Induction Bend Charpy values

[Andy49]

I have seen % shear requirements from 50%, 75% to 85% depending on the code (API, ASTM etc.) and some of the technical papers and vendor specs. The test would be conducted at 32F. So I am confused as to which values are acceptable. The test piece would be from a weld in the tangent area.

 

[SJones]

If you are writing a specification why not simply ask for the same acceptance criteria as the seam weld in the adjacent pipe - shear area, or no shear area? Manufacturers get touchy about shear area determination for strict criteria in weld metal Charpy tests because of difficulties in measurement.

Steve Jones
Corrosion Management Consultant

http://www.linkedin.com/pub/8/83b/b04

All answers are personal opinions only and are in no way connected with any employer.

 

[SNORGY]

My initial thought for a guideline would be to say a 3 specimen average of 60% with no single specimen below 50%. This would align at least as well as the criteria used to qualify line pipe materials (and, by association, fittings fabricated therefrom) to Category II notch toughness in Canada.

 

[Andy49]

Thanks for the replies. I am looking for some concrete spec that includes testing requirements and acceptable values for the test performed that will be in compliance with DOT 195 and other codes that apply to 10" pipeline bends.

 

[SJones]

Then ASME B16.49 (2007 Version) would require an average of 50% shear area with a minimum individual value of 40%. Most manufacturers can live with that for weld metal results, but they will squeal if you try for higher. For body material, those requirements are not high enough as, essentially, you would be trying to apply the criteria of a drop weight tear test.

Steve Jones
Corrosion Management Consultant

http://www.linkedin.com/pub/8/83b/b04

All answers are personal opinions only and are in no way connected with any employer.

 

[Andy49]

Would APL 5L PSL2 apply here? That requires higher velues.

 

[SJones]

It will apply if you make it apply, but note that the API 5L shear area requirements are for parent material not welds. The intention being to substitute for a drop weight tear test in diameters deemed too small for such a test. Since seam welds in contiguous pipeline items should not be aligned, the focus for weld seams is fracture initiation evaluated by Charpy energy. Parent material cannot be staggered, and so a fracture propagation approach has to be considered as well as initiation. The best paper to review in this context is:

A Cosham et al, Don't Drop The Drop Weight Tear Test, Journal of Pipeline Engineering, Vol 9, (2), 2010, pp 69-84

However, do you need to worry about brittle fracture propagation in a bend when it is sandwiched between two correctly tested pieces of linepipe?

Steve Jones
Corrosion Management Consultant

http://www.linkedin.com/pub/8/83b/b04

All answers are personal opinions only and are in no way connected with any employer.

 

[Andy49]

I will go through the paper to gain more knowledge about the subject and some of the other papers I have found. Its been many decades since I took the materials science course in my sophomore year. I do find it more interesting now.

 

[Andy49]

It looks like the paper on Drop Weight Test in not in the public domain and is only available through the Journal subscription.