Rational Stress Limits and Load Factors for Finite Element Analyses in Pipeline Applications: Part II — Limit-State Load Factor Development

Abstract

In this paper, a load factor for use in a limit-load analysis of a pipeline and its components is established. The load factor is based on the ASME pipeline Code’s design margin for the service and location of the installation [1, 2]. These Codes are recognized by 49 CRF192 [3]. A load factor for internal pressure loads can be derived analytically based on the equations of determining design pressure and wall thickness in the ASME B31 piping Codes. Once the load factor is established, the limit-load methodology may be used in a Finite Element Analysis (FEA) of pipelines and related components. Two application examples are presented showing analyses done with Abaqus [4], a commercial, general purpose FEA software package. The first example calculates the design pressure of an X65 pipe given the pipe dimensions (outer diameter and wall thickness). Second example deals with the re-certification of a Y-connector. This paper is not intended to revise or replace any provision of ASME B31.4 and/or B31.8 [1, 2]. Instead, it provides a limit-load approach for assessment with same design margin as the ASME B31 Codes for use in a detailed FEA of pipelines and the associated components.