Substitution of steels with same P-number in welding

[RNDguy]

I need to know of resources giving tips and sharing experience on the question of when is it safe to substitute a parent metal with same P-number but a different group number without bringing into question the validity of PQR & WPS. For instance, SA-414 grade C is qualified to be welded to SA 240 type 316L under a certain PQR with GTAW. When can one substitute SA-414 grade G instead of grade C in the same circumstances (grade G is group 2, grade C is group 1, both under P-number 1)? What may be the drawbacks of doing this if any? Thanks.

 

[DesignerMike]

I believe that you posted this in the wrong forum.

one of the materials section would probably get more responses.

 

[jlcochran1]

You probably want to post in either the "Boiler and Pressure vessel engineering" forum or "ASME mechanical code issues" or "welding, bonding & fastener engineering" forum since this is an ASME Section IX welding question.

 

[RNDguy]

Thank you gentlemen, I have posted in another forum and got my replies.