The present invention relates to the field of offshore reel lay method pipelaying.

In the field many dedicated pipe lay vessels have been built to perform subsea pipelay operations wherein the pipeline to be laid, either rigid or flexible, is spooled from a storage reel. The storage reel is commonly held and driven by a so-called reel drive system.

Pipelaying projects exist in all sizes and at all sorts of locations. The mentioned dedicated reel lay pipelaying vessels are not always most practical or economically beneficial.

Therefore the need exist for a more versatile system to perform reel lay of pipeline. The present invention provides a system according to claim 1. Herein the system comprises a set of launch tower modules that are interconnectable in series to assemble at least a portion of the launch tower, said set at least comprising:

- a pivot structure module,

- a tensioner module, - a straightener assembly module, wherein each of said pivot structure module, tensioner module, and straightener assembly module has a rigid structural frame of an elongated cuboidal shape with longitudinal main chords that each extend between corners of the structural frame at opposed axial ends thereof and with brace members interconnecting adjacent main chords in faces of said cuboidal shaped structural frame, wherein the system comprises releasable fastener members adapted to rigidly interconnect said pivot structure module, tensioner module, and straightener assembly module in series as part of the launch tower and, when no straightening of pipeline is required, rigidly interconnect the pivot structure module to the tensioner module, wherein - in operation - the firing line extends through said axially interconnected modules, wherein the pivot structure module is provided with a horizontal pivot axis device that is accommodated within the structural frame of the pivot structure module and is adapted to pivotally secure the pivot structure module to the vessel, e.g. to a base member arranged on the vessel, wherein the tensioner module is provided with said tensioner, which tensioner is accommodated within the structural frame of the tensioner module, wherein the straightener assembly module is provided with said pipeline straightener assembly, which pipeline straightener assembly is accommodated within the structural frame of the straightener assembly module, wherein the system further comprises ISO container corner fitting members which are structurally integrated in and/or releasably mountable onto the axial ends of the rigid structural frames of the pivot structure module, tensioner module, and straightener assembly module, and wherein each of said pivot structure module, tensioner module, and straightener assembly module, has a length that is such that said module with said associated ISO container corner fitting members allows for handling of said module as an ISO intermodal freight container, preferably each of said modules having a length that allows for handling of said module as a 20 ft. (6.1 m) ISO intermodal freight container. As is commonly known standard ISO intermodal freight containers are 8 ft. (2.44 m) wide by 8 ft. 6 in (2.59 m) high, and the taller High Cube containers measure 9 feet 6 inches (2.90 m) have also become very common. The common lengths are 20-foot (6.1 m) and 40-foot (12.2 m) long.

The inventive system allows for example to make use of an existing offshore supply vessel as pipelay vessel, as the system can be effectively shipped to the port where the vessel is located and then assembled. The transportation as ISO intermodal freight containers of at least these three modules forming part of the launch tower may involve shipment by lorry, container cargo vessel, and/or by train.

If the pipeline to be laid is a so-called flexible pipeline the straightener assembly module can be dispensed with as no straightening is then required. If rigid pipeline is to be laid, the straightener assembly causes the straightening of the pipeline spooled from the reel.

The rigid structural frames of these three basic modules of the system of claim 1 each have longitudinal main chords that each extend between corners of the structural frame at opposed axial ends thereof and with brace members interconnecting adjacent main chords in faces of said cuboidal shaped structural frame. This allows to compose a sturdy launch tower at relative low weight of each module as the joined structural frames from the basic frame of the tower and as the firing line extends through these joined structural frames, so not along the outside thereof. In embodiments the tensioner module is shorter than 20 ft. (6.1 m) and the system comprises, for intermodal transport of the tensioner module, two ISO container corner fitting members each having four corner fittings, which are releasably mountable onto the axial ends of the rigid structural frame of the tensioner module. In embodiments the pivot structure module is shorter than 20 ft. (6.1 m) and the system comprises, for intermodal transport of the pivot structure module, two ISO container corner fitting members each having four corner fittings, which are releasably mountable onto the axial ends of the rigid structural frame of the pivot structure module.

In embodiments the straightener assembly module is shorter than 20 ft. (6.1 m) and the system comprises, for intermodal transport of the straightener assembly module, two ISO container corner fitting members each having four corner fittings, which are releasably mountable onto the axial ends of the rigid structural frame of the straightener assembly module.

By embodying one or more of the tensioner module, pivot structure module, and straightener assembly module shorter than 20 ft. it is not required to provide the respective module itself with ISO corner fittings, at least not at both axial ends. For example this allows for direct interconnection of the main chord of one of these modules to the aligned main chord of the neighbouring module, so as to obtain optimal load transmission through the interconnected chords. In embodiments the structural frame of the tensioner module is provided at each axial end thereof with protruding lugs each having a pin receiving hole therein, wherein the pivot structure module and the straightener assembly module have, at least at the axial end thereof that is to be secured to the tensioner module, mating protruding lugs each having a pin receiving hole therein, said lugs being arranged in line with the main chords of the structural frames of the modules, wherein the releasable fastener members comprise pins that are insertable through the holes of aligned lugs.

