightlyhigher pressure. In order to ensure that the economizer (or the exhaust gas boiler) operates under flooded conditions at all times, it is customary to adjust the safety valves of the economizer to a slightly higher pressure than the safety valves of the boiler steam receiverof which they are connected.After setting the safety valve as above to satisfaction locking it to make it tamper proof, the oil-fired boiler firing is stopped, the steam receiver safety valves gags removed and all the easing gear properly connected.The exact lifting pressures are recorded in the logbook authenticated by the CEO and a copy of the above is to be forwarded to the classification society upon arrival next port.In the setting of the safety valve of a boiler, three items are of great importance. They are:1. Setting pressure at which the valve should lift.2. The accumulation of pressure, which will be above the former due to the valve springcharacteristics3. “Blow down” which is a drop in pressure below the setting pressure after the valve haslifted and reseated.4. For example the following values are relevant:a. Boiler working pressure: 7 bar.

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b. Safety valve setting pressure: 9 bar.c. Accumulation of pressure: Maximum of 10% of the setting pressure = 9.9 bar.d. Blow down at 3% of lifting pressure.

41. How will you drill hole for fitted bolts in a flange?First put the markings where the hole is required.Cut the flange piece from the pipe.Put it in the drill machine.Use correct size tool bit.Drill the holes and reweld the flange on the pipe.

43. wat ll u do if d threads r damaged in a stud? hw ll u correct it?IF threads are damaged and you can not be able to remove the nut, then we have to cut to stud and remove it.If somehow we can able to remove the stud, then we can rethread it to use it again-- first fix it in the chucks of the lathe-fil the weld metal on the surface and fill the threads.-rethread it using lathe.46. hwll u overhaul a sluice valve?Sluice valve is a type of gate valve.-first remove the handle.-remove the gland flange and gland.-remove the bonnet.-remove the gate and the spindle now.

69. recharging LO in refrigerant compressor.- Collect the refrigerant into the condenser by shutting off the condenser outlet valve.- Stop the compressor and shut off the inlet and outlet valves of compressor.- Open the oil filling plug and start filling the oil slowly.- Start the compressor momentarily(0.5- 0.6 seconds) to facilitate speedy charging.- After charging to the correct level, tightened up the oil plug.- Bleed off air in the compressor casing by slightly opening the suction valve and loosening connecting caps from the highpressure gauge (In case connection fittings for vacuum pump are provided, use the vacuum pump to extract the air from thecompressor crankcase).Extracting Oil- i. Pump down the refrigerant into the compressor only. Ensure that refrigerant- pressure is higher than the atmosphere.- ii. Loosen the oil drain plug in the compressor crankcase and extract the amount oil.Precautions:- 1.) Care to be taken when charging oil so that no air will be trapped in the- compressor crankcase.- 2.) Ensure to bleed off air every after charging and extracting refrigeration oil.

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70. botom end bolts slackening procedure , step by step .71. piston ring calibration.Groove clearences : Necessary because– to ensure free in and out movement of the ring in the groove to suit the liner bore.- to allow the gas to pass in the clearance space to press the ring against the liner.If their is cabon deposits in the groove or the groove clearance is too low then gases may pass directly between liner and pistonring outer surface and pushing the ring in to the groove causing Ring collapse.If the Ring clearance is too high then hammering and reduction of piston ring landing surface area in grooves, resulting breakingof ring and liner crack.Vertical Groove clearance : around 0.4mm and ring should be renewed if it reaches 0.7mmButt clearance : Will allow thermal expansion. If too large -à blow past.Between 0.5 – 1% of the liner bore.MAXIMUM ALLOWABLE BUTT CLEARENCE IS NOT USUALLY SPECIFIED AS LIMIT OF 15% WEAR ON THE RADIALTHICKNESS OF THE PISTON RING AUTOMATICALLY PUTS A LIMIT TO THE BUTT CLEARENCE.

72. boiler burner maintenance

73. OMD alarm , what will u do ?First check the OMD is not a false alarm by reset it. If the alarm is again coming, then it is a false alarm. Also to check ( crankcase doorbecome hot, pealing of paint, bearing and piston cooling high temperature).Then proceed.83. with respect to A/E Piston what is the name of the top most piston ring? How will one identify which piston ring goes in whichgroove if the rings get intermixed????Top most ring is known as compression ringEvery piston ring has engraved marking....that can be matched with that given in manual. Also can be compare with the sequence in whichthe piston ring of other piston of the unit is arranged.

95. removal of broken studput molycoteIf no nut is there on both side, then fit a nut and start tightening it until the stud will come out fully.If nut on one side, then put another nut on it (which will act as a locking nut) and start unscrew the inside nut until stud will comeout.

102. black smoke,, white smoke,, blue smokeBlack smoke – poor combustion, poor fuel quality, poor fuel preparation, insufficient charge air supply , scavange fire, leaky/defective fuel

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injector, late injection.White smoke: water or excessive air . Turbocharger water pockets cracked, ege water tube leaks, from w.o. tanks.Blue smoke: LO, excess cylinder oil burn, Piston cooling oil find its way to combustion space due to cracked piston crown.Yellow smoke: High sulphur content

112. maintanance of hydrant hose nd nozzle?coupling name?Hydrants: drains are provided in the line, line should be drained after use.Check the condition of the hoses. Hoses should not have water, after use the water should be removed properly.Monthly testing and inspectionsMonthly inspection should be earlier out to ensure that :

all firemans outfits, fire extinguishers, fire hydrants, hose and nozzles are in place, properly arranged, and are in proper condition;

114. Life boat engine maintanence?how to check engine cooling arrangementWeekly inspection: Lifeboat engine must be run for a minimum 3minutes.Each 3months the lifeboat must be lowered to sea.Monthly checks: Life boat equipments.

1. how can we make thinner internal thread?2. how to start centrifugal p/p?3. what will happen if discharge v/v is closed?4. what will u do if some noise is coming from centrifugal p/p?5. maintenance and overhauling?6. generator maintenance at 1000hr1- joint of seawater is leaking,how will you repair,what is tha name of the tool used?2- how will you come to know shell n tube type cooller tubes are leaking and how to rectify the same?which side cover dia is more insame?3-how M/E air coller cleanig is done what chemical is used what is interval of cleaning,what is manometer normal pr. and what pr. itshould be cleaned ?

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