Btl Uprvunl Present II

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PRESSURE PARTS FAILURE

REPORTING, INVESTIGATION & ANALYSIS SYSTEM

&

BOILER TUBE FAILURE MANAGEMENT THROUGH QUALITY UNIT OVERHAULS By Anil Kumar AGM (Mech) – PIE

7th August 2007-UPRVUNL: Panki

NTPC

Limited

WELCOME TO THE PRESENTATION



OBJECTIVE:

TO ACHIEVE ZERO TUBE LEAKAGE BASED. BTF ACCOUNTS FOR

60-80% OF TOTAL DOWN TIME

SCOPE:

PRESSURE PARTS FAILURE REPORTING, INVESTIGATION, ANALYSIS

& DATA SYSTEM AIMS TO ACHIEVE ZERO BTL BASED ON RCA & TIME

BOUND CORRECTIVE ACTION PLAN IT DEFINES RESPONSBILITIES OF

VARIOUS GROUPS WITHIN THE ORGANIZATION & COORDINATION

WITH EXTERNAL AGENCIES TO CARRY OUT DT/NDT INSPECTIONS,

INVESTIGATION & ANALYSIS, FEEDBACK & DOCUMENTATION AND

ACTION PLAN TO ACHIEVE THE OBJECTIVE BASED ON GENERATEDDATA BASE

PRESSURE PARTS FAILURE

REPORTING,

INVESTIGATION, ANALYSIS

& DATA SYSTEM



1. BTL Reporting Format

2. BTL Site Level Investigation Committee :

Sampling Methodology:

Two photographs 100x150 mm :

One in situ, if possible & another after cut

Identification plate 300x200 mm painted black with information

containing Name of the station, unit no, location 7 details of failure,

Date of Failure, Id. No etc

Tube shall be cut by saw with 18” either side of failure. If gas cut it

must be 24” either side & dressed to 18” by saw later

Site Level Investigation: Observations, Analysis, Recommendations &Implementation Plan

BOILER TUBE FAILURE

MANAGEMENT



3. Reporting at HQ- Operation Services for Further Action

4. Need of Metallurgical Investigation at R&D Lab

5. Documentation, Report Integration & Corrective Action Plan

6. Knowledge Forum for New Technological Adoption

7. Pre-OH predictive scope of work & preparedness

8. Quality Surveillances during unit overhauls

(in-house/HQ/External Agency directly under FQA)

BOILER TUBE FAILURE

MANAGEMENT



BOILER TUBE FAILURE REPORTING FORMAT



BOILER TUBE FAILURE REPORTING FORMAT



BOILER TUBE FAILURESITE LEVEL INVESTIGATION

COMMITTE

1. HOD - Maintenance Management Services: Coordinator

2. HOD- Boiler Maintenance Division

3. HOD- Operations & Energy Efficiency Division

4. HOD- Operations Division



BTF INVESTIGATION

PROCESS

Site BTF Committee(Maint. Planning, BMD,

Operation, O&EE)

[REPORT-within 72 Hrs

of completion of repairs]

1. Format:Duly filled with all relevant details

2. Photographs:Specifying station/unit no/date of failure

3. Sample :Tube must be saw cut 18” either side of failure

HQ-OS

Observations

Corrective Action Plan

Monitoring of CAP

R&D Investigations

(if required)

Unit OH Plan

BTF

QC: External Inspections & NDT

Scope of Work for Unit Overhauls

New Technology

Interventions



BOILER TUBE FAILURE

MANAGEMENT

PREVENTION ASPECTS



BTF REDUCTION

STRATEGY

OPERATION ASPECTS

MAINTENANCE ASPECTS

DESIGN ASPECTS



LOW PARAMETER OPERATIONOF BOILER PRESSURE PARTS

(AT LOW PRESSURE & LOW TEMPERATURE)

DOES NOT NECESSARIALLY ENSURE

LESS PRESSURE PART FAILURES

BOILER TUBE FAILURE

MANAGEMENT

OPERATIONAL ASPECTS

IMPACT ANALYSIS OF PP-OPERATIONAL REGIME RESTRICTIONS

at one of the NTPC-PIE Stations

D-3: Restricted to 95-100 kg/cm2 from design 149 kg/cm2

D-4:Restricted to 120 kg/cm2 from design 149 kg/cm2

UNIT NO Before (April-Aug’ 06)