In an embodiment the straightener assembly comprises two axially spaced first and second roller sets of one or more rollers arranged on one side of the firing line, and a third roller set of one or more rollers arranged on the opposite side of the firing line. One or more hydraulic cylinders are provided to engage on one or more of these roller sets, e.g. only on the third roller set with the other sets being held stationary, in order to produce an adjustable straightening of the pipeline. In an embodiment each roller set of the straightener assembly is displaceable between an operative position wherein it can engage on a pipeline to be straightened and a retracted position, further away from the firing line in order to allow for the passage of larger diameter components in the pipeline.

In an embodiment the system further comprises a pipeline guide module, that is adapted to be secured to the straightener module, and when no straightener module is included in the launch tower, to the tensioner module. Therefore it is preferred for the straightener module to have at its end normally facing away from the tensioner module the same configuration of connector members, e.g. protruding lugs, as the tensioner module at the axial end that is to be connected to the straightener module. This allows for the pipeline guide module to be connected as desired to the straightener module, or in absence thereof in the assembled launch tower, to the tensioner module.

In an embodiment the pipeline guide module comprises an arc shaped pipeline guide, preferably a segmented arc shaped pipeline guide comprising multiple guide segments pivotally interconnected to one another. For example the pipeline guide has exactly two guide segments, e.g. each segment being provided with a series of pipeline guide rollers. The segmented design of the arched pipeline guide e.g. allows to keep the pipeline guide fitted at the top end of the launch tower even when the entire tower is brought in a horizontal position. The latter position is e.g. envisaged for initiation of a reel lay process, wherein a new pipeline to be unreeled from a storage reel is pulled by means of a cable into the firing line of the tower. The segmented pipeline guide will then be folded in a sort of flattened configuration as the guide would in normal operative shape collide with the deck of the vessel and so prevent the tower from being brought into a horizontal position.

In an embodiment the pipeline guide module is shorter than 20 ft. (6.1 m), and the system comprises, for intermodal transport of the straightener pipeline guide module, two ISO container corner fitting members each having four corner fittings, which are releasably mountable onto the axial ends of the rigid structural frame of the pipeline guide module. This embodiment is in particular feasible in combination with the segmented design of the pipeline guide as discussed above, e.g. with the segmented pipeline guide having a folded non- operative configuration wherein the guide fits within the contour of a 20 ft. ISO container and a deployed operative configuration. In an embodiment the hang off device is accommodated within the pivot structure module, which allows for the optimal design of the structure that holds the hang off device and the transmission of the loads on said hang off device, when in operation, to the vessel.

Preferably the hang off device comprises a friction clamp having mobile clamp members and associated clamp cylinders that press the clamp members onto the pipeline to be held. Preferably a work platform is included in the pivot structure module so as to allow personnel access to be pipeline above the hang off device, e.g. in the course of severing the pipeline above the hang off clamp, e.g. in the course of an A&R procedure. For example there is a variable inclination work platform and associated inclination actuator, allowing to bring and maintain said work platform in horizontal orientation within the range of inclination of the launch tower.

In embodiments, the pivot structure module comprises also a roller box device and/or an A&R sheave, the former preferably below or downstream of the hang off device and the latter above or upstream of the hang off device. The roller box may serve to guide the pipeline downstream of the tensioner.

In embodiments the system further comprises a stinger module that has a rigid structural frame of an elongated cuboidal shape with longitudinal main chords that each extend between corners of the structural frame at opposed axial ends thereof and with brace members interconnecting adjacent main chords in faces of said cuboidal shaped structural frame, wherein the system comprises releasable fastener members adapted to rigidly interconnect said stinger module to the downstream axial end of the pivot structure module, wherein said stinger module accommodates at least one of a roller box device and a departure sheave.

The stinger module may have the same cross-sectional dimensions as the mentioned three basic modules.

In an embodiment the stinger module accommodates therein a variable inclination work platform and associated inclination actuator, allowing to bring and maintain said work platform in horizontal orientation within the range of inclination of the launch tower, said work platform being located adjacent the firing line allowing for personnel standing on the work platform to access the firing line and the pipeline therein.

For example the personnel standing on a work platform of the tower downstream of the tensioner attaches an umbilical to the pipeline, e.g. the system including a umbilical guide structure that is adapted to be releasably fitted to the outside of one or more of the mentioned three basic modules of the system and adapted to guide an umbilical coming from an umbilical storage reel to the location where personnel attaches the umbilical to the pipeline.

