Mntce Ofboiler Pressure Parts

7/30/2019 Mntce Ofboiler Pressure Parts

1/56

WELCOME


2/56

MAINTENANCE OF WATER

WALLS, ECO,SH AND RHCOILS


3/56

MAINTENANCE PLANNING

Maintenance Planning is callednerve center

Maintenance Planning enables tocarryout maintenance activities atthe appropriate time, method and

at minimum cost.


4/56

Maintenance planning is deciding in

advance about

Jobs

Material

Tools

Machines

Labour Time required

Sequence


5/56


6/56

Maintenance Planning

Lowers the cost of overhaul

Lowers maintenance time

Helps to utilize the overhaul period effectively

It eases the problems of purchase of criticalspares.

It plays a vital role in achieving higher production.

Prevents accidents.

Helps to solve complicated problems.

Helps to utilize the manpower and machines

effectively.


7/56

HOW TO DECIDE OVERHAUL

PERIOD

Monsoon season ( July to Dec )

Previous overhaul period

Furnace conditions

Operational parameter

Spares position Major problems in Boiler, TG etc.

Which quarter to be utilized for O/H


8/56

AGENCY FOR O/H

Past experience

License holders

Fixing pre-qualification requirements

Fixing responsibility

Safety to be followed

Statutory requirements

Minimum wages, PF etc. CIB approval, IBR approval

Inspection


9/56

Criteria for maintenance planning

Commitment to grid

Periodicity between overhauls

Fuel availability

Engineering factors related

Rolling plan for five years

Target by CEA

Spares availability Cost optimization

Modernization / up gradation


10/56

Types of maintenance

Preventive maintenance as per schedule

Break down maintenance

Short shut downs

Major overhauls

RLA / LEP / R & M


11/56

Pressure Parts & Furnace

Coil cleaning

Furnace cleaning

Thickness survey

Header inspection

Inspection of De-superheaters

Window normalizing Sample cutting

Fixing of sleeves and baffles


12/56

PREVENTIVE MAINTENANCE

- Physical Inspection During Cleaning

- Overheating

- Clamping

- Integrity of the Coils

- Erosion Pattern- Condition of Sleeves / Baffles


13/56

THICKNESS SURVEY

Cleaning of Coils

Measuring of Thickness

Around 2500 to 3000 Spots Per Boiler

Preparation of Report

Comparing the Results With PreviousValues


14/56

REMEDIAL ACTIONS

Analysis of erosion

Planning for procuring of spares &

consumables

Planning for execution

Thickness reduction up to 20%, putsleeves

More than 40% replacement


15/56

Thickness Reduction -Causes

Ash erosion

Soot blowers

Due to failure of adjacent tubes

Corrosion

Rubbing with clamps / other coils Overheating/ bulging

Oxidation


16/56

SAMPLE CUTTING

Presence of micro cracks

Fe3 O4 coating.

Pitting if any

Internal / external corrosion

Physical dimensions


17/56

BREAK DOWN MAINTENANCE

INDICATIONS

- Noise at local

- More make up

- FG temperature variations

- Furnace vacuum

- ID fan loading- Drum level

- Difference between SF / WF


18/56

Follow up of previoushistory

No. of outages

Location of failure

Nature of the failure

Probable causes

Remedial actions taken

Performance


19/56

IDENTIFICATION

Local inspection

Shutting down of boiler Start one ID fan

Physical inspection at 10 ksc

Draining clearance

Forced cooling

Assess the damage Analyze the cause for the failure

Take prevent actions


20/56

COILS

Reasons for punctures

Erosion

Weld defects

Rubbing

Corrosion

Overheating Faulty material

Steam soot blowers


21/56

WATER WALLS

Erosion

Mechanical impact

Weld defects

Starvation

Blockage

More bends Faulty materials

Soot blowers


22/56

REPLACEMENT

Sufficient cooling

Removal of insulation

Removal of WSB if required

Removal of refractory if required Identification of damaged tube

Level cutting ,edge preparation

Spool piece preparation

Positioning , alignment Welding

welding of clamps / fin


23/56

GENERAL RULES FOR WELDING

REPAIRS

Carefully cut away fins and clamps to have

enough access for chamfering.

Remove the damage tube.

Clean the tube ends to bright metal inside and

outside for at least an inch.

Remove all scales and deposits

Tube edges shall be squared and chamfered.

Minimum length of the tube should be 150mm.


24/56

Correct fit up shall be given

Maintain correct root gap. Both joints shall be tack welded.

First pass shall be done by TIG welding.

Complete the root, inter and final pass

welding.

Use correct polarity for TIG and SMAW.

Weld back fins and clamps.


25/56

MAJOR OVERHAUL

Follow up of previous history

No. of outagesLocation of failure

Nature of the failure

Probable causes

Remedial actions taken

Performance


26/56

Furnace & coil cleaning

Soot blowers are to be operated at periodic

intervals

During overhaul coils are to be cleaned

either by air, water or manual.

Acid cleaning if the internal deposits are

more.