Duration= 5 Months

After (Sept’ 06-March 07)

Duration= 7 Months

Nos MU Lost BTF/M Nos MU Lost BTF/M

D-3 8 63.73 1.6 10 92.42 1.4

D-4 4 72.79 0.8 2 21.65 0.3



BOILER TUBE FAILURE MANAGEMENT

OPERATIONAL ASPECTS

1. NEED OF STANDARD & MANAGEMENTAPPROVED OPERATIONAL PRACTICES

2. KNOWLEDGE MANAGEMENT: Forum for discussion &

deliberations3. FOCUS ON WATER CHEMISTRY: Strategic control of

Boiler water & steam purity to keep boiler tubes interior clean for effective heat transfer need to be given top most priority

4. MONITOR TEMPERATURE EXCURSIONS: Discussduring daily review meeting for larger awareness & better control as agood operational practice.

5. Ensure availability of all P&I and auto loops/logics.Avoid drum level surge




OPERATIONAL ASPECTS

5. ENSURE ADEQUATE/PROPER SOOT BLOWING: Soot Blower operation optimization to prevent erosion due

to excessive soot blowing, high steam pressure or pittingdue to low /wet steam parameters is essential. There is needto optimize parameter regime as well as frequency of soot

blower operation

6. CPU IN SERVICE: to remove all cruds from condensate,to reduce water wall internal deposits

7. CLEAN APH BASKETS: to ensure smooth flue gas flow& reduce second pass deposit & high temperature.




OPERATIONAL ASPECTS

08. COMBUSTION OPTIMIZATION: to reduce slagging &clinker fall, to prevent fin weld fouling, to reduce the need

to soot blow, to ensure smooth flue gas velocity, to preventthermal shocks & vibrations to pressure parts, to preventimplosions/explosions etc combustion optimization isessential.

Excess air/ Air ingress control Flue gas temperature optimization

09. TRIP MANAGEMENT: dedicated group for honest tripanalysis. Avoid trips



BOILER TUBE FAILURE

MANAGEMENT

OPERATIONAL ASPECTS

Ownership role of Operations Training & Skill dominant career growth plan

Single point responsibility with HoD (Operation) for

House Keeping & Routine equipment/ panel cleanliness.Good illumination to ensure safe & efficient work conditions

Adequate attention & full preparedness in Fire Fighting Systems

wrt fire related eventualities.Water Management to ensure adequate availability of water forCW system/Emergency services etc.

Ash Dyke Management to ensure trouble free ash evacuationwithout affecting generation



ORGANIZED & QUALITY

UNIT OVERHAULS

WITH FULL PREPAREDNESS


MAINTENACE ASPECTS



1. BTL ANALYSIS & TRENDING OF FAILURE PATTERN

2. BOILER CONDITION ASSESMENT DURING EVERY OVERHAUL BY

THIRD PARTY & DOCUMENTATION

Erosion Survey

Tube Condition Assessment for Deposits & need for acid cleaning etc. Inspection of Hangers & Supports, Expansion Guides etc

3. GOOD PLANNING OF UNIT OVERHAULS

Adequate Scope of Work

Advance Resource Planning wrt Spares, Skill (Quality & Quantity), T&P

Boiler OH only with full preparedness wrt spares, material & contracts

Use of Maintenance Quality Checks & Protocol (M-QCP) Sheets

Third party inspection, NDT & Radiography under Station QualityControl.


MAINTENACE ASPECTS



3. GOOD PLANNING OF UNIT OVERHAULS (Contd….)

Use of independent inspection/survey/NDT agency under boiler maintenanceengineer for erosion survey & radiography etc. 80% -100% radiography of joints. Tube thickness survey at right locations.

Inspection of tubes after fin cutting and DPT of Fin welding & old

joints/supports/stub/ attachment etc. Radiography of old welding joints, IPW & DMW joints. Radiography of bends to detect internal chokages/blockages

In-situ NDT tests like Oxide scale thickness measurement/Boroscope/hardness etc. at regular intervals

4. HP WELDERS TEST & REJECTION RATE MONITORING In-house testing of HP welders. Monitor HP welder performance through

rejection rate.

