Tear of Head weld

[ahmadire]

Dear experts,
The issue is about tearing along long seam weld of SS (304L) head.this head is formed from 3 segments.along with forming action the L.W's were torn to a length of about 20 mm exactly at the place of weld seam.Fortunately the base metal is sound. What I want to know is the needed test after repair of weld such as ferrite checking and hardness(criteria) and NDT ? could you please help me?

 

[racookpe1978]

How was it torn?
Is this PV head in operation, or ebing built?

Why do you think you can save the PV head by re-welding at a previously and badly distorted head seam at the failed weld, instead of replacing the head? Or cutting out the failed area completely, and using new material?

 

[metengr]

If the long seam weld ruptured during final forming of the head, you have introduced a significant amount of cold work into the head material and long seam welds. You will most likely require the head material and remaining long seam welds to be re-solution annealed after removing the ruptured long seam weld metal. The first step is to remove the damaged long seam weld metal by grinding and ensure the remaining weld metal is not cracked. Ensure complete removal of the cracked weld metal using Liquid Penetrant testing (LPT). You may want to consider removing all of the original long seam weld metal in the head segments that were cold formed and start over.

Once all of the ruptured weld metal has been removed, and verify as being removed using LPT, you will need to re-solution anneal the head material to remove the affects of cold working. Once this is completed re-weld the long seams. Perform final LPT on the welds.

 

[MJCronin]

Can you share some pictures of the tear ?

MJCronin
Sr. Process Engineer

 

[ahmadire]

For sure Mr. MJCronin

 

[ahmadire]

For sure Mr. MJCronin

 

[ahmadire]

^{Dear Mr. Metengr if we gouge the weld and then perform PT and then reweld it, would it be enough? why would you offer solution annealing?
If the rupture happens due to poor quality of weld such as brittleness or hot cracking of weld isn't it enough to just reweld and do NDE?}

 

[metengr]

ahmadire
The re-solution anneal would only be necessary if a significant amount of cold work had been introduced during forming to rupture an acceptable quality long seam weld.

If the weld was defective as you believe and is possible, removal of the entire weld could be done with no re-solution anneal to the base material. You will need to proceed with caution on re-use and you need to make this call because this is a nonconformance.

 

[weldstan]

This appears to have resulted from a major manufacturing error. Re solution treating is warranted to save the head.

 

[Don56]

It looks like the weld was not properly dressed on the edge of the plate before flanging. This stress riser most likely propagated the crack. Did this weld require radiography? See the partial data report if it is an ASME Code head. If so in addition to LPT the repair should also be fully radiographed.