Gate-to-seat metal sealing is supported by non-elastomeric S-seals or C-seals made from Inconel 718 with silver plating. These provide secondary metal-to-metal sealing after elastomer failure in fire conditions while primary elastomeric seals handle normal operation and low-pressure sealing https://globalsealstech.com/product-category/oil-gas-seals/api-6a-gate-valve-seals/