Gasket stresses in flanged joints decrease due to creep deformation of gaskets. Prediction of long-term viscoelastic properties of a gasket is important to ensure the tightness of flange joint for a long-term use, especially in elevated temperature applications. Nanoindentation creep test was carried out using TMA with Berkovich indenter to evaluate the viscoelastic characteristics of a PTFE based sheet gasket. The time-temperature superposition principle using W.L.F equation was applied to obtain the master curve of the creep compliance of gasket material at elevated temperature. The elastic-viscoelastic correspondence principle was also applied to estimate the gasket creep strain in the flanges from the master curve of the creep compliance. It is improved the repeatability of the test result by the pre-processed specimens. It is necessary to perform the pre-processing at the test temperature. Each creep compliance overlaps when applying time-temperature superposition to the results obtained from the pre-processed specimens. Creep strain predictive expression is useful for estimating the long-term creep modification in a flange with a high temperature.
