Internal Blowout Preventers (IBOPs), also called “Grey Valves,” are vital safety components in oil and gas drilling. These dart-style positive check valves within the drill string act as secondary safeguards against well blowouts, supporting the primary Blowout Preventer (BOP) system. Operating as non-return check valves, IBOPs permit fluid pumping into the drill string, establishing a secure, one-way seal to prevent well kicks—uncontrolled fluid or gas flows upwards. Despite their smaller size, IBOPs are crucial for preserving well integrity and ensuring safety in drilling operations.