PQR P4 to P8 questions?

[Pickaspot]

The application this will be used for in the field is a steam line with a design temp of 869F and design pressure of 769 psig. The weld's are open butt on 1/2" diameter SA-335 P-11 to SA-312(316)both having a wall thickness of 0.147" The engineering spec requires that max hardness not exceed 225HBW they do not require PWHT per the t.

My planned PQR variables:

Pre heat of 300F

Process- GTAW (manual)
Base metals-
Pipe/tube specification SA-335 (P-11), nominal composition 1.25Cr-0.5Mo-Si, P-4 Group 1, Nominal pipe/tube size 4” Schedule 80s, 0.337”t

Pipe/tube specification SA-312 (TP304L) nominal composition 16Cr-12Ni-Mo, P-8 Group 1, Nominal pipe/tube size 4” schedule 80s, 0.337”t

Filler material-
ERNiCr-3, F-43, SFA 5.14, UNS# N06082


Single bevel groove w/o backing
Shielding gas (A5.32 SG-A)
Backing gas (A5.32 SG-A)


Typically 309 would be used for joining these two base metals? I concluded with consideration of the design temperature that the Inconel filler would be best utilized for this procedure.

I have a couple of questions.
1. Does this look like I am on the right track?
2. Should I go ahead and have impact's done on this PQR, I can't find any data for minimum design temp!

Thank you for your consideration and input of my first dissimilar PQR plan.....!

 

[metengr]

1. Yes, your proposed variables and approach are acceptable. The Inconel is correct for the filler metal to avoid problems with 309 long term in elevated temperature service.
2. No, impact testing is not required. No need, the steam line operates at a design temperature where low temperature service is not applicable.

 

[Pickaspot]

Thank you meteng!

Would it make sense to have the impacts to qualify this PQR for future WPS's? I believe once this PQR is qualified it will be good for welding each P-number to itself as well, just trying to maximize the PQR for alternative applications down the road?

Again, thank you for your reply!

 

[metengr]

No. I prefer to do impact qualification when necessary. You may need to have the impact qualification for thicker materials.