In an embodiment the tensioner is a two track tensioner with two track assemblies, each comprising an endless chain carrying pipeline gripping pads and a chassis with rollers supporting the endless chain, each chassis being mounted to brace members in a corresponding side of the structural frame, and the tensioner having one or more hydraulic squeeze actuators for each chassis to press the gripping pads onto the pipeline, e.g. each chassis being operated by three pairs of hydraulic squeeze actuators arranged in series in axial direction, the actuators of a pair being arranged on opposite sides of the chassis. The two track design allows for accommodation thereof with the contour of the ISO container dimensions.

If desired one can provide a second tensioner module to be connected in series with the first tensioner module in order to increase the capacity of the launch tower in that regard. In an embodiment the system further comprises a base module that is adapted to be placed on deck of a vessel, e.g. on deck of an offshore supply vessel, wherein the base module comprises a horizontal pivot axis device that is adapted to be releasably connected to the horizontal pivot axis device of the pivot structure module. The base module preferably is embodied like a flat rack open topped container with the horizontal pivot axis device at one end thereof, upwardly protruding from the flat bed or platform.

In an embodiment the pivot structure module also comprises a firing line cable sheave, preferably at a location upstream of the hang off device, which firing line cable sheave is mobile, e.g. by a motorized actuator, between a retracted parking position and an operative position wherein a cable passed about the sheave is aligned with the firing line. Herein, as preferred, also the base module comprises a cable sheave, and the system further comprises a winch module comprising a motor driven winch having a drum and a cable spooled thereon, said cable being passable from said winch via said cable sheave of the base module, to the firing line cable sheave. The winch module can also be adapted to have a structural frame corresponding to an ISO freight container. For example the winch module is adapted to be arranged to one side of the base module, with the cable passing in substantial lateral direction to the cable sheave thereon and departing therefrom to the cable sheave in the pivot structure module. Preferably the cable sheave on the base module is mounted pivotally so as to align this sheave with the cable sheave in the pivot axis module for each inclination position of the launch tower, preferably include (when provided for) a fully horizontal position of the launch tower.

In an embodiment 15the firing line cable sheave is embodied so as to pass said cable about this particular sheave in two configurations; the one configuration being an A&R configuration wherein the cable extends from said sheave in the downstream direction along the firing line in order to perform A&R procedures, and the other configuration being an initiation configuration wherein the cable extends from said sheave in the upstream direction along the firing line in order to perform an initiation procedure wherein the cable is connected to the leading end of a pipeline to be pulled from a storage reel into the launch tower to the tensioner.

In embodiments the system further comprises a base module that is adapted to be placed on deck of a vessel, e.g. on deck of an offshore supply vessel, wherein the base module comprises a horizontal pivot axis device that is adapted to be releasably connected to the horizontal pivot axis device of the pivot structure module, and wherein the system comprises an inclination adjuster module that is adapted to be placed on deck of a vessel and to interconnected to the base module, wherein the inclination adjuster module is provided with an inclination adjuster device, e.g. one or more hydraulic cylinders, that is adapted to be connected to the tensioner module in order to adjust the inclination of the launch tower. For example the inclination is adjustable between a fully horizontal position, e.g. in the course of initiation procedure, and an inclination of 60 degrees or even more.

In an embodiment the system comprises a rigid locking device that is adapted to be secured between the pivot axis module and a base module in order to form a rigid connection between them for holding the launch tower in a predetermined inclination.

In an embodiment the system comprises the system further comprises an underbender module, that is adapted to be arranged on deck of a vessel at a location in between the launch tower and the storage reel, said underbender module comprising an arc shaped pipeline guide, preferably a segmented arc shaped pipeline guide comprising multiple guide segments pivotally interconnected to one another, e.g. exactly two guide segments, e.g. each segment being provided with a series of pipeline guide rollers. The underbender module can for example be stationed on deck of the vessel in between the launch tower and a pipeline storage reel, so that pipeline coming from the reel can pass to the underbender and then curve along said underbender upwards to the pipeline guide on the inclined tower. Preferably the underbender module comprises a structural frame that is embodied to mimic an ISO 20 ft. freight container, e.g. with four main chords extending between corners of the structural frame of the module. The module may be provided with ISO corner fittings and/or one or more ISO corner fitting members are mountable to the structural frame. In an embodiment the system further comprises a crane module comprising a platform that is adapted to be placed on deck of a vessel, e.g. adjacent a base module for the launch tower, e.g. adapted to be connected to said base module. The crane module comprises a slewable telescopic boom crane mounted on said platform. As preferred the platform is shorter than 20 ft. (6.1 m), and the system comprises, for intermodal transport of the crane module, two ISO container corner fitting members each having four corner fittings, which are releasably mountable onto the axial ends of the platform of the crane module.

The present invention also relates to a vessel, e.g. an offshore supply vessel, provided with a marine reel lay method pipeline installation system for laying on the seabed a pipeline as described herein.

