410 clad vessel

[REGRUMBLE]

I need to fabricate a large pressure vessel that is made from 516-70 clad with 410s stainless. My problem is how to compete the weld overlay of the seams without cracking. The customer insists all weld ovelays must be 410 (we cannot use 309) with PMI, UT, DP and every other test to ensure ther is no cracks or voids in overlay. Because of the size of the vessel preheating is not practical and it cannot be stress relieved due to internals that cannot be heated. Anyone have a solution?

 

[metengr]

Weld the seams with 309 stainless at the root and switch to 410 stainless steel for the cover pass. The 309 will tie in nicely with the seams and base metal, the 410 cover pass will cover the 309 weld deposit completely. Yes, you must preheat (local will do) the 410 stainless steel clad for welding, and no PWHT is required based on clad thickness.