Ensure use of right electrode. Ensure electrodes are baked properly beforestart of welding


MAINTENACE ASPECTS



5. ADOPTION OF GOOD MAINTENANCE PRACTICES Cleaning of pressure parts by HP Jet Pump & Use of scrapper or wire brush

Access Platforms, Safety Appliances etc: Use of quick erect scaffolding foreasy access at all places and to carry out extensive erosion survey

Tube Cutting using Portable Saw. No gas cutting of tubes. Adequate

Protection in case of use of gas for tube cutting. Capping of cut tubes withPVC caps

Removal of HAZ by Saw

Removal of all Pad Welding & Window Welding Repairs with New Tubes

Use of Bend, Shield etc from reputed Vendors. Avoid local/ in situ making

Through & Safe Access to all Pressure Part Areas for Inspection & Work Boiler Flushing & Draining and Inspection of Down Comer Headers

Cyclic Hydro before Start of Repairs in Old Boilers

Keep coil alignment perfect


MAINTENACE ASPECTS



5. ADOPTION OF GOOD MAINTENANCE PRACTICES (Contd….) Use of proper & safe platform at ECO/LTSH area along with coil handling

facility

Make adequate mechanized arrangement for pent house ash removal if leakage is suspected

Tubes/bends to be checked for thru ness before fixing. Header flushing &inspection after completion of OH

Avoid stray arcing on tubes. Adjacent tubes are damaged. Care while fincutting to avoid damage to adjacent tube while cutting

Ensure tube/coil alignment during each OH in first and second pass

Replace coal nozzles & proper alignment. Repair & proper operation of SADC

DMW joint NDT & replacement plans

Fin welding by 2.5 mm electrode

Avoid fabrication of different types of bends at site


MAINTENACE ASPECTS



5. ADOPTION OF GOOD MAINTENANCE PRACTICES (Contd…) Pressurisation of Re-heater circuit/MS Circuit to check for leakage detection

Air testing with Sponge ball for testing of loops/coils

Develop experiences based schedule for economizer/ Primary SH etc for coillifting/inspection/reversal

Air testing with Sponge ball for testing of loops/coils Inspection of orifice in FSH area to find the cause of overheating

Replacement of spacer tube of platen super heater

Replacement of DMW, Clamp, shield in primary SH area

Phase wise reversal/replacement of ECO coil with new coils instead of total

replacement at one time to achieve low down time

Thorough & adequate cleaning of pressure parts to ensure effective heattransfer


MAINTENACE ASPECTS



5. ADOPTION OF GOOD MAINTENANCE PRACTICES (Contd….) Restore Supports/ clamps which are cut during work

Check Looseness of hanger supports & rectify

Check for misalignment of the coils. Replace missing/broken connectors.Ensure all coils are aligned

Ensure proper fixing of shields and cassette baffles. Replace all impropershield/baffles

Use of latest maintenance tools & techniques eg Portable Bevelling Machine,Plasma Arc Cutting Machine, Portable welding Machine, Headers Hand holeplate cutting machine etc

Adequate illumination inside boiler. Use of 24 V supplies & pneumatic toolsto prevent loss of life due to electrocution. Use safety nets in S-Panel area.Usage of fibre body hand tools

Joint inspection along with safety inspector for scaffolding & planks fix up.Load testing of all T&P


MAINTENACE ASPECTS



6. MISCELLEANOUS AREAS NEED ATTENTION:

USE OF PPE & Safety Training to all contract workmen

VALVES: All the safety valves are to be serviced and trevi testing done.

Actual floating of valves on which maintenance has been carried out should bedone. All root valves in the hydraulic test circuit are being serviced and bluematched & witnessed by team of maintenance, operation & quality

SOOT BLOWERS: Monitoring of availability of wall blowers &Restoration of LRSB

COAL BURNERS: Proper repair hard facing of splitter plates & in sidesurface/replacement of nozzle etc . Ensure proper alignment of coal/airnozzles.


MAINTENACE ASPECTS



UNIT OVERHAUL QUALITY ASPECTS

USE OF M-QCP FOR STRUCTURED & PLANNED EROSION SURVEYSDATA ANALYSIS & TRENDING FOR FUTURE PLANNING & UNIT OVERHAULS
























MAINTENANCE

PREVENTION ASPECTS



Wear bars on S- panel

PROVIDING WEAR BARS ON S-PANEL



cassette baffles protection for economizer bend



ECO COIL PROTECTION SHIELD

LOCKING ARRANGEMENT



economizer end erosion

use of cassette baffles &

refractory for protection



Erosion of SCW bifurcates and its

prevention



REVERSAL OF ECONOMIZER

COILS



LTSH inlet header- Shielding

arrangement on tube surface



use of sacrificing shield



UNIT

OVERHAUL

MANAGEMENT Advance Planning: 18 – 24 month (minimum)

Defining Scope Of Work in detail Identification of requirement of resources

(Spares, consumables, skill & contracts)

Organizing resources in time

STRATEGIC PLANNING



STRATEGIC PLANNING

& OVERHAUL

MANAGEMENTThree tier planning system need to be adopted.