The present invention also relates to a method for providing a vessel with a marine reel lay method pipeline installation system for laying on the seabed a pipeline as described herein, wherein at least said pivot structure module, a tensioner module, and straightener assembly module, of the system are stored at a remote location, and wherein at least said pivot structure module, a tensioner module, and straightener assembly module are transported to said vessel as an ISO intermodal freight container, preferably each of said modules having a length that allows for handling of said pivot structure module, a tensioner module, and straightener assembly module, as a 20 ft. (6.1 m) ISO intermodal freight container.

The present invention also relates to a method for marine reel lay method installation of a pipeline, wherein use is made of a system as described herein.

The present invention also relates to one or more of the modules as described herein, e.g. the following modules:

- the pivot axis module,

- the tensioner module, - the straightener assembly module,

- the pipeline guide module

- the stinger module,

- the base module,

- the underbender module, and/or - the crane module.

The present invention also relates to a method for initiation of pipelaying of pipeline to be spooled from a pipeline storage reel, wherein a launch tower as described herein is brought into horizontal position and an initiation cable is passed from a firing line sheave downstream of the tensioner along the firing line to the reel and connected to the leading end of the pipeline, e.g. to a connection fitting pre-assembled at said leading end. The pipeline is then pulled by means of said initiation cable into the firing line in the tower as least as far that the tensioner can engage on the pipeline. When a segmented or articulated pipeline guide is present on the launch tower, it may be that the pipeline guide is then in a flattened state to allow for the horizontal orientation of the tower. After pull-in the tower is inclined to the desired angle of inclination and the pipeline guide is brought into its operative configuration with the segments together forming an arched guide for the pipeline.

In the drawings:

Fig. 1 shows an example of a vessel that is to be temporarily equipped with a system according to the invention to perform a reel lay method pipeline installation process, Fig. 2 shows in side view an example of a system according to the invention and a storage reel as placed on deck of the vessel of figure 1 ,

Fig. 3 shows the launch tower of figure 2 at a maximum inclination,

Fig. 4 shows a plan view of the system according to the invention and a storage reel as placed on deck of the vessel of figure 1 , Fig. 5 shows the view on the launch tower and the underbender of figure 2 on a larger scale,

Fig. 6 shows the launch tower of figure 5 in the same side view with many details stripped away to reveal the structural frames of the depicted modules and some components of said modules,

Fig. 7 shows the launch tower of figure 5 in plan view with many details stripped away to reveal the structural frames of the depicted modules and some components of said modules

Fig. 8 shows the same as figure 7 with even more details stripped away and also the pipeline guide removed,

Fig. 9 shows a part of the plan view of figure 4 on a larger scale,

Fig. 10 shows the launch tower of figure 2 in horizontal orientation during initiation of a pipelay procedure,

Fig. 1 1 shows a part of the launch tower of figure 10 including the stinger module, the pivot axis module, and the base module on a larger scale,

Fig. 12 shows a part of the launch tower of figure 10 including the tensioner module and the adjuster module on a larger scale, Fig. 13 shows a part of the launch tower of figure 10 including the straightener assembly module on a larger scale,

Fig. 14 shows a part of the launch tower of figure 10 including the pipeline guide on a larger scale, Fig. 15 shows a part of the inclined launch tower of figure 3 including the stinger module, the pivot axis module, and the base module on a larger scale,

Fig. 16 shows a part of the inclined launch tower of figure 3 including the pivot axis module, and the base module on a larger scale,

Fig. 17 shows a part of the inclined launch tower of figure 3 including the tensioner module and the adjuster cylinders on a larger scale,

Fig. 18 shows a part of the inclined launch tower of figure 3 including the straightener assembly module and the pipeline guide, as well as the umbilical guide, on a larger scale,

Figs. 19a-d illustrate the pivot axis module of the launch tower of figure 2,

Figs. 20a-c illustrate the tensioner module of the launch tower of figure 2, Figs. 21a-f illustrate the straightener assembly module of the launch tower of figure 2,

Figs. 22a-c illustrate the pipeline guide module of the launch tower of figure 2,

Figs. 23a-e illustrate the stinger module of the launch tower of figure 2,

Figs. 24a-c illustrate the underbender module of the system of figure 2,

Fig. 25 illustrates the handling of the stinger module by means of the crane of the system of figure 2, as well as part of the base module,

Fig. 26 shows the base module and pivot axis module of the launch tower of figure 2 in horizontal orientation,

Fig. 27 shows the base module and pivot axis module of the launch tower of figure 2 in horizontal orientation during initiation procedure, Fig. 28 shows the base module, stinger module, and pivot axis module of the launch tower of figure 2 in horizontal orientation during operation,

Fig. 29 shows the base module and pivot axis module of the launch tower of figure 2 in inclined orientation during A&R, Fig. 30 shows the base module and pivot axis module of the launch tower of figure 2 in inclined orientation during initiation,

Fig. 31 shows the base module, stinger module, and pivot axis module of the launch tower of figure 2 in inclined orientation during pipelay operation, Figs. 32a, b illustrate the crane module of the system of figure 2.

