Both styles are interchangeable on the modern flat bottom groove,
however only the oval style can be used in the old type round bottom
groove.
Style R ring type joints are designed to seal pressure up to 6,250 psi
in accordance with ASME B16.5 pressure ratings and up to 5,000 psi in
accordance with API 6A pressure ratings.
Style RX and SRX
The Style RX ring type joint is manufactured in accordance with API 6A and
ASME B16.20, to suit API 6B and ASME B16.5 flanges.
Style RX ring type joint is a pressure energized adaptation of the Style R
ring type joint. The Style RX is designed to fit the modern flat bottom
groove, and is interchangeable with the standard Style R ring type joint.
However, since the Style RX is significantly taller than a Style R, larger
flange make up distances will result.
Style RX ring type joints are designed to seal pressures up to 6,250
psi in accordance with ASME B16.5 pressure ratings, and up to 5,000 psi in
accordance with API 6A pressure ratings. The design uses a pressure
energized effect which improves the efficiency of the seal as the internal
pressure of the system increases. Selected sizes incorporate a pressure
passage hole to allow for pressure equalization each side of the sealing
faces.
Style BX and SBX
The Style BX ring type joint is manufactured in accordance with API 6A.
The Style BX ring type joint design exhibits a pressure energized effect
which improves the efficiency of the seal as the internal pressure of the
system increases. All BX ring type joints incorporate a pressure passage
hole to allow for pressure equalization each side of the sealing faces. On
assembly, metal to metal contact of the flange face is achieved. The Style
BX is not interchangeable with any other style, and is only suited for API
6BX flanges. Style BX ring type joints are designed to seal pressure up to
20,000 psi in accordance with API 6A pressure ratings.
NOTE: Style SBX and SRX rings are manufactured in accordance
with API 17D for use on subsea wellhead and Christmas tree equipment.

v See
Double Jacket Gaskets