Slab gate valves use a single-piece gate with a rectangular port, while expanding gate valves employ a two-piece gate-seat assembly that mechanically wedges outward during closing. Expanding gates provide superior metal-to-metal sealing but generate higher operating torque. Seal design differs significantly: slab gates rely more on elastomeric or TFS inserts, while expanding gates are... https://globalsealstech.com/product-category/oil-gas-seals/api-6a-gate-valve-seals/