Welding P1 to P5A

[iam42]

Guys,

I need to weld a piece of 3/4" SA-335 P22 pipe to a A105 coupling (P5A to P1).

ASME IX QW-403.12 tells me that I can use a WPS qualified using only P5A material to weld P5A to P1A if I use "the melt-in technique"

I have a qualified PQR for welding P5A to P5A, can this be used for welding P1 to P5A?

QW-403.12 A change from a base metal listed under
one P‐Number of Table QW/QB-422 to a base metal listed
under another P‐Number. When joints are made between
two base metals that have different P‐Numbers, requalification
is required even though the two base metals have
been independently qualified using the same procedure.
When the melt‐in technique is used for joining P‐No. 1,
P‐No. 3, P‐No. 4, and P‐No. 5A, a procedure qualification
test with one P‐Number metal shall also qualify for that
P‐Number metal welded to each of the lower P‐Number
metals, but not vice versa

Forgive my ignorance but what is the "melt in technique". Is this only relevant for PAW or LBW? Or can this be used for GTAW too?

Thanks for the help.

 

[iam42]

Guys,

I think I found my answer in Table of QW-424.1.

 

[DVWE]

Melt-in technique is specific to PAW only. If you look at the Tables QW-252 thru QW-267, you will see that the essential variable only applies to PAW. With PAW, there are two basic techniques; keyhole and melt-in. This article explains them well enough.

You are correct in finding QW-424.1 for your particular case, but you should also read QW-200.3, especially the part that says base metals cannot be indiscriminately substituted without consideration of compatibility. 2.25Cr to Carbon Steel is done often enough, but do consider things like PWHT and service very carefully before just doing it.

The devil is in the details; she also wears prada.

 

[iam42]

Thanks DVWE