Figure 1 depicts a monohull offshore supply vessel 1 of the type that supplies goods to offshore platforms and/or handles anchors, with a bow having a superstructure 2 with control bridge and crew accommodations and a large flush deck 4 leading to the stern 5 of the hull 6.

This type of vessel is very common and they can be found all over the world. Normally these vessels are not provided with any pipelay equipment. The inventive system is envisaged to allow the transformation, primarily of temporary nature, of a vessel like the one depicted here into a reel lay method pipelay vessel. In particular the invention envisages a system that can be easily transported all over the world so that if a vessel is to be used for this pipelaying the system can be transported to the port where the vessel is and then the system can be assembled for use onboard the vessel. Once the job is completed the vessel can sail to port and the system disassembled, and then easily transported to another port for use aboard another vessel.

The figure 2 shows a schematically a pipeline storage reel 10 with side flanges and a hub on which a length of pipeline 11 to be laid is stored, e.g. flexible or rigid pipeline. In the depicted example the pipeline is rigid and requires straightening. For example the reel 10 may hold several hundreds of tonnes of pipeline, e.g. having flanges with a diameter of 1 1. 4 meters.

The pipeline reel 10 here is held by a reel drive system 15 that, as preferred, can also form part of the transportable system in order to be transported along with the other modules and components of the system. As known in the art the reel drive system 15 may include two towers 16, each having a hub drive with motors 17 to impart torque to the reel 10 as the hub drive connects to the respective end of the hub of the reel. The towers may each include a lifting mechanism to lift the reel 10 from a cradle on which the reel rest during transit. The towers may also be arranged on rail with skid system allowing to move the reel in the direction towards or away from the launch tower and/or in a direction of the axis of the reel. The latter may e.g. be done for the purpose of connecting and disconnecting the hub drive 17 from the respective end of the hub of the reel, as known in the art.

Reference numeral 18 denotes a hydraulic power unit providing power to operate the reel drive system 15. The system comprises a variable inclination launch tower 20 that is to be mounted on the deck 4 of the vessel 1.

The launch tower is adapted to launch the pipeline 11 in a firing line 21 through the structural frame of the launch tower 20 as will be explained in more detail below. The launch tower 20 is pivotable relative to the vessel about an essentially horizontal tower pivot axis 22 to adjust the inclination of the tower 20, here - as preferred - at least into a fully horizontal position and an inclined position of at least 60 degrees. Possibly the tower may be tilted to vertical position.

The system comprises a set of launch tower modules that are interconnectable in series to assemble at least a portion of the structural frame of the launch tower. This set here includes

- a pivot structure module 100,

- a tensioner module 200,

- a straightener assembly module 300.

The tower is pivotally secured to a base module 50 placed on the deck 4. Onto the top end of the launch tower a pipeline guide 410 of module 400 is fitted,

Onto the lower or downstream end of the launch tower the stinger module 500 is fitted.

Between the reel drive system 15 with reel 10 on the one hand and the tower 20 on the other, an underbender module 600 is placed on deck 4 of the vessel.

The system further comprises a crane module 700, a winch module 800 for A&R and initiation procedures, as well as an umbilical reel 900 and umbilical guide 910 fitted on the tower 20.

The figure 4 also shows stacks of mattress elements 40 that can be handled by the crane of module 700 and overboarded, e.g. to the placed on top of the pipeline 1 1 that has been laid on the seabed by means of the depicted system. The figure 4 also shown an anchor 45 that can be handled by the crane of module 700, e.g. an anchor that is used in the first stages of pipelaying. An anchor cable winch 46 can be provided to lower and lift the anchor cable.

As can be derived from e.g. figures 6, 7, and 8 each of the pivot structure module 100, tensioner module 200, and straightener assembly module 300 has a rigid structural frame of an elongated cuboidal shape with longitudinal main chords MC that each extend between corners of the structural frame at opposed axial ends thereof and with brace members BM. interconnecting adjacent main chords MC in faces of said cuboidal shaped structural frame.

The pivot structure module is shorter than 20 ft. (6.1 m) and the system comprises, for intermodal transport of the pivot structure module 100, two ISO container corner fitting members 105, 106 (see fig. 19) each having four ISO corner fittings, which are releasably mountable onto the axial ends of the rigid structural frame of the pivot structure module 100.

As depicted the structural frame of the module 100 is provided at the upper axial end thereof, in line with each of the axial ends of the main chords MC so at these very corners of the frame, with sets of one or more axially protruding lugs 102, each having a pin receiving hole therein. Here lower axial end has sets 201 of protruding lugs adapted to mate adjoining stinger module frame.

As can be seen the fitting members 105, 106 are provided with mating lugs so that these members can be fitted to the frame of module 100 for intermodal transportation thereof by means of non-depicted pins that are inserted through the aligned holes of mated lugs.

