Cavity relief in DPE valves uses automatic valves opening at 1.3x rating. In LNG, relief prevents seat damage during warm-up. Valbart’s relief integrates rupture discs, ensuring safety in 15,000 psi boil-off lines. https://globalsealstech.com/product-category/oil-gas-seals/api-6d-ball-valve-and-lng-seals/