IBOP Valve is a large pressure drop check valve, the tapered plug of valve, reduce the cutting action of the mud on the seat to ensure the closed position. Inside BOP Valve connected with drill string can protect swivel, hose and stand pipe. It can also be used It is also a releasing tool to make the valve opening usually and allows the backflow through. This optional release tool is installed in the float valve and the whole assembly is kept ready on the platform for quick installation at the frist sings of backflow when drill pipe is pulled out of the well.