Dear All,
Regarding post heat treatment(DHT) for SA 387 GR 12 CL2 Low alloy steel material,
I have PQR'S with post heating a temperature of 300 Degree C for 2 Hrs,
My question are,
1) Is it possible to make WPS (production weld) without post heating(DHT)?
2) Is it any code(ASME SEC VIII or IX) call for DHT after welding?
3) Why we have to do DHT, if it is required?
4) Is it any where mentioned that the SA 387 GR 12 CL2 material is required post heating(DHT)?
we are doing DHT because avoid cold cracking(Hydrogen cracking) in weld and HAZ . any other major reason to carry out DHT for low alloy steel.
Kindly provide your valuable guidance/ advice/ experiance on this subject.
Regards
Vijay Katkar
-- Regarding post heat treatment(DHT) for SA 387 GR 12 CL2 Low alloy steel material,
I have PQR'S with post heating a temperature of 300 Degree C for 2 Hrs,
My question are,
1) Is it possible to make WPS (production weld) without post heating(DHT)?
2) Is it any code(ASME SEC VIII or IX) call for DHT after welding?
3) Why we have to do DHT, if it is required?
4) Is it any where mentioned that the SA 387 GR 12 CL2 material is required post heating(DHT)?
we are doing DHT because avoid cold cracking(Hydrogen cracking) in weld and HAZ . any other major reason to carry out DHT for low alloy steel.
Kindly provide your valuable guidance/ advice/ experiance on this subject.
Regards
Vijay Katkar
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3 comments:
Hi,
This material SA387Gr12CL2 is normally used for cryogenic reactors fabrication.Since H2 content shall be maintain as low,post heating procedure becomes an mandatory.
Some relevant answers for your queries.
1) Is it possible to make WPS (production weld) without post heating(DHT)
Post heating procedure same as preheat and it's obvious any change in temp range from PQR range need an qualification
2)Is it any code(ASME SEC VIII or IX) call for DHT after welding?
No.None of the codes mentioned DHT after welding as mandatory.It depends upon the client specification only.
3)Why we have to do DHT, if it is required?
DHT involves heating of weldments for long period at preheat range.This allow H2 to diffuse out from the metal since cooling rate will be low and can give ductile structure.
4) Is it any where mentioned that the SA 387 GR 12 CL2 material is required post heating(DHT)?
No.
Regards,
Gowrish
Hi,
Here please find some relevant answers for your query
1) Is it possible to make WPS (production weld) without post heating(DHT)
Yes can make.But Post heating will follow the same essential variables for preheating.so any change in temp range will need an seperate PQR
2)Is it any code(ASME SEC VIII or IX) call for DHT after welding?
None of the code mention about post heating.It depends on your client spec.
3)Why we have to do DHT, if it is required?
DHT allows H2 to diffuse out from weldment resulting more ductile strucuture.
4)Is it any where mentioned that the SA 387 GR 12 CL2 material is required post heating(DHT)?
No ASME doesn't mentioned about post heating.
Regards,
Gowrish
Hi,
Here please find some relevant answers for your query
1) Is it possible to make WPS (production weld) without post heating(DHT)
Yes can make.But Post heating will follow the same essential variables for preheating.so any change in temp range will need an seperate PQR
2)Is it any code(ASME SEC VIII or IX) call for DHT after welding?
None of the code mention about post heating.It depends on your client spec.
3)Why we have to do DHT, if it is required?
DHT allows H2 to diffuse out from weldment resulting more ductile strucuture.
4)Is it any where mentioned that the SA 387 GR 12 CL2 material is required post heating(DHT)?
No ASME doesn't mentioned about post heating.
Regards,
Gowrish
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