LamonsLGC US Asset Holdings, LLC

Ring Joint Gaskets

Lamons manufactures and supplies a large variety of ring joint gaskets. The RTJ standard size gaskets are manufactured in accordance to API-6A and ASME B16.20 specifications. Lamons is licensed by the American Petroleum Institute (API).

Oval (Style 377) and Octagonal (Style 388)

API ring Joint gaskets come in two basic types, an oval cross section (Style 377) and an octagonal cross section (Style 388). These basic shapes are used in pressures up to 10,000 psi. The dimensions are standardized and require specially grooved flanges. The octagonal cross section has a higher sealing efficiency than the oval and would be the preferred gasket. However, only the oval cross section can be used in the old type round bottom groove. The newer flat bottom groove design will accept either the oval or the octagonal cross section. The sealing surfaces on the ring joint grooves must be smoothly finished to 63 micro inches and to be free of objectionable ridges, tool or chatter marks. They seal by an initial line contact or a edging action as the compressive forces are applied.
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BX (Style 390)

The BX ring gasket differs from the standard oval or octagonal shape since it is square in cross section and tapers in each corner. They can only be used in API 6BX flanges. BX is used at pressures up to 15,000 psi. Standard sizes are stocked in low carbon steel, 304 and 316.
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RX (Style 391)

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 both made to API 6A and interchangeable with standard octagonal rings for oil field drilling and production applications in API 6B flanges. RX is used at pressures up to 15,000 psi. Standard sizes are stocked in low carbon steel, 304 and 316.
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Type SRX and SBX gaskets per API 17D for Subsea Wellhead and Tree Equipment are vented to prevent pressure lock when connections are made up underwater. They have identical measurements to RX and BX ring gaskets with the same number designation, and they will fit the same corresponding connectors. The "S" indicates these gaskets have cross-drilled holes, as fluid entrapment in the ring groove can interfere with proper make up underwater (subsea). With the vent hole, any water trapped between a ring groove bottom and the sealing area of the gasket can escape to the equipment I.D. bore. Material per spec is defined as a corrosion resistant alloy.

Style 377R (Rubber coated rings)

Style 377R is a rubber coated oval ring gasket (usually steel) used in pressure testing to minimize damage to flanges. The rubber contact points provide additional seals while protecting the flange surfaces.

Style 377T (Transition Rings)

Style 377T, combination rings combine two different sizes having the same pitch diameter permitting bolt up of differing size flanges.

Bridgeman (Style 393)

The Bridgeman gasket is a pressure activated gasket for use on pressure vessel heads and valve bonnets for pressures of 1500 psi and above. The cross section of the gasket is such that internal pressure acting against the ring forces it against the containing surface making a self-energized seal. Bridgeman gaskets are frequently silver plated or lead plated to provide a softer surface and minimize the force required to flow the gasket metal into the flange surface.

Delta (Style 392)

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. As with the lens gasket, complete drawings and material specifications must be supplied. Internal pressure forces the gasket material to expand when the pressure forces tend to separate the flanges. Extremely smooth surface finishes of 63 micro inches or smoother are required when using this type of gasket.

Lens (Style 394)

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 and requires special machining on the flanges. These gaskets will seat with a small bolt load since the contact area is very small and gasket seating pressures are very high. Normally the gasket materials should be softer than the flange. In ordering lens gaskets, complete drawings and material specifications must be supplied.

Kammprofile RTJ


The Kammpro-ORJ is sized to the standard octagonal API 6A or ASME B16.20 dimensions but with the addition of the Kammpro design applied to the sealing areas and faced with oxidation inhibited flexible graphite. This design is ideal for applications where cracking or embitterment has been experienced in ring joint groove. It is available in a large variety of metal material and it can be fabricated as custom engineered designs.


Kamm-PEG represents a Pressure Energized Gasket with Kammprofiled sealing surfaces, where a RX type ring is typically used for high pressure reactors. Frequently, custom rings are used in the top and bottom of hydro processing reactors. To greatly enhance sealing ability, top and bottom OD angled sealing gasket surfaces are serrated per Kammprofiled specifications and faced with oxidation inhibited flexible graphite. It has the benefits of under compression graphite flows into minor imperfections creating higher seal tightness.

Kammpro-Adapter (RTJ to RF)

Kammpro-Adapter gaskets allow for ring type joint flanges to be mated up to a raised face flanges, utilizing the strengths of the full metallic with the added benefit of kamm profiled sealing surfaces laminated with flexible graphite. Provided the pitch of the groove is sufficiently located under the raised face, this design is among the stoutest of adapter styles.
KammproOvalAdapterRF RTJ
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Specialty Machined Products

Lamons maintains a high capacity of programmable mill and lathe capability for custom machine work on most any specialty component. As a leading manufacturer of custom machined products for the refining, petrochemical and industrial markets, Lamons recognizes the quality and service levels these industries require.

specialty machined