The tensioner module 200 is shorter than 20 ft. (6.1 m) and the system comprises, for intermodal transport of the tensioner module 200, two ISO container corner fitting members 205, 206 (see fig 20) each having four corner fittings, which are releasably mountable onto the axial ends of the rigid structural frame of the tensioner module. As depicted the structural frame of the tensioner module 200 is provided at each axial end thereof, in line with each of the axial ends of the main chords MC so at the very corners of the frame, with sets of one or more axially protruding lugs 201 , 202, each having a pin receiving hole therein. Here lower axial end has sets 201 of two protruding lugs and upper axial end has sets 202 of one lug. As can be seen the fitting members 205, 206 are provided with mating lugs so that these members can be fitted to the frame for intermodal transportation thereof by means of non- depicted pins that are inserted through the aligned holes of mated lugs.

The straightener assembly module is shorter than 20 ft. (6.1 m) and the system comprises, for intermodal transport of the straightener assembly module 300, two ISO container corner fitting members 305, 306, each having four corner fittings, which are releasably mountable onto the axial ends of the rigid structural frame of the straightener assembly module. As depicted the structural frame of the module 300 is provided at each axial end thereof, in line with each of the axial ends of the main chords MC so at the very corners of the frame, with sets of one or more axially protruding lugs 301 , 302, each having a pin receiving hole therein. Here lower axial end has sets 301 of two protruding lugs and upper axial end has sets 302 of one lug.

As can be seen the fitting members 305, 306 are provided with mating lugs so that these members can be fitted to the frame for intermodal transportation thereof by means of non- depicted pins that are inserted through the aligned holes of mated lugs.

In all the frame of pivot structure module 100 and of the straightener assembly module 300 have, at least at the axial end thereof that is to be secured to the tensioner module 200, mating protruding lugs each having a pin receiving hole therein, said lugs being arranged in line with the main chords MC of the structural frames of the modules, wherein the releasable fastener members comprise pins that are insertable through the holes of aligned lugs.

These pins then form releasable fastener members adapted to rigidly interconnect the pivot structure module 100, tensioner module 200, and straightener assembly module 300 in series as part of the launch tower 20 and, when no straightening of pipeline is required, rigidly interconnect the pivot structure module 100 to the tensioner module 200, wherein - in operation - the firing line 21 extends through said axially interconnected modules.

The pivot structure module 100 is provided with a horizontal pivot axis device 1 10 that is accommodated within the structural frame of the pivot structure module and is adapted to pivotally secure the pivot structure module to the vessel, e.g. to a base member 50 arranged on the vessel 1.

The tensioner module 200 is provided with a 2 track tensioner 210, which tensioner is accommodated within the structural frame of the tensioner module. The straightener assembly module 300 is provided with said pipeline straightener assembly 310, which pipeline straightener assembly is accommodated within the structural frame of the straightener assembly module.

As will now be clear each of said pivot structure module 100, tensioner module 200, and straightener assembly module 300, has a length that is such that said module with said associated ISO container corner fitting members allows for handling of said module as an ISO intermodal freight container. Here, as preferred, each of said modules has a length that allows for handling of said module as a 20 ft. (6.1 m) ISO intermodal freight container. As is commonly known standard ISO intermodal freight containers are 8-ft. (2.44 m) wide by 8 ft. 6 in (2.59 m) high, and the taller High Cube containers measure 9 feet 6 inches (2.90 m) have also become very common. The common lengths are 20-foot (6.1 m) and 40-foot (12.2 m) long. As depicted the system includes a pipeline guide 410 which is supported at an elevated position by the launch tower 20, which pipeline guide is adapted to guide the pipeline 1 1 from a storage reel 10 over the pipeline guide into the firing line.

The pipeline straightener assembly 310 serves it known purpose of straightening a rigid pipeline entering the firing line from the pipeline guide 410. In an embodiment the

straightener assembly 310 comprises two axially spaced first and second roller sets 31 1 ,

312, of one or more rollers arranged on one side of the firing line, and a third roller set 313 of one or more rollers arranged on the opposite side of the firing line. One or more hydraulic cylinders 314 are provided to engage on one or more of these roller sets, e.g. only on the third roller set 313 with the other sets being held stationary, in order to produce an adjustable straightening of the pipeline. In the depicted embodiment each roller set of the straightener assembly is displaceable between an operative position wherein it can engage on a pipeline to be straightened and a retracted position, further away from the firing line in order to allow for the passage of larger diameter components in the pipeline. The latter is depicted in figures 21e, f. The figures 21c, d show the straightener operating on the smallest diameter pipeline (fig. 21 c) and the largest diameter pipeline (fig. 21d).

The tensioner 210 has multiple tracks, here two 211 , 212, adapted to engage the pipeline 11 and to support at least part of the weight of the launched pipeline in the firing line. Therefore the tensioner is a two track tensioner with two track assemblies, each comprising an endless chain carrying pipeline gripping pads and a chassis with rollers supporting the endless chain, each chassis being mounted to brace members in a corresponding side of the structural frame. The tensioner has one or more hydraulic squeeze actuators for each chassis to press the gripping pads onto the pipeline, here each chassis being operated by three pairs of hydraulic squeeze actuators arranged in series in axial direction, the actuators of a pair being arranged on opposite sides of the chassis. The two track design allows for accommodation thereof with the contour of the ISO container dimensions.

