A standardized approach for reliability-based design and assessment of pipelines

A new Annex on reliability-based design and assessment of onshore natural gas pipelines has been adopted for inclusion in the 2007 edition of the Canadian Standard Association's pipeline standard (CSA-Z662). The same Annex is also being reviewed for inclusion in the next edition of the ASME gas pipeline code (ASME B31.8). The Annex defines a set of specific reliability targets as a function of pipeline diameter, pressure and population density; prescribes the process of demonstrating compliance with these targets; specifies the key requirements of a valid reliability calculation; and gives guidance on specific analysis methods, limit state functions and input parameter distributions. It is one of the few full reliability-based standards in the industry and is the first to mandate specific reliability targets. This paper describes the reliability-based approach adopted, the risk-based methodology used in defining the reliability targets and the key elements of the codified approach. It discusses current applications of the methodology as well as existing and potential plans developing similar codes for liquid and offshore pipelines.