Post bend heat treatment of cold bent tubes

[tamal1475]

EN 12952-5 demands cold bent tubes with R/d less than 1.3 must be stress relieved. However, stress relieving can be waived if it can be demonstrated with a suitable procedure test that heat treatment is not required. The tubes are low alloy steel. What kind of tests can demonstrate the heat treatment is not required? We have to convince the inspector.

 

[SnTMan]

I'd guess corrosion test.

Regards,

Mike

 

[metengr]

Hardness testing of several bend samples at the intrados and extrados. Depending on service conditions, hardness above 22 HRC scale can result in stress corrosion cracking in low alloy steels.