Octagonal,Oval,BX type,RX type,IX type and Lens Ring Joint Gaskets |
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 (64 MPa). The dimensions are standard- ized 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. The hardness of the ring should always be less than the hardness of the flanges to prevent flange deformation.Dimensions for standard ring joint gaskets and grooves are covered in ASME B16.20 and API 6A, API 17D and ASME B16.5/B16.20.


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 15,000 psi (103 MPa).Standard sizes are stocked in low carbon steel, 304 and 316.




Typical minimum yield stress and ultimate stress of the seal ring material shall at maximum design temperature be 300MPa and 360MPa, respectively, in order to allow for reasonably elastic spring-back. Lower strength may be used, but is not recommended. The user is responsible for selecting a seal ring material which is suitable for the service medium and the design temperature conditions. Seal ring materials are commonly chosen to be compatible with the flange material, I.e. Duplex seal ring in duplex flange.














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