A hang-off insert for hanging-off a flexible elongate subsea element from a surface vessel has a circular loop that includes circumferentially-spaced support segments. Collectively, the segments define a substantially planar support face of the insert and have respective radially inner faces that define an inner radius of the loop. The radially inner faces of the support segments can be positioned at various radial positions to determine the inner radius of the loop and hence to adapt the circumference of the loop to suit different diameters of elongate subsea elements. With the hang-off insert supported by a hang-off structure of the vessel, a laterally-protruding hang-off feature of the elongate subsea element extending through the loop may be rested on the support face to transfer suspended weight loads to the hang-off structure.

A deepwater hoisting system includes a synthetic fibre rope winch assembly including a motor driven first winch and a length of synthetic fibre rope driven by said first winch. The synthetic fibre rope has an end remote from the first winch. The system further includes a steel wire winch assembly including a motor driven second winch and a length of steel wire driven by said second winch. The steel wire has an end remote from the second winch. At least the second winch is an active heave compensation motor driven winch. The system further includes a lifting block having a lifting block sheave, through which the synthetic fibre rope is run. The end of the synthetic fibre rope is connected to the end of the steel wire, so that the lifting block is suspended in a double-fall arrangement.

A pipeline bundle for a riser tower or tie-back is manufactured offshore by suspending the bundle from an installation vessel, adding structural core sections successively to an upper end of the suspended bundle, lowering the bundle after adding each successive core section, and feeding one or more lengths of flowline pipe beside the core sections for incorporation into the bundle. The flowline pipe is coiled on a reel or carousel as a full-length piece before being uncoiled progressively as core sections are added to the lengthening bundle. The flowline pipe is then engaged with guide frames and/or buoyancy blocks supported by the core sections, by movement in a radially-inward direction through a radially-outer opening in a retainer formation. The opening is then closed to hold the flowline pipe in the retainer formation.

A pipeline bundle for a riser tower or tie-back is manufactured offshore by suspending the bundle from an installation vessel, adding structural core sections successively to an upper end of the suspended bundle, lowering the bundle after adding each successive core section, and feeding one or more lengths of flowline pipe beside the core sections for incorporation into the bundle. The flowline pipe is coiled on a reel or carousel as a full-length piece before being uncoiled progressively as core sections are added to the lengthening bundle. The flowline pipe is then engaged with guide frames and/or buoyancy blocks supported by the core sections, by movement in a radially-inward direction through a radially-outer opening in a retainer formation. The opening is then closed to hold the flowline pipe in the retainer formation.

A self-propelled integrated ship for transporting and installing immersed tubes of an underwater tunnel comprises a first ship body and a second ship body which are parallel with each other, a connection structure is arranged between the first ship body and the second ship body; the first ship body, the second ship body and the connection structure are provided with hauling and hoisting devices, a loading space is formed between the first ship body and the second ship body and below the connection structure; a to-be-installed member is arranged in the loading space and is connected with the ship; and the first ship body and the second ship body are provided with propelling power devices and positioning devices. The loading space is provided in a lower part of the integrated ship, and a member to be transported is placed in the loading space and floated in the water, so that most of the weight of the member is shared by buoyancy. The member is transported to a designated site and installed precisely. Thus, the independent transportation and installation of immersed tubes of the underwater tunnel or similar large members with various sizes can be successfully realized by one self-propelled ship without assistance of other additional ships. Moreover, there is no need to close navigation lanes to other ships, thus not affecting the navigations of the other ships.

A self-propelled integrated ship for transporting and installing immersed tubes of an underwater tunnel comprises a first ship body and a second ship body which are parallel with each other, a connection structure is arranged between the first ship body and the second ship body; the first ship body, the second ship body and the connection structure are provided with hauling and hoisting devices, a loading space is formed between the first ship body and the second ship body and below the connection structure; a to-be-installed member is arranged in the loading space and is connected with the ship; and the first ship body and the second ship body are provided with propelling power devices and positioning devices. The loading space is provided in a lower part of the integrated ship, and a member to be transported is placed in the loading space and floated in the water, so that most of the weight of the member is shared by buoyancy. The member is transported to a designated site and installed precisely. Thus, the independent transportation and installation of immersed tubes of the underwater tunnel or similar large members with various sizes can be successfully realized by one self-propelled ship without assistance of other additional ships. Moreover, there is no need to close navigation lanes to other ships, thus not affecting the navigations of the other ships.

Draw tape for cables including an elongated flexible element made of a helical multifilament rope composed of three filaments or strands helically wound about a common longitudinal axis. According to an additional feature, the rope is hammered. Still according to an improvement, the rope is externally covered by a jacket.

A method of joining a first pipe section to a second pipe section includes positioning the two pipe sections in an end-to-end configuration to define therebetween a joint to be welded, measuring the degree of alignment of the pipe sections when they are in the end-to-end configuration in a position ready for welding, ascertaining the relative movement required of the pipe sections in order to improve their alignment, effecting the relative movement so ascertained, and welding together the two pipe sections. The method may include the use of geometric data of the end of the pipes in order to ascertain the relative movement required of the pipe sections. A control unit may be used to calculate, using such data, a target orientation that lines up the pipe sections. The measuring step may be performed using, for example, a laser or a camera and backlight.

A method of joining a first pipe section to a second pipe section includes positioning the two pipe sections in an end-to-end configuration to define therebetween a joint to be welded, measuring the degree of alignment of the pipe sections when they are in the end-to-end configuration in a position ready for welding, ascertaining the relative movement required of the pipe sections in order to improve their alignment, effecting the relative movement so ascertained, and welding together the two pipe sections. The method may include the use of geometric data of the end of the pipes in order to ascertain the relative movement required of the pipe sections. A control unit may be used to calculate, using such data, a target orientation that lines up the pipe sections. The measuring step may be performed using, for example, a laser or a camera and backlight.

A method of aligning first and second pipes end-to-end in a position ready for welding. Each pipe has an end bevelled with a shape scanned and stored in memory of a control unit. At least one of the pipes has machine readable codes distributed around their circumference of the pipe. The method includes effecting relative movement of the ends of the first and second pipes towards each other, reading at least one of the codes with a reader, and ascertaining the relative movement required to align the pipes in accordance with a target orientation. The relative movement is ascertained with information provided by the read code and the shapes of the bevelled ends stored in the control unit memory. In other aspects, a closed loop control method and machine-learning may be used to align the pipes. A pipe-laying vessel including pipe handling equipment and the control unit is also provided.