Hello Caesar users,
I am doing a manual calculation for Bend SIF from B31.3 Appendix S Example. I don't usually do this since this is already programmed in any piping stress analysis software. But when I compare my calculated results to any piping stress analysis software they are not matching. I was tasked to do some training to junior stress engineers, so for the sake of example I want to do it manually. I don't know if I misinterpreted something in B31.3 Appendix D formula for SIF calculation such as nomenclature interpretation & other factors. Anyway, these are the parameters:
1. This is my manual calculation
DN400 (NPS 16)
D=406.4mm----------------------->Pipe OD
T=9.53mm------------------------>Nominal wall thickness
R1=1.5xNPS=1.5x16x25.4=609.6mm--->Bend Radius of Elbow
r2=(D-T/2)=198.435mm------------->mean radius of header pipe
h=TxR1/(r2)^2= 0.147537122------->Flexibility Characteristic
SIFin=0.9/(h)^(2/3)=3.223356229-->In plane SIF
SIFout=0.75/(h)^(2/3)=2.686130191-> Out plane SIF
2. This is taken from piping stress analysis softwares:
SIFin ~ 2.572
SIFout ~ 2.143
Please note that the SIF is taken from Stress Report for Expansion stress not the sustained SIF.
I'm curious what did I miss in the formula or interpretation of appendix D for long radius elbows.
Many Thanks in advance for the help.
Cheers,