A Risk-Based Safety Class System for Onshore Pipelines

Abstract

A consequence-based safety class system was developed as an alternative to the class location system currently used as the basis for defining the maximum allowable hoop stress in Canadian Standard Association’s Standard Z662. The system accounts for the key pipeline, service fluid, and right-of-way parameters affecting the safety and environmental impact of releases from pipelines transporting natural gas, low- and high-vapour-pressure liquid hydrocarbons, sour gas, carbon dioxide, multiphase, and oilfield water pipelines. This paper describes the safety class system and the simplified release consequence modelling approach developed to support its implementation. Companion papers provide more detail on the release hazard analyses used as a basis for consequence modelling, and the application of the safety class system as a basis for defining pressure design hoop stress factors that achieve acceptable and consistent public safety and environmental protection levels for all pipelines considered.