From Note-8 of Appendix-D of 2002 ed of B 31.3 code, it seems that reinforcement pad thickness can be greater than 1.5 times run pipe nominal thickness; is there any limit of pad thickness for such reinforced tees?

regards,

sam

Hi Sam,

Whatever metal is in the "reinforcing zone" counts. The only limit is that any reinforcing metal that is ouside the "reinforcing zone" (too far away from the run pipe centerline) can not count in the calculation of "area replacement" reinforcement. If the OD of the reinforcing pad is too great, the attaching weld metal may fall outside the "reinforcing zone".

Regards, John

Thank you, Sir, for this clarification.

In B 31.3:2002 Ed Fig 304.3.3 L4 = smaller of 2.5*(Th-C) & Tr+2.5*(Tb-C) being quite large for Tr to fallout of reinforcement zone & reinforcement OD considered at twice the branch OD Db, we can get much to play with reinforcement pad thickness for SIF reduction, if we can arrange for higher thickness plates for this purpose.

When we feel our heart skip a beat after being screamed by some internal client that with the same size piping, same layout, no use of liberal stress allowable, the piping must not fail in stress, your judgement will come to rescue. God is Great & flexible enough to provide us mentors to realise Truth in multiple Ways!

regards,
sam

REMEMBER TO APPLY NOTE 8 WHEN CALCULATING SIF'S WHERE THE PAD THICKNESS IS GREATER THAN 1.5 TIMES RUN THICKNESS. Tr > 1.5T use h=4T/r2

Thanks Bill Robbins - we, both the analyst & reviewer, must remain careful about all these notes in code. But, isn't CAESAR II itself checking this one of note-8 while calculating SIF of reinforced branch?

Sometimes we feel that nowadays we use CAESAR II as black box calculator as Coade has incorporated all the relevant logics of B 31.3, we blindly follow a few checklists & lessons learnt & never try to simplify the problem & understand. But, it deprives us from fine-tuning possible by a conscious user who looks for exceptions by using the intuition based on experience.

Just for example, we don't put a node in between supports in a pipe to find out the sustained sag at that point, because we know that supports have been put using a supports span chart with both
stress & sustained sag criteria. But, if we remain confident & vigilant enough, we can minimize the number of supports yet fulfilling the stress & sustained sag criteria of the span chart by efficient use of CAESAR II.


regards,

sam

Good point Bill, I had a VERY heated argument with a chartered engineer when i dismissed his Code calculations due to him not modifiying the H factor.

But, why there will be any argument when B 31.3 code is quite clear about the modification of 'h' factor discussed for Tr > 1.5T . Is there really any room for different interpretation ? Using NOZZLEPRO or any similar FEA program, we can utilize more realistic figure of SIF as per Note-1 of Table D-300 although.

regards,

sam