Development of Welding And Testing Technique/s For · PDF fileTesting (RT) Weld+buttering...
Transcript of Development of Welding And Testing Technique/s For · PDF fileTesting (RT) Weld+buttering...
By
Khalid Mahmood Pakistan Welding Institute (PWI)
PAKISTAN ATOMIC ENERGY COMMISSION (PAEC)
PAKISTAN
Development of Welding And Testing
Technique/s For Dissimilar Metal Welding Of
SA-508 Gr-3,class-1 Material With SS-316L.
• Introduction
• Objectives of development work
• Scheme of execution
• Experimental work
• Results and analysis
• Conclusions
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Scheme of Presentation
Introduction
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• Dissimilar metal welding: is a specific requirement where a transition in
metallurgical interfaces is attained in such a way that
the intended mechanical properties are achieved.
• Dissimilar metal welding presents a number of
engineering challenges such as: complex configurations,
control of weld microstructure,
difference in chemical, physical, mechanical properties,
difficulties in testing & inspection techniques etc.
Introduction
• SA-508 Cl. 1 Gr-3 is a constructional steel used mainly
in the form of forgings for the manufacture of:
Reactor Pressure Vessel (RPV),
Steam Generator (SG),
Pressurizer (PZ) and
Reactor Coolant Pump (RCP) in nuclear power plants.
• It is specifically needed to weld the safe ends of
SS-316 with SA-508 Gr-3, Cl. 1, material during NPP
construction phase which in term of welding is called
the dissimilar metal welding and is difficult to achieve.
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Introduction
Introduction
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Objective The primary objectives were:
Development of welded coupons (for calibration and with known defects) for training/certifications of UT personnel.
Development of welding procedure and performance qualifications for dissimilar welds repair and maintenance, if required and allowed.
To assess and enhance the capability level for testing and examination of dissimilar welds at PAEC level.
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Objectives of Development Work
Objective Total NPPs = 07 Nos.
Operational = 04 Nos.
Under-construction = 03Nos.
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Present status of NPPs in Pakistan
• PHASE 1: Collection of relevant information and
selection of variables
• PHASE 2: Preparation of welded coupons.
• PHASE 3: DT and NDT scheme for prepared coupons
and interpretation, discussion and analysis of the obtained results.
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Scheme of Execution for Development
Work
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PHASE 1: Collection of relevant information and selection of variables
Welding Coupons:
• Material And Dimensions: – Two (02) coupons were prepared.
– Plates of SA508 Cl-1, Gr-3 and SA-240 TP 316L were used.
– Dimensions (each)= 300mm x 300mm x 50mm
• Welding: – Process: Shielded Metal Arc Welding (SMAW)
– Filler metal: ASME SFA5.11, ENiCrFe-3 (for coupon only)
• Testing Of Produced Welds: – Available information of SNERDI , China (being designer)
was taken as reference for all testing and their acceptance criteria.
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PHASE 2 : Preparation of Welded Coupons (Process Chart)
Chemical analysis of base materials
Chemical analysis of SA-508 Chemical analysis of SS-316L
Cutting of SA-508 and
SS-316L plates
Inspection of prepared edges
of Plates
Buttering of SA-508
Plate
Applying buttering up to 5-8mm
PT+UT of Buttered
plate In process hydrogen relievment
Completion of buttering up to 30mm
Machining for edge preparation of
buttered SA-508 and 316L Plates for
welding
Stress relieving after buttering
PT of edge/bevel of
buttered plate PT of edge/bevel of SS-316L
plate
Welding of plates to produce
coupons
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SA-508 SS-316L Joint design used for the latest NPPs i-e C-3/C-4.
Joint design for the old NPP i-e C-1.
