Anti-blowout stem designs in API 6D LNG ball valves integrate integral back-seat shoulders with secondary PTFE lip seals. This double-barrier approach prevents stem ejection under pressure even if primary packing fails, meeting ASME B16.34 and API 6D safety requirements for critical LNG service applications https://globalsealstech.com/product-category/oil-gas-seals/api-6d-ball-valve-and-lng-seals/