PWHT per API 620

[Faree]

Dear Experts

We are going to construct Isomerate above ground storage tank per API 620. The compression rings on this tank are 88mm thick of A573 Gr 70. As per API 620 I was not able to find PWHT requirements of Carbon steel welding of this much thickness. Please guide whether PWHT of this compression ring is required or nor, If anyone can share the reference of code?

Thanking all in Advance.

Regards
Farhan

 

[JStephen]

I don't see a requirement for it- looking at 5.25.3 and 6.18. Nor do I see a thickness limitation.
That said, a compression ring that thick would certainly be uncommon, and it would be preferable to adjust roof slope, design pressure, or compression ring configuration if possible.