Life Cycle Plan (LCP) Station Rolling Plan (SRP)

Station Location Annual Plan (SLAP)

LIFE CYCLE PLAN (LCP)

Focus on major replacement plan for the entire life cycle of 25-30 years.

Covers replacement of the equipment/parts which are likely to fail before or nearthe life expectancy & have a long lead time.

Examples: super heaters, re-heaters, high pressure valves, safety valves, gear reducers, ash disposallines, slurry pumps, chemical piping, resins, conveyor belts and drives, coal crushers, turbine rotorblades, turbine bolts, boiler feed pump rotor, H.P. heater coil, H.T. motor, transformer, switch gears,cables, etc.

Replacement plans are conceived on the consideration of Coal quality, Creep life

of various components, Equipment duty conditions, Actual Wear rate andBehavioral trend of plant /equipment inspection and RLA reports etc.

LIFE CYCLE PLAN (LCP)



Years Activity Description01 Statutory Inspection, Coal Burners, APH Seals.

02 Statutory Inspection, Coal Burners, APH Seals. ECO/LTSH bends & tubes, Refractory

04 Statutory Inspection, Coal Burners, APH Seals.

ECO/LTSH bends & tubes, Refractory, ESP Electrodes, ID Fan Impellers, Defective Valves

08 Statutory Inspection, Coal Burners, APH Seals.ECO/LTSH bends & tubes, Refractory, ESP Electrodes, ID Fan Impellers, Defective Valves, APHBaskets, PF Bends, ECO/LTSH Coil Reversal, DC Batteries Replacement


ECO/LTSH bends & tubes, Refractory, ESP Electrodes, ID Fan Impellers, Defective Valves, APHBaskets, PF Bends, ECO/LTSH Coil, DC Batteries HP/IP Turbine Casing Studs, HP/IP CV/GV Bolts,

Turbine Bearings, Turbine Inter stage seals, Electrical Cables, Control Cables


ECO/LTSH bends & tubes, Refractory, ESP Electrodes, ID Fan Impellers, Defective Valves, APHBaskets, PF Bends, ECO/LTSH Coil, DC Batteries HP/IP Turbine Blades, Diaphragm, Casing Studs,HP/IP CV/GV Bolts, Turbine Bearings, Turbine Inter stage seals, Electrical Cables, Control Cables,Heaters/Condensers/ Heat Exchangers tubes/tube nest etc.

LIFE CYCLE PLAN (LCP) [TYPICAL]



Stn/Unit Cap Last O/H Done FY 2005-06 FY 2006-07 FY 2007-08 FY 2008-09 FY 2009-10

XXX

Unit-1 500 HPT 27-Nov-03 From 12-Aug-05 12-Aug-06 12-Aug-07 12-Aug-08 12-Aug-09

IPT 23-Oct-01 To 29-Aug-05 29-Aug-06 11-Sep-07 29-Aug-08 6-Sep-09

LPT 23-Oct-01 Duration 18d 18d 30d 18d 30dGen 27-Nov-03 O/H Type Boiler Boiler Blr+IP+LP Boiler B+HP

Blr 27-Nov-03

Unit-2 500 HPT 1-Oct-97 From 12-Sep-05 12-Sep-06 12-Sep-07 1-Sep-08 12-Sep-09

IPT 9-Oct-02 To 29-Sep-05 29-Sep-06 29-Sep-07 30-Sep-08 29-Sep-09

LPT 9-Oct-02 Duration 18d 18d 18d 30d 18d

Gen 9-Oct-02 O/H Type Boiler Boiler Boiler Blr+IP+LP Boiler

Blr 29-Sep-03

Total 1000 P/M % 4.93 4.93 6.57 6.55 6.57

Rolling Plan of a Thermal Station (Typical)

Station rolling plans are drawn on six year spread so that capacity outage is

optimized to match the regional grid demand.

