Presentation of

Residual Life Assessment (RLA)

By

H.S.BediSr. Vice President

(Power Engineering and Energy Services)

RESIDUAL LIFE ASSESSMENT (RLA) STUDY: ENERGO STRENGTH

Accredited by -Central Boiler Board Govt. of India. RLA study is carried out by conducting NDT & DT as

per IBR 391 A Table –I & II. NDT tests of turbine components are carried out

generally as per the scope of work of the client and based on the experience of the agency.

RLA study of Generators, Electricals & Civil structures is also carried out generally as per the scope of work of the client and based on the experience of the agency.

OUR APPROACH IS

CONCERNED FOR

EXTENDED OPERATION OF PLANT SAFELY

DESCRIPTIOPN MAKE MODEL

Ultrasonic Flaw Detector: EEC DS322

Ultrasonic Thickness Gauge EEC ETM-2ETM-2ETM -2DL

Magnetic Particle Magnaflux EF-2Ytesting electromagnetic yoke: EEC

List of In-House Instruments

CREDIBILITY

1. WE HAVE COMPLETED RLA OF BOILERS RANGING FROM 25 MW TO 500 MW POST CERTIFICATION FOR OUR VARIOUS CLIENTS.

2. COMPLETED RLA OF TG & AUXILIARIES.

DESCRIPTIOPN MAKE MODEL

In-Situ Advanced Ultrasonic Panametrics,37 DL PlusOxide Scale Thickness USA With additionalMeasurement Gauge: Probes for

150 micron

Black light source: Magnaflux ZB 100 K 100

DPT Kit: Magnaflux

List of In-House Instruments

DESCRIPTIOPN MAKE MODEL

Hardness tester: OPTEL HT-7  TIME TH130

Fibroscopy Scholly MP 600

Vernier Caliper: Aero space DigitalOutside Caliper:Outside Micrometer : Precision Manual Parent metal analysis (PMI) : X-MET

List of In-House Instruments contd..

OUR RLA INVOLVEMENT IS

FOR

BOILER TURBINE GENERATOR AND AUXILLIARIES

ACTIVITIES WHICH ARE CARRIED OUT OBTAINING PERMISSION FOR RLA FROM STATE CIB

HOT WALK DOWN SURVEY-PLANT OPERATING DATA.

COLD WALK DOWN AND DECIDING TEST LOCATIONS.

CONDUCT NDT AS PER IBR 391 A. / B & REPORT

COLLECT SAMPLES FOR LAB. / DESTRUCTIVE TESTS

BASED ON OBSERVATIONS, NDT DATA ANALYSIS, ESTIMATED REMENANT LIFE IS WORKED OUT BY VARIOUS METHODS ( eg, TH. / DIM, REPLICA OF MICROSTRUCTURE, DEPOSIT ANALYSIS, OXIDE SCALE & ACRT IF REQD, CHOOSING THE LEAST / SAFEST LIFE.

SUBMISSION OF FINAL REPORT COMPRISING OF RUN REPAIR, REPLACEMENT RECOMMENDATIONS

RLA RELATED, IBR RECOMMENDED & CUSTOMER REQUIRED TESTS ON BOILERS

VISUAL EXAMINATION PLANT OUTAGE DATA & HISTORYASME B & P V Code: Section: V.

SAG, SWELL, DIM, OD AND THICKNESS MEASUREMENT DYE PENETRANT TEST as per ASTM-E 165 MAGNETIC PARTICAL INSPECTION as per ASTM-E 709 & A-275, E-1444 ULTRASONIC TEST (THICKNESS / FLAW DETECTION) as per ASTM-E 114 & 587 IN-SITU HARDNESS TEST IN-SITU METALLOGRAPHY & REPLICATION as per ASTM-E 139 FIBROSCOPIC / VIDEOSCOPY ( INTERNAL INSPECTION ) IN-SITU OXIDE SCALE / CORROSION THICKNESS MEASUREMENT. HYDOGEN EMBRITTLEMENT TEST DEPOSIT SAMPLES COLLECTION FOR ANALYSIS IN LAB. TUBE SAMPLES ( Mech., Met., ETC.) IN LAB. HANGER AND SUPPORT CHECKING

