A vessel is adapted to perform subsea wellbore related operations including module handling and laying flexible pipeline, e.g. wellbore intervention. The vessel includes a hull with a moonpool and a stationary drilling mast adjacent said moonpool. The front side of the drilling mast is provided with vertical trolley rails along whichduring module handlinga module handling trolley is movable. Further one or more tensioners are provided to engage a flexible pipeline, also being supported by the by the drilling mast. The tensioner frame of a tensioner is mounted pivotably about a vertical pivot axis to the drilling mast, such that the tensioner frame is pivotable between the pipeline laying configuration wherein the lower tensioner is provided in the module handling area and an open configuration wherein a vertical trolley path is unobstructed to allow module handling.

A transfer mechanism (28) for transferring a fitting (46) on a flexible tubular conduit (48) about a guiding means (26) of a pipelay tower (20). The transfer mechanism (28) includes a frame (30) adapted to rotate about said guiding means (26); and a clamping mechanism (34) connected to the frame (30) and adapted to connect and secure the fitting (46) to the transfer mechanism (28). Actuation of the transfer mechanism (28) is configured to rotate the frame (30) about the guiding means (26) and cause at least one part of a fitting (46) connected to the transfer mechanism (28) to move along a path outside a surface of the guiding means (26) from a first position upstream of the guiding means (26) to a second position downstream of the guiding means (26).

A self-propelled vehicle used to lay pipe sections within trenches located on sloped terrain, and a method for using it, including: an undercarriage carrying a vehicle chassis and capable of climbing sloped terrain; a rotating platform which can be maintained level relative to the sloped terrain; and a boom with an angled boom head, capable of using two independent winch cables to lift and position individual pipe sections having differing lengths and diameters. The vehicle may be used to sequentially lift two or more pipe sections, one at a time, and to swing and position the pipe sections in a trench, end-to-end.

A self-propelled vehicle used to lay pipe sections within trenches located on sloped terrain, and a method for using it, including: an undercarriage carrying a vehicle chassis and capable of climbing sloped terrain; a rotating platform which can be maintained level relative to the sloped terrain; and a boom with an angled boom head, capable of using two independent winch cables to lift and position individual pipe sections having differing lengths and diameters. The vehicle may be used to sequentially lift two or more pipe sections, one at a time, and to swing and position the pipe sections in a trench, end-to-end.

A subsea pipeline coated with a thermally insulating coating has a radially outer surface shaped to define external hold-back formations. In a J-lay operation, the weight load of a pipeline catenary is held back using a complementary bushing or clamp of an installation vessel engaged with the hold-back formations. The weight load is transferred from the catenary to the bushing or clamp by shear forces acting through the coating. The coating extends continuously along the pipe and is interposed between the hold-back formations and the underlying pipe. The hold-back formations may be integral with the coating.

A subsea pipeline coated with a thermally insulating coating has a radially outer surface shaped to define external hold-back formations. In a J-lay operation, the weight load of a pipeline catenary is held back using a complementary bushing or clamp of an installation vessel engaged with the hold-back formations. The weight load is transferred from the catenary to the bushing or clamp by shear forces acting through the coating. The coating extends continuously along the pipe and is interposed between the hold-back formations and the underlying pipe. The hold-back formations may be integral with the coating.

A manipulator device to apply modules around a pipeline during assembly has two jaws mobile between an open and a closed position and configured to house the respective portions of the module, and an articulated mechanism having a plurality of degrees of freedom to place the jaws in a loading position and in a position wherein the jaws are aligned with the pipeline during assembly.

A manipulator device to apply modules around a pipeline during assembly has two jaws mobile between an open and a closed position and configured to house the respective portions of the module, and an articulated mechanism having a plurality of degrees of freedom to place the jaws in a loading position and in a position wherein the jaws are aligned with the pipeline during assembly.

A method of launching an elongate subsea structure such as a pipeline bundle unit into water provides buoyant support to the structure by displacing water with a hollow buoyancy unit that applies buoyant upthrust to the structure. By lowering the buoyancy unit in the water to bring a permanently open aperture of the buoyancy unit beneath a surface level of the water, the buoyancy unit is flooded with water through the or each permanently open aperture to reduce the buoyant upthrust applied to the structure. A corresponding elongate subsea structure is also claimed.

A method of launching an elongate subsea structure such as a pipeline bundle unit into water provides buoyant support to the structure by displacing water with a hollow buoyancy unit that applies buoyant upthrust to the structure. By lowering the buoyancy unit in the water to bring a permanently open aperture of the buoyancy unit beneath a surface level of the water, the buoyancy unit is flooded with water through the or each permanently open aperture to reduce the buoyant upthrust applied to the structure. A corresponding elongate subsea structure is also claimed.