PHASE 2 : Preparation of Welded Coupons (JOINT DESIGN )
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PHASE 2 : Preparation of Welded Coupons
SA-508 Cl.1, Gr-3 Plate Dimensions =300mmx150mmx50mm
Applying Buttering Process: SMAW Filler metal: ASME SFA5.11, ENiCrFe-3,
ɸ3.2/4.0mm Currents: 130-140 amps Pre- heating: (min) 150°C Inter-pass temperature: (max) 250°C PWHT: Hydrogen and Stress relieving
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PHASE 2 : Preparation of Welded Coupon
SA-508 Buttered Plate
Prepared edge of buttered SA-508 Plate
Inconel Buttering
SA-508 plate
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PHASE 2 : Preparation of Welded Coupon
SS-316L Beveled Plate
Fit up of buttered SA-508 and SS-316L Plate
SA-508 plate
SS-316L plate
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PHASE 2 : Preparation of Welded Coupons
With single-U joint design (for NDT+DT)
With Double-U joint design (for UT reference block)
• Non-Destructive Testing (NDT)
• Destructive Testing (DT)
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PHASE 3 : Testing Scheme* for welded Coupons
Description
100% PT, 100%RT, 100%UT
Description
•Chemical Analysis
•Tensile Testing (02 specimens at each Temperature) At RT At 350°C
•Guided Bend Testing (04 specimens)
•Impact testing (03 specimens each from SA508 and weld regions) At RT At -10°C
•IGC Testing (specimens from buttering and inconel weld/SS-316L interface region) •Metallographic Examination
Micro-examination
*Available information of SNERDI , China was taken as reference for all testing and their acceptance.
• Both tests were performed at NCNDT, PAEC.
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PHASE 3 : Non Destructive Testing (NDT) Results
Test Area of interest Results Remarks
Dye Penetrant Testing (PT)
Weld+buttering +HAZs
Acceptable Facility available
at PAEC Radiography Testing (RT)
Weld+buttering +HAZs
Acceptable
Dye Penetrate Test Radiography Test
• Ultrasonic Testing (UT)
• Manual Pulsed echo technique
was adopted for calibration
and scanning of produced
DMWs by using:
45° and 60° Longitudinal probes
with frequency 2MHz.
Calibration work has been
completed with required
sensitivity.
Weld was scanned and two
acceptable discontinuities (slag
inclusions) were found.
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PHASE 3 : Non Destructive Testing (NDT) Results
• Specimens slicing of welded coupon:
– Slicing to obtain samples for different tests was carried out at PWI with band saw.
– Diagram shows the location of different samples and their locations are according to SNERDI designer specifications & ASME section IX code QW-463.1 (b).
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PHASE 3 : Destructive Testing (DT)
Chemical Analysis: – Chemical analysis of buttering and weld was done by technique called spark emission
method at PWI, PAEC.
All elements were found in acceptable range.
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PHASE 3 : Results of Destructive Testing (DT)
Elements C Si Mn P S Cr Fe Nb Ni Others
weld 0.027 0.60 5.60 0.0055 0.011 16.51 7.82 1.84 67.1 Bal.
Buttering 0.027 0.61 6.29 0.0047 0.011 15.11 6.93 1.51 69.0 Bal.
Acceptance
criteria
≤ 0.10
≤ 1.0
5-9.5
≤ 0.03
≤ 0.015
13-17
≤ 10
1-2.5
Bal.
≤ 0.50
Tensile Test: – At Room Temperature (RT/20°C) .
– At 350°C.
• Two samples for each case were tested.
• Tensile test samples were machined according to ASME section IX code QW 462.1 (c) for room temperature and QW 462.1 (d) for 350°C.
• Samples were tested as per ASME section IX code QW-150.
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PHASE 3 : Results of Destructive Testing (DT)
Reduced Section Flat Tensile Samples Reduced Section Rounded Tensile Samples
Tensile Test:
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PHASE 3 : Results of Destructive Testing (DT)
Tested flat reduced section samples
UTM with tensile flat sample
Tested rounded reduced section samples
Tensile Test Results:
Acceptance criteria: The samples were in acceptable range.
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PHASE 3 : Results of Destructive Testing (DT)
Temperature
(°C)
Sample
No
Sample Description Ultimate
Tensile
Strength
(MPa)
Yield
Strength
(MPa)
Remarks Dimensions
(mm)
Area
(mm)2
Room temp.
TT-3 19*19 361 585 350 Broken from
SS316L
TT-2 21*19 399 595 355 Broken from
SS316L
350°C
TT-1 ǿ 12.7 126.7 450 260 Broken from
SS316L
TT-4 ǿ 12.6 124.7 495 295 Broken from
SS316L
Filler type Testing
temp.
(°C)
Tensile
Strength
(MPa)
Yield
strength
(MPa)
%
Elongation
(A)
ENiCrFe-3 RT ≥ 550 ≥ 314 ≥30
ENiCrFe-3 350 ≥ 425 ≥ 167 ≥30
Guided Bend Test:
– Bend test samples were machined according to ASME section IX code QW 462.2.
