A Novel Approach to Establishing Remaining Strength of Line Pipe and Fittings with Corrosion Type Defects

Main Objective

A successful Phase I will demonstrate, through mathematical models and scientific analysis, a determination as to whether RSTENG needs to be modified when pipes with X65 and above.

Public Abstract

The US DOT's PHMSA is exploring technologies and methods which could increase the integrity, reliability and safety of the U.S. pipeline network. Corrosion metal loss is one of the major damage mechanisms to gas transmission pipelines worldwide. Current methods to assess the remaining strength of corroded pipelines, such as the ASME B31G (including the Modified B31G) and RSTRENG models that have been incorporated into the US Code of Federal Regulations for a number of years may now be inadequate and perhaps non-conservative for higher grade modern line pipe steels, X65 and above. Also recent work supported by PHMSA has shown that existing methods may be non- conservative.

Emc2 will study the feasibility of a novel mathematical and computational model to assess the remaining strength of pipelines and fittings with natural corrosion type defects and a failure criterion that accounts for the transitional changes from a sharp crack to generally thinned corroded regions. The successful demonstration of the approach "Simulation of Natural Corrosion via Computation" (SNC2) along with carefully selected laboratory experiments will allow appropriate correction factors to the existing methodologies and also provide a high- performance computational tool for reliable prediction of the remaining strength of both line pipe and fittings made with higher grade steels.

Future work may include validating the new models along with additional revisions of the mathematical models.