NO319934B1 - Barge for laying rudder - Google Patents

Description

FIELD OF THE INVENTION

The present invention relates to a barge for laying pipes, comprising: a hull; a deck mounted on said hull; a spool holding the pipe, the pipe being wound onto the spool, and the spool being rotatable, horizontally mounted on and secured by means of attachment to the tire.

BACKGROUND

As the search for oil continues to move to deeper and more distant areas, there has been a drive within the oil industry to create multi-purpose vessels. In addition, the oil industry is moving in the direction of equipping a vessel with the ability to perform multi-tasking operations regarding heavy lifting, offshore construction, diving support, deepwater pipelaying and deepwater umbilical cable systems. It is a goal of the present invention to have the ability to continuously lay all types of submarine pipelines in a conventional or coiled manner to include, but not be limited to: 1) single wall concrete, 2) single wall plastic coated, 3) single-wall without coating, 4) pipe-in-pipe systems coated/uncoated (referred to in this description as "pipe" or "pipe 215"). Conventional laying refers to a method where individual pipe sections are welded together on a barge before being placed on the seabed. This differs from the coil method where a continuous length of pipe is coiled on a coil.

Many studies have been done to compare conventional and coiled subsea pipeline laying methods. The main advantage of the conventional laying ("stock on") method is the ability to remain on site and construct a pipeline and have the individual pipe lengths brought out to the vessel by means of a material barge. The advantage of the coil method is the ability to lay long lengths of pipe during limited weather windows. With the coil method, the pipe construction is carried out at the quay, where costs relating to tugboats, boats, fuel, personnel, etc. are not required for the construction of the pipeline. The prior art only shows the use of either conventional section or coil laying for a single barge apparatus. It is an object of the present invention to provide a barge apparatus capable of changing operating conditions between conventional section or coil laying to be job specific.

The industry uses two types of storage coils for coiled pipe systems, 1) vertical coil, 2) horizontal coil. Both types present advantages and disadvantages inherent in their design. A disadvantage of the vertical coil is that the stability of the vessel is jeopardized with a higher center of gravity. Another disadvantage of a vertical coil is that the construction weighs more than that of a horizontal coil that gives it the same storage capacity. It is another object of the present invention to have a significantly lower center of gravity which creates a more stable vessel.

In certain pipeline scenarios, the same pipeline may change its physical parameters due to operational requirements and water depth. The pipeline can change wall thickness, bend barriers, anodes, poly-coated to concrete-coated, etc. Pipe-laying vessels of the previously known type can only satisfy an operational requirement as the pipe must be left on the seabed and another vessel must be mobilized to complete the work. This disposal and recovery process is extremely time-consuming and expensive. Another goal of the present invention is to have the ability to change from a coil piping condition to a conventional piping condition and be able to handle all types of pipes without having to leave the pipeline in open water on site.

The fatigue of the tube is an important parameter in coil systems. Minimizing fatigue in coiled tubing systems is prevalent in very deep laying operations. For example, in the Chickasaw design, the tube is subject to reverse bending during the coiling and unwinding process. The pipe always goes through a bending operation after which it is plastically deformed around the hub of the coil which reverses bends in the pipe. It is a further aim of the present invention to only plastically deform the pipe by winding and unwinding the pipe on/off the storage coil.

As pipe laying operations continue in deeper water, anchoring systems for positioning the barge are limiting with increasing water depth. To operate in very deep water, dynamic positioning systems are used. In pipeline systems of the previously known type, the pipe-laying operations and the positioning of the vessel are independent systems with specialized personnel who operate them. The efficiency and control of laying pipes using these independent systems may be degraded. It is further a goal of the present invention to integrate the control of both systems described in a simple unit, and thus have the ability to achieve maximum efficiency and control of both systems at the same time.

The laying of submarine pipelines has been done either by the S-laying or J-laying method. The S-laying method determines the pipe orientation from the deck of the vessel to the seabed in the shape of an "S", namely S-laying. The J-laying procedure determines the orientation of the pipes from the vessel to the seabed in the shape of a "J", namely J-laying. Both methods "S-" and "J-" laying have their limitations. In general, "J-" laying has limitations depending on the minimum water depth and "S-" laying has limitations in the maximum water depth. Otherwise, the "S" laying operation is limited by the water depth, and also the large stress applied by the over-bending of the pipe caused by the laying ramp which exceeds the structural integrity of the pipe. It is an aim of the present invention to include both methods.

US 5 011 333 mentions a vessel for laying a continuous pipe on the seabed, where the continuous pipe can either be formed by assembling individual pipe sections on board the vessel (so-called conventional laying), or can exist as a continuous pipe coiled up on a coil . The continuous pipe is then led through a bending and straightening device which bends the pipe before it is led down to the seabed, and which makes it possible to set the exit angle between 1 and 90°, regardless of whether conventional laying or coil laying is used. The vessel is thus basically capable of carrying out both types of pipe laying. US 3,237,438 and US 4,262,287 also mention vessels for laying continuous pipes that are wound up on a coil.

However, it has been shown that moving and removing the mentioned coils, especially if these are large and heavy, is a demanding operation. The aim of the present invention is therefore to arrive at a practical way of moving a very heavy coil from the vessel without damaging the coil or the vessel.

SUMMARY OF THE INVENTION

The objectives of the present invention are achieved by a barge for laying pipes according to the introduction of the description and which is characterized by the fact that the coil is divided into parts which are arranged to be removed separately from the deck. Preferred embodiments of the barge are further elaborated in claims 2 to 10 inclusive.

This invention relates to a combination of both conventional laying and coil laying operations, including module removal of the coil to allow conventional laying operations. However, the specialized equipment relating to the spool is obviously more related to the spooling process of pipeline than its design for easy removal to provide a station for conventional piping. Control of both piping conditions is integrated into the dynamic positioning system of the vessel.

