SA333 gr. 3 welding

[weldgal]

I'm welding 4" sch XXH SA333 gr. 3 pipe for ASME B31.3, and I'd like some of your thoughts on using E80C-Ni3 for the GTAW root and E8018-C2 for the SMAW balance. Do they seem like a good combination for a system with MDMT of -20 deg F?

 

[metengr]

Yes, with PWHT.

 

[stanweld]

Why would you specify 333 Gr3 to meet a -20 F MDMT? Carbon steel piping can easily meet the impact properties at -20 F.

 

[weldgal]

I really appreciate the feedback on filler metals, and am glad you brought up PWHT. Table 331.1.1 of B31.3 says that for my thickness of .674 P-9B base metal w/ A-10 filler metal, no PWHT is required, but in addiiton to your comments, others have also suggested PWHT. I want to get this right, and I want to learn at the same time; what am I missing?

 

[weldgal]

I asked my customer why he's specified grade 3 too, and they replied that they'd originally intended for the service to be much much colder, and even though they know they could've gone with something else, the material's already bought and drawn into the project, so they don't want to change it.

 

[metengr]

The only reason I suggested PWHT was to assure weld metal low temperature impact properties. Granted, -20 deg F is not that low a service temperature for this material. However, if you are stuck with this material, I would at least perform the PWHT to assure similar low temperature impact properties as the base metal SA-333, Grade 3 material.

 

[weldgal]

Your information has helped a great deal; thanks. One last question. Am I reading Table 323.2.2 correctly, that since the design min temp is not less than -20 deg F, I do NOT have to perform charpy testing?

 

[codeeng]

But your Grade 3 material comes with impact testing at -150F anyways.

 

[metengr]

Yes, you are interpreting this Table and the associated Figure correctly.