What do I need to be concerned with when Gaskets are installed in Grooves or recesses?

Gaskets installed in grooves or tongue and groove flanges require one extra consideration: the compressed height of the gasket must be considered. This is typically important where a highly compressible gasket such as Phelps PTFE Gasket materials or one of the Phelps Flexible Graphite material is used to replace a compressed sheet gasket. The fully compressed thickness, not the original thickness, must be greater than the groove depth or the space between the tongue and groove when flanges contact each other. Ideally, the tongue should be at least as tall as the groove depth.