Bolted flanged connections are especially prone to leakage when operating at elevated temperatures.In 1986-87, the API Subcommittee on Pressure Vessels, Piping and Tanks expressed a need for gasket performance data and technical formulations to permit the design of gasket systems for high temperature service.The objective was to gain initial understanding of flange behavior, gasket deformation and leakage behavior under simulated elevated temperature service conditions.