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Ring Joint Gasket

Ring joint gaskets are metallic sealing ring suitable for high pressure and high temperature applications. They are manufactured in two kinds of cross section: octagonal and oval accordance.

Ring joint gasket are used in connection with RTJ flange, generates a strong seal between two mating flanges. When the flanges are fixed by bolts, ring joint gasket is squeezed into the groove of the flange, forming a tight seal between the mating flanges. In order to avoid destruction of the flanges, the material of the ring joint gaskets must be softer than the material of the flanges.

Ring joint gasket

Ring Joint Gasket

Basic Types of Ring Joint Gaskets

Ring joint gaskets are manufactured in three types: Style R(including R octagonal gasket and R oval ring gasket), Style RX and Style BX. Style SRX and Style SBX are respectively as the adaptation version of Style RX and Style BX.

Style R Gasket

Style R Gasket

Style R gaskets  are divided into R octagonal gasket and R oval ring gasket according to the different cross section. Style R gasket is used for pressures up to 5,000 PSI. The ring gasket is regarded as semi-pressure energized ring gasket. They are manufactured in API 6A and ASME B16.20 to suit API 6B and ASME/ANSI B16.5 flanges.  Style R Ring Joint gaskets are manufactured in accordance with all relevant standards to suit the following flange designations:

API 6A > ASME / ANSI B16.5 > MSS SP44 ( ASME 16.47 SERIES A ) > BS 1560

R octagonal gasket is designed with octagonal-shaped section. The average diameter of the R octagonal gasket is slightly larger than the average diameter of the gasket groove. The angle between ring gasket and bevel face of gasket groove is around 23°. The octagonal shape fits only the modern flat bottom groove flange.

R oval ring gasket is manufactured in oval-shaped section. The oval ring fits the round and flat bottom ring groove flange. R octagonal gasket and R oval ring gasket in a similar function : they seal by an initial line contact or a edging action as the compressive forces are applied. However, the R oval ring gasket has a lower sealing efficiency than the octagonal ’s.

Style RX Gasket

Style RX Gasket

Style RX gaskets comply with the standard of API 6A and ASME B16.20 to suit API 6B and ASME/ANSI B16.5 flanges. Style RX Gasket, as one special kind of octagonal gaskets is developed and improved in the basis of style R gasket. It has good sealing as the contact between gasket and the ring joint faces, especially the outside face, and is pressed tightly to keep good sealing performance. Style RX gasket is used for pressures up to 5,000 PSI. RX Ring Joint Gasket is one kind of pressure energized ring gaskets.

Style BX Gasket

Style BX Gasket

Style BX, as one special kind of octagonal gaskets, is manufactured in accordance with API 6A and are suitable for use in high pressure API 6BX flanges. Style BX is designed for use on pressures up to 20,000 psi. All BX sizes have a pressure relief hole to equalise pressure across sealing faces. BX ring type joint gasket is one kind of pressure energized ring gaskets.

Type SRX and SBX Gasket

Type SRX and SBX Gasket

Type SRX and SBX gaskets  are the same design as the Type RX and BX gaskets. They are manufactured to API 17D and apply for Subsea Wellhead and Tree Equipment. The “S” indicates these gaskets have cross-drilled holes to assure that any liquid trapped behind the ring gasket on either side will flow to the I.D. bore. SRX Ring Gaskets usually be designed in 6BX and/or 17D RTJ flanges under water.


Ring Joint Gaskets are manufactured according to any standard and non-standard sizes, including the standards of API 6A, API 17D, ASME B16.20, DIN 2693-67, JPI-7S-23-72 and other standards to suit ASME B16.5, ASME B16.47 Series A & Series B, API 6A Type 6B and 6BX flanges.


• Oil and gas industry
• Petrochemical industry
• Power plant technology
• Flange connections
• Pipe connections
• Heat exchangers, valves, pumps, compressors, boilers and other types of industrial equipment

Technical Literature of Ring Joint Gasket

  • Surface Finish

Style R and RX gaskets shall have a surface finish not rougher than 1.6μm (63μin.) roughness. Style BX gaskets shall have a surface finish not rougher than 0.8μm (32μin.) roughness.

  • Material

Ring joint gaskets generally are made from soft iron, low carbon steel, alloy steels (such as F5 and 410), stainless steels (including 304, 304L, 316, 316L, 321, 347, 410), and also be designed by some non-ferrous metals, for example, high nickel alloys, super alloy steels and Titanium, etc.

Brinell HBRockwell HRB
Soft Iron1.1003 -9056
Mild Carbon SteelSt 37.2ASTM A10512068
Low Alloy(Cr-Mo)1.7362 ASTM A182 F513072
SS 3041.4301 ASTM A182 F30416083
SS 304L1.4306 ASTM A182 F304L16083
SS 3091.4828 ASTM A182 F30916083
SS 3161.4401 ASTM A182 F31616083
SS 316L1.4404 ASTM A182 F316L16083
SS 3211.4541ASTM A182 F32116083
SS 3471.4550ASTM A182 F34716083
SS 4101.4000 AISI 41017086
254SMO1.4547 UNS S3125418089
Duplex SS1.4462 UNS S31803/3220523299
Super Duplex SS1.4410UNS S3275023299
Aluminium3.0255AL 105030-
Copper2.0090UNS C1220081-
Brass2.0321 C2720062-
Nickel 2002.4066 UNS N0220011062
Monel 4002.4360UNS N0440015080
Inconel 6002.4816UNS N0660015080
Inconel 6252.4856 UNS N0662515080
Incoloy 8001.4876 UNS N0880015080
Incoloy 8252.4858 UNS N0882519592
Hastelloy B22.4617 UNS N1066523099
Hastelloy C2762.4819 UNS N1027621095
SS 9041.7440 UNS N0890416083
Titanium Grade 23.7025 UNS R50400--
  • Dimensions for ASME B16.20 Ring Joint Gasket

Dimensions for ASME B16.20 Ring Joint Gasket
Style R GasketStyle RX GasketStyle BX Gasket
  • Pipe Size for Ring Joint Gasket Suitable for Flange Standards

Pipe Sizes for Ring Joint Gasket
Style R GasketStyle RX gasketStyle BX gasket


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    Hebei Metals Industrial Limited
    (Shijiazhuang Metalsin Pipeline Tech Co., Ltd)
    No. 176, Zhonghua South Street, Shijiazhuang, China.
    Tel: +86-311-89642206