Cold deformation in NACE MR0175 applicable to API 5L?

[JasonLouie]

Hello,
In NACE MR0175 / ISO 15156 Part 2: A.2.1.6, cold deformation is restricted to 5% if stress relief is not applied. Does this apply to the pipe forming process?

We are ordering 30" DSAW API 5L-B pipe. The pipe forming operation will certainly exceed 5% outer fibre deformation. None of this pipe is stress relieved. Does this 5% limit apply in this case?

Thanks for all your help.

 

[gr2vessels]

JasonLouie,
NACE MR 0175 and all the Corrigendums also.
The Clause A.2.1.6 (I believe) does not refer to the pipe manufactured at the mill, which is fabricated and tested as per the second paragraph of this clause. It refers to the pipe section rolled in an equipment fabricator's shop, with limited control and testing capabilities over his fabrication processes.
Also, Clause A 2.1.4 has accepted the welded pipes in "As Welded" condition, for SMYS not exceeding 360 MPa (52ksi). Heat treatment is required only for pipe not complying with this Clause (A.2.1.4).
cheers,
gr2vessels

 

[JasonLouie]

gr2vessels,
Thank you very much for your reply. The clauses seemed contradictory to me, so thank you very much for your clarification.

 

[SJones]

ISO 15156 does not differentiate between a pipe mill and 'an equipment fabricator's shop'. You may also wish to check with the pipe mill supplying the pipe as to the strain that they intend to impart when manufacturing the pipe. Strains over 5% can lead to problems such as strain ageing and dimensional control difficulties.



Steve Jones
Materials & Corrosion Engineer

http://www.pdo.co.om/pdoweb/

 

[gr2vessels]

It seems that ISO 15156, Clause A 2.1.4 has accepted some welded pipes without stress relief, obviously because the strain over 5% does not always lead to problems.
Also, when you order pipe material compliant with NACE MR 0175 you don't ask for any particular strain, that's the mill responsibility and liability covered in their guarantee of compliance.
cheers,
gr2vessels