Hi all

i had some questions on use of ASME B31J on Branch connections mainly 45 Deg. branches. mainly the below queries.

1) is B31J applicable for branches in same plane of header to 45 Deg or
less than 45 Deg
2) is the applicability limited to D/T < 50 and d/D<= 0.6 . i had
understood the applicability to D/T <=100 for 90 deg branches but not
sure for 45 Deg.

have attached a sketch for reference

You can use FEA tools for 45 deg. lateral flex and sif's

Hi Borzki

thanks for your response. I had an additional query

if i do not have FEA tools enabled , Still i suppose we can use B31J utility of C-II FEA Translator for D/d < 50 and d/D <=0.6. Please refer to attached image.

i was asking on the applicability of B31J for 45 deg branches wherein
D/d > 50 and d/D > 0.6

does B31J allow these options or do we have to use FEA.
in my earlier post, i had attached a snap of B 31J, the last note referring to Sketch 2.2 seemed a little unclear to me

as to map these connections into FEA, boundary restraint conditions of header in header-branch connections are quite difficult to determine and are often assumed as fixed which makes the calculation very conservative.

B31J was an enhancement to what's already within B31.3. Neither cover branch connections outside of 90 degrees.

Michael is right. My senior stress engineers before just use 2 x SIF of 90 deg. since FEA during that time is scarce if not available.

With the tools available now, it's better to use it and compare it to 2 x SIF of deg.

Physical testing is another option but costly and not practical. If I'm not mistaken, these tools are also verified thru physical testing.

But for me, it's a must to have a good fundamental background of FEA before using it. Make your own verification to have confidence in the tool being used.

We have many tools around us as engineers, but in the end, it's not the tool that will stamp the calculations or drawings.

Cheers!!

THANKS ALL FOR YOUT TIMELY HELP

However i am still not sure for applicability of B31J to only 90 deg branches due to the below statement in 31J. Any views on the same?

Better write to the committee and clarify.

Warm Regards,

It would be quicker to email Tony Paulin over at PRG.

THANKS A LOT BORZKI AND RICHARD SIR FOR YOUR HELP ON THIS ISSUE

B31J SIFs are not applicable for torsional branch loads. Since torsional branch loads on a lateral connection act on a thin oblong opening, better to use FEATools as it automatically calculates the torsional SIF and incorporates it into the model.

Yes that is correct. FEATools (the full licensed version) is more advanced than B31J. B31J implements empirical equations (based on testing and FEA results), while the full FEATools also includes full finite element analysis of tee components.