PRACTICAL SEALING FOR COMMON GASKET MATERIALS AND CONSTRUCTION TYPES

This paper surveys common gasket materials and construction types evaluated against sealing conditions. The end-user often asks the question, "Which type of gasket should I use for this application?" While much attention has been recently focused on temperature/pressure performance, other end-user concerns include whether or not a particular joint is capable of achieving a desired leakage range (e.g., tightness) and how well a gasket may compensate for some non-ideal flange issues. Different gasket materials/constructions are more forgiving than others. Selected gaskets often used in the chemical process industry will be compared for minimum gasket seating stress to achieve various tightness levels, the required "chemical service tightness" gasket stress against the "max out" component stress for a typical joint, and associated gasket compression. This paper compares ASME Class 150 NIPS 3" and 4" joints using gaskets of various materials and constructions. Materials include fiber, filled and expanded PTFEs, flexible vermiculite, and flexible graphites. Construction types include sheet-based rings, spiral wounds, groove-profiles, and corrugated metal. Comparing typical stress and compression ranges for the various materials and constructions will help the end-user learn to narrow the selection of available gaskets and achieve a more economical bolted joint design.