Fire-safe certification per API 607/6FA is mandatory even for cryogenic LNG valves. Secondary metal-to-metal seating takes over if soft seals are destroyed by fire. Graphite-free designs using high-temperature PEEK or metal backup rings ensure sealing after fire exposure without contamination risk https://globalsealstech.com/product-category/oil-gas-seals/api-6d-ball-valve-and-lng-seals/