Custom Ring Joint Gaskets

The Bridgeman gasket is a pressure-activated gasket for use on pressure vessel heads and valve bonnets for pressures of 1500 psi (10 MPa) and above. The cross section of the gasket is such that internal pressure creates a self-energized seal between the ring and containing surface. Bridgeman gaskets are frequently silver plated or lead plated, providing a softer surface and minimizing the force required to flow the gasket metal into the flange surface.

The BX ring gasket differs from the standard oval or octagonal shape since it is square in cross section and tapers in each corner. These metal ring gaskets can only be used in API 6A BX flanges. BX is suitable for pressures up to 20,000 psi. Standard sizes are stocked in low carbon steel, 304 and 316.

A delta gasket is a pressure actuated gasket used primarily on pressure vessels and valve bonnets at very high pressures in excess of 5000 psi (34 MPa). Internal pressure forces the gasket material to expand when the pressure forces tend to separate the flanges. Extremely smooth surface finishes of 63 microinches or smoother are required when using this type of gasket. Complete drawings and material specifications must be supplied during ordering.

A lens type gasket is a line contact seal for use in high pressure piping systems and in pressure vessel heads. The lens cross section is a spherical gasket surface requiring special machining on the flanges. Since the contact area is very small and gasket seating pressures are very high, these gaskets will seat with a small bolt load. Complete drawings and material specifications must be supplied during ordering.

RX ring gaskets are similar in shape to the standard octagonal ring joint gasket, but their cross section is designed to take advantage of the contained fluid pressure in effecting a seal. They are made to API 6A and interchangeable with standard octagonal rings. RX is suitable for pressures up to 5,000 psi. Standard sizes are stocked in low carbon steel, 304 and 316.

Per API 17D for Subsea Wellhead and Tree Equipment, Type SRX and SBX gaskets are vented to prevent pressure lock when connections are made up underwater. These gaskets have identical measurements to RX and BX ring gaskets with the same number designation and will fit the same corresponding connectors. Cross-drilled vent holes prevent fluid entrapment in the ring groove that could cause interference with proper make up underwater. Material per spec is defined as a corrosion resistant alloy.

Style 377R (oval) and 388R (octagonal) are rubber coated ring gaskets used in pressure testing to minimize damage to flanges. These gaskets, which are usually manufactured with steel, feature rubber contact points that provide additional seals while protecting the flange surfaces.

Style 377T (oval) and 388T (octagonal) consist of rings combining two different sizes with the same pitch diameter, which permits bolt up of differing size flanges.

API ring joint gaskets are available in two basic types, an oval cross section (Style 377) and an octagonal cross section (Style 388), both of which are suitable for pressures up to 10,000 psi. The octagonal cross section features higher sealing efficiency, while only the oval can be used in the older type round bottom groove. Both octagonal and oval types are compatible with the newer type flat bottom groove design.