Will PWHT Affect SA-302 Gr-B

[tc7]

I need to weld flanges on to a P-1 Gr-1 (SA106 gr B Sched 120) pipe. This is a Section 8 Division 1 Category C weld. The pipe is already attached (by others, long ago) to a P-3 Gr-3 (SA302 Gr B) nozzle. My new weld will be approximately 12-inches away from the existing weld at the SA302 nozzle.

I am required to PWHT the new weld on the P-1 pipe at 1100 deg F for about 1.5 hours. I expect that in keeping the new weld section at temperature, the SA302 Gr B nozzle temperature will also approach 1100 deg F.

My question is this: will the 1100 deg F soak negatively affect the strength or character of the SA302 material?

If so, what alternative is considered acceptable?

Thanks.

 

[metengr]

tc7;
No, there should be no problem with PWHT of SA 302 Grade B material. This is a Mn-Mo low alloy steel that is supplied in either hot formed or normalized and tempered (1100-1300 deg F), depending on thickness.

 

[tc7]

I have an obscure reference in the history file on this equipment that the SA-302 Gr B material was normalized. Do we assume that any reference to "normalized" really intends to mean "normalized and tempered" ?

And if the original material was N&T at 1100 deg F, will not the additional PWHT temp of 1100 deg being discussed alter grain size and toughness values?

Thankyou

 

[metengr]

tc7;
Normalized means normalized and tempered in accordance with SA 302. Second, as long as the PWHT is at or above the minimum tempering temperature, this is acceptable by Code. Remember, ASME B&PV Code only requires reaching the minimum tempering temperature for PWHT to assure adequate ductility in service. PWHT above the minimum tempering temperature is acceptable as long as you remain below the lower critical transformation temperature.