Ring joint gaskets
The RX type RTJ gasket is manufactured in accordance to API 6A and ASME B16.20 to suit API 6B and ASME / ANSI B16.5 flanges. The RX is a pressure energized version of the R octagonal gasket and fits the R type flat bottomed groove.

The RX has an increased height and utilizes the internal system pressure to energize and improve the seal as internal pressure increase. Some RX sizes have a pressure relief hole to equalize pressure both sides of the sealing faces.