The first two-three years should be planned and presented in detail. The subsequent three

years shall be indicative. These plans are updated every year in a rolling manner

STATION ROLLING PLAN (SRP)



It provides an accurate assessment of generation & unit outage plans for the year.

OBJECTIVE: is to identify all the constraints to achieve the generation level andorganize resources for effective operation and maintenance. It requires technicalassessment of the units capability and plan unit overhauls.

It also identifies interface with OEM, manufacturing facilities and skill requirements

Statn Unit Inst. Cap.MW

2006-2007

June July Aug Sept Oct Nov Jan Feb

xxx 1 00 1 to 20/11

2 00 1 to 20/2

3 00 10/9 to 30/10

4 00

5 00

6 00 1/6 to 30/7

STATION LOCATION ANNUAL PLAN (TYPICAL)

STATION LOCATION ANNUAL PLAN

(SLAP)

UNIT ANNUAL OVERHAULS



OBJECTIVES OF UNIT OVERHAUL PLANNING

• QUALITY FOR RELIABILITY (O2O MAINTENANCE)

• OPTIMIZE TIME SCHEDULE & COST

Overhaul planning process is initiated with Engineering Declaration 18-24 months in

advance. The planning process of any unit outage has essentially three stages:

¢ X Pre Shut down Planning activities

¢ X Shut down activities

¢ X Post shut down activities

The cost of unit overhauls in terms of generation loss are very high Adequate work and resource planning for unit overhauls in an integrated manner is essential to avoid last minute shock and surprises as also to have reliable

performance of the unit after overhauls.

THE DECLARATION OF UNIT OVERHAULS SUBSEQUENT TO ANY FORCED

OUTAGE HAS TO BE AVOIDED BECAUSE OF ITS UNDESIRABLE AFFECTS ON

RESOURCE AVAILABILITY AND UNPREPARED EXECUTION.

ONLY OUTAGES BUDGET UNDER STATION LOCATION ANNUAL PLANS SHALL BE TERMED

AS PLANNED OUTAGE. ALL OTHER OUTAGES SHALL BE TERMED AS FORCED OUTAGE

UNIT ANNUAL OVERHAULS

PLANNING PROCESS

PLANNING PROCESS FOR UNIT OVERHAUL



Bill

of

Material

Job

List

(24M)

Skill Resource

Analysis (18 M)

Skill

&

Manpower

Indent &

Procurement (18 -24 M)

Tender &

Contracts (12 M)

Pre shut

Down Planning

(24 M)

Maintenance

QCP(12 M)

Isolation

Plans

(6 M)

Recommissioning

Check sheets

(12 M)

MonitoringSheets

(12 M)

PERT

Net work

(12-18 M)

Pre

Outage

Survey

(15-30 D)

UNIT

OFF LOAD

Resource

Mobilization

(1 M)

Overhaul Execution

OUTAGE

OMPLETION

REPORT(1 M) Overhaul Monitoring

Quality Checks

UNIT

ON BAR

Re commissioning

checks

Post

OHReview



“Engineering Declaration” of the unit includes brief review of the past

performance of the unit, define objectives of the proposed overhaul and the

quantified projections of the return in terms of gain in reliability and efficiency.

The first “Engineering Declaration” is issued 18-24 months ahead of unit’s planed overhaul.

Periodic review of outage preparedness facilitates revisions of the plan if any.

OVERHAUL MANAGEMENT ORGANISATION (OUTAGE COMMITTEE)

This committee will be responsible to conduct the overhaul of all the units of a station during a

particular financial year as planned and shall ensure that all the jobs are carried out as per laid

down specifications and quality plans. The committee may change for next financial year according

to availability of personnel and workload of the station.

The various members of the outage team shall be as follows:The various members of the outage team shall be as follows:

a. Outage manger b. Executive: Long Term Planning c. Executive: Contractsa. Outage manger b. Executive: Long Term Planning c. Executive: Contracts

d. Executive: BMD e. Executive: TMD f. Executive: BoPd. Executive: BMD e. Executive: TMD f. Executive: BoP

g. Executive: C&I h. Executive: Electrical i. Executive: Operationsg. Executive: C&I h. Executive: Electrical i. Executive: Operations

j. Executive: MMS k. Executive: Operations Efficiency l. Executive: Materials j. Executive: MMS k. Executive: Operations Efficiency l. Executive: Materials

Members from Finance, HR etc are drawn as deemed necessary.Members from Finance, HR etc are drawn as deemed necessary.

