Metal-seated ball valves use tungsten carbide (TC) or chromium carbide coatings via HVOF, sealing 15,000 psi at 650°F. Schlumberger’s metal seats with DLC coating achieve Ra 2 μin, reducing torque 40%. In high-temp LNG boil-off, TC seats survive 1,000 cycles with https://globalsealstech.com/product-category/oil-gas-seals/api-6d-ball-valve-and-lng-seals/