PHMSA RESEARCH PAPER
Determine the Maximum Permissible Temperature Drops for Steel when Exposed to Cryogenic Liquid
Summary and Conclusions
The main objectives of this research project were to assess the performance of steel components exposed to cryogenic liquid and determine the requirements to ensure mechanical integrity. We investigated full-containment steel-steel LNG tanks with a secondary metal outer container, jacketed pipe-in-pipe systems, and large-diameter insulated LNG piping in various bend configurations. We developed finite element (FE) models to analyze the response of these systems to several types of LNG release scenarios. The stresses from our FE analyses are used along with material fracture toughness and postulated crack-like defects to perform fitness for service (FFS) assessments to evaluate the risk of rupture due to cryogenic liquid exposure. We focused on two types of steel material: 9% Ni steel (ASTM A553) used in the construction of secondary containers of full containment LNG tanks and austenitic stainless steel (type A304L alloy) used in the LNG piping systems. Material properties are based on published studies and laboratory testing that we performed on modern welded 9% Ni steel.
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--Einstein gave the same test to students every year. When asked why he would do something like that, "Because the answers had changed."
Determine the Maximum Permissible Temperature Drops for Steel when Exposed to Cryogenic Liquid
Summary and Conclusions
The main objectives of this research project were to assess the performance of steel components exposed to cryogenic liquid and determine the requirements to ensure mechanical integrity. We investigated full-containment steel-steel LNG tanks with a secondary metal outer container, jacketed pipe-in-pipe systems, and large-diameter insulated LNG piping in various bend configurations. We developed finite element (FE) models to analyze the response of these systems to several types of LNG release scenarios. The stresses from our FE analyses are used along with material fracture toughness and postulated crack-like defects to perform fitness for service (FFS) assessments to evaluate the risk of rupture due to cryogenic liquid exposure. We focused on two types of steel material: 9% Ni steel (ASTM A553) used in the construction of secondary containers of full containment LNG tanks and austenitic stainless steel (type A304L alloy) used in the LNG piping systems. Material properties are based on published studies and laboratory testing that we performed on modern welded 9% Ni steel.
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--Einstein gave the same test to students every year. When asked why he would do something like that, "Because the answers had changed."
