Pure graphite die-formed packing rings serve as tertiary high-temperature seals in LNG ball valves. Rated to 650°C continuous, they prevent external leakage during fire events and act as final barriers when polymeric seals are destroyed, ensuring compliance with API 6D fire-test qualification requirements globally. https://globalsealstech.com/product-category/oil-gas-seals/api-6d-ball-valve-and-lng-seals/