Slab gate valve body-to-seat seals use spring-energized PTFE or PEEK S-seals that maintain constant contact pressure. These non-elastomeric designs deliver fire-safe, zero-leak performance even after elastomer burnout, meeting API 6A Appendix F fire-test requirements for offshore safety-critical service. https://globalsealstech.com/product-category/oil-gas-seals/api-6a-gate-valve-seals/