Repairing vessel shell - SA 516 Gr. 70 - Post Weld Heat Treatment
Repairing vessel shell - SA 516 Gr. 70 - Post Weld Heat Treatment
(OP)
Anyone have any guidance on the following:
We are going to cut out and then replace a section of shell from a pressure vessel. Shell material is SA 516 Gr. 70. Shell thickness is 3/4". MAWP of shell is 160 psig. Shell inside diameter is approximately 62". Fluid in shell is treated boiler water.
The vessel was heat-treated after it was manufactured.
After we weld the shell section back in, is it advisable to do post-weld heat treatment or stress relief at the repair welds ?
We are going to cut out and then replace a section of shell from a pressure vessel. Shell material is SA 516 Gr. 70. Shell thickness is 3/4". MAWP of shell is 160 psig. Shell inside diameter is approximately 62". Fluid in shell is treated boiler water.
The vessel was heat-treated after it was manufactured.
After we weld the shell section back in, is it advisable to do post-weld heat treatment or stress relief at the repair welds ?
Jonathan Ives
Project Engineer
Transalta, Alberta Thermal Plants
Duffield, Alberta





RE: Repairing vessel shell - SA 516 Gr. 70 - Post Weld Heat Treatment
So, I would not perform a PWHT. I would, however, increase then preheat to 250 deg F for the weld repair and use low hydrogen electrodes.
RE: Repairing vessel shell - SA 516 Gr. 70 - Post Weld Heat Treatment
If so, and this would apply to DC storage tanks, I would perform a local PWHT of the repair welds. Despite the minimum PWHT requirements in the Code for not having to perform PWHT on nominal thickness less than 1.25”, I would perform a local PWHT pf the repair welds in this vessel. It has been shown that reducing the residual stresses form repair welds will reduce the susceptibility to either stress corrosion cracking or corrosion fatigue in vessel welds located below the water line.
RE: Repairing vessel shell - SA 516 Gr. 70 - Post Weld Heat Treatment
The repairs will be made on the shell of a high-pressure feedwater heater. The shell will see boiler water at up to 160 psi, so I think we'll PWHT the repair welds to avoid stress-corrosion cracking.
Jonathan Ives
Project Engineer
Transalta, Alberta Thermal Plants
Duffield, Alberta
RE: Repairing vessel shell - SA 516 Gr. 70 - Post Weld Heat Treatment
Could you post the reason for the repair, a nosey person would like to know ?
RE: Repairing vessel shell - SA 516 Gr. 70 - Post Weld Heat Treatment
Steve Jones
Materials & Corrosion Engineer
http://www.pdo.co.om/pdo/
RE: Repairing vessel shell - SA 516 Gr. 70 - Post Weld Heat Treatment