EXAMINATION OF VARIOUS BENDING MOMENTS ON THE RUN SIDE AND ON THE BRANCH SIDE FOR THE STRESS INDEX C2 OF ASME NB-3600 CLASS 1 BRANCH CONNECTIONS

摘要

Previous stress analyses have shown that the requirement of exclusively using the branch pipe cross-section properties for the NB-3600 Class 1 branch connection stress analyses can be very severe (conservative), when compared with using the branch nozzle cross-section properties. In the analyses performed for a 2015 PVP technical paper (Ref. 2), one of the questions raised was the fact that only two specified bending moments were used in those previous stress analyses: 1,000,000 in-lbf as the run bending moment and 20,000 in-lbf as the branch bending moment. In fact, that was the main question that was raised. Therefore, the purpose of this technical paper is to perform additional stress analyses, based on various bending moments on the run side and on the branch side. The impact of using these various bending moments will be evaluated. The 2001 Edition of the ASME-Code removed a note at the bottom of the branch connection NB-3600 Figure. This note is required to be able to perform more accurate NB-3600 piping stress analyses of the branch connection. There is at this time a suggestion to restore that note.