Time Delay betwwen Welding and Post Weld Heat Treatment

[m.wasif]

I want to confirm that what is maximum time delay between welding and PWHT for welding on ASTM A335 P9 pipe. Can we do PWHT "immediately" after welding or there is some standard time of wait before doing PWHT. Further how much maximum delay is allowed before PWHT?

Thanks and Regards,

 

[weldstan]

There is no min/mx time. I have done PWHT almost immediately after welding and cooling to near ambient and several days after welding and slow cooling to ambient due to RT before and after PWHT requirements from the Owner/Engineer.