Fiber Elongation and PWHT

[JBW76]

This will probably be an easy one for most of you here, but I'm stuck so here goes:

I've got a Carbon Steel Vessel 5/8" thk. shell and 1/2" thk. 2:1 heads that are Cold Formed.

I'm getting a "fiber elongation exceeds 5%" warning and I'm wondering if I must heat treat the ENTIRE vessel?

If I must heat treat, can't I just heat the heads? If I would've gotten the heads "HOT Formed" I wouldn't be worried about this,
so what is the difference if I just do a quick heat treat of the heads?

Thanks in Advance
JW

 

[Jano6924]

You shall read UCS-79(d) carefully. If your heads are P 1, groups 1 or 2, the extreme fiber elongation can as large as 40%, OR 5% maximum IF any of the five conditions listed in UCS-79(d) exists.

If at the end you find that you shall heat treat the heads then they shall be heat treated following the rules of UCS-56. Read also interpretations VIII-1-83-105 and VIII-1-95-50.

Hope this helps.

 

[racookpe1978]

Check your process for welding heat-treat as well.