Residual Life Assessment Study: Energo Strength

Steam Path Audit Hangers Study Oxide scale measurement Natural Frequency Test(NFT) in HP,IP & LP Turbine Rotor blades Eddy Current Test in condenser tubes Eddy Current Test in turbine blades Magnetic Particle Inspection(MPI) in coil method Boroscopy & Borosonic Tests ELCID test on core RSO test on rotor winding Frequency Response analysis Test Measurement of Tan Delta Step voltage test Surge comparison test

FATIGUE: NUCLEATION AND GROWTH OF CRACKS UNDER A TIME DEPENDENT LOADING

CREEP: VISCOPLASTICITY UNDER STATIC LOADING

CORROSION: CHEMICAL REACTION OF MATERIAL WITH ENVIRONMENT

DAMAGE MECHANISMDIFFUSIONAL DECOMPOSITION OF PHASES

MAJOR AFFECTING VARIABLE(S):

ENVIRONMENT, STRESS, & TEMPERATURE

1. PURE CHEMICAL ATTACK (SELECTIVE LEACHING / PHASE ATTACK, GRAIN BOUNDARY OXIDATION, & PITTING)

2. CORROSION-FATIGUE

INTERACTION OF CHEMICAL ATTACK WITH FATIGUE (NON-DUCTILE, MIXED MODE FAILURES)

MECHANISM OF CORROSION

CREEP AFFECTING THE AGE OF COMPONENTS

CREEP BEING TIME & TEMPRATURE DEPENDENT PHENOMANON, IT IS IMPERATIVE TO CONTROL TEMPERATURE OF SUPER HEATER, REHEATER TUBES EITHER BY INSTALLING METAL TEMPERATURE MEASUREMENTS OR BY INDIRECT METHODS.

COMPONENTS OPERATING AT EVEN FEW DEGREES HIGHER THAN THE DESIGN TEMPERATURE CAN DRASTICALLY REDUCE THE OPERATING LIFE IN CREEP REGION.

FATIGUE & HIGH VIBRATION LEVEL RESULT IN ACCELERATED LOSS OF LIFE OF COMPONENTS OPERATING IN CREEP REGION.

POOR METAL SURFACE CLEANLINESS AFFECTS THERMAL CONDUCTIVITY TO A GREAT EXTENT.

CREEP DAMAGE BY MICROSTRUCTURAL ANALYSIS

NEUBAUER & WEDEL METHOD OF INTERPRETATION OF CREEP DAMAGE AND PREDICTION OF REMNANT LIFE.

Structural Classification

Microstructure features

Expended life fraction (x)

Undamaged Ferrite & pearlite 0.12

1 Isolated Cavities 0.46

2 Oriented Cavities 0.50

3 Limited Cavities (Microcracks

0.84

4 Macrocracks 1.00

REMAINING LIFE trem = texp X (1/x-1)

GRAIN GROWTH

SPHERODIZATION OF PEARLITE / BAINITE

BREAKUP OF PEARLITE / BAINITE WITH RE-PRECIPITATION AT GRAIN BOUNDARIES

COARSENING OF CARBIDE PHASES

EARLY SIGNS OF DEGENERATION BEFORE ISOLATED CAVITIES

OPTICAL SIGNATURES OF DIFFUSIONAL DECOMPOSITION SEEN IN MICROSTRUCTURE

Microstructure show ferrite and bainite. Bainitic breakdown just started. Mag: 800X

Microstructure show major degradation of bainite. Distribution of carbides in ferrite. Mag: 800X

IN-SITU METALLOGRAPHY

Energo Engineering Projects Limited, New Delhi

Microstructure show ferrite and grain boundary carbides. Thick grain boundary. Mag: 100X

