Attachment welds over circumferential seams 1

[dbday]

Hi,

I have an ASME VIII Div 1 vessel where I need to place a pad for a support over a circumferential head to shell weld.

I understand that it is acceptable, with suitable radiography, to put openings across welded seams, and by inference, a reinforcing pad for said opening which would of course cover the welded seam, but does this thinking also extend to pads that need to be welded onto the vessel to attach lugs or supports.

Obviously covering a weld like this is not great design, but sometimes things can't be moved around and is it really that different to the situation presented by a reinforcing pad.

The pad would have a vent hole so that any leaks at pressure test would show up and radiography could be done before and after welding of the pad onto the vessel, post weld solution annealing could be done if necessary.

The material is super duplex (shell head at 10mm thick, pad at 6mm thick).

Any thoughts would be appreciated.

 

[r6155]

1) Air pressure test the repad (1 bar)
2) Hydraulic pressure test the pressure vessel

Regards

 

[EdStainless]

Super duplex has no PWHT, there is none possible.
Is the pad SS? Same alloy? At least 2205 so that CTE matches fairly well.

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P.E. Metallurgy, consulting work welcomed

 

[dbday]

EdStainless
The pad is to be the same material as the shell - client requirement

 

[Christine74]

The distinction is that components that overlap weld seams must be ground flush per UG-82(a) if they are "pressure" components like reinforcing pads, but non-pressure parts such as saddle supports and lugs can either be ground flush or appropriately coped/notched to clear the weld seam per UG-82(b).


-Christine

 

[Trestala]

Add a 100% PT or MT after grounding the weld flush to check for any surface cracks.