RTJ gasket ring Ring joint gasket The ring type joint was initially developed for high pressure and temperature applications found in the petroleum industry and is primarily used in the oil field on drilling and completion equipments. However, today this product range can also be found on valves and pipework assemblies, along with some high integrity pressure vessel joints. Standard Standard style R/RX/BX/lense ring type joints are manufactured in accordance with both API 6A and ASME B16.20 size and ratings. Available in both oval and octagonal configurations, both types are interchangeable on the modern octagonal type grooved flanges. As with all metal ring type joints including style R/RX/BX/lense ring, it is recommended to replace the ring when flange connection is broken.