Category B, Type 1, Sport RT....E = ??? 5

[dtn6770]

I hate to resurrect a topic that’s been utterly beaten to death…but I will. Actually, I more so hate being "that guy” who brings the subject up AGAIN.

It’s the dreaded UW-11(a)(5)(b) paragraph relating to the joint efficiency. Here’s a very specific situation; Non-lethal, non-steam service, NPS 12 XH seamless shell section (SA-106-B) attached to a seamless formed, 0.500 in nominal, 2:1 ellipsoidal head (SA-516-70) with 2 inch straight flange. RT-2 is the claim. The circumferential joint will be of Type 1 and will be spot radiographed.

What joint efficiencies should be used to calculate the longitudinal stress calculations? My interpretation pushes me towards E = 0.85 but I suspect that a lot of folks would contest that for E = 1.0.

My rational is as follows.

UW-11(a)(5) applies to the full radiography requirements of Category A and D butt welds whereas the circumferential joint in question is a Category B butt weld.
UW-11(a)(5)(a) criteria is met because the Category B weld in question will be of Type 1.
UW-11(a)(5)(b) criteria is met because the Category B weld in question connects seamless vessel sections or heads and will be spot radiographed.

UW-12(d) throws out joint efficiencies (E) for calculations involving circumferential stress (longitudinal seams) NOT for longitudinal stress calculations (circumferential seams).

FIG. L-1.4-1 leads me to E = 0.85 for Category B, Type 1 butt welds because of the spot radiography.

FIG. L-1.4-2 implies E = 1.0 for a seamless head when UW-11(a)(5)(b) is met but may only apply to seamless hemispherical heads joined to main shell (Cat. A welds).

FIG. L-1.4-4 leads me to E = 0.85 because the joint is a Type 1 and will be spot radiographed.

Example L-1.5.2(b) supports the use of an E not equal to 1.0 for a Category B, Type 2, spot radiographed joint meeting UW-11(a)(5)(b).

Example L-1.5.5(b) supports the use of an E not equal to 1.0 for a Category B, Type 2, spot radiographed joint meeting UW-11(a)(5)(b).

Example L-1.5.5(f) supports the use of an E not equal to 1.0. However for a Category B, Type 2, spot radiographed joint meeting UW-11(a)(5)(b) I would expect E = 0.80 instead of the given solution of E = 0.65 which implies no radiography…a possible mistake in the solution?!

Lastly but not imply that Code software packages are always correct...APV defaults to the same longitudinal stress E (0.85) for RT-2.

 

[CodeRef]

dtn.....I think the answer to the 4th question is (as was stated)

Expressed in terms of equivalent longitudinal efficiency:

just to establish a reference point at which to compare......As you, I was confused until I read it over again.

FAQ731-376

 

[CodeRef]

Also....in reference to that article and question 4..

.0.7 for the circ joints is appropriate instead of 0.85 because spot RT [in addition to UW-11(a)(5)(b)] was not performed.

FAQ731-376

 

[dtn6770]

CodeJackal,

I get the x2 multiplier now that you reiterated the “equivalent longitudinal efficiency” term. It relates to the (now) footnote 16 on page 19, “…circumferential joint efficiency is less than one-half the longitudinal joint efficiency…” All I can say is that’s one way to look at it.

With respect to the 0.70…I’m starting to see the light and can understand the rationale behind its selection in this article as well as in HSB article pointed out by jamesl.

If I may request one additional indulgence of you, please take a look at examples L-1.5.2 and L-1.5.5 in Sec. VIII’s Appendix L. Specifically L-1.5.2(b) and L-1.5.5(b) identify Category B, Type 2, welds that have, “spot, meets UW-11(a)(5)(b)” radiography. The solutions identify efficiencies from column (b) in Table UW-12 rather than column (c). Does that imply that “spot, meets UW-11(a)(5)(b)” would be more accurately stated as "spot in addition to UW-11(a)(5)(b)?"

 

[CodeRef]

dtn..... regarding those examples, I suppose you could say "spot in addition to UW-11(a)(5)(b)" and it would be more clear to those not familiar with the requirements of UW-11(a)(5)(b).
I would agree that it would be more appropriate to use your words in the examples provided. Especially when providing them as examples.....But...... using the term "meets UW-11(a)(5)(b)"in addition to TABLE L-1.5-1 should be enough to clear up any misunderstanding.

Additionally, if I read on a drawing, calculation, design specification, or any other fabrication paperwork that a joint is called out for spot RT, I would know that I would have to check other documents to verify the spot RT in addition to that used for UW-11(a)(5)(b)was present and accounted for.

FAQ731-376

 

[dtn6770]

Thanks all.

I appreciate the shared knowledge and experience.