ENGINEERING DECLARATION

OUTAGE COMMITTEE



(a) To assess skill availability and the technical capability of the contractors.

(b) To coordinate amongst different working departments and contractors.

(c) To Check and ensure that the job execution is as per technical specificationand work quality is being complied as per Maintenance Quality Checks &

Protocol (M-QCP) Sheets.(d) To ensure observance of safety rules as per laid down principles of the

company.

(e) To monitor work progress to ensure timely work completion, reduce downtime and cost.

(f) To ensure optimum utilization of resources.

(g) To coordinate for an effective work control.

(h) To facilitate de-bottle necks in planning and take appropriate measures forimprovements and effective planning.

OUTAGE COMMITTEE

FUNCTIONS

OUTAGE PREPAREDNESS INDEX (OPI)



OUTAGE PREPAREDNESS INDEX (OPI) : is devised to be a tool to measure the

“ Degree Of Preparedness” to execute the planned outage.

OPI provides a quantified measure of the “Degree of Preparedness” for planned outage of a

given unit overhaul. OPI monitoring shall begin 18 -24 months in advance of the proposed

planned date of Unit overhaul.

OVERHAUL COMPLETION REPORT (OCR) : Each completion report should bear a

unique number for identification. The cross reference of the completion report should beentered in the equipment history.Each section shall contain detail of work undertaken, surprises observed, new methods &fixtures used, quality checks & protocol sheets and shall contain following sections SECTION-1: EXECUTIVE SUMMARY

SECTION-2: BOILER & AUXILIARIES

SECTION-3: TURBINE & AUXILIARIESSECTION-4: GENERATOR & AUXILIARIES

SECTION-5: ELECTRICAL EQUIPMENTS

SECTION-6: CONTROL & INSTRUMENTATION

SECTION-7: OFFSITES AND MISCELLANEOUS

SECTION-8: RE- COMMISSIONING & EFFICIENCY EVALUATION WITH COST BENEFIT ANALYSIS

SECTION-9: MANPOWER & BUDGETS

SECTION-10: CONCLUSIONS AND RECOMMENDATIONS

( )

OUTAGE COMPLETION REPORT (OCR)

Need of Professionalism



X NEED BASED MAINTENANCE & QUALITY APPROACH: It is essential that maintenance needs are

condition based, even in boiler also. All maintenance activities must have a requisite maintenance

quality checks & protocols (M-QCP) - by maintenance.

X OPPORTUNITY MAINTENANCE TO AVOID SUDDEN SHOCKS:

Ever preparedness & Judicious decisions

to carry out opportunity based maintenance to avoid partial loading & to address pending defects &

pre-scheduling of PM etc. should be governed by economic considerations.

X KNOWLEDGE BASED MAINTENANCE:

The basic beliefs about age of the plant asset and its impact on failure “As things got older,

they were more likely to fail” have also begun to change. The concept of `infant mortality‘ & “bathtub"

curve has come in for a change.

Today it is understood that need based quality maintenance with technological improvements can

contain the failures. It involves a diagnostic process with of analytical approach.

MAINTENANCE PRACTICES & METHODS NEED A CONTINUOUS REVIEW &

UPDATE.

Need of Professionalism

in maintenance





DESIGN ASPECTS

1. Reduced flue gas velocity

Erosion=(Velocity)2.6, Preferred Velocity=10m/sec

2. Smooth change in flue gas velocity

Reduced flue gas velocity in second pass reduces fire side heat transfer

coefficient and hence the requirement of heat transfer area increases. It also increase

the fouling tendency on horizontally placed tubes in the second pass thus reducing the

heat transfer further. Therefore flue gas velocity need to be carefully optimized. Change

in flue gas velocity or direction may affect the erosion rate in new areas

3. Reduced SH/RH spray:

High spray also causes thermal shocks to headers, stubs & tubes.

4. Reduced operating limits of tube metal temperatures

5. Use of suitable material to avoid dissimilar metal welds

(DMW) joints

Use of inconel as filler material for root weld reduces failure frequency of

austenitic/ ferritic joint , SA 213 T91 avoids use of DMW but making a T91 joint iscom lex.



THANK YOU

Documents

Btl Uprvunl Present II