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. Development of the safety class system required models to quantify the safety-related consequences of pipeline releases expressed as simple analytical functions of a limited number of parameters that are typically known at the pipeline design stage. These simple analytical formulas were developed using an empirical approach, in which validated numerical models were first used to estimate the hazard zone sizes for a matrix of cases representing the feasible input parameter ranges for pipelines associated with each service fluid. Subsequent work, described in a companion paper, employed regression analysis of the parametric analysis results to develop the required simplified analytical formulas.

This paper describes the safety hazards posed by releases of the various service fluids; the numerical models employed in the parametric analysis to determine the associated hazard areas as a function of key pipeline, service fluid, terrain, and weather-related parameters; and the hazard intensities adopted to delineate the size and extent of the hazard areas bound by both the 1% and 99% lethality contours. It also discusses the sensitivity analysis undertaken to establish the minimum set of pipeline and service fluid parameters that could be used to credibly estimate the size and extent of the applicable lethality zones. It concludes with a set of examples that illustrates the relative size and extent of the model-predicted lethality zones associated with the various hazards that could develop for each service fluid in a representative set of pipelines.

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