stress reliving on 3mm 625 plate butt weld during PQR qualification for utilising in cladded vessel

[Ratheesh_n]

Team,

PQR:- 4mm butt weld
MOC: SB 443 UNS 6625
Service : Sour
Design Code : ASME sec VIII Div 1
Vessel MOC :- 516 gr 70 with UNS6625 clad
Method of cladding:- Explosion bonding

We have received a WPS from our vendor and it's for 4mm 625 plate butt weld. However vendor has performed explosion bonding of the welded coupon prior to stress relieving. After stress relieving, sample drawn for mechanical testing from 6625 material.

Query:
1. Is it allowed to do the explosion bonding during WPS qualification. WPS is only for butt weld of UNS 6625 material. there is no details regarding explosion bonding in WPS. Whether Sec IX allows it.
2. What's the impact on material property when testing bare 6625 butt weld vs explosion bonded material
3. Is it practically possible to do the heat treatment of 6625 material with 3mm thickness.

 

[EdStainless]

Typically you explosive bond, then you SR the steel (not the alloy), and then you fabricate.
Usually with Ni alloy overlay the SR temp for steel will not stress relieve the alloy.
If they did the weld and extracted a coupon of the 625 for testing the SR of the steel is irrelevant.
So you have a separate WPS for the welding of the steel and the handling of the joining between the materials?

 

[Ratheesh_n]

@EdStainless

Thanks for your response.

Yes. SR is performing for the CS. However, since the vessel is heat treated, these alloy 625 welds are also subjected to heat treatment along with this. PWHT considered as an essential variable as per ASME Sec IX. Thats the concern.