The module 100 includes a hang off device 120, e.g. including a friction clamp, adapted to clamp and support the weight of the launched pipeline 1 1 in the firing line. In the depicted example the module 100 also includes a roller box 130 downstream of the hang off device 120. Figure 19c depicts above one another a cross section of the module 100 with the roller box 130 set to the smallest pipeline diameter (top figure), largest pipeline diameter (central figure), and fully opened to allow for passage of a bulky accessory, e.g. end connector of the pipeline (lower figure). Figure 19d depicts above one another a cross section of the module with the hang off device 120 engaging on the pipeline with two sets of friction members and the device still open (top figure), with the device closed and the other two sets together with the first two clampingly holding the pipeline 1 1 (central figure), and with the hang off device fully opened (lower figure) for the passage of e.g. an end connector of the pipeline 11. The pipeline guide module 400 comprises an arc shaped pipeline guide 410, here a segmented arc shaped pipeline guide comprising multiple guide segments 411 , 412 pivotally interconnected to one another. The pipeline guide has exactly two guide segments, each segment being provided with a series of pipeline guide rollers. The segmented design of the arched pipeline guide e.g. allows to keep the pipeline guide fitted at the top end of the launch tower even when the entire tower is brought in a horizontal position. The latter position is e.g. envisaged for initiation of a reel lay process, wherein a new pipeline to be unreeled from a storage reel is pulled by means of a cable into the firing line of the tower. The segmented pipeline guide will then be folded in a sort of flattened configuration as the guide would in normal operative shape collide with the deck of the vessel and so prevent the tower from being brought into a horizontal position.

In this embodiment the pipeline guide module is shorter than 20 ft. (6.1 m), and the system comprises, for intermodal transport of the straightener pipeline guide module, two ISO container corner fitting members 404, 405 each having four corner fittings, which are releasably mountable onto the axial ends of the rigid structural frame of the pipeline guide module. This embodiment is in particular feasible in combination with the segmented design of the pipeline guide as discussed above, e.g. with the segmented pipeline guide having a folded non-operative configuration wherein the guide fits within the contour of a 20 ft. ISO container and a deployed operative configuration.

The frame of the pipeline guide module has mating lug sets 407 at the axial end that is adapted to be secured to the straightener module 300, and when no straightener module is included in the launch tower, to the tensioner module 200. Therefore the straightener module 300 has at its end normally facing away from the tensioner module 200 the same

configuration of lug sets as the tensioner module at the axial end that is to be connected to the straightener module 300. This allows for the pipeline guide module to be connected as desired to the straightener module, or in absence thereof in the assembled launch tower, to the tensioner module.

The module 100 also includes a work platform 140 so as to allow personnel access to be pipeline above the hang off device 120, e.g. in the course of severing the pipeline above the hang off clamp, e.g. in the course of an A&R procedure. For example there is a variable inclination work platform and associated inclination actuator, allowing to bring and maintain said work platform in horizontal orientation within the range of inclination of the launch tower.

The pivot structure module also has an A&R sheave 150, above or upstream of the hang off device 120. The roller box 130 may serve to guide the pipeline downstream of the tensioner. The stinger module 500 has a rigid structural frame of an elongated cuboidal shape with longitudinal main chords that each extend between corners of the structural frame at opposed axial ends thereof and with brace members interconnecting adjacent main chords in faces of said cuboidal shaped structural frame, and the system comprises releasable fastener members adapted to rigidly interconnect said stinger module to the downstream axial end of the pivot structure module, wherein said stinger module accommodates at least one of a roller box device and a departure sheave.

The stinger module may have the same cross-sectional dimensions as the mentioned three basic modules.

The stinger module accommodates therein a variable inclination work platform 520 and associated inclination actuator 525, allowing to bring and maintain said work platform in horizontal orientation within the range of inclination of the launch tower, said work platform being located adjacent the firing line allowing for personnel standing on the work platform to access the firing line and the pipeline therein.

The stinger module has a roller box 530 and a departing sheave 540 for support of the pipeline 11 downstream at the lower end of the tower 20.

The stinger module 500 has a staircase 550 that extends into the lower end of the module 100 when attached to one another. As the staircase extends above the frame of the module 500 the transportation involves the provision of an end piece 560 with corner fittings so as to mimic a 20 ft. ISO container. For example the personnel standing on a work platform of the tower downstream of the tensioner attaches an umbilical to the pipeline, e.g. the system including a umbilical guide structure 910 that is adapted to be releasably fitted to the outside of one or more of the mentioned three basic modules of the system and adapted to guide an umbilical coming from an umbilical storage reel to the location where personnel attaches the umbilical to the pipeline.