The reel system comprises a storage reel located at the front of the vessel with the remaining equipment aft. The capacity of the coil can be quite large, such as storing 84 miles of 6 inch steel pipe or 11 miles of 18 inch steel pipe (wall thickness = 1.25 inch). The tube is coiled on the storage coil at the dock. After the pipe has been spooled, the vessel relocates offshore to lay the pipe on the seabed. During the coiling operation, by using the complementary side i.e. the side of the barge where the pipe exits the coil of the vessel, the pipe is plastically deformed once. Centering devices of this invention coil and uncoil at different levels on the complementary side requiring only 20 degrees of straightening. To accomplish this, the remaining equipment aft of the straightener/straightener must be level with the winding after the tube is unwound to achieve a desired tube profile and so minimize the stress applied to the tube.

This invention is capable of changing from coil operation mode to conventional operation mode without leaving the pipeline. With the desired amount of coiled pipe on the seabed, the pipe is separated by a straightener. The coil may be removed by either skid transfer or divided into piece lifts due to the modular nature of the coil. With the spool moved, the pipe lengths and the pipe handling system can be set at a special station to continue pipe laying in the conventional condition without leaving and reclaiming the pipeline. For the present invention, both modes, conventional and spool, of pipe laying operations will utilize a rigid laying ramp which creates the ability to lay pipe in very deep water.

DESCRIPTION OF THE DRAWINGS

For a further understanding of the origin and objectives of the present invention, reference should be made to the following drawings seen in connection with the description, and in which like parts are given like reference numbers and in which: Fig. 1 is a general arrangement side view of a preferred embodiment of the present invention; Fig. 2 is a general partial arrangement side view of a preferred embodiment of the present invention; Fig. 3 is a general arrangement plan view of a preferred embodiment of the present invention; Fig. 4 is an elevational view of the storage coil; Fig. 5 is an exploded, elevational view of the storage coil divided into its five pieces; Fig. 6 is a general arrangement plan view of a second preferred embodiment of the present invention; Fig. 7 is an elevational view of a coil drive motor; Fig. 8 is a plan view of the coil drive motor system; Fig. 9 is an end elevation view of the straightener/rectifier aft looking forward, Fig. 10 is a side elevation view of the straightener, the straightener at the starboard lock port; Fig. 11 is a plan view of an insert of the straightener; Fig. 12 is a side elevation view of the straightener/straightener in fig. 11; Fig. 13 is a diagram of the level winding synchronization system of the insert in the rectifier; Fig. 14 is an elevational view of the center track synchronizing system of the insert of the straightener; Fig. 15 is a plan view of the synchronizing system for the center track of the insert of the straightener; Fig. 16 is an elevational side view of the tensioner; Fig. 17 is an elevational view of the tensioner; Fig. 18 is a three-dimensional partial embodiment of the tensioner, including a trace of the level winding system; Fig. 19 is an elevational view of the three output rollers; Fig. 20 is an elevation view of the paving ramp jack system in two positions; Fig. 21A is the end view of the jack system in fig. 20 taken along section lines 21A-21A; Fig. 21B is the end view of the jack system in fig. 20 taken along section lines 21B-21B; Fig. 22 is a jacking sequence for the jacking system in fig. 20; Fig. 23 illustrates the pipe handling system at the dock during spooling; Fig. 24 is a line diagram of the control system of the first preferred embodiment of the present invention; and Fig. 25 is a wiring diagram for the 4160V electrical supply to one of the four drive receptacles.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

As shown in fig. 1, 2 and 3, a barge 100 includes a storage spool 200. The spool 200 is rotatably attached to the deck, such as t-rails 105, of a barge 100 by means of preventing the spool from lateral movement, such as welding preferably as discussed below. Alternatively, shear blocks (not shown) may be used to block movement of the coil relative to the barge 100 in directions of shear for the block. To remove the coil 200 from the barge 100, in the preferred embodiment, the welds will be removed and then the coil 200 removed as discussed below. In alternative embodiments, such as for the shear blocks, the blocks will be mechanically removed from their fit between the barge t-rails 105 where the shear blocks will be mounted within a plate and positioned next to the coil 200.

The coil 200 is mounted on the complementary side of the barge 100 i.e. the side of the barge where the pipe exits the coil which requires only 20 degrees for

straightening. Coil 200 is driven by a coil drive system 300. Coil 200 has tube 215. coiled on it. The pipe 215 is coiled on the spool 200 after the spool 200 is mounted on and connected to the barge 100. Normally, a tensioner 500 and straightener 400 will maintain sufficient tensile force on the pipe 215 to maintain its coil on the spool 200 as discussed below. Alternatively, for example, lifting eyes 218 are mounted on spool 200 and the end of tube 215 may be tethered by cable (not shown) between the end of tube 215 and lifting tube 218 to maintain tension on the tube after it is wound on spool 200. For spooling purposes, are typically 40 foot segments of pipe 215 welded together into 2700 foot sections of pipe 2150 stationary on pier 2200 (Fig. 23). This pipe 215 as long sections 2150 will then be fed to a laying ramp 800 in its highest position and thus through a laying ramp jacking system 700, output rollers 600, straighteners 500, a straightener/aligner 400, to the coil 200 where winding on coil 200 takes place as discussed in more detail below. During normal pipe laying, the pipe 215 is fed to straightener 400, and then through two straighteners 500, three output rollers 600, laying ramp jack system 700, and

is finally fed to a lay-out ramp 800, where the whole thing is controlled by a control system 900.

STORAGE COIL 200 (FIG. 4 AND 5)

The storage coil 200 is shown in fig. 4 and 5 to be divided into five pieces ("pieces") outer truss 214, middle truss 213, lower flange 203, drum 201, and top flange 202 (see fig. 5) bolted together. In fig. 5 is a cross-sectional view taken along dashed lines 5-5 of the storage drum 200 shown in FIG. 3. The drum 200 thus comprises in descending order of the pieces: (1) the top flange 202; (2) the drum 201 with surface 217 and bolt 209 at its top to flange 202; (3) the lower flange 203 bolted 210 to the drum 201 at the lower end of the drum 201; (4) the middle spar 213 rests on the t-rails 105 (not shown but well known in the art) of the deck 101 of the barge 100 and is welded at 110 to the t-rails 105 of the deck 101 and is also connected to the inner strut 216 of the drum 201 at a bearing outer surface 205, to rotatably connect the drum 201 and the fixed central sprinkler 213; and (5) the outer sprinkler system

214 also rests on the barge 100's deck 101, which abuts the center spar 213. The outer spar 214 is not welded to the deck 101. The outer spar 214 is bolted 211 to the outer spar 213 and supports wheels 206 that run on t-rails 207 or at lower or other rotatable structure that rotatably supports lower flange 203. The rotatable axes of all the pieces are coaxial with axis 219. Flange 203, drum 201, flange 202 will thus rotate around axis of rotation 219 in relation to outer and inner latticework 214, 213, which are attached with respect to lower flange 203. It is in fig. 2 shows a cross-section of the storage drum with coiled tube 215.

