Third-party validation of seal performance is often required by operators. Independent labs such as DNV, Lloyd’s, or Southwest Research Institute perform extended PR2 testing, shell tests at 1.5× rated pressure, and endurance cycling beyond API minimums. Certificates of compliance with API 6A monogram and Annex F qualification are issued only after successful completion of the entire ... https://globalsealstech.com/product-category/oil-gas-seals/api-6a-gate-valve-seals/