Microstructure show austenitic grains with grain boundary Carbide Precipitation . Mag: 200X

IN-SITU METALLOGRAPHY

CBB Approval Presentation 4 May 2010\OBSERVATION DURING Metalurgical Testing.ppt

HIGH TEMPERATURE HEADERS, TUBING & WELD METAL

CONVECTIVE SUPER HEATER

RADIANT SUPER HEATER

FINAL SUPERHEATER

• ATTEMPERATOR

• MAIN STEAM PIPE & AUX. STEAM PIPING &

• HIGH TEMPERATURE VALVES

FOR HEALTH RECORDS ADDITIONALY ON STEAM DRUM ALSO

POWER / PROCESS BOILER COMPONENTS ARE GENERALLY EVALUATED USING IN-SITU

METALLOGRAPHY ON:

OXIDE SCALE DEPOSIT THICKNESS BASED LIFE CALCULATIONS BY IN-HOUSE DEVELOPED

PROGRAM

Continued…

PARAMETERS UNIT SYMBOLOXIDE SCALE THICKNESS MICRON XTHICKNESS mm TO

OUTSIDE DIAMETER mm ODWORKING PRESSURE Kg/mm2 WPMATERIAL SPECIFICATION --- 1-3 Cr Mo SteelTOTAL OPERATING HOURS Hrs. Tr

NOMINAL TEMPERATURE 0R T1-4

INPUT PARAMETERS REQUIRED

Ultrasonic Thickness Measurement of Internal Oxide Scale

A significant limiting factor that affects tube life in fossil fired steam boilers is the growth of iron oxide scale (magnetite) on the inside tube surfaces. The oxide scale, which forms under long term exposure to very high temperature, acts as a thermal insulator.

Nondestructive measurement of internal oxide scale thickness is of major interest in the power generation industry.

The very high temperatures found inside steam boilers (in excess of 800 degrees Celsius) can cause the formation of a specific type of hard, brittle iron oxide called magnetite on the inside surfaces of boiler tubes. At very high temperature, water vapor will react with the iron in the steel to form magnetite and hydrogen.

This oxide layer is detrimental to life of the tube which can be measured with the high frequency broad bad ultrasonic equipment.

OXIDE SCALE THICKNESS IN MILS (X0)= (0.04) x (X)…EQN-1

CALCULATION OF OXIDE SCALE GROWTHASSUMPTION: - OXIDE SCALE GROWTH AS LINEAR

GROWTH CONSTANT K (mils / year) = (X0) / (NO OF YEARS EXPENDED SAY 20)

OXIDE SCALE AFTER FIRST INTERVAL Tr1

X1 (SAY FIVE YEARS) = K x (5) mils

OXIDE SCALE AFTER SECOND INTERVAL Tr2

X2 (SAY TEN YEARS) = K x (10) mils

OXIDE SCALE AFTER THIRD INTERVAL Tr3

X3 (SAY FIFTEEN YEARS) = K x (15) mils

OXIDE SCALE AFTER FOURTH INTERVAL Tr4

X4 (SAY TWENTY YEARS) =K x (20) mils

…EQNS- 2

Log

(Oxi

de th

ickn

ess

in M

ils)

0.2

30K26K24K 28KP

CORRESPONDING VALUE OF P FOR OXIDE THICKNESS X1, X2, X3, X4 ARE P1, P2, P3, P4 RESPECTIVELY…

Continued…

0.4 0.6

…EQNS- 3

Value of P (LMP) for Oxide thickness from Graph

T0 = P / (13.62 + Log t)

Where t IS TOTAL TIME IN HRS UPTO END OF EACH INTERVAL

BY PUTTING THE VALUE OF P1, P2, P3, P4 AND t1, t2, t3, t4

CORRESPONDING VALUES T1, T2, T3, T4 OF CAN BE OBTAINEDT1 = P1 / (13.62 + Log t1)

