Spring-energized seats use Inconel X-750 springs, applying 200 lbf at low pressure. PEEK seats with springs seal 5,000 psi in LNG transfer lines. Encapsulated springs resist LNG embrittlement. This design ensures bubble-tight shutoff per API 6D Annex B. https://globalsealstech.com/product-category/oil-gas-seals/api-6d-ball-valve-and-lng-seals/