Dears,

I have computed a branch SIF by FEA (FESIF); it is found to be much above B31.3 SIF for D/T <100 with run and branch lengths of 5D & 4D where D is the run pipe diameter, as my location of branch is having long lengths around the branch point. Which SIF will I choose - as suggested in B31.3 App-D as D/T <100 or from FEA, which is realistic ?

If I consider first, I will save in initial cost, losing in lifecycle cost, as the second one can give proper fatigue strength.

regards,
sam