Fire fighting boom assembly for service vessel

摘要

An extendable utility boom assembly for assisting fire- fighting operations performed from a semi-submersible service vessel upon an offshore platform is disclosed. The boom assembly is moved to operating position by means of a carriage assembly which is mounted for movement along a track secured to the deck of the service vessel. Orientation of the boom assembly in azimuth and pitch is provided by a supporting frame which is pivotally mounted on the carriage assembly for angular movement through a horizontal plane, and a boom housing which is pivotally mounted on the supporting frame for angular movement through a vertical plane. An elongated utility boom is supported by roller bearing elements for axial movement through the boom housing. A first linear actuator is interconnected between the carriage assembly and supporting frame for displacing the supporting frame through the horizontal plane. A second linear actuator is interconnected between the boom housing and the carriage assembly for displacing the boom housing through the vertical plane, and a third linear actuator is interconnected between the boom and the boom housing for displacing the boom along the axis of the boom housing. The elongated utility boom is characterized by a polygon in transverse section, with the aft section of the boom being substantially constant in cross section along its length, and the forward section of the boom being tapered in cross section along its length. This particular configuration provides a high strength-to-weight ratio and can withstand the high operating temperature encountered during fire fighting operations. A hydraulic utility claw assembly is mounted on the end of the extendable boom for forcibly removing structural components from the offshore platform during a firefighting operation. The utility claw assembly is characterized by a movable jaw which is coupled to a drawbar by a linkage arrangement which provides substantialy constant shearing force throughout the closure range of the movable jaw.