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that might help evaluate the thermal safety performance of means of containment for LNG and CNG under fire conditions.
CRYOGENICS • HOW WILL TANK CARS WITH LNG OR CNG BEHAVE IN AN ACCIDENT? THE FEDERAL RAILROAD ADMINISTRATION IS TRYING TO FIND OUT BEFORE ONE HAPPENS Increasing availability of liquefied gases in the US, primarily resulting from the exploitation of shale gas reserves and higher availability of natural gas and natural gas liquids (NGLs), is generating additional demand for cryogenic transport services. Ensuring safety in this developing business will be critical if political and public opinion is to allow its growth, which will be one way to help the country with its eventual transition away from traditional fuels to lower carbon fuels based on natural gas. One area that has been explored is the movement of LNG by rail, not least since the railroad industry itself is interested in using
Administration (PHMSA) published a notice of proposed rulemaking (NPRM) in October 2019 proposing changes to the Hazardous Materials Regulations (HMR) in Title 49 of the Code of Federal Regulations (49 CFR) so as to permit the transport of LNG in rail tank cars. PHMSA has also issued special permits to allow the transport of compressed natural gas (CNG) by road, although there have been at least two incidents involving such transport, leading to calls for it to be restricted. The Federal Railroad Administration (FRA) has also been doing some work. Noting that the railroad industry is actively working on
SET IT ON FIRE Research in this area began in September 2016, when FRA engaged the Southwest Research Institute (SwRI) to fire-test a portable tank filled with liquefied nitrogen and demonstrate the performance of the pressure relief valve (PRV) system installed on the tank. Tests showed that the PRVs opened and were able to relieve the pressure in the tank fast enough to avoid a boiling liquid expanding vapour explosion (BLEVE) event. The fire test generated a great deal of data to help understand how the fire exposure affects the internal and external heating of the tank, which will inform future computer models to predict performance in different types of tank and different fire scenarios. The next phase of the project will include a fire text with a tank filled with LNG; this will provide additional validation data for
gas-based fuels for its locomotives. The US Pipeline and Hazardous Materials Safety
plans to move LNG and CNG in bulk by rail, FRA says that the safety performance of the tank cars involved in such transport under derailment-induced fire conditions has not been verified. This is a cause for concern, FRA says. As such, it is interested in developing methods, both analytical and experimental,
modelling calculations. FRA has published the initial report on the SwRI test project, which presents the following conclusions: - The temperature of a tank will greatly influence the failure pressure of that tank. The failure pressure for a heated tank has
RAILROADS ARE ALREADY EXPERIMENTING WITH USING LNG AS FUEL FOR THEIR LOCOS
HCB MONTHLY | APRIL 2020
