Patent ID: 6173770
Filing Date: 2001-01-16
Classification: E21B

Abstract:
A ram assembly for positioning in opposed cavities in a body of a blowout preventer having a vertical bore, comprising:a first and a second ram movable in the cavities along a central guideway axis and between an open position to permit passage of a tubular member through the bore and a closed position to shear the tubular member; anda first and a second shear member mounted on the first and second rams, respectively, each shear member having a pair of shearing portions disposed on opposite sides of a blade axis, each shearing portion having a first cutting edge inclined to the blade axis at a first angle and a second cutting edge inclined to the first cutting edge at a second angle the first angle being greater than 45 degrees but less than 90 degrees, the second angle being less than 180 degrees;wherein the cutting edges are arranged to shear the tubular member, and the first and second angles and the lengths of the first and second cutting edges are related such that the tubular member is constrained between the shearing portions as the cutting edges shear the tubular member.