Operational maintenance for API 6D ball valves in LNG service focuses primarily on stem seal adjustment or replacement, lubrication management, periodic exercising to prevent seizing, and monitoring for external leakage or abnormal operating torques indicating potential internal problems requiring detailed inspection during planned facility shutdowns. https://globalsealstech.com/product-category/oil-gas-seals/api-6d-ball-valve-and-lng-seals/