Importance

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Abstract

A stabilized hoist rig for lowering, lifting, and supporting a pipe string from a vessel or floating platform in a deep ocean is disclosed. A resilient bearing member is disposed in load supporting relation intermediate the vessel and the hoist rig. A powered system is provided for angularly displacing the hoist rig with respect to the vessel to maintain vertical alignment of the hoist rig with respect to the pipe string as the vessel rolls and pitches during pipe stabbing and removal operations. In a preferred embodiment, the pipe string is supported by a slip bowl and a second resilient bearing member disposed intermediate the slip bowl and the hoist rig, and a system is provided for locking the hoist rig in a fixed position with respect to the vessel for permitting the vessel and hoist rig to roll and pitch with respect to the slip bowl in response to movements of the ocean in a passive support operating mode.

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First Claim