Ring joint gaskets (R, RX, BX) are the backbone of API 6A flanged connections, machined from soft iron, 304/316 SS, or Inconel 625 to API 6A Annex D. R-type oval gaskets seal 2,000–5,000 psi in 6B flanges; RX octagonal improves contact for 10,000 psi; BX handles 20,000 psi with pressure-energized sealing. Surface finish Ra 32 μin ensures metal-to-metal contact stress >25,000 psi. BX g... https://globalsealstech.com/product-category/oil-gas-seals/api-6a-wellhead-equipment-seals/