Storage reel 200 utilizes a tapered drum 201. The tapered drum 201 helps the tube 215 to be wound onto the drum 201 in a tight uniform formation. The pipe 215 will be coiled on the coil 200 and starts at the lower diameter part of the drum 201 and coils downwards towards the lower flange 203. At the end of the lower flange 203 after which the pipe 215 works upwards to the bottom end 220 of the top flange

202, it will tend under tension to be caught in the cracks (gaps) of the previously coiled tube 215 which prevents the new coiled tube 215 from sliding upwards. Thus, the coiling starts at the top section of the drum surface 217. The tube 215 is held by the top flange 202 and supported by the drum 201 and the lower flange 203, The drum 201 is supported by internal bracing 216.

The rotating portion of the storage drum 200 includes top flange 202, drum 201 and lower flange 203. The spool 200 is rotated by means of a single ring (English bull) gear 204, positioned around the periphery of the lower flange 203, and engaged by four driven gears 204 .The rotating portion of storage drum 200 is held centrically oriented by bearings 205.

The rotating coil 200 with tube 215 is carried by several wheels 206, such as 366 wheels 206, or lower engaged on sets, such as two rails per set, with circular rails 207, 208, for example five sets of two rails, one rail of the set, rail 207, which rotates and the other rail of the set, rail 208, is static. The wheel 206 is supported by the middle truss 213 and the outer truss 214. The middle truss 213 and the outer truss 214 include rectangular and circular l-beams connected by welding structures. The sprinklers 213, 214 uniformly distribute the combined load on the tire 101 to the parent fabric 100.

The conventional slagging condition requires that the storage drum 200 and the drum drive system 300 be removed from the vessel. Storage drum 200 can be removed by either sliding on T-rail cutter 115 or five piece elevators for the pieces. The top flange is separated from the drum at 209. The drum is separated from the lower flange at 210. The lower flange rests on top of the wheel 206 without bolted connections and can rotate freely. The middle sprinkler 213 must have welds 110 removed to separate sprinkler 214 from the vessel 100, and outer sprinkler 214 is separated from middle sprinkler 213 at location 211 after removing bolts holding sprinkler 213, 214 together. The spool 200 is also equipped to be lifted in a single lift using the lifting ears 212. Connections 240 mechanically connect the rotating sections 201, 202, 203 to the non-rotating sections 213 and 214.

The amount of welding 110 to connect the coil 200 to two t-rails 110,105 must be sufficient to prevent the coil 200 from moving relative to the deck 101 or in shear with respect to the t-rails 105. Alternatively, other methods such as shear blocks available. Such blocks must be thick enough, so that when a block is placed in the plate set in t-rails 105, the block will not yield to shearing forces if applied to a block at spool 200 loaded with pipe 215 which is the main weight that causes the shearing force.

CONVENTIONAL LAYING SYSTEM FOR TIGHTENERS (FIG. 6)

For conventional condition, the coil 200 is removed from deck 101 by, for example, using crane 170 as in one of the ways discussed above, and is replaced with pipe handling ramp 150. Pipe 215 is located in storage area 155 for utilization of a conventional laying process. Pipe 215 is lifted from storage 155 and introduced into pipe handling ramp 150 which is well known in the field. In pipe handling ramp 150, the individual sections of pipe 215 are connected together as by welding which is also well known in the field. Finally, the welded pipe 215 leaves the pipe handling ramp 150 and is introduced into roller boxes 160 at the exit of the pipe handling ramp 150. All of the above is well known in the art.

The roll boxes 160 transport the pipe 215 to the straightener/aligner 400 location. For this purpose, as discussed below, the level winding carriage 402 is raised to its highest level (Fig. 9 in phantom line), and pipe 215 moves under the level winding carriage 402 to the first of the tensioners 500. It should be noted that the weight of the pipe 215 coming from laying ramp 800 supplies the driving force for the connected pipes 215 and, as the roller boxes 160 have bearing-supported rotary rollers, is equally driven and depends on the operation of the device aft of the straightener/rectifier 400. These devices are described below and regulate the feed rate of pipe 215 to the straightener/rectifier 400. The speed of tube 215 is controlled by control system 900 which controls such devices.

COIL DRIVE SYSTEM 300 (FIG. 7 AND 8)

As shown in fig. 8, the coil drive system 300 includes four drive sets 306, 307,

308, 309 attached to single slide frame 301.

Skid frame 301 is bolted to outer truss 214 at locations 310, 311, 312, 313 and is welded 110 to t-rails 105. Each drive set 306, 307, 308, 309 is driven by a single DC motor 302, (such as a 285 kw engine). Each motor 302 is coupled to a two-speed gearbox 303. One of the speeds of gearbox 303 is to facilitate a first operating state of coil drive 300, a fast speed, and the other speed will be a slower speed, the exact speed depends on how fast the tube 215 must be coiled, coiled up, slacked out or hauled in. Gearbox 303 is coupled to disc brake 304, coupled to right-angle planetary gear 305, coupled to drive 320. Disc brake 304 is preferably used as a static brake although it may have dynamic braking properties to prevent coil 200 from turning either because motor 302 acts on speed gear 303 or from the tube 215 acting to push the track 200. Disc brake 304 will be used each time braking is applied to the spool 200. Just before the spool 200 stops, disc brake 304 will be hydraulically (not shown) activated, to keep the surface of the brake shoes and discs free from corrosion by being applied just before stopping.

