Live-loading systems using multiple Belleville spring washers maintain packing stress within ±10% across the entire cryogenic-to-ambient temperature range. This compensates for thermal contraction of stem and gland materials, preventing leakage during repeated LNG transfer operations and vessel cooldown cycles. https://globalsealstech.com/product-category/oil-gas-seals/api-6d-ball-valve-and-lng-seals/