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Welding defects validation using stress analysis

Welding defects validation using stress analysis

Welding defects validation using stress analysis

(OP)
Hello Members,

I am currently facing an issue concerning the installation of a Hot water and chilled water piping networK.

The design is made according to the EN 13480 and the welds needs to be checked with 5% RT according to the same norme.
The types of defects are classified according to table 1 of the standard ISO 6520-1.
The acceptance criteria are level 1 in accordance with table 2 of the standard ISO 10675-1.

after examination we have 4 main defects, Type 2011 according to ISO 6520-1, with a defect size of 1 mm.
My client is open to downgrade those defects, with a condition to justify it with calculation.

My question is : Since i have all the stresses values in those points which are ( but weld seams), is there any formula to deduct a minimum required wall thickness accordingly?

Or do you have another idea to jutify this issue with calculation?

Thank you in advance for all your feedback.

And have a nice time

RE: Welding defects validation using stress analysis

Welding defects are not simply reductions in cross sections. They can be initiators of cracking, stress corrosion and a variety of other issues that have nothing to do with a calculable cross section equivalence.

RE: Welding defects validation using stress analysis

(OP)
Thank you RON for your feedback.

You are right.but as i said and client was agree, the type of the defect is 2011 which is means : Gas Pore,A gas cavity of essentially spherical form, according to the Tbale 1, ISO 6520-1.

Also since i have lower temperature and pressure ( 80 degre and 6 7 bar) the risk of creep dos not exist.

RE: Welding defects validation using stress analysis

I agree with Ron. I have looked into EN 13480 part 3, part 5, etc.) and theres no clause that allows any such waiver. Regardless if clients accepts. There might not be an exact wording for this in the code, are an Interpretation (like B31.3 issues), but the following section from EN 13480-5 para 8.6 comes close;

Quote:

8.6 Weld repairs
Welding procedures shall be in accordance with EN 13480‐4.
Repaired welds shall be retested with the same NDT methods and testing techniques.
NOTE The evaluation of weld imperfections may require additional inspections during the repair.
Where imperfections are identified but cannot be adequately evaluated, an alternative test shall be
performed or the imperfection repaired.

Huub

RE: Welding defects validation using stress analysis

There's always BS7910.
Might not be the easiest way, but it has saved my live (*) more than once

(*) to be taken with a grain of salt.

RE: Welding defects validation using stress analysis

I agree with all the previous comments but have an issue with this:

My client is open to downgrade those defects, with a condition to justify it with calculation.

How can the piping be code-compliant if the specified code does not address acceptance by stress analysis ?
Your client can accept anything they want from you but I strongly suggest you get everything in writing to CYA if needed at a later date.

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