Maintaining a 1/16 inch mating tolerance of the ring gear 204 and drive gear 320 is an important parameter, and also true concentricity of the circular ring gear 204 with respect to rotating about the center of the coil 200 is required. The procedure to ensure correct mating tolerance is as follows: Rotate coil 200 and inscribe a circle 230 on the outer edge of top to bottom flange 203 using operating tolerances for center bearing 205. The control of tolerances for ring gear 204 is defined by inscribed circle 230.

Disc brake 304 is coupled to a gear-reducing right-angle planetary gear 305 which drives a drive 320 which drives the ring gear 204 to the storage drum 200.

The drive 320 is a connected and disconnected of two hydraulic cylinders 321 (fig. 7). Each drive set 306, 307, 308, 309 is held securely in a linear arrangement by four linear bearing sets 322. Drive sets 306, 307, 308, 309 are all mounted on a single slide frame 301. Slide frame 301 can be removed as a single unit separately from coil 200 or during the same time period coil 200 is removed. Sliding frame 301 is removed for the same reason that coil 200 is removed to make room for the conventional pipe laying devices such as a pipe handling ramp 150. Alternatively, sliding frame 301 can be bolted or otherwise attached to outer latticework 214 and thus coil drive 300 can be removed at the same time with the coil 200 by a sliding action.

MORE WORKS (FIG. 1)

When winding pipe 215 on spool 200, it is possible to spool several jobs of pipe 215 on spool 200. These will be spooled serially on spool 200 and each will be individually disconnected as described above, so that they maintain their own stretch. For example, two lifting eyes 218 could be used to disconnect the first job or it could be welded in place and then a second job wound on the spool 200. Alternatively, two pipes 215 could be wound on the spool 200 at the same time if a job allows the simultaneous laying of two tubes 215. As discussed below, the coiled tubes 215 would be straightened by straightener 400 simultaneously.

EXTRACTORS/ADJUSTERS 400 (FIG. 9-15)

The straightener 400, referred to as "u/i", receives tube 215 from coil 200 (Figs. 2, 3). The u/i 400 includes a steel support structure 401 supporting the level winding carriage 402 (shown in two positions, one in phantom line, in Figs. 9, 10), and an operator's cabin 403 facing aft. Four hydraulic cylinders 404 are used to level the carriage 402. Four hydraulic cylinders 404 are mechanically connected together by a synchronizing system 450. The synchronizing system 450 (Fig. 13) includes four racks 405 and racks 406, the racks 405 being mounted on the vertical support frame 412 to the corners of the u/i 400, and the gears 406 are mounted on the underside of the carriage 402 which mate with the racks 405. The synchronization system 450 also has the gears 406 freely rotating as a carriage 402 moves up and down on the racks 405.

Gear 406 on the forward part of vessel 100 connects to a right-angled gear box 409, and aft gear 406 also connects through a torque tube 408 which extends forward to box 409. This is important for both port and starboard side of u/i 400. The two boxes 409 is connected to a torque tube 465 which connects the adjacent sides of port and starboard. The toothed drives 406 of the synchronization system 450 thus mechanically couple the torque pipes 408 which extend forward and aft of the vessel 100 and maintain the level winding carriage 402 horizontally in alignment. This synchronization system 450 of the level winding carriage 402 creates redundancy and eliminates single point failures, such as failure of any of the hydraulic cylinders 404 or the brackets/disks 460 which have no effect on the level of carriage 402. Thus, with the synchronization system 450, a total failure of a hydraulic cylinder 404 does not prevent the carriage 402 from correct level winding due to the mechanical coupling of the hydraulic cylinders 404 in the level winding system.

The purpose of the u/i'en 400 is to control the pipe 215 on and off the coil 200 in a straightened state. The level winding position of carriage 402 is preferably manually controlled from the operator cabin 403, although it may be automatically controlled. The level winding position of the equipment aft of the u/i'en 400, i.e. the tensioners 500 and the output rollers 600, are automatically controlled to produce a specific desired pipe profile pre-programmed in the control system 900. This level winding position is carried out by using the output of one of two linear variable differential converters (LVDTs) 410 for the level winding cylinders 404 per each of the two level winding cylinders 404, preferably only two cylinders with LVDTs 404 and these two cylinders 404 are on opposite corners of the u/i 400 on the vessel 100 as a zero point, and which preferably use a signal when they are both used with the other as a back-up, and alerts the operator if only one is in operation. The output of the LVDT 404 is an input to the calculation of an algorithm which, by methods well known in the art, reproduces a desired pipe 215 profile and orientation of the pipe 215 aft of the u/i 400. This, sets the desired height of the level winding cylinders of both tighteners 500 where output rollers 600 to achieve the desired pipe 215 profile set in advance before the pipe laying starts. The LVDT 410 provides the necessary feed forward signal for the control system 900 (Fig. 3). This signal is transmitted to an accurate level control profile which sets the level winding position of the two tensioners 500 and the three output rollers 600, as more fully described below, to match the desired tube 215 profile. Pipe bending or loop formation is avoided by using two tension control loops, one which controls the tension aft of the aft tensioner 500, and the other which controls the tension between coils 200 and forward tensioner 500. These two control loops operate in cascade. The level winding position of the tensioners 500 and output rollers 600 are important to minimize the compressive stress applied to the tube 215.

The carriage 402 includes three tracks 413, 414, 415 (Fig. 12,13) and an operator's cabin 403. Each track 413, 414, 415 utilizes elastoplastic pads 411 so as not to damage the pipe 215 and pipe coating during the coiling and pipe laying operation. During coiling, both tracks 414, 415 are disconnected from the path of tube 215 and the only tube for pad contact is track 412.

Tube 215 is only plastically deformed in one direction during the coiling operation. In contrast to the prior art, there is only one bending operation of tube 215

during flushing. Also, there is no significant reversing bending of pipe 215.1 the pipe straightening process, the reversing bending is minimized to achieve minimal residual stress in the pipe 215, with no tendency for over-straightening. This process has been adopted to minimize the amount of work on tube 215 and to maintain tube 215's roundness. In the prior art, the pipe passage is located on the port side of the vessel. The tube is rotated from the port side to the starboard side by the coil which coils in the counterclockwise direction, and then reversing bends the tube. This invention utilizes the starboard side of the vessel coil 100 in a counterclockwise direction. This invention does not reverse bend tube 215 significantly. Track 413 is the only one used for coiling because no straightening operation has been carried out underneath

the coil operation. Tracks 414 and 415 are used for straightening purposes, which are unnecessary when winding. They are therefore not used. Track 413 directs tube 215 onto the appropriate portion of coil 200, thereby minimizing stress on tube 215 during the coiling operation as it emerges from its storage area.