T2 = P2 / (13.62 + Log t2)

T3 = P3 / (13.62 + Log t3)

T4 = P4 / (13.62 + Log t4)

CALCULATION OF HOOP STRESS (f) IN Ksi

f = [{WP (OD - TO)} / 2TO] / 0.7031

Continued…

…EQNS- 5

…EQNS- 4

Obtaining Corresponding Value of Temperature To in Rankine

Continued…

P = T (20 + Log tr) x 10-3, where T is in OR

PSt

ress

(Ksi

)LARSON MILLER RUPTURE PARAMETER WITH STRESS FOR 2¼ Cr-1 Mo Steel

Value of Larson MillerRupture Parameterwith stress fromthe graph as shown:

BY PUTTING THE VALUE OF P&T IN THE FORMULA

P = T (20 + Log tr) Where tr is the rupture timeCALCULATION OF CORRESPODING RUPTURE TIME tr1, tr2, tr3 tr4 FROM ABOVE FORMULA BY PUTTING THE CORRESPONDING VALUE OF P1, P2, P3,

P4 AND T1, T2, T3, T4

CALCULATION OF EXPENDED LIFE FRACTION

a1 = Tr1 / tr1 ; a2 = T r2/ tr2.; a3 = Tr3 / tr3. ; a4 = Tr4 / tr4.TOTAL LIFE FRACTION EXPENDED a = a1 + a2 + a3 + a4

REMAINING LIFE (trem) = {(1-a) / a} x Tr

IN-SITU MEASUREMENT & CALCULATIONS OF

REMNANT LIFE THROUGH OXIDE SCALE THICKNESS

SEPARATE SOFTWARE DEMO…

ENOXIDEPROG-X047

IN-SITU MEASUREMENT & CALCULATION OF REMNANT LIFE

THROUGH OXIDE SCALE THICKNESS

SEPARATE SOFTWARE DEMO…

ENOXIDEPROG-X047

ACCELERATED CREEP RUPTURE TEST – ACRT

PARAMETERS UNIT SYMBOL

NOMINAL OD mm OD

NOMINAL THICKNESS mm Thk

WORKING PRESSURE Kg/mm2 WP

MATERIAL SPECIFICATION --- 1-3 Cr Mo Steel

SERVICE EXPOSURE RUPTURE

TIME FOR ACRT

Hrs. tr

NOMINAL TEMPERATURE FOR

ACRT

0K T

INPUT PARAMETERS REQUIRED

STEPS FOR CALCULATIONS FOR

Hoop stress f in kg/cm2 = [{WP (OD - Thk)} / 2Thk]

WhereWP = Work Pressure in kg/cm2 OD = Tube OD (mm)Thk = Tube thickness (mm)f MPa = f kg/cm2 x 0.09804

LM(P) = T (20 + log tr) EQN

For ACRT hoop stress f (in Mpa) is taken

15 to 20% more.

LMP (P) is calculated for the rupture / test period of ACRT at elevated Temperature Te say (600+273)°K and elevated test hoop stress.

Considering above LMP and operating temperature say (540+273)°K, rupture time is evaluated at test hoop stress which is say ‘X’.

Similarly the ratiio of rupture time for working hoop stress and elevated test hoop stress is evaluated from LMP v/s hoop stress curve which is say ‘Y’

Net rupture time or life of tubes shall be thus ‘X’ x ’Y’

FOR ASSESSING THE REMNENT LIFE THROUGH…

WORKING PR. SAFETY RE-CALCULATIONS DUE TO THICKNESS REDUCTION. ( 1 )

CREEP DAMAGE BY MICROSTRUCTURAL ANALYSIS. ( 2 )

OXIDE SCALE THICKNESS MEASUREMENT IN BOILER TUBES, BASED ANALYSIS. ( 3 )

STRESS RUPTURE / ACCELERATED CREEP RUPTURE TEST (ACRT) BASED REMAINING LIFE. ( 4 ).

