The Omega Method–An Engineering Approach to Life Assessment

Abstract

Many petroleum companies have been using a tool developed by MPC for evaluating materials operating in the creep range. This method has now been recognized for inclusion in API RP579 on fitness-for-service. This paper reports on the method and explains the materials properties used therein. The MPC Omega method concentrates on the application of estimates of performance of materials at low design level stresses. The database upon which the materials properties are based was acquired by testing service exposed and softened steels and minimizing environmental effects. Use of the MPC properties in some cases could increase allowable stresses. However, the great advantage of the method is its capability as a tool for predicting strains, benchmarking materials, incorporation into finite element analysis, developing sensible testing strategies, and dealing with realistic stress situations. [S0094-9930(00)02903-6]