RING JOINT 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 (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.
 

 
Style No: RS2-RA   
                   

  Dimensions for Type R Octagonal and Oval Ring Gaskets to Suit ASME B16.20 and API 6A
 

 
 RX Ring Designations for API 6B Flanges

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 15,000 psi (103 MPa). Standard sizes are stocked in low carbon steel, 304 and 316.
 
Style No: RS2-RX
 

 
 
Dimensions for Type RX Ring Gaskets per
ASME B16.20 and API 6A
 
 
 
BX Ring Designations for API 6BX Flanges
 
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.
 
Style No: RS2-BX

 
BX Ring Designations for API 6BX Flanges