PostWeld Heat Treatment (PWHT) dissimilar materials

[alomejorfofi]

Hello,

i'm an engineer working on the piping department of on a power generation EPC contractor company. i'm doing a study on postweld heat treatments (PWHT) possibilities between alloy steel (A335-P91, P22 and P11)and carbon (A106) or stainless steel.
I have not yet found practical information on procedures for performing the PWHT in these joints, either the ASME B31.1(or .3) or AWS D1.5.
Does anyone know how PWHT are conducted in these cases? or, where can i find this information?

Thanks in advance

 

[stanweld]

Review the requirements in ASME I, Table PW-39 for P No. 15E.

 

[alomejorfofi]

ok, This code says several things about the temperatures required.
so, if i have understood well, it's no possible to weld carbon steel and P91 grade alloy because PWHT "shall be that specified for the material requiring the higher PWHT temperature", so, how is the better way in the practice to weld (or to join -maybe with a flanged union-) these materials?

i'm so lost

 

[stanweld]

Read Note (2)in the Table previously stated.

 

[alomejorfofi]

so, carbon steel can not be welded to alloy steeel P No. 15E

 

[mtv3180]

Hi,
In this case, buttering can be done on P91 Pipe by using SA335Gr.P11 & P22 Electrodes and conduct PWHT at 760 Deg on Buttering surface.

Then follow the procedure for SA335GR.P11/P22 material welding.

For Stainless steel Welding,Use ENicrFe-3 and conduct PWHT as per P91 Materials.

During welding the Dis-similar materials, Use the filler metal on higher grade side. Sure, the mechanical test will be qualified on PQR.

I Hope Mr.BIGINCH will give us valuable comments on this subject

 

[stanweld]

Carbon steel can be welded to P91. When welding with a "B3" welding filler metal, PWHT should be limited to 1300 F to 1340 F. Whether it's a good idea is another matter; we have long prohibited carbon steel to P91 welds, requiring a P22 tranition pup between the materials spec break.

 

[BigInch]

No chance.

We are more connected to everyone in the world than we've ever been before, except to the person sitting next to us. Lisa Gansky

 

[alomejorfofi]

I do not know, but I guess not a good engineering practice to weld P91 to A106, and less in services with moderately high temperatures, but if it is absolutely necessary I think the best are transition pieces welded, even P11 after P22. Will have to see what the best option considering the factor 'money'.