API TR 938-C | Cold work on super duplex tubing

[XL83NL]

We need to make some tubing systems (up to 1/2", ASTM A789) from SAF 2507. API TR 938-C reads that all 25% CR DSS require solution annealing when you cold bend tube
Calculating the amount of strain/cold work when applying a standard Swagelok hand bender to bend a tube, ASME VIII-1 UNF-79(a)(2)(c) tells me I get 16.7% strain (input; 1.1/2" bend radius for a 1/2" tube, based on Swagelok's Tube Fitter's Manual).
Does anyone have any experience with bending super duplex tubing and post heat treatment?

 

[metengr]

XL83NL;
I would check with a company like Sandvik or the company that supplied you the product line directly. Normally, when I review ASME Code Case submittals, the material supplier of the product, like Sandvik, provides all necessary technical information for committee review.

http://www.smt.sandvik.com/en/produ...ials/duplex-stainless-steel/sandvik-saf-2507/

 

[XL83NL]

Good idea. Ill look into it.

 

[SJones]

The API heat treatment requirement is related to sulphide stress cracking resistance. If the application is not process related with H2S, subclause A.2.6 might be more appropriate. However, the cold work might impact upon chloride SCC resistance too, and this would need to be reviewed.

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.

 

[XL83NL]

Ive contacted Sandvik, Ill see what they come up with.
FYI: the service is either lactic acid with w/ traces of Cl (say 10 ppm), or MIBK.