Abstract: A seal assembly for sealing an annular space between an inner and an outer pipe in a double-walled subsea pipeline which seal assembly comprises an annular member (1) and moveable blocking means (2, 3) and: (a) under normal operating conditions is in a non-sealing position which allows the passage of a gas through said seal assembly; and (b) is actuatable from a non-sealing position to a sealing position in response to the entry of liquid into said annular space.

Abstract: A seal assembly for dividing an annular space defined between an inner and an outer pipe in a double-walled pipeline. The seal assembly comprises an annular member fitted within the annular space and at least one longitudinal conveyor passing through the annular member, wherein the longitudinal conveyor communicates with the annular space on either side of the seal assembly. The longitudinal conveyor may comprise for example an electrical conductor or an optical fiber.

Abstract: An insert for use in connecting two lengths of pipe, each having a plastic liner. The insert consists of an inner tubular member of plastics material for connection at either end to the plastic liners of two pipe lengths, an insulating sleeve surrounding a central portion of the inner tubular member and a ring of heat-resistant material overlying a part of the insulating sleeve to be positioned, when in use, beneath a location at which the pipe length is butt welded, wherein the insulating sleeve includes an insulating material which is at least partially enclosed with a sheath, such that the sheath can be mechanically connected to the interior of one pipe length.

Abstract: An apparatus for substantially horizontal connection of a conduit to a subsea structure: A frame connectable to and supportable by the subsea structure, the frame has a docking device operable to allow a horizontal connection device, including one of a remotely operated vehicle and a toolskid, to dock with the frame such that the frame is capable of bearing at least part of an operational load associated with the horizontal connection of the conduit to the subsea structure.

Abstract: Apparatus for connecting a conduit to a subsea structure includes a frame connectable to the subsea structure by a docking mechanism, a conduit handling mechanism on the frame to facilitate positioning of the conduit for attachment to the subsea structure and a second docking mechanism for attaching a mobile manipulating device to the frame. In use, the mobile manipulating device connects to the conduit by means of a pull-in rope on a winch, and travels under its own power to the subsea structure while paying out the pull-in rope. There, it docks with the frame and the pull-in rope is reeled in by the winch on the mobile manipulating device. The conduit is then connected to the subsea structure by the conduit handling mechanism on the frame. The invention also includes the method of attaching a conduit to a subsea structure using the described apparatus.