Abstract: An end fitting for a subsea riser comprises an engagement head to be engaged with a subsea foundation in a vertically downward longitudinal direction. A structure of the end fitting surrounds a longitudinally extending flow axis and is arranged to bear a tensile load on a load path extending longitudinally from the engagement head parallel to the flow axis. The structure includes a pivot joint assembly having a first part attached to or integral with the engagement head and a second part pivotable relative to the first part about a centre of rotation substantially aligned with the flow axis. The structure can be fixed to the engagement head or removably attached to the engagement head. The engagement head supports an upwardly facing connector hub that is offset laterally from the flow axis. A connector pipe in fluid communication with the connector hub extends from the flow axis to the connector hub. A counterweight is opposed to the connector hub and the connector pipe about the flow axis.

Abstract: A pliant link to mitigate fatigue-inducing motion of a subsea catenary riser has an articulated spine having a longitudinal series of interconnected rigid segments. The spine can be coupled to upper and lower sections of the riser to transmit loads along the riser through the link on a load path that extends through the segments. The link also has a pliant pipe terminating in end fittings that can be joined, respectively, to the upper and lower sections of the riser for fluid communication along the riser through the link.

Abstract: An in-line accessory structure for a subsea pipeline has an elongate pipe section arranged to be integrated into the pipeline, hence defining a flow axis through the structure. A branch has a lower end in fluid communication with the pipe section and an upper end in fluid communication with a connector hub. The structure further has a subsea foundation such as a mudmat, arranged to support the structure installed orientation. When the structure is in that orientation, the branch inclines inwardly from its lower end toward its upper end in a transverse direction, toward an upright longitudinal plane containing the flow axis.

Abstract: An end fitting for a subsea riser comprises an engagement head to be engaged with a subsea foundation in a vertically downward longitudinal direction. A structure of the end fitting surrounds a longitudinally extending flow axis and is arranged to bear a tensile load on a load path extending longitudinally from the engagement head parallel to the flow axis. The structure includes a pivot joint assembly having a first part attached to or integral with the engagement head and a second part pivotable relative to the first part about a centre of rotation substantially aligned with the flow axis. The structure can be fixed to the engagement head or removably attached to the engagement head. The engagement head supports an upwardly facing connector hub that is offset laterally from the flow axis. A connector pipe in fluid communication with the connector hub extends from the flow axis to the connector hub. A counterweight is opposed to the connector hub and the connector pipe about the flow axis.

Abstract: A pliant link to mitigate fatigue-inducing motion of a subsea catenary riser has an articulated spine having a longitudinal series of interconnected rigid segments. The spine can be coupled to upper and lower sections of the riser to transmit loads along the riser through the link on a load path that extends through the segments. The link also has a pliant pipe terminating in end fittings that can be joined, respectively, to the upper and lower sections of the riser for fluid communication along the riser through the link.

Abstract: An in-line accessory structure for a subsea pipeline comprises an elongate pipe section arranged to be integrated into the pipeline, hence defining a flow axis through the structure. A branch has a lower end in fluid communication with the pipe section and an upper end in fluid communication with a connector hub. The structure further comprises a subsea foundation such as a mudmat, arranged to support the structure in an installed orientation. When the structure is in that orientation, the branch inclines inwardly from its lower end toward its upper end in a transverse direction, toward an upright longitudinal plane containing the flow axis.

Abstract: A subsea riser support buoy is disclosed having a riser support member and a jumper support member that extend generally parallel to each other and that define a lengthwise direction extending between them across the buoy. Pontoons extend lengthwise beyond the riser support member and the jumper support member to provide attachment points for connecting tethers to the buoy. In this way, the attachment points are spaced more widely than lengthwise extremities of the riser support member and the jumper support member, beneficially altering the dynamic behavior of the buoy and especially its pitch characteristics.

Abstract: A subsea riser support buoy is disclosed having a riser support member and a jumper support member that extend generally parallel to each other and that define a lengthwise direction extending between them across the buoy. Pontoons extend lengthwise beyond the riser support member and the jumper support member to provide attachment points for connecting tethers to the buoy. In this way, the attachment points are spaced more widely than lengthwise extremities of the riser support member and the jumper support member, beneficially altering the dynamic behaviour of the buoy and especially its pitch characteristics.

Abstract: A rigid-to-flexible connector (RFC) is provided on the rigid pipe section instead of a pipeline end termination (PLET), and the pipe end having the RFC is raised to the surface of the sea, while leaving a portion of the rigid pipe section on the seabed. The RFC is then connected to one end of the flexible pipe section, and the latter lowered to the seabed, with the raised, end of the rigid pipe section attached, to return the rigid pipe section to the seabed. Since the RFC on the rigid pipe section is connected to the flexible pipe section at the surface of the sea, the RFC can have a simpler, lighter, technical design, resulting in significant cost, manufacturing time and quality control time savings.

Abstract: A rigid-to-flexible connector (RFC) is provided on the rigid pipe section instead of a pipeline end termination (PLET), and the pipe end having the RFC is raised to the surface of the sea, while leaving a portion of the rigid pipe section on the seabed. The RFC is then connected to one end of the flexible pipe section, and the latter lowered to the seabed, with the raised, end of the rigid pipe section attached, to return the rigid pipe section to the seabed. Since the RFC on the rigid pipe section is connected to the flexible pipe section at the surface of the sea, the RFC can have a simpler, lighter, technical design, resulting in significant cost, manufacturing time and quality control time savings.