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API Approved Ring Joint Gaskets



Flexiteck style: 320

API ring joint gaskets come in two basic types, an oval cross section and octagonal cross section.
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 microinches and be free of objectionable ridges, tool or chatter marks. They seal by an initial
line contact or a wedging action as the compressive forces are applied. The hardness of the ring
should always be less than the hardness of the flanges. Dimensions for API ring joint gaskets and
grooves are covered in ANSI B 16.20 and API 6A.


Manufactured in latest CNC Machine from solid material only.
Materials : Soft Iron, Low Carbon Steel, 4-6 Chrome (F5), 304, 304L, 316, 316L, 347, 410, Monel, Inconel and Incoloy, etc. 

R - ( Oct. & Oval ), RX & BX series manufactured to API 6A STD.

Delta Ring, Lens Ring, Double Cone, Bridgeman Ring, Round Ring, & Etc.

Ring-Joint Gaskets

Type R

Model : S10 Oval Standard Ring joint Gasket, oval in section. Designed for flanges with standard ring joint grooves.

Model : S11 Octagonal Standard Ring Joint Gasket, octagonal in section. Designed for flanges with standard ring joint grooves.


These rings are manufactured in accordance with JPI-7S-23, ANSI B16.20 and API 6A used on the ring type joint flanges specified in JPI-7S-15, ANSI B16.5, API spec 6A and MSS sp-44  




B (width of ring)



h (average pitch diameter of ring)



23 Deg. (angle)

+-1/2 deg.


Ring-Joint Gaskets

Type RX

Model : S12 Ring Joint Gasket for pressures up to approx. 700 bar. With this model, which can be characterized as self-sealing, the outer sealing surfaces make the first contact with flanges. A higher system pressure produces a higher seating stress. Ring Joint Gaskets of the RX type are interchangeable with the standard R models. The bolt lengths have to be extended because of the additional height of the RX- series.

RX type ring joint gasket is manufactured in accordance with API Spec 6A and ANSI B16.20 being used on 6B flanges of API Spec 6A.




B* (width of ring)

+0.008, -0.000

h * (height of ring)



OD (od of ring)



23 Deg. (angle)

+-1/2 deg.



Ring-Joint gasket


Type : BX

Model : S13 Ring Joint Gaskets for very high pressures (up to approx. 1500 bar). BX gaskets are self energized by the internal system pressure which increases the gasket’s seating stress on flange contact surfaces. This Ring Joint Gasket is the only suited for API-type BX flanges and grooves.

BX type ring joint gasket is manufactured in accordance with API Spec 6A and used on 6BX flanges of API Spec 6A.




b* (width of ring)

+0.008, -0.000


d (hole size)



h* (height of ring)

+0.008, -0.000


OD (od of ring)

+0.000, -0.006


23 deg. (angle)

+-1/4 deg.


Radius of the ring shall be 8% to 12% of the ring height “h”.



Ring-joint Gasket

Type : Lens Ring



Model : S14 The sealing section is based on point contact sealing. This gasket produces a seal with limited bolt load. Widely used in high-pressure pipe systems (PN64-PN400)

Manufactured in accordance with DIN 2696.

Lens Ring has a spherical surface and are suitable for use with conical flange faces (other styles are available on request).

As with all metallic joints, the re-use of Lens Ring is not recommended. During assembly and use, work hardening of the material occurs. With subsequent re-use, increased bolt loads are required to achieve similar sealing performance. This can lead to damage to the flange faces.


A (Ring width)                              +-0.20mm


H (Ring high)                                +-0.51mm


D2 (Average pitch size, ring)        +-0.18mm


R (Groove radius)                          max.


E (Groove depth)                           +0.51 / 0.00mm