Abstract: An insulating insert is positioned around a field joint of a pipeline to insulate the field joint. The insert comprises a longitudinal series of annular or part-annular filler segments of insulating material, curved about a longitudinal axis, that are each joined to one or more adjacent segments of the series by at least one link. The links may be webs, rods or articulated links. The links are flexible relative to the segments to facilitate bending of the insert along its length by enabling relative angular displacement between adjacent segments of the series.

Abstract: A system for coating a field joint of a pipeline places at least one body having a thermoplastics material around the field joint. The body is heated in a mould cavity around the field joint to effect thermal expansion of the thermoplastics material. Thermal expansion of the body in the mould cavity is constrained to apply elevated pressure between the body and pipe sections joined at the field joint. The elevated pressure improves bonding and fusing between the body, which forms a field joint coating, and the parent coatings and the exposed pipe sections of the pipe joints. The body need not be fully molten, which reduces the mould residence time including in-mould heating and cooling phases.

Abstract: A method protects a field joint of a pipeline, where chamfered edges of thermally-insulating parent coatings on conjoined pipe lengths are in mutual opposition about a longitudinally-extending gap. The method includes manufacturing an hourglass-shaped inner layer around the pipe lengths, which layer may be moulded. The inner layer extends longitudinally along the gap between the chamfered edges and at least partially overlies the chamfered edges. A thermally-insulating solid insert is assembled from two or more parts to lie in the gap surrounding the inner layer, and pressure is applied radially inwardly from the insert to the inner layer. An outer layer of molten material is manufactured around the insert to form a watertight barrier and to form one or more melted interfaces with the inner layer. Corresponding field joint arrangements are also disclosed.

Abstract: An insulating insert is positioned around a field joint of a pipeline to insulate the field joint. The insert comprises a longitudinal series of annular or part-annular filler segments of insulating material, curved about a longitudinal axis, that are each joined to one or more adjacent segments of the series by at least one link. The links may be webs, rods or articulated links. The links are flexible relative to the segments to facilitate bending of the insert along its length by enabling relative angular displacement between adjacent segments of the series.

Abstract: A method of protecting a layered coating on a length of pipe for subsea use includes applying an edge finisher to the coating to encase an edge of the coating by fusing the edge finisher with the coating or by moulding the edge finisher at an edge of the coating. Where the coating and the edge finisher are of thermoplastics such as PP, fusing can be achieved by injection moulding the edge finisher or by welding a discrete edge finisher component to the edge of the coating. Mirror welding may be employed for this purpose, with a hot plate being interposed between the edge of the coating and the edge finisher.

Abstract: An injection molding apparatus has a mold tool that is positioned around a field joint of a pipeline to define a mold cavity. Two or more pumping chambers communicate with the mold tool. Each chamber is expansible to draw in molten polymer and contractible to drive the polymer into the mold cavity. Expansion of one chamber is synchronized with contraction of another chamber. The operation of supply and injection valves associated with the chambers is also synchronized, both with each other and with expansion and contraction of the chambers. In the embodiment described, two pumping chambers are defined within a common pressurizing cylinder, in which the chambers are separated by a piston. The piston is movable within the cylinder to determine and to synchronize expansion and contraction of the chambers.

Abstract: A method of protecting a layered coating on a length of pipe for subsea use includes applying an edge finisher to the coating to encase an edge of the coating by fusing the edge finisher with the coating or by moulding the edge finisher at an edge of the coating. Where the coating and the edge finisher are of thermoplastics such as PP, fusing can be achieved by injection moulding the edge finisher or by welding a discrete edge finisher component to the edge of the coating. Mirror welding may be employed for this purpose, with a hot plate being interposed between the edge of the coating and the edge finisher.

Abstract: A method protects a field joint of a pipeline, where chamfered edges of thermally-insulating parent coatings on conjoined pipe lengths are in mutual opposition about a longitudinally-extending gap. The method includes manufacturing an hourglass-shaped inner layer around the pipe lengths, which layer may be moulded. The inner layer extends longitudinally along the gap between the chamfered edges and at least partially overlies the chamfered edges. A thermally-insulating solid insert is assembled from two or more parts to lie in the gap surrounding the inner layer, and pressure is applied radially inwardly from the insert to the inner layer. An outer layer of molten material is manufactured around the insert to form a watertight barrier and to form one or more melted interfaces with the inner layer. Corresponding field joint arrangements are also disclosed.

Abstract: A thermoplastics injection molding process coats a field joint of a pipeline by positioning a mold tool around the field joint to define a mold cavity. Thermoplastics material injected into the mold cavity forms a field joint coating that will set in the mold cavity. As the thermoplastics material shrinks in the mold cavity while the field joint coating sets, compacting pressure is applied radially inwardly within the mold cavity against a radially outer side of the field joint coating. A compacting fluid introduced into the mold cavity between the mold tool and the field joint coating may be used to apply pressure against the field joint coating. This accelerates and controls cooling of the field joint coating while maximizing quality.

Abstract: A system for coating a field joint of a pipeline places at least one body having a thermoplastics material around the field joint. The body is heated in a mould cavity around the field joint to effect thermal expansion of the thermoplastics material. Thermal expansion of the body in the mould cavity is constrained to apply elevated pressure between the body and pipe sections joined at the field joint. The elevated pressure improves bonding and fusing between the body, which forms a field joint coating, and the parent coatings and the exposed pipe sections of the pipe joints. The body need not be fully molten, which reduces the mould residence time including in-mould heating and cooling phases.

