Forming defect in dish ends

[ukmet]

Dear All!

We got dish end formed of A-516 Gr 70 thickness 12mm and ID = 1735mm. On performing DPT at the outer side of knuckle radius some linear defects on one portion were visible seemed like cracks. What it could be? Some plastic deformation? Any forming Defects? Will it be repaired by weld over lay?

Looking forward for your help and guidance.

 

[MiketheEngineer]

What are you using it for --- what is the pressure. If it is there just to look at - no problem - if it is holding a nuclear reactor together - another problem.

 

[tr1ntx]

Gouges caused by foreign material in the die, perhaps.

 

[ukmet]

It is the dish end of knock out drum having a pressure of 350 psi

 

[MiketheEngineer]

Sounds like you have problem that needs to be solved. How?? Not sure knowing what you are doing exactly.

 

[austsa]

ukmet,
Your numbers suggest that you're working to a high-stress code (ASME VIII Div 2, or similar). Thus, I would be very cautious about weld repair on the knuckle (high stress area). Was the dished end cold or hot-formed?

 

[ukmet]

The vessel is on ASME Sec VIII Div.I. The dishes are cold formed.

 

[chicopee]

I would scrap the dished head . Don't weld the defective section of the knuckle. The knuckle is a section of the head on which no welding, machining etc should be performed.At least that the information that I learned back in the 70's--may be the ASME/NB code has changed their posture since then.

 

[austsa]

If I was a betting man, I would say that it is a forming defect. Suggest you discuss the issue with your supplier.

 

[ukmet]

Dear All!!! Thank you very much for your valuable suggestions. I am so grateful