Definition
Inside Blowout Preventer — An inside blowout preventer is a back-pressure check valve installed in the drill string that lets fluid pass downward but shuts off upward flow, stopping the well from flowing up through the pipe bore during a kick.
Also known as: IBOP, inside BOP, drop-in check valve, gray valve
What an inside BOP does
An inside blowout preventer (IBOP) is a drill-string safety valve that prevents flow up through the pipe while still allowing mud to be pumped down. Where surface BOPs seal the annulus, the IBOP seals the bore of the string itself. It is stabbed into the top of the drill pipe when the well threatens to flow through the pipe, for example after a kick is taken while tripping or when the string is off bottom.
Because it is a check valve, an IBOP holds pressure from below but opens to downward circulation, so the crew can stab it under flow and then resume pumping to circulate the kick out. It complements the full-opening safety valve, which is manually operated and closes the bore fully.
How it fits well control
- Stabbed under flow to stop the string from unloading during a kick.
- Allows pumping down so circulation and well-control procedures can continue.
- Works with the FOSV and surface BOP stack as part of the full barrier system.
Why it matters for rentals
IBOPs are pressure-critical barriers that must carry current certification and pressure test records. Rental valves should match your drill-pipe connection and working pressure. Explore our pressure control equipment and well control application, or contact us.