Detail Investigation of Omega Method for Creep Analysis of Pressure Vessel Components

A comprehensive creep material model for evaluation of high temperature applications of ferritic, martensitic and austenitic steels is available in API 579-1/ASME FFS and in ASME VIII Div 2 CC-2605-1 codes based on MPC Project Omega.Although the model can be used directly to analyze pressure vessels components behavior in a non-linear finite element creep analysis, several numerical and theoretical limits are to be taken into account in the implementation of the FE user-subroutine of the material model.In this context, a deep parametric analysis, both theoretical and numerical, based on different possible operating conditions and material behavior (temperature, pressure, stress field, elastic-plastic material properties and plastic flow rules) has been performed to review the model results on a high pressure vessel component.Based on results of these analyses, a theoretical critical review of the method is presented.Copyright © 2013 by ASME