Preparing for LNG by Rail Tank Car: A Review of a U.S. DOT Safety Research, Testing, and Analysis Initiative (2021) / Chapter Skim
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1 Summary Most natural gas produced and consumed in the United States is transported long-distance through a nationwide network of transmission pipelines, but the country's pipeline capacity is limited in some regions and pipelines are an impractical option for transportation outside North America. For transportation by other modes, natural gas can be cooled to a liquid state to produce a much denser liquefied natural gas (LNG)
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2 PREPARING FOR LNG BY RAIL TANK CAR To support development of the final rule and inform subsequent decisions to ensure the safe movement of LNG by rail, PHMSA and FRA jointly established an LNG-by-rail task force (Task Force) during January 2020.
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SUMMARY 3 TABLE S-1 Tasks in the Liquefied Natural Gas (LNG) Task Force Project Plan as Categorized by the Pipeline and Hazardous Materials Safety Administration and the Federal Railroad Administration KNOW the Risk PREDICT the Risk REDUCE the Risk PREPARE for the Risk International Experience Transporting LNG by Rail Punctures and Derailment Simulation Modeling Electronically Controlled Pneumatic Brakes Emergency Responder Opinions and Needs Loading and Unloading Safety Assessment Worst-Case Scenarios Model Train Operational Controls Educational and Outreach Plan Quantitative Risk Assessment Safety and Security Route Risk Assessment Automated Track Inspection Program Full-Scale Impact Testing Train Energy and Dynamics Simulator Portable Tank Fire Testing Modal Conversion Between LNG by Truck and Rail STUDY APPROACH The committee was not tasked with conducting its own analyses, but rather to exercise its expert judgment on the basis of what it learned from PHMSA and FRA briefings and materials describing and documenting the outcomes, plans, and status of the Task Force's work.
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4 FI G U R E S -1 R el at io ns hi ps a m on g th e 15 t as ks g ro up ed b y re le va nc e to L N G t ra ns po rt at io n by r ai l.
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SUMMARY 5 characteristics of LNG would affect the type and severity of the consequences of a rail incident. Next, in terms of relevance, the committee examined the tasks that concern rail transportation of hazardous materials more generally, an example being the Safety and Security Route Risk Assessment task.
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6 PREPARING FOR LNG BY RAIL TANK CAR acquisition about track infrastructure conditions. Likewise, PHMSA has decades of experience collaborating with and supporting the emergency response community.
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SUMMARY 7 with respect to the fire. The test also used a portable tank on a flatcar rather than a tank car.
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8 PREPARING FOR LNG BY RAIL TANK CAR are also differences in loading and unloading operations. In addi tion, train assembly and classification activities were also missing from this task.
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SUMMARY 9 Worst-Case Scenarios Model Enhancing the modeling for worst-case scenarios will require inputs from the pending tasks on full-scale impact testing, punctures and derailment simulation, and portable tank fire testing. Once these pending tasks are completed and data are collected and analyzed for incorporation, PHMSA and FRA should further update the model for worst-case scenarios in the following manner: • Provide upper bound values of predicted number of punctures to identify the worst-case release rather than using nominal values; • Use a train speed of 50 mph for the predicted number of punctures rather than the 40 mph used; • Evaluate the heat flux from a jet fire from a punctured tank and impinging on an adjacent tank; • Evaluate the total amount of LNG that could potentially be released from cascading damage to adjacent tank cars from partial submersion in an unignited pool of LNG and/or partial exposure to the heat flux from a pool fire; • Evaluate the potential hazard to emergency responders of a rapid phase transition from an LNG spill onto a body of water, considering that track infrastructure commonly runs along rivers; and • Evaluate explosion hazards from an unignited spill of LNG resulting in vapor dispersion in an environment with confined or congested spaces.
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10 PREPARING FOR LNG BY RAIL TANK CAR systematically integrating and reporting the results from the tasks. Ensuring the safety of LNG by rail, like all hazardous materials shipments, is an ongoing process that will require continued monitoring and adjustment of practice and regulations.
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