– Four samples were tested as per ASME section IX code QW 160.
– The type of bend was transverse side bend.
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PHASE 3 : Results of Destructive Testing (DT)
Side bend test samples
Guided Bend Test:
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PHASE 3 : Results of Destructive Testing (DT)
UTM with side bend sample
Side bend tested samples Side bend tested samples
Guided Bend Test: Acceptance criteria for Bend test is:
Results of bend test are shown below.
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PHASE 3 : Results of Destructive Testing (DT)
Sample
No
Type of
Bend
Size
(mm)
Angle of
Bend
Observation Status
SB-1 Side
Bend
240*45*10 180° Opening ≤ 3mm Accepted
SB-2 Side
Bend
240*45*10 180° Opening ≤ 3mm
Accepted
SB-3 Side
Bend
240*45*9.5 180° Opening ≤ 3mm
Accepted
SB-4 Side
Bend
240*45*10 180° Opening ≤ 3mm
Accepted
Type of Bend Angle of Bend Max. opening no. Max. opening
length
Side Bend 180° 2 3mm
Impact Test: • Impact test samples were machined according to ASTM E23.
• Six samples were taken from HAZ of SA-508 and weld regions.
• Three samples form each region were tested at:
Room temperature
-10 °C.
• The acceptance criteria was that energy absorbed should be ≥ 71J and lateral expansion should be ≥ 0.8mm.
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PHASE 3 : Results of Destructive Testing (DT)
Impact test samples (for Ref.)
Impact Test:
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PHASE 3 : Results of Destructive Testing (DT)
Impact tested samples at room temp. Impact tested samples at -10°C.
Impact Test Results:
All samples were in acceptable range of absorbed energy and lateral expansion at
RT and -10°C.
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PHASE 3 : Results of Destructive Testing (DT)
Temperature
(°C)
Sample No Region Notch Type
Energy Absorbed
(J)
Lateral Exp.
(mm)
Room temp.
1 weld V 120 3.91
2 weld V 116 4.16
3 weld V 115 3.53
11 HAZ (SA-508) V 164 4.24
12 HAZ (SA-508) V 126 4.4
13 HAZ (SA-508) V 129 4.3
-10°C
4 weld V 131 3.91
5 weld V 120 3.78
6 weld V 130 4.11
14 HAZ (SA-508) V 128 4.54
15 HAZ (SA-508) V 124 4.24
16 HAZ (SA-508) V 127 4.54
• IGC Results:
– ASTM A262 Practice-E was used for testing. No cracking/opening was observed at required magnification even
after bending of sensitized samples.
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PHASE 3 : Results of Destructive Testing (DT)
Metallographic examination:
• Metallographic examination was performed at NCNDT, PAEC.
• Regions of interest were
– weld,
– buttering,
– HAZ (SA-508),
– HAZ (SS-316L)
– Base metal SA-508 and SS-316L.
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PHASE 3 : Results of Destructive Testing (DT)
• Metallographic examination: The acceptance criteria and results for metallographic examination are:
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Type of Region Type of structure Result
Base Metal SA-508 Tempered Bainite No abnormality was
observed against the
required microstructure.
Base Metal SS-316L Austenite + few carbide
HAZ (SA-508) Tempered Bainite
HAZ (SS-316L) Austenite + few carbide
Weld Austenite + few carbide
Buttering Austenite + few carbide
PHASE 3 : Results of Destructive Testing (DT)
Problems faced: • Non-availability of material/s, particularly SA508, for development on DMWs.
• Very limited access to technology for development of welding coupons and training of NDT personnel on DMWs (SA508/SS316).
• Specific UT procedure and probes were not available at local level for scanning of these welds.
Positive outcomes: • Acceptable results of Destructive testing (DT) proved that weld produced was of
required quality from strength, ductility, toughness and corrosion resistance point of view. Same variables can be adopted for welding qualifications in future.
• After confidence in manual scanning of these welds using pulse echo technique, a dedicated team of NCNDT personnel is still working for skill enhancement by using TOFD and PAUT techniques.
Future course of action: • More welded coupons even with known welding defects will be prepared for training of
welding and NDT teams by PWI.
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Conclusions
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