The IBOP is a heavy-duty drop check valve with a conical plug to reduce the cutting action of the mud on the valve seat, ensuring positive closure whenever required. Installed in the drill string, it can protect the rotary swivel, rotary hose, stand pipe, and mud pumps from drill pipe kicks. It may be used along with high-pressure pumps to maintain well control by preventing high-pressure backflow. A special release tool allows the valve to be held open to permit sabbing into position against a backflow of fluid, this optional release tool can be installed on the float valve and the entire