Double block and bleed (DBB) capability is inherent in API 6A gate valves. When closed, both upstream and downstream seats seal independently, allowing the body cavity to be bled to verify zero leakage. This feature is critical during well intervention and maintenance. Seat seal autonomy must be demonstrated during factory hydrostatic and gas testing at both low (200 psi) and high (1.... https://globalsealstech.com/product-category/oil-gas-seals/api-6a-gate-valve-seals/