Patent ID: 9234401
Filing Date: 2016-01-12
CPC Classification: E21B

Claim Text:
1. A blowout preventer which comprises: an elongated BOP housing; a BOP bore which extends axially through the BOP housing; and a pair of ram assemblies which are mounted on diametrically opposite sides of the BOP housing, each ram assembly comprising: a cylinder housing which comprises a recess that extends generally transversely relative to the BOP bore from a radially inner end of the cylinder housing to a transverse first wall located at a radially outer end of the cylinder housing; a cylinder-ram which is slidably received in the recess and which comprises a cavity that extends from a radially outer end of the cylinder-ram to a transverse second wall located at a radially inner end of the cylinder-ram; a back plate which is connected to or formed integrally with the outer end of the cylinder-ram, the cylinder-ram being sealed to the cylinder housing proximate the back plate; a piston head which is positioned in the cavity between the second wall and the back plate and is sealed to the cylinder-ram, the piston head being connected to the cylinder housing; a first piston chamber which is defined between the back plate and the first wall; and a second piston chamber which is defined between the piston head and the second wall; wherein application of hydraulic pressure to the first and second piston chambers will move the cylinder ram from an open position in which the cylinder-ram is retracted from the BOP bore to a closed position in which the second wall of the cylinder ram extends across the BOP bore to approximately the centerline of the BOP bore.