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 waz also applied to estimate the gasket creep strain in the flanges from the master curve of the creep compliance. It was able to obtain equally prediction equation with results of HPIS Z 105 test by taking into account the pre-strain. In order to obtain a creep strain predictive expression, it is necessary to consider the prestrain. Creep strain predictive expression is useful for estimating the long-term creep modification in a flange with a high temperature.