Importance

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Abstract

A two-position pilot-operated SPM valve includes an improved cage for controlling fluid flow to a ram of a subsea blowout preventer. SPM valve 10 includes a piston 48 axially movable with respect to a valve body 12, a spool 38 for moving within the valve body between an open position and a closed position, and a piston rod 34 structurally interconnecting the spool and the piston. A cage 40 within the valve body receives the spool 38, and includes an axially intermediate body 84 formed from a selected plastic material, an upper body 86 removably secured to the intermediate body and having one or more radial throughports 106 therein, and a lower body 88 removably secured to the intermediate body. An external seal 92 is provided for sealing between the intermediate body and the valve body, an internal seal 96 provides dynamic sealing engagement between the intermediate body and the exterior cylindrical surface 72 of the spool. Interior cylindrical surface 100 of the intermediate body is in sliding engagement with the exterior spool cylindrical surface 72, and substantially reduces wear on the spool due to the plastic-to-metal sliding engagement of these surfaces. During servicing of the SPM valve, an intermediate body 84 may be replaced with a new intermediate body and both the upper and lower cage bodies installed on the new intermediate body. An improved technique is also provided for compressing the coil spring which biases the spool to the closed position.

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First Claim