Once the desired length of tube 215 is coiled on storage drum 200, all three tracks 413, 414, 415 through u/i 400 are positioned at a predetermined calculated setting upon testing to achieve the desired horizontal orientation. In these calculations, pipe-retracted and upstream and downstream equipment distances and geometries also serve as input data. To effectively straighten a pipe, it must be forced into a special reversing curve. A small amount of elasticity in coatings and the thick elastic shape of track pads redistributes local deviations from the ideal "exact" roll settings. It is not necessary to provide "touch of button" hydraulic cylinder adjustments for each roll. This will greatly add to the complexity of the tracks and can reduce the necessary rigidity of the control of the pipe bend.

Tracks 413, 414, 415 can position themselves only in the horizontal plane, not in the vertical plane. Thus, vertical setting of pipe 215 is only carried out by carriage 402. The purpose of tracks 413,414,415 during the pipe laying operation is to correctly position pipe 215 in a horizontal orientation. This straightens the pipe 215. The optimal settings for the grooves of the pipe straightener are those that generate uniform pad 411 pressure on the pipe 215 wall, or coating, at each pad 411 for each groove 413, 414, 415. When multiple pipes of different diameters are to be laid in a single run then standard track contours can be adopted so that only full body movements of center track 414, and possibly aligner 413 and outlet 415 tracks, are required to readjust aligners 400 for different pipes 215. Default Settings is chosen so that the groove contours are close to the uniform pad pressure case, for the maximum pipe size and wall thickness to be exposed, and also so that specified coating pressures are not exceeded for other pipes 215, where the pad pressures are not uniform. The most effective straightening is achieved by uniform pad pressure at each groove, and with pipe elasticity over the entire length of the middle straightener groove 414. This distribution of moments minimizes both the local compressive stresses in the pipe section and the necessary reversing curvature of the pipe to achieve straightening. Accordingly, when it is necessary to perform rapid readjustment of the pipe straightener 400 to fit different pipes 215 this can be achieved by using groove contours (patterns) for a pipe 215 and by full-body movement of the individual grooves 413, 414, 415. The standard groove contours relate to uniform pad 411 pressure for a larger diameter pipe 215 and of the highest quality material. When pipes 215 of a lower quality, or pipes 215 with similar diameters are to be straightened, it usually only requires that the center groove 414 be moved, thereby maintaining a reasonably even pad 411 pressure at the interface with the pipe 215.

Tracks 413, 414 are manually adjustable tracks. The position of tracks 413, 415 is set after the coiling process during pipe laying trials. The carriage 402 of the straightener 400 is precisely aligned relative to the tube 215 on the spool to provide near constant pre-straightening conditions for the tube from different layers and coils on the spool. Tracks 413, 415 are preset as part of the experiments to achieve sufficient reverse bending of pipe 215 such that the final result from the deplasticized pipe 215 on the coil 200 is the desired straightened pipe in the horizontal direction, i.e. to look down on the pipe and see it straight down the exit from u/i 400. This straightening process is in conjunction with slots 414 as well as slots 413 and 415. Thus, slots 413, 415 are positioned to receive tubes 215 and to allow slots 414 to perform the actual reversing bending operation, thereby removing the curvature of tube 215 that it experiences as it emerges from coil 200.

Before piping operations can begin, the straightness of the pipe 215 coming from the u/i 400 must be determined from the pipe 215 straightening test as discussed above to determine the curvature of the pipe 215 in the horizontal direction at the exit of the u/i 400 for alignment of tracks 413, 414 , 415. Pipe straightening tests are carried out until a desired straightness is achieved. If multiple jobs for pipe 215 are wound on the same spool 200, each job will have its straightening attempt made after its winding before the next job is executed. If tubes 215 are used simultaneously, the alignment tests will adjust the track settings 413,415 and then track 414 for each tube 215 simultaneously. Normally, the same pipe 215 would have to be used on both parts of the simultaneous lay due to the degree of freedom of the preferred embodiment not being sufficient to vary the forces directing the pipe in the horizontal direction for individual pipes 215.

Finally, each track 413, 414, 415 is adjusted during the straightening trials until a suitable straightness is achieved by confirming the pipe 215 runs straight down the pipe passage. Both tracks 413, 414 are manually adjusted by control valves 470 for hydraulic fluid that control piston 471's extension from hydraulic cylinders 412. The hydraulic cylinders 412 push against carriage 402 and adjust the position of the rigid tracks 413, 415 respectively. The desired position of track 413 , 415 is secured when achieved manually by trimming blocks or plates 472. Trim plates 472, of varying thickness, are either added or removed manually until the desired position of each groove 413, 415 is achieved to achieve pipe 215's straightness.

Track 414 (center track) is a highly specialized unit because, unlike tracks 413, 415, it has the remote control feature of a synchronized positioning system 480. By using only such track 414 (use in the preferred embodiment of screw jacks) this helps to control the costs of the system and is thus preferred. Four hydraulically driven screw jacks 407 (Figs. 14 and 15) similarly to cylinders 412 push against carriage 420 to u/i 400 and position tracks 414 in relation to tracks 413, 415. The driven screw jacks 407 are mechanically coupled like carriage 402 for to determine the position of the tracks 413, 414, 415. The control of tracks 414 can be either manual/visual or computer controlled. For the synchronized positioning system 480, each of the screw jacks 407 is connected to a coupling 476, two of the couplings are attached to torque tubes 477 which run from the front to the rear on the upper and lower ends of the positioning system 480 to tracks 414. All these torque tubes 477 is on the port side of track 414. A drive device 478 is positioned between upper and lower screw jacks 407 (fig. 14) connected by couplings 476 to gearboxes 479. The connection to the driven screw jacks 407 is for all to work together as a unit, and apply the same force at the same time to avoid one of these screwing the slot 414, as it is in operation.

