There are two main types of bolted joint assemblies, the “FLOATING” ASSEMBLY and the “RIGID” ASSEMBLY.  Each with their own characteristics which need to be considered when selecting the kind of gasket to be used and its proper installation.

The “floating” assembly is one where there is no metal to metal contact after bolting the flanges. This would be the commonly encountered raised face flange having a fibre-based material gasket. Here, for an increase in system pressure a higher gasket stress would be required. How ever, with increasing bolt force the gasket undergoes greater compression. Additionally the bending moment on the flanges is increased, so that the bolts, flanges and gasket could all be considered to be ‘spring elements’ within the system.

A ‘rigid’ assembly, is where metal to metal contact occurs after bolting. An example of a ‘rigid’ assembly can be illustrated by an O-ring in a recess. Once the flanges have achieved a metal-to-metal contact, then further tightening of the bolts against the system pressure has no further effect upon the sealing element. As an O-ring is self energizing, then the degree of sealing should be good, provided no extrusion gap exists between the flanges.

Article adopted from James Walker Gasket Technology Handbook.

For more information about the selecting the right type of gasket for your application contact Four States Gasket and Rubber, Inc.

In the Greater Denver Region –
Contact Steven Liparoto at 720-878-1053 or send to sliparoto@fourstatesgasket.com

In the Four Corner area (New Mexico, Arizona, Utah, Southern Colorado)
Contact Bryan Crawford at 505-325-9806 or send an email

Or Call our office in Farmington, NM and ask for Scott Blades at 505-325-9806