The Influence of Elevated Temperature in Creep Relaxation of Various PTFE Gaskets Production Methods

Abstract

Polytetrafluoroethylene (PTFE) products have been widely used for industrial sealing applications due to their outstanding chemical resistance as well as their electrical, anti-stick, impact resistance and low friction properties. Diverse PTFE flat gaskets production methods are available in the industry, which include the combination of a selected Resin Type and a determined manufacturing process, being able to provide a wide range of several types of PTFE gaskets, with different mechanical characteristics. The production method has significant impact on the mechanical properties of the PTFE gaskets, especially the creep relaxation property at elevated temperatures. Therefore, the gasket behavior at high temperatures and, consequently, the bolted flanged joint (BFJ) performance, directly depends on both selected Resin Type and gasket manufacturing process. One of the most used PTFE gasket types is produced from multiaxially expanded PTFE sheets. As it is known, different types of stretching, among other factors, confer to the gasket particular mechanical characteristics. This type of gasket exhibits a very low gasket seating stress, and it is the preferred type for most low bolt load flanges. This paper presents a study of the creep relaxation property at room and elevated temperatures of expanded PTFE gaskets manufactured by different Resin Types and processes of expanding PTFE materials. Experimental results are presented comparing EN 13555 [1] Qsmax, PQR and ΔeGc parameters of the produced PTFE gaskets.