lateral expansion
GANESH GANESH
One of our Pqr is failed twice, material stainless stell 316l grade , welded gtaw and smaw. Testing failed in lateral expansion .
pls suggest a procedure for achieving the lateral expansion.(coupon thickness 25 mm)
Ganesh
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pgoswami
Hi Mr. Ganesh,
Sec-VIII, DIV-1, UHA 51, elaborates impact test requirements for austenitic S.S base metal, weld metal and HAZ. Typically as per UHA-51(a) (4)
For 316L weld metals:-
:
· each heat of filler metal used in production shall have a Ferrite Number 5 FN max, as measured by a ferritescope or magna gauge, which shall be calibrated in accordance with AWS A4.2, or as determined by applying the chemical composition from the test weld.
· notch toughness testing of the base metal, weld metal, and heat affected zone (HAZ) shall be conducted using a test temperature of −320°F (−196°C); and each of the three specimens from each test set shall have a lateral expansion opposite the notch not less than 0.021 in. (0.53 mm).
What was the impact test temperature adopted in PQR qualification?
From my past experience in fabrication of cryogenic tank and other equipments, I could provide the following guidelines:-
· Get the base metal impact tested at the mill at the design temperature or less. Mills could guarantee impact in 304/304L and 316L S.S down up to −320°F (−196°C);
· Similar guidelines should apply for welding consumables also.
· Insist on Ferrite 5 FN max for 316L S.S. and consistent impact test results at −320°F (−196°C);
· Should you have problem with 316L S.S. consumables, may think about a switch to 308L S.S, with a MAX 2.FN. 308L electrodes usually have better impact properties than 316L S.S electrodes.
· Adopt the conventional precautions required for welding austenitic S.S.
· If you still face problems, check back with the manufacturers on “oxygen “ content in the weld metal. However hope this issue should not be major, as S.S weld metals contain enough de-oxidizers (Cr) to produce a very clean weld metal.
Let me know if it helps.
Thanks.
Pradip Goswami,P.Eng.
Welding & Metallurgical Engineer/Specialist
Component Integrity Section.
Engineering and Training Services
Ontario Power Generation Inc.
Res:-88,Garth Trails Crescent
Hamilton,Ontario, L9B2X1,Canada
Tel-905-679-9677
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