Ring Joint Gaskets

Style R Ring Gasket 

Ring joint gaskets come in two basic types, an oval cross section and an octagonal cross section. These basic shapes are used in pressures up to 10,000 psi (64MPa). 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 be free of objectionable ridges, tool, or chatter marks. RTJ assemblies seal by an initial line contact or an edging action as the compressive forces are applied.

Style RX Ring Gasket 

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 for oil field drilling and production applications in API 6B flanges. RX is used at pressures up to 5,000 psi (34.37 MPa). Standard sizes are stocked in low carbon steel, soft iron,304, and 316.

Style BX Ring Gasket 

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 20,000 psi (137.90 MPa). Standard sizes are stocked in low carbon steel, soft iron,304, and 316.

IX Seal Ring 

IX Seal rings are designed to be used in Norsok Compact Flange connections (NCF). Available in different materials, IX rings are supplied with color-coded PTFE coating to denote the base material supplied. Identification markings are on the inside of the ring following the NORSOK L-005 standard.

Lens Ring 

The lens ring is a line contact seal for use in high-pressure piping systems and 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.

Rubber Coated Ring Type Joint 

A Rubber Coated Ring Type Joint – RTJ is enclosed in a Nitrile rubber coating. The material of the Ring Type Joint – RTJ is usually Soft Iron or Low Carbon / Mild Steel.
This type of Ring Type Joint or RTJ has three main functions. 
It is used in pressure or hydro testing to minimize damage to flanges.
The rubber contact points provide additional seals while protecting the flange surface.
It provides increased assurance against corrosion, which can occur between conventional Ring ring-type joints and the engaged surfaces of the groove.
They are available coated in a range of materials including 316 Stainless Steel, Soft Iron, Carbon Steel, Low Mild Steel, F5, and Super Duplex. 

Common Material Used 

Gasket metal should be selected to suit the specific service conditions. In addition to this, the material hardness should be lower than that of the flange metal to ensure the gasket deforms under compression and not the groove of the sealing surface. Descriptions of common materials and hardness values are as follows: