Almost 350,000 miles of interstate gas and hazardous liquid transmission pipelines transport products across the U.S. The quality of individual components used in constructing these pipelines is critical to protect life, property, and the environment.
The Government Accountability Office (GAO) reviewed data on the quality of fittings, flanges, and valves on interstate transmission pipelines, and found that manufacturing defects rarely contribute to accidents.
Manufacturing defects involving certain pipeline components—specifically fittings, flanges, and valves—accounted for less than two percent (23 of 1,529) of all accidents on gas and hazardous liquid interstate transmission pipelines from 2016 through 2020, according to GAO’s analysis of Pipeline and Hazardous Materials Safety Administration (PHMSA) data. During this period, none of the reported 10 fatalities or 24 injuries requiring in-patient hospitalizations were related to accidents involving such defects. The amount of product released was also lower than average for all accidents that GAO reviewed. For example, accidents involving manufacturing defects in these pipeline components resulted in the spillage of 69 barrels of hazardous liquid on average, compared to an average release of 242 barrels for all accidents. Many selected stakeholders GAO interviewed also said that manufacturing defects in pipeline components rarely contribute to accidents.
All selected operators GAO interviewed described taking a number of steps to design, inspect, and test pipeline components to ensure quality prior to placing the components into service. Many of these selected operators described taking steps above PHMSA’s minimum safety standards. For example, some operators described conducting inspections of manufacturers’ processes or requiring manufacturers to maintain voluntary management and design certifications. According to these selected operators, these actions help ensure that manufacturers have the skills and expertise to construct high-quality pipeline components. While selected operators generally did not describe additional testing steps, many of these operators and other stakeholders agreed that defects are often identified during the testing of components. Specifically, PHMSA generally requires that operators conduct a hydrostatic test—whereby the pipeline is pressurized to a level above the normal operating pressure—to ensure the integrity of the pipe and components prior to the pipeline being placed in service.
