I would like to verify if the proposed load cases of our vendor is defined by the B31.3 code. They treated W+P1+T1(Ope) + U1/Win1 (Occ) as OCC. Stress. They also did not performed code check for Sus + Occ. I know that the stress allowable of Sus + Occ is defined by the code and Operating case is checked through expansion case. But how can we check Stress allowable for Ope. + Occ?

I am reading the code for this one but I would like also to know the opinions of others.

Thanks in advance.

Hi Pipedrifter,

Temperature is not an issue for occasional load. I would say SUS+U1/Win as OCC.

Regards!

Pipedrifter

I don't think the problem is in you, it's in your vendor
Operating case(W+P+T)is made for some purposes (restraint check, algebraic summation for extracting nonlinear case, etc)
For the case you mention OPE+OCC, I don't think it's included in B31.3 code for stress check. So You'd better ask your vendor to verify what code they use.


cheers

"W+P1+T1(Ope) + U1/Win1 (Occ)" is not a code case.

However, for nozzle load compliance, it is sometimes practiced to check nozzle load for non-rotary equipments at "Ope+Occ load" at operating conditions.

Pipedrifter,

I think you can explain to them that in ASME B31.3 primary load (W+P) (SUS) and secondary load (T)(EXP)cause pipe fail in different mechanism yielding and fatigue and has no interaction eachother. That's why they are seperated. Explain them also that OCC stress defenition to the code ASME B31.3 are SUS+Win, SUS+Earthquake, SUS+F , ect. No stress check as per OPE case.

I think they are misunderstanding, W+P1+T1+ U1/Win1 output force and moment shall be used by them as load to calculated stress to equipment connection imposed by piping using another calculation/sofware.

LC1 W+T1+P1 (ope)
LC2 W+T1+P1+Win(x....) (Occ) Non Code Case
LC3 W+P1 (Sus) Code Stress
LC4 LC2-LC1 (OCC) Non Code Case (Algebraic)
LC4+LC3 (OCC) Scalar Code Stress
LC1-LC3 (EXP) Code Stress

This can be found in the online help as well as much more read the documents first before posting this type of question... also USE THE SEARCH function of this forum.

Simple questions are fine but first YOU must at least try to find the answers on your own!