'Set-in vs set-on' strikes back! 1

[ElCidCampeador]

Hello, I've read many threads in this forum about set-in/set-on nozzles and what is the "best" solution for a pressure vessel.
I usually design according ASME VIII Div.1 but this code seems not to suggest a preference for a insert or a set-on configuration as long as you follow figure UW-16.

But from a "SIF" point of view, it seems to me that a set-on weld is worse than inserted. Do you know any research paper or standard that I can read about?

I've read B31J (which was appendix D of ASME B31.3) , e.g. table 1-1, but I don't understand sketch shown and "Run SIF" defined. What am I supposed to take away from all this? Please help me, thank you.

 

[TGS4]

I have to concur with r6155 on this one. The calculation of an SIF, necessarily implies the calculation of a peak stress (range). Following the rules of ASME Section VIII, Division 2, Part 5, the peak stress (range) will be modified by a FSRF (Fatigue Strength Reduction Factor). And these FSRFs are a function of the type and extent of the NDE performed. If there are location that cannot receive any type of inspection (such as the root of a fillet weld), then that particular location will receive an FSRF=4.0. Other surfaces that may receive different NDE will necessarily have a different FSRF.

 

[RadiateurFou]

I do not

 

[RadiateurFou]

Very insightfull TGS4, thank you for the explanation. I'm not familiar with SIF calculation as per Section VIII Div2. In my work for SIFs calculations we only use B31.3 and B31J, which appear to be simplified compared to section VIII Div 2. Stress range calculated with B31.3 is straightforward. It is not modified by a coefficient which depends on the type and extend of NDE done.

 

[jt1234]

Some people here will need to be educated to understand what "SIF" is before making any unrelated nonsense comments that wasting people's time to read or reply.

SIF can be roughly considered as stress concentration factor, which will multiply to the theocratical calculated stress to make the final stress. Doing that leads to the reason why fatigue analysis can be exempted (6,000 cycles or less if I remember concretely).
It is purely based on the configuration of the junction, type of component and weld style that code committee has invented many formula in B31.3. Higher SIF means it is weaker due to higher pipe stress, nothing to do with any calc. by Div.1. So it is not surprising if set-in and set-on can have different SIFs. Just go by what B31.3 says.