Secondary emergency LNG packing seals incorporate graphite-impregnated PTFE with anti-extrusion mesh. Positioned above primary PTFE sets, they provide fire-safe backup42 backup sealing after primary seal degradation and remain functional after 30-minute 980°C fire exposure per API 607 7th edition and ISO 10497 requirements https://globalsealstech.com/product-category/oil-gas-seals/api-6d-ball-valve-and-lng-seals/