Impact exemption per UCS 67(a)(3) + PWHT by service

[Santiago Vacca]

Dear Colleagues,

We are purchasing a ASME VIII div 1 vessel.
MDMT required is -40°C.
PWHT required by service.
Base metal es ASME 516gr70n curve D.
Base metal es exempted of impact testing.
By UCS 67(a)(3) impact testing of the PQR is not required as long as:

“each heat and/or lot of filler metal or combination of heat and/or
lot of filler metal and batch of flux has been classified
by their manufacturer through impact testing per the applicable
SFA specification at a temperature not warmer
than the MDMT”

Applicable SFA´s are impact certified in the "as welded" condition.

Is it acceptable by the code to use a non-impact PQR w/PWHT + "as welded" impact classified consumable if the fabrication is with PWHT?

Thank you al in advance.

 

[DVWE]

This is my opinion, perhaps others will comment further.

SA-516 Gr 70 Normalized is exempted per Curve D, but not necessarily Normalized + PWHT. Section VIII, Div. 1 does not consider PWHT for service.

Reference UG-84 (f)(1) and (2). If the welds are subject to PWHT and the filler metal manufacturer only guarantees impact values "as welded", then I believe welds should be impact tested either by the PQR or by the filler metal manufacturer.

To be safe, I would test Base, HAZ, and welds after PWHT, based on UG-84 (f)(1), with a PQR.

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

 

[weldstan]

If you believe that all SA-516 70 plate will meet absorbed energy requirements at -40C, think again. If you really need toughness at-40 C, require the plate to be impact teted, regardless of Code minimum requirements. And qualify procedure per DVWE above.

 

[Santiago Vacca]

Thank you both for the reply,

I appreciate your recommendations of testing and qualification in excess of code minimum requirements. I also think impact test of a PWHT weld test plate is the ultimate verification for this case.

weldstan: Base metal es A516 gr 70 in the normalized condition, so curve D, thickness is 13 mm and 16 mm (shell and head) both fall above the curve. This matter is well calculated by software but for the welding part I don’t know if there is software that verifies code requirements, do you know any?

Regarding minimum code requirements, under UCS-67(a)(3), as I see welding procedure as well as production impact test are waived regardless of PWHT condition diferent in SFA and vessel.
I read a 2004 version of USC-67 and the above condition is on UCS-67(a)(2) instead. This is important when reading ASME interpretations most ow which are for older versions of the code. Requirements vary a little.

Another problem I encounter is how to interpret when UCS-67(a)(3) says: “each heat and/or lot of filler metal or combination of heat and/or lot of filler metal and batch of flux has been classified by their manufacturer through impact testing per the applicable SFA specification”.
Filler metal certificates indicate “typical” results for impact (and mechanical properties), and only “specific” results for chemical analysis. And this aprears to be valid for SFA standards. However I tend to interpret that in UCS-67(a)(3) “each” means impact tests “specific” of a weld test plate made with filler metal of that heat or lot.

 

[weldstan]

These are all weld metal impact tests as defined in the applicable ASSME SFA speciifications performed by the filler metal manufacturer and certified as such on the test certificate.

 

[weldstan]

You need to order the filler materials to have the manufacturer to perform the tests to comply. I have often required same on a number of filler metal manufacturers on specific projects. It does cost more.