SA-53 E/B used as a vessel shell Section - UW-12(e) UW-12(d), UW-11(a)(5)(b) and what JE to use

[sshep7]

Need some help interpreting UW-12, values listed on a U1A and what JE to use in circ pressure calcs (UG-27 c.1). I have a slew of vessels constructed of SA-53 E/B pipe, where U1A/nameplate provided by manufacturer states following information.

Shell Material SA-53 E/B
Long seam - Type E, radiography None,100% JE
Girth seam - Type 2, radiography spot,65% JE.
Nameplates also state RT-4.

UW-12(e) states "Welded pipe or tubing shall be treated in the same manner as seamless, but with allowable tensile stress taken from the welded product values of the stress tables, and the requirements of (d) applied". This allowable stress value already has 85% JE applied per note G3. Now since I'm treating as a seamless vessel section, UW-12(d) states E=0.85 when the spot radiography requirements of UW-11(a)(5)(-b) are not met. Here I believe UW-11 a.5.b is not met. Does this mean I apply 85% JE AGAIN, essentially double dipping the JE? Feels weird since it's already been applied to the allowable stress values, and I can't imagine anyone would intentionally write this "double dip" into the code. I also believe the manufacturer may not have a good understanding of this section either but maybe I'm off base here.

 

[r6155]

See Figure L-1.4-1

Regards

 

[Christine74]

It seems like double-dipping but it isn't. You're paying a 15% penalty for not meeting the requirements of UW-11(a)(5)(b) plus another (unrelated) 15% penalty for not using a seamless product.

If you didn't discount by 15% twice you would end up with a situation where the required thickness would be exactly the same regardless of whether the pipe was welded or seamless.


-Christine

 

[sshep7]

Thanks. With the two 15% penalties the nominal thickness is lower than pressure Tmin. I've seen this issue now on multiple vessels between two manufacturers that are now out of business. Might be why they are out of business :/

 

[david339933]

The only mistake I see is that the vessel should have been marked RT-2.
E=1.0 for shell and head calc. are correct.
UW-11(a)(5)(b) has been satisfied.