If desired one can provide a second tensioner module to be connected in series with the first tensioner module in order to increase the capacity of the launch tower in that regard. The base module 5 is adapted to be placed on deck 4 of vessel 1 , and comprises a horizontal pivot axis device 55 that is adapted to be releasably connected to the horizontal pivot axis device 1 10 of the pivot structure module 100. The base module is embodied like a flat rack open topped container with the horizontal pivot axis device 55 at one end thereof, upwardly protruding from the flat bed or platform. In an embodiment the pivot structure module also comprises a firing line cable sheave 150, at a location upstream of the hang off device, which firing line cable sheave is mobile, e.g. by a motorized actuator 155, between a retracted parking position and an operative position wherein a cable passed about the sheave 150 is aligned with the firing line.

Herein, as preferred, also the base module 50 comprises a cable sheave 75, and the system further comprises winch module 800 comprising a motor driven winch having a drum and a cable 801 spooled thereon, said cable 801 being passable from said winch via said cable sheave of the base module, to the firing line cable sheave. The winch module can also be adapted to have a structural frame corresponding to an ISO freight container. For example the winch module 800 is adapted to be arranged to one side of the base module 50, with the cable 801 passing in substantial lateral direction to the cable sheave thereon and departing therefrom to the cable sheave in the pivot structure module. Preferably the cable sheave on the base module is mounted pivotally so as to align this sheave 75 with the cable sheave 150 in the pivot axis module for each inclination position of the launch tower 20, preferably include (when provided for) a fully horizontal position of the launch tower. In the depicted embodiment the firing line cable sheave 150 is embodied so as to pass said cable 801 about this particular sheave in two configurations; the one configuration being an A&R configuration (see figure 29) wherein the cable extends from said sheave in the downstream direction along the firing line in order to perform A&R procedures, and the other configuration being an initiation configuration (see e.g. figure 27, 30) wherein the cable 801 extends from said sheave in the upstream direction along the firing line in order to perform an initiation procedure wherein the cable is connected to the leading end of a pipeline 11 (via end connector 12) to be pulled from a storage reel into the launch tower to the tensioner.

The system comprises an inclination adjuster module 850 that is adapted to be placed on deck of a vessel and to interconnected to the base module, wherein the inclination adjuster module is provided with an inclination adjuster device 851 , e.g. one or more hydraulic cylinders, that is adapted to be connected to the tensioner module 200 in order to adjust the inclination of the launch tower 20. For example the inclination is adjustable between a fully horizontal position, e.g. in the course of initiation procedure, and an inclination of 60 degrees or even more.

The system comprises a rigid locking device 950 9see figure 15) that is adapted to be secured between the pivot axis module 100 and a base module 50 in order to form a rigid connection between them for holding the launch tower 20 in a predetermined inclination.

The underbender module 600 is adapted to be arranged on deck 4 of vessel 1 at a location in between the launch tower and the storage reel. The underbender module 600 comprises an arc shaped pipeline guide 610, preferably a segmented arc shaped pipeline guide comprising multiple guide segments 61 1 , 612 pivotally interconnected to one another, e.g. exactly two guide segments, e.g. each segment being provided with a series of pipeline guide rollers. The underbender module can for example be stationed on deck of the vessel in between the launch tower and a pipeline storage reel, so that pipeline coming from the reel can pass to the underbender and then curve along said underbender upwards to the pipeline guide on the inclined tower.

The underbender module comprises a structural frame that is embodied to mimic an ISO 20 ft. freight container, e.g. with four main chords extending between corners of the structural frame of the module. The module may be provided with ISO corner fittings and/or one or more ISO corner fitting members are mountable to the structural frame.

The crane module 700 comprising a platform 710 that is adapted to be placed on deck 4 of a vessel, e.g. adjacent a base module for the launch tower, e.g. adapted to be connected to said base module. The crane module comprises a slewable telescopic boom crane 720 mounted on said platform. As preferred the platform is shorter than 20 ft. (6.1 m), and the system comprises, for intermodal transport of the crane module, two ISO container corner fitting members 704, 705 each having four corner fittings, which are releasably mountable onto the axial ends of the platform of the crane module.

As depicted e.g. in figure 27 the present invention also relates to a method for initiation of pipelaying of pipeline to be spooled from a pipeline storage reel, wherein a launch tower as described herein is brought into horizontal position and an initiation cable 801 is passed from a firing line sheave downstream of the tensioner along the firing line to the reel and connected to the leading end of the pipeline, e.g. to a connection fitting pre-assembled at said leading end. The pipeline 11 is then pulled by means of said initiation cable into the firing line in the tower as least as far that the tensioner can engage on the pipeline. When a segmented or articulated pipeline guide is present on the launch tower, it may be that the pipeline guide is then in a flattened state to allow for the horizontal orientation of the tower. After pull-in the tower is inclined to the desired angle of inclination and the pipeline guide is brought into its operative configuration with the segments together forming an arched guide for the pipeline.