Patent 8424607 was granted and assigned to National Oilwell Varco on April, 2013 by the United States Patent and Trademark Office.
The invention relates to techniques for severing a tubular. A blowout preventer is provided with a housing having a bore therethrough for receiving the tubular, an actuator positionable in the housing, and a plurality of cutting tools positionable in the housing and selectively movable into an actuated position with the actuator. Each of the cutting tools have a base supportable by the actuator and selectively movable thereby, and a cutting head supported by the base. The cutting head comprising a tip having a piecing point at an end thereof and at least one cutting surface. The piercing point pierces the tubular and the cutting surfaces taper away from the piercing point for cutting through the tubular whereby the cutting head passes through tubular.