An optical encoder 481 provides the necessary feedback of the position of a screw jack 407, and thus they are mechanically coupled, all screw jacks 407 to determine the real position of track 414 relative to tube 215 in the horizontal plane. The computerized track 414, whether running manually or automatically, gives the u/i' 400 the flexibility to achieve the imposed operational constraints for straightness of pipe 215.

In most cases, the guide is set so that the cross-section of the pipe 215 is uniform with no obvious obstructions. In deep water applications, coil tubing 215 may contain bend arresters, anodes, or other obstructions that are related to pipe-in-pipe systems. In the manual condition, should an obstruction that is part of coiled tube 215 occur, the operator will see this coming and override jack 407 operation on track 414 until the operator sees the obstruction pass and on command instructs jack 407 to re-store track 414 to its exact position before the start of the obstruction. There is no automatic condition in the preferred embodiment to accomplish this same purpose, such as with print or front view optics.

As shown in fig. 11, feeds tube 215 around track 413 and is reversibly bent at track 414 which forces tube 215 against tracks 413 and 415. Tracks 414 and 413 are also driven to rotate to lower the amount of frictional force between each of tracks 413, 414 with the tube 215 so as not to damage the coating of pipe 215 during track and laying. Each of grooves 413, 414, 415 has several u/i pads 411. The pads 411 are designed so that they will work with any pipe size within the parameters of the preferred embodiment, without switching from pipe to pipe. However, if simultaneous pipe laying is used, where two pipes 215 are laid at the same time, then the pads will be changed to reflect having double pipes 215. Such change will be by manual means between jobs, which keeps pipe 215 taut, on the spool 200 when tying of the pipe to be bolted to the coil 200 as discussed above.

To increase the efficiency of conventional laying operations, the carriage 402 is positioned at the top of the support structure and mechanically locked in place. This is done to allow room for an additional work station under the carriage in the conventional piping condition of the operation discussed above.

The preferred condition would require an observer to command the first level winding platform (aligner/rectifier platform) to the desired height. In this design, all the other platforms discussed below will track themselves to where they should be with reference to the first platform's point-by-point pipeline database. A manual trim facility (not shown) is also provided.

A first alternative condition would be semi-automatic, with the ideal position derived within the control system 900 relating to the length of product taken on or off the spool 200. A manual trim facility would be provided. A software-based calculation will determine the height of the pipe 215 in relation to the set zero point. The feedback for this calculation will be related to the product length taken on or off the coil 200 combined with a coil revolution/product diameter calculation. The level winding control system 900 will then determine all level winding platform positions, and monitors to see if they are within a certain tolerance. If not, the control system 900 will control the respective cylinder actuator to move to the correct position and thus adjust the respective level winding platform to the desired height.

A second alternative condition would allow all platforms to be controlled independently through the use of raise/lower push buttons located on the control console or local to the level winding platform being controlled. Local or control console control will be determined from the control console only. Indication will be provided to show where local or control console control is active or not.

TIGHTENERS 500 (FIG. 16, 17, 18)

Back-stretching of pipe 215 to coil 200 is required to ensure efficient straightening and constant input pipe geometry for the straightening process. To minimize the cumulative tube stress, it is advantageous to set the back tension on the tube 215 so that the pull from the coil 200 straightens the tube 215 to approximately the radius of the groove

413. In this way, bending of pipe 200 is avoided at groove 413, and the ovality of pipe 215 is minimized. The back tension from the tensioners 500 must not be set at an exact size, but should be determined within a band of the recommended size +/-20%.

Two tensioners 500 are placed in a row aft of u/i 400. Each tensioner 500 consists of a steel support frame 501 on which is rotatably mounted at pivot joint 506 a steel track assembly frame 502. Two carriages 503 for each tensioner 500 slide on bearing belts 504, the vertical length of the support structure -sion legs 520. The carriages 503 support the track frame 502 and the track frame 502 rotates with respect to the carriages 503 about pivot joint 506. The position (pitch) of the track assembly frame 502 can be adjusted with two hydraulic cylinders 505 which rotate around two bearings 506 of the carriage. The reason why the jack assembly frame 502 will need to be adjusted by the two hydraulic cylinders 505 so that the coil assembly 502 can rotate around the bearing 506 is to shape to the desired pipe 215 profile as it is inserted into the tensioners 500 due to that profile will still be convex due to the stiffeners 500 being in the overbend region of the pipe 215.

The level winding of the carriages 503 is positioned by four hydraulic cylinders 507 attached to the carriage 503, two on each side of the track assembly frame 502. More precisely, the cylinders 507 are attached at their foundations by brackets 525 to knee braces 530 of legs 520. The other ends are attached to four chains 508. Chains 508 are attached at their other end by balancing mechanism 531 to both adjacent carriages 503 and "dead man" terminate on bracket 532. Level winding of both carriages 503 is mechanically coupled by a balancing shaft 509.

Balance shaft 509 forces each chain 508 to have equal tension. The purpose of cylinders 507 is that as they extend, i.e. the pistons extend farthest out of the cylinders, the effect is to cause the carriages 503 to be lowered in relation to the tire 101.

The track assembly frame 502 houses two tensioner tracks 510 and clamp assembly 540. The clamp assembly 540 includes four mechanically coupled 511 screw jacks 512. The mechanical coupling 511 includes a hydraulic motor 513. The hydraulic motor 513 turns gearbox 541. The gearbox 541 turns torque tube 542 in a similar manner to that of u /i' 400. Bottom track 510, i.e. the one closest to the deck 101 does not move relative to the track frame assembly 502. Only top track 510, i.e. the furthest from the deck 101 moves relative to the track frame 502. The mechanical linkage 511 maintains the level condition of the track 510. For the purpose of being able to see how the pipe lies between the top and bottom tracks 510, the top and bottom track 510 left open in the drawings. In actual practice, these will be very close to each other, and lie around tube 215 between upper and lower track 510. This will close any opening shown in the figures. The closing of the opening is carried out through the screw jacks 512 as discussed above. As the screw jacks 512 position the slots, air bags 513 are provided which inflate and provide the normal force to clamp the tube 215. The number of air bags (bags) 513 and their position with respect to overall control, e.g. four airbags are inflated and compressed as a unit, are regulated for safety reasons. Thus, an error for a setting of air bags 513 does not cause a loss of normal power for a long section of track 510. It is

