Failure modes and consequences for API 6D ball valve seals in LNG service span a range from minor external leakage causing nuisance ice formation and small product losses to catastrophic internal seat seal failure allowing massive uncontrolled flow when isolation is required for downstream maintenance or emergency response, with severity depending on leak location, leak rate magnitude... https://globalsealstech.com/product-category/oil-gas-seals/api-6d-ball-valve-and-lng-seals/