Fatigue weld finish 1

[Moersleutel]

Hi

Does ASME VIII Div 2 specify a surface finish and profile for vessels operating in fatigue service? For example fillet welds that are radiussed and circ/long welds that are ground smooth.

OR is there a recognised standard which states or provides samples/photos/etc, by which the weld finish can be inspected for fatigue service?

We are busy inspecting a vessel with a section in fatigue service and would appreciate any input. The quality of the finishing varies, some areas seem exccesively smooth and other areas are too roughly grinded.

Thanks

 

[jte]

Rudol-

As far as I'm aware, Div. 2 does not specify a surface finish for welds. For fatigue service, there would be no such thing as excessively smooth, and "rough" will be subjective, though I have seen a molded plastic series of sample weld roughnesses. One thing to note though is that fillet welds are lousy in fatigue. I'm hoping that you are referring to a full pen weld with a fillet...

jt

 

[metengr]

You can have a CWI perform the weld inspection with criteria (adopted from other Standards) like blend grinding weld toes to remove undercut, or flat topping welds. These requirements would be self imposed, and are above the minimum requirements in the Code. However, they would go a long way toward increasing resistance to fatigue crack initiation and propagation in service.

 

[Xianglu]

There are two approaches to this issue:
1. Using SCF (Stress concentration factor) to reflect the welds condition;
2. Check with PD5500 or BS EN13445 (British standard for Unfired pressure vessel) for reference.