obvious that the number of air cushions 513 and the grouping of the necessary control must be minimized for economy in connection with the construction. The tensioner grooves 510 are positioned against the pipe 215 to provide the necessary normal force to maintain the tension on the pipe 215. The tension on the pipe 215 is maintained in any direction, i.e. if the coiling occurs or if the laying occurs as an operation. LVDTs 529 determine the level winding position of 215 passing through tensioners 500 as discussed above. In addition, compensating valves 543 are arranged at the inlet end and outlet end of track 510 to hold up a

the 544 to air cushion plates 545. The desired positions for compensation cylinders 543 are preferably manually set at the beginning of each job. Furthermore, rear axle 547 of drive chain 548 is of track 510 on a slider 549 and is positioned in accordance with pressure reflection changes of varying drive chain 548 tensionings.

There are four direct current motors 302 arranged to operate the tracks 510. The direct current motors 302 are used to drive the tracks 510 at varying speeds to adjust the tension on pipe 215 exerted by track 510. The control system 900 regulates these much in the same way as the coil motor 302 is regulated. The drive system for tensioners 500 comprises DC motor 302 coupled to speed gearboxes 550, coupled to disc brake 551, coupled to right-angled planetary gear 552, coupled to drive sprocket 553, coupled to drive chain 548. Cross tensioners 554 are bolted to chain 548. Tensioner pads 555 are bolted to transverse tensioners 554. This forms the connection from direct current motor 302 to pipe 215.

The pitch of track 510 is automatically controlled to form the desired convex overbend in pipe 215 at the specific location relative to barge 100 at cylinders 505. LVDTs 588 provide the necessary feedback to control system 900 to control the desired pitch of the tracks 510.

EXIT ROLLERS 600 (Fig. 19)

To provide vertical support of pipe 215 to maintain a proper pipe profile, as discussed above, three output rollers 600 are used between the tensioners 500 and the laying frame 800. Each output roller 600 has level winding capability to support the pipe 215 to a specified pipe profile , as discussed above. The level winding of each of the output rollers 600 is positioned by two hydraulic cylinders 601. The control of such cylinders uses double hydraulic proportionality control valves 602.

A pressure transducer 604 for each cylinder 601 is located so that it will sense the pressure between pipe 215 and cylinders 601 to indicate the vertical load on pipe 215 at that location on barge 100. Thus, if a pressure transducer 604 reads a greater pressure value , this will be indicative that the tube 215 has rolled more to one side. The hydraulic proportional control valves 602 in accordance with track LVDTs 603 position cylinders 601. LVDTs 603 provide the necessary sensor input for control system 900 to determine the current vertical position of each roller 605. The input to LVDTs 603 is used by control system 900 as a feedback for to ensure that the correct pipe profile is maintained by each of the output rollers 600, as discussed above. Alternatively, instead of computer control by control system 900, if the system is on manual, the vertical position of each of the output rollers 600 may be manually input to a local level control or may be manually set.

LAYOUT RAMP JACKING 700 (FIG. 20, 21, 22)

The laying ramp jack systems 700 position the laying ramp 800 to meet the operational requirements of the individual pipe laying job, such as pipe diameter, wall thickness, tensile requirements (including whether it is laid in a filled or air condition) and the like. There is a connecting rod 701 for each laying ramp jack system 700 to the laying ramp 800, thereby connecting the laying ramp 800 to the barge 100. The connection is made by means of a wing wall 705 for each laying ramp jack system 700. Wing wall 705 is an integral part of the barge chute 100. Two jack systems 700, one on each connecting rod 701, provides means of adjustment for the positional compensation discussed above.

Each paving ramp jack system 700 consists of a stationary box 702, a strike box 703, bolts 708, 707, 711, 710 and hydraulic cylinders 704. The stationary box 702 is bolted to the wing wall 705 through lifting eyes 712 into which are inserted three permanent bolts, an inner or center bolt 710 and two outer bolts 711. By using three bolts 710, 711, certain degrees of latitude (freedom) are allowed for a connection tank 701 discussed below. The impact box 703 is mounted to reciprocate adjacent the stationary box 702. The impact box 703 is actuated by four hydraulic cylinders 704. Extensions of the pistons of the cylinders 704 are measured using LVDTs 706 to provide the necessary feedback to determine the true position of the hitting box 703 in relation to the stationary box 702. Fig. 20 shows the extreme positions of the hitting box 703 in relation to the stationary box 702. A connecting rod 701 that changes its position in relation to the wing wall 705, but the lay-out ramp 800 is not dimensioned to freely move within the stationary 702 box and the impact box 701. The connecting rod 701 is free to move between the three permanent bolts 710, 711's.

With bolt 708 inserted and bolt 707 pulled, the jacking process begins by extending the strike box 703 using hydraulic cylinders 704 and inserting its bolts 707 by hydraulic bolt cylinders 713, which lock the connecting rod 701 in place relative to the strike box 703. Confirmation of the setting of bolts 707 are a necessary control feature of proximity switches 714. The next step is to remove the stationary box bolts 708 parallel to bolts 707. Box bolts 708 are removed using hydraulic bolt cylinders 715 in a manner similar to hydraulic bolt cylinder 713. Once bolts 708 is removed, the jack cylinders 704 can be activated to move the connecting rod 701 through the stationary box 702. This process of incremental movement involving connecting rod 701, stationary box 702 and impact box 703 is repeated until the desired position of the laying ramp 800 is achieved for pipe 215 to have the correct profile at the exit into the laying ramp 800 or for moving the laying ramp into a movement position when there is no pipe passing through it. The Jack sequence is shown in fig. 22. The figure shows the lifting sequence with a positive load on the jack mechanism. Outer circles represent jack rod holes. Shaded circles represent locking bolts. The first sequence represented by 1 shows the starting position where the weight of the lay-out ramp is taken on the front locking bolts and the jack cylinders are retracted. The second sequence shown at 2 shows the retraction of the aft locking bolts where the jack cylinders are withdrawn and the aft locking bolts inserted into the next set of holders. The third sequence shown at 3 shows the retraction of jack cylinders on a small scale to take the weight of the lay-out ramp on aft locking bolts. The fourth sequence 4 shows withdrawal of front locking bolts and then withdrawal of jack cylinders and further reinsertion of front locking bolts. The fifth sequence shown at 5 shows the jack cylinder slightly extended to transfer the weight of the lay-out ramp from the aft locking bolts to the forward locking bolts, i.e. back to the starting position.

