Revised C2 Stress Index for 90-degree Piping Elbows
The purpose of this technical paper is to present a methodology that has been used to show that, based on the NB-3200 definitions; the Piping Elbow C2 stress index can be smaller than the C2 stress index currently defined in the ASME-Code. The revised C2 stress index is derived through Finite-Element elasto-plastic calculations. A conservative practical approximation is presented for the calculation of the revised C2 stress index, based on the current ASME-Code equations. This revised C2 stress index leads to a revised Piping-Elbow K2 stress index which is greater than 1.0 and which is required because the maximum stress anywhere in the elbow is greater than the newly calculated secondary stress.