What are ‘m’ and ‘y’ values and how do they relate to flange design?

The gasket stress required to achieve the initial seal is considered the “y” constant. The “m” value ensures that the flange has adequate strength and available bolt load to hold the joint together, while withstanding the effects of hydrostatic end force or internal pressure (y-seating stress and m-gasket factor). In simple terms, a flange must be designed to create sufficient compressive load on the gasket contact area to create an initial seal and the gasket must conform to the flange surface and must be compressed enough to seal off any internal voids or spaces.