Abstract: A method protects a field joint of a pipeline, where chamfered edges of thermally-insulating parent coatings on conjoined pipe lengths are in mutual opposition about a longitudinally-extending gap. The method includes manufacturing an hourglass-shaped inner layer around the pipe lengths, which layer may be moulded. The inner layer extends longitudinally along the gap between the chamfered edges and at least partially overlies the chamfered edges. A thermally-insulating solid insert is assembled from two or more parts to lie in the gap surrounding the inner layer, and pressure is applied radially inwardly from the insert to the inner layer. An outer layer of molten material is manufactured around the insert to form a watertight barrier and to form one or more melted interfaces with the inner layer. Corresponding field joint arrangements are also disclosed.

Abstract: A rigid pipe-in-pipe structure for subsea transportation of fluids includes inner and outer pipes defining a thermally-isolating annulus between them. Thermal insulation material is disposed in the annulus. The outer pipe is of metal, preferably carbon steel. The inner pipe is a polymeric composite structure of bonded layers including a first, radially outer tubular polymeric electrically insulating layer, which can be of pure polymer, surrounding a second, composite layer including carbon fibers, preferably continuous fibers, embedded in a polymer matrix. Conveniently the second layer is a heating layer in which the carbon fibers conduct electricity to heat the inner pipe. The inner pipe can also comprise a radially inner tubular polymer layer within the second composite layer.

Abstract: A method of coating a field joint of a pipeline places at least one body having a thermoplastics material around the field joint. The body is heated in a mold cavity around the field joint to effect thermal expansion of the thermoplastics material. Thermal expansion of the body in the mold cavity is constrained to apply elevated pressure between the body and pipe sections joined at the field joint. The elevated pressure improves bonding and fusing between the body, which forms a field joint coating, and the parent coatings and the exposed pipe sections of the pipe joints. The body need not be fully molten, which reduces the mold residence time including in-mold heating and cooling phases.

Abstract: An insulating insert is positioned around a field joint of a pipeline to insulate the field joint. The insert includes a longitudinal series of annular or part-annular filler segments of insulating material, curved about a longitudinal axis, that are each joined to one or more adjacent segments of the series by at least one link. The links may be webs, rods or articulated links. The links are flexible relative to the segments to facilitate bending of the insert along its length by enabling relative angular displacement between adjacent segments of the series.

Abstract: A rigid pipe-in-pipe structure for subsea transportation of fluids includes inner and outer pipes defining a thermally-isolating annulus between them. Thermal insulation material is disposed in the annulus. The outer pipe is of metal, preferably carbon steel. The inner pipe is a polymeric composite structure of bonded layers including a first, radially outer tubular polymeric electrically insulating layer, which can be of p polymer, surrounding a second, composite layer including carbon fibres, preferably continuous fibres, embedded in a polymer matrix. Conveniently the second layer is a heating layer in which the carbon fibres conduct electricity to heat the inner pipe. The inner pipe can also comprise a radially inner tubular polymer layer within the second composite layer.

Abstract: A method of protecting a layered coating on a length of pipe for subsea use includes applying an edge finisher to the coating to encase an edge of the coating by fusing the edge finisher with the coating or by molding the edge finisher at an edge of the coating. Where the coating and the edge finisher are of thermoplastics such as PP, fusing can be achieved by injection molding the edge finisher or by welding a discrete edge finisher component to the edge of the coating. Mirror welding may be employed for this purpose, with a hot plate being interposed between the edge of the coating and the edge finisher.

Abstract: A method protects a field joint of a pipeline, where chamfered edges of thermally-insulating parent coatings on conjoined pipe lengths are in mutual opposition about a longitudinally-extending gap. The method includes manufacturing an hourglass-shaped inner layer around the pipe lengths, which layer may be moulded. The inner layer extends longitudinally along the gap between the chamfered edges and at least partially overlies the chamfered edges. A thermally-insulating solid insert is assembled from two or more parts to lie in the gap surrounding the inner layer, and pressure is applied radially inwardly from the insert to the inner layer. An outer layer of molten material is manufactured around the insert to form a watertight barrier and to form one or more melted interfaces with the inner layer. Corresponding field joint arrangements are also disclosed.

Abstract: A method of coating a field joint of a pipeline places at least one body having a thermoplastics material around the field joint. The body is heated in a mould cavity around the field joint to effect thermal expansion of the thermoplastics material. Thermal expansion of the body in the mould cavity is constrained to apply elevated pressure between the body and pipe sections joined at the field joint. The elevated pressure improves bonding and fusing between the body, which forms a field joint coating, and the parent coatings and the exposed pipe sections of the pipe joints. The body need not be fully molten, which reduces the mould residence time including in-mould heating and cooling phases.

Abstract: An injection moulding apparatus has a mould tool that is positioned around a field joint of a pipeline to define a mould cavity. Two or more pumping chambers communicate with the mould tool. Each chamber is expansible to draw in molten polymer and contractible to drive the polymer into the mould cavity. Expansion of one chamber is synchronised with contraction of another chamber. The operation of supply and injection valves associated with the chambers is also synchronised, both with each other and with expansion and contraction of the chambers. In the embodiment described, two pumping chambers are defined within a common pressurising cylinder, in which the chambers are separated by a piston. The piston is movable within the cylinder to determine and to synchronise expansion and contraction of the chambers.

Abstract: A thermoplastics injection moulding process coats a field joint of a pipeline by positioning a mould tool around the field joint to define a mould cavity. Thermoplastics material injected into the mould cavity forms a field joint coating that will set in the mould cavity. As the thermoplastics material shrinks in the mould cavity while the field joint coating sets, compacting pressure is applied radially inwardly within the mould cavity against a radially outer side of the field joint coating. A compacting fluid introduced into the mould cavity between the mould tool and the field joint coating may be used to apply pressure against the field joint coating. This accelerates and controls cooling of the field joint coating while maximising quality.