27/56

VISUAL INSPECTIONBulging

Erosion

Corrosion

Bowing

Overheating

Loss of integrity

Pitting

FoulingAlignment

Support system

Sleeves & Baffles


28/56

DIMENSIONAL ANALYSIS

Thickness survey

OD measurement

Oxide scale measurement


29/56

INSPECTION OF ORIFICE

At Eco inlet, 8 mm orifice is provided in

each coil.

In random ID of the orifice is to be checkedfor any blockage/ enlargement


30/56

SAMPLE CUTTING

Cutting of sample tubes at various locations

to assess the internal conditions for

following checks. Surface cracks, pitting, erosion, deposits,

chemical analysis and microstructure

analysis.


31/56

Fiberoscopic inspection

To inspect the internal conditions of the

components at intricate locations for

accumulation of debris, cracks, blockage,erosion, pitting and integrity.


32/56

REPLICA

To find out the pattern of microstructure to

assess the degradation.

HARDNESS MEASUREMENT

Weld

HAZ

Parent metal


33/56

DESUPERHEATERS

VISUAL INSPECTION

Bulging, overheating, bowing, support

system, orientation, conditions of NRV,filter and branch lines are to be checked.

Dimensional check

Measurements of OD and thickness checks

are to be carried out in random.


34/56


To assess the internal conditions of DESHS

for

Shifting of thermal sleeve

Cracking of thermal sleeve

Missing / tilting / blockage of nozzles


35/56


To assess the internal conditions of DESHS

for

Shifting of thermal sleeve

Cracking of thermal sleeve

Missing / tilting / blockage of nozzles


36/56

INSPECTION OF SUPPORTS

Hanger support readings

Boiler expansion readings

Buck stay movements

Functioning of boiler guides

Roof supports are to be checked both in hot

and cold conditions


37/56

Manholes

Rectify door clamps and hinges

Replace sealing rope and bricks

Provide refractory on doors

Ensure perfect closing


38/56

Ways to protect boiler pressure parts

Metal temperature should be kept with inpermissible limits.

Raising and lowering of steam parametersshould be as per recommended pattern.

Tube leakage shall be attended at theearliest.

Maintain chemical regime properly.

Maintain drum level as recommended


39/56

Do not by pass drum level and steam temperature

protections.

DESHs shall be maintained above saturation

temperature of spray water.

FGT Temperature between left and right side

should be kept minimum.

Use defect free injection valves.

Avoid entry of foreign materials in to the circuit.

Avoid material defect, material mix up, andwelding defect.


40/56

Do proper heat treatment

Maintain tight inspection and quality

control.

Maintain optimum gas velocity Use quality fuel.

Maintain excess air as recommended.


41/56

Allow strain free expansion

Insulation shall be carried out properly

Proper storage of spare tubes and

consumables.

Engage qualified highly skilled welders.

Maintain proper record for future reference.


42/56

TYPES OF WELDING

- Butt

- Fillet

- Socket

- Build up

- Window


43/56

REQUIREMEMNTS

JOINT DETAILS

BASE METAL DETAILS

FILLER METAL SELECTION SHIELDING GAS

POSITION OF THE JOINT

PREHEAT PWHT


44/56

TECHNIQUE

STRINGER / WEAVE BEAD

SMAW, SAW, TIG etc.


45/56

PREPARATORY WORKS

Welding machine

Cutting set

Gas cylinders

Welding rod

Tungsten rod

Supply points 24V/230V/415V

Safety accessories


46/56

MATERIALS USED

SA 210 Gr-C

SA 106 Gr-B

SA 209 T 1

SA 213 T 11

SA 213 T 22

SA 213 T 91 X 20 Cr Mo V 121


47/56


48/56

PRE HEATING

Preheating is raising the

temperature of the parent metal around

the area to be welded to the specifiedtemperature before welding and holding

the temperature until completion of

welding


49/56

PURPOSE OF PRE HEATING

Prevents risk of cracking in the weld and

HAZ

Reduces rate of cooling

Reduces formation of residual stresses

Reduces distortion due to welding


50/56

POST HEATING

Post heating is the heating the

weld metal below the transformation

range, holding for predetermined timeand reducing the temperature at a

controlled rate after completion of

welding.


51/56

PURPOSES OF POST HEATING

Reduces HAZ hardness

Relieves residual stresses

Improves ductility

Improves toughness

Prevents premature cracks

STATUTORY


52/56

STATUTORY

Central Boiler Board Controls Manufacturer

Fabricator

Erector

Repairer

Welder

Testing agency

Stress relieving agency


53/56

IBR Certificates

Form III - A for pipes

III- B for tubes

III C for fittings

III D for pipes (Well known manufacturer)

III E for tubes


54/56

STORAGE

Pipes & Tubes

Both ends shall be plugged

With identification marks ( Size & Material)

Electrodes

To be procure from reputed firms with validcertificates

To be stored in a dry room.


55/56

REPLACEMENT PROCEDURE

Intimation of failure

Commencement report

Obtaining permission Rectification

ND testing

Completion reports Hydraulic test

Obtaining permission for light up


56/56

THANK YOU

Documents

Mntce Ofboiler Pressure Parts