Fire-safe design per API 6A and API 607/6FA requires that even after external fire exposure, the valve maintains pressure containment with only minor allowable leakage. Graphite secondary stem seals and metal-to-metal seating surfaces replace elastomers as the primary barrier post-fire. During type testing, valves are burned for 30 minutes at 1,400–1,800°F then cooled while maintainin... https://globalsealstech.com/product-category/oil-gas-seals/api-6a-gate-valve-seals/