High-Pressure Cap Equalization Valve

A subsea hydrocarbon production system, comprising:

• a Christmas tree to control the flow of hydrocarbons from a wellhead, comprising a hub;
• a cap to protect a sealing surface of the hub, comprising:
• a pressure-seal portion configured to form a pressure seal between an inner face of the cap and the hub;
• an equalization valve, comprising:
• a valve body comprising a pressure equalization conduit;
• a sleeve disposed about the valve body and comprising a port allowing fluid communication across the sleeve, the sleeve being exposed to the environment outside the cap;
• a valve spring configured to bias the sleeve to a closed position;
• wherein the sleeve is configured to move to an open position in response to a force that depresses the sleeve and causes the valve spring to compress;
• wherein the port is fluidly isolated from the pressure equalization conduit in the closed position and is in fluid communication with the pressure equalization conduit in the open position;
• and
• a fluid conduit that couples the inner face of the cap and the pressure equalization conduit such that, in the open position, an interior environment of the Christmas tree is in fluid communication with the environment outside the cap through the equalization valve.

A method of protecting a sealing surface of a hub of a subsea device and isolating an interior environment of the subsea device from an exterior environment, comprising:

• installing a cap on the hub, thereby creating a pressure seal between the cap and the hub;
• lowering the subsea device into a fluid, the fluid comprising the exterior environment, wherein the densities of the exterior environment and interior environment are different such that a pressure differential is created across the cap when lowering the subsea device;
• depressing a sleeve of an equalization valve to an open position creating a fluid path between the exterior environment and the interior environment, wherein the sleeve is biased to a closed position;
• removing the cap from the hub.