Underwater Christmas tree cap and lockdown apparatus

摘要

A cap for an underwater Christmas tree having locking probes to lock down the operating rods of a connector connecting the Christmas tree to an underwater wellhead housing. The tops of the operating rods are housed within hollow canisters at the top of the Christmas tree. The cap includes a body having circumferentially disposed locking dogs housed therein for engagement with the top of the Christmas tree. The dogs are actuated by a cam ring which telescopically receives the body and has a tapered surface for sliding over a correlatively tapered surface on each of the dogs. The body includes a metal gasket seal for sealing engagement with the top of the Christmas tree, and seals are provided between the cam ring and body. The cap has downwardly extending locking probes which extend telescopically into the canisters above the operating rods. The locking probes each include a housing and a releasable tubular piston slidably disposed in the housing. The piston is biased in a downward direction, and is held in a cocked or loaded raised position prior to release by a trigger held in engagement with the piston and housing by a pin on a running tool telescopically slidably disposed in the piston. The piston is released by removal of the pin, which cams the trigger out of engagement with the housing. Upon release the piston is biased into engagement with the rod. The piston is provided with locking dogs which engage the walls of the housing and prevent upward movement of the piston and rod after release of the piston.