Importance

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Abstract

A drill string shut-off valve system for controlling the mud circulation system for deepwater marine drilling operations is disclosed, the drill string shut-off valve having a valve body having a cylinder, a main flow path, and a drilling mud flow channel, an upper and a lower connector on the valve body for installing the drill string shut-off valve into a drill string, and a valve positioned to selectively interrupt in the main flow path through the valve body or to complete the main flow path through the drilling mud flow channel. A piston in the cylinder is operably connected to the valve to drive it from an open to closed position. The piston has a first pressure face, a port presenting pressure from the upstream side of the valve to the first pressure face, and a second pressure face on the back of the piston. Exhaust ports present pressure from the annulus to the second pressure face and a spring biases the drill string shut-of valve to a closed position, but balanced with the area of the first pressure face to ensure valve opening at normal pump operation pressures. A spring adjustment assembly whereby the tension of the spring can be readily adjusted to allow for different drilling conditions is also disclosed.

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First Claim