LOWEST CALCULATED VALUE IS CONSIDERED FOR REMAINING LIFE

ANALYSIS OF TEST RESULTS / DATA

FEW OBSERVATIONS AS SEEN DURING

VISUAL INSPECTION AND FIBROSCOPY

VISUAL EXAMINATION

Corrosion Pitting on Link Pipe bend external surface (SHH-4 to SHH-6)

Sagging of Link pipe from PSH outlet header to platen SH inlet header.

Rupture type failure of Final super heater coil tubes

Weld mebuild-up of eroded PSH tubestal

VISUAL EXAMINATION

Deformation of FSH tubes due to overheating.

Platen SH coils under bowing due to overheating.

VISUAL EXAMINATION

Heavy weld build-up on the stub welding joints of LTSH inlet header.

VISUAL EXAMINATION

Deformation in water wall tubes.

Damaged Refractory, Insulation & Skin Casing in Ist Pass.

VISUAL EXAMINATION

Cracked Spring loaded support assembly of main steam piping .

Sagging / deformation of ceiling super heater tubes.

VISUAL EXAMINATION

Deformed secondary super heater coil tubes, failure of spacers & over heating impression on tube surface.

Overheating signs on platen SH coils after cleaning deposits.

VISUAL EXAMINATION

Convection zone rear wall tube with erosion effect during long service.

HEAVY CORROSION & SCALE BUILD UP ON LHS STEAM DRUM DISH END.

WW TUBES SHOWING EXTERNAL CORROSION EFFECT IN FRONT PANEL.

VISUAL SWELLLING OBSERVED AT 3&4 SPOTS ON WW TUBE AS SHOWN IN PHOTOGRAPH.

PHOTOGRAPH SHOWS RUPTURED TUBES OF WW PANEL FRONT SIDE.

APPERANCE OF CREEP DAMAGE OBSERVED ON TUBES.

LOCALIZED CORROSION MARK IN THE FORM OF PITTING NOTICED ON EXTERNAL SURFACE OF TUBE AT DIFFERENT LOCATION OF WW PANELS.

OVERHEATING EFFECT ON FSH O/L HDR &TUBES .

MISSING OF LOCK PIN IN HANGER SUPPORT OF SH HDR.

FIBROSCOPY

CORROSION INSIDE BOTTOM RING HEADER

CORROSION INSIDE BOTTOM RING HEADER

CRACKS IN NOZZLE OF DESUPERHEATER SPRAYING NOZZLE.

FIBROSCOPY

IN SITU METALLOGRAPHY

IN SITU METALLOGRAPHY

FIBROSCOPY OF HEADER

DPT ON BEARING

DPT ON ROTOR

MPI ON CASING

MPI CARRIED OUT ON TURBINE

BLADE

ULTRASONIC TESTING

CARRIED OUT ON PIPING

CORE CUTTING IN FOUNDATION

UPV TEST ON FWP FOUNDATION

FAIRLY REASONABLE LIFE IS DEPENDENT UPON: CONTROL OF METAL TEMPERATURE WITHIN DESIRABLE ACCURACY THROUGH OPERATION

RECOMMENDED WATER QUALITY BEING MAINTAINED

RELIABLE INPUT OPERATIONAL DATA & ASSUMPTIONS

EXTRAPOLATION OF REFERENCE POINTS TO ARRIVE AT EASONABLE ASSESSMENT

OPTIMIZING THE ECONOMICS OF RLA EXERCISE

MINIMIZING SHUT DOWN TIME USING CAPITAL MAINTAINENCE TIME FOR REFURBISHMENT

SAVING THE ENERGY & PROCESS COST BY DOWN TIME REDUCTION

REDUCING THE RISK OF LOW PRODUCTION & ALSO ACCIDENT AND RISK OF LIFE

IMPROVING THE PLANT AVAILABILITY & PROFITABILITY