A Framework for Calculating Life Safety and Environmental Reliability Benchmarks for Highly Volatile Liquid (HVL) Pipelines

Abstract The pipeline industry is increasingly utilizing reliability methods as a basis for decision-making when managing the integrity of pipeline systems. Life-safety reliability thresholds for onshore natural gas pipelines and environmental thresholds for low vapor pressure (LVP) pipelines have been published in pipeline standards (e.g. CSA Z662-23, ISO 16708-2006), however limited precedent exists for defining reliability benchmarks for highly volatile liquids (HVL) pipelines which constitute around one third of U.S. hazardous liquids transmission pipeline infrastructure. To address this gap, Flint Hills Resources (FHR) and Integral Engineering (Integral) developed a framework for calculating reliability benchmarks for onshore HVL transmission pipelines to enable FHR to evaluate the performance of their pipelines relative to their industry peers in support of continuous improvement consistent with FHR’s Pipeline Safety Management System implementation. Separate thresholds were developed to address life-safety and environmental considerations. This paper describes the framework and methodology for calculating both life safety and environmental benchmarks at Average and Top Quartile industry historical performances levels. Elements of the life-safety benchmark framework that will be discussed in this paper include the development of risk benchmarks from PHMSA failure data, the use of a product-specific event tree to consider the potential for different hazardous outcomes, the incorporation of detailed hazard area analysis modelling results, and the use of location-specific geospatial analyses to consider population density and surface conditions. For the environment benchmarks, this paper describes a statistical analysis of PHMSA hazardous liquids incident data where costs including property damage, emergency response, and environmental remediation were analyzed along with release volume for both LVP and HVL releases. This analysis was used to relate the impact of an LVP release to an equivalent HVL release by adjusting the expected release volume and relative impact per barrel. In addition, the impact ratio, which is a measure of the relative impact of a barrel release in an HCA vs. a Non-HCA location was obtained using the analysis of PHMSA LVP and HVL release cost data. The result of this study is a framework to calculate Average and Top Quartile HVL life safety reliability benchmarks which consider both individual and societal risk, and HVL environmental reliability benchmarks which consider the relative severity of an HVL release compared to an LVP release.