REWIND/TIGHTENING/LAND SYSTEM

Control system (General)

The pipe laying system 10 has both a conventional pipe laying (stock on) and a coil feature, all specially designed for deep water pipe laying. The pipe laying system includes the laying ramp 800, laying check 700, the three support rollers (output rollers) 600, the two tensioners 500 and in addition for the coiling capability the straightener/straightener 400, and the horizontal coil 200. Both the pipe laying control system 900 and a dynamic position control system 1000 which control trusters 273 also mounted on vessel 100 utilize similar independent systems integrated for full control as a single unit.

The drive devices for the tensioners 500 and the coil 200 are direct current motors (such as 285 kw) four for each tensioner 500 and four for the coil 200, twelve in total.

Regenerative four-quadrant torque of DC motors using SCR drives

Specifically, the tensioners and spool are each driven and braked by four 285 kw separately excited AC motors. The speed and torque of each engine is controlled by an SCR system 905 that uses four-quadrant control and regenerative braking.

Power regenerated by these systems in the braking process is fed back into the vessel's power network and absorbed by the power plant 904 which is well known in the field.

For safety purposes, input power is derived from segregated sources. The 4,160 volt, 17.2 megawatt vessel power distribution system is constructed with two main switch panels 902 located in physically separated compartments. These switch panels 902 are each fed from three generator sets (not shown) which are typically isolated in two engine bays (not shown). The switch panels are connected by a Tie Breaker 901, which allows them to share power from all six generators (not shown). This design allows complete failure of one engine compartment or switchgear compartment without loss of vessel power.

Power from the SCR systems 905 driving and braking the tensioners 500 and coil 200 is derived from, and regenerated into, two 4160 VAC/480 VAC converters. The primary windings of these converters are connected to the main breaker panel with one on each side of the "Tie Breaker" 901 in physically isolated compartments.

Each of the coil/stretch converters has a dual secondary. Each step-down converter has an output circuit breaker. The four circuit breakers each feed power to and absorb power from three, four quadrant control regenerative SCR systems 905. The SCR systems 905 are physically mounted three each in four separate portable containers. Each container is permanently mounted on the vessel 100.

Each SCR system 905 is connected to a separately excited AC motor 302. The three SCR systems 905 mounted in each vessel feed a motor 302 on the forward tightener 500, a motor 302 on the aft tightener 500, and a motor 302 on coil 200.

The four quadrant control regenerative SCR systems 905 are Eurotherm 590 series model 720A. System 905 controls the motors 302 by controlling the armature current to each motor 302. Regulated field (not shown separately) supplies control motor field 302. The field-to-feeds have field excitation characteristics for accurate speed control and constant horsepower control. Power is delivered to each engine 302 via a microprocessor-controlled rectifier and returned to the vessel's 100 power network via a microprocessor-controlled converter. These are standard features and options for Eurotherm 590 series power converters.

Sensors held within each SCR system 905 determine the magnitude and direction of current circulating in the armature of each motor 302. Armature speed is derived from tachometers (tachometers) 370 pressed to the armature shaft end. The tachometer 370 input is connected to the SCR system 905 by a fiber optic cable (not shown).

Standard four-quadrant regenerative control algorithms are preprogrammed into the microprocessor by the manufacturer. These include armature current control, speed control and field control.

Special control blocks are pre-programmed into the SCR system's 905 microprocessors by the manufacturer. These include: PlD control blocks, emboss handling and center winding blocks, diameter calculator blocks, taper calculator blocks, compensation calculator blocks, torque calculator blocks, and speed requirement calculator blocks.

Input/output connection points are provided by Eurotherm for analog and digital points. These are the connection points for external command signals, sensor inputs and data output. These connections are used to command the system and provide feedback.

The SCR system 905 utilizes these input/output points to communicate with Opto22 Mystic Controllers using digital and analog inputs and outputs. Opto22 Mustic Controllers are fully programmable distributed process controllers. They are programmed using the Cyrano command and control language. Input/output is carried out by Opto22 intelligent input and output "bricks" and modules.

SCR systems communicate operating parameters via RS232 communication ports. Serial information is fed to a SCADA computer 903 for display and logging. The SCADA computer system 903 is capable of communicating with and controlling the Opto22 Mystic controllers. This ensures clear access to adjustment parameters and acts as a back-up device for control.

The tube control console, PCC 906 communicates with SCR systems 905 through distributed control system. Reference of system parameters is provided by two systems, analogue and digital displays on the PCC 906, and through mimic screens developed in Wonderware software and displayed on a CRT in the PCC 906.

DEFINITIONS

1. Regeneration - When an electric motor 302 is driven by its load, such that the coil 200 can be unwound, it acts as a generator that absorbs kinetic energy from the load. The kinetic energy is converted into electrical energy. 2. Regenerative braking - The braking effect on the load of an electric motor 302 caused by power absorbed in the regeneration of electrical energy. 3. SCR - Silicon Controlled Rectifier - A solid state device used to rectify alternating current. An SCR allows current to pass in only one direction. Current will not pass through the device unless it is allowed to do so by the presence of a gate pulse when the device is forward biased. 4. SCR system - A type of system (Fig. 26) commonly used in industry, which converts an alternating current source into a direct current source and controls the speed, direction and torque of a direct current motor. Transformation is carried out by rectifying the AC input via an SCR bridge. 5. Converter - A device that converts direct current electricity into vec- . cell current. 6. Four Quadrant - Descriptive term referring to a motion control system that can operate in all four quadrants, i.e. speed in any direction and moment in any direction. 7. Four Quadrant Control - Control methodology common in industry that controls an engine and causes it to accelerate, run, and decelerate in any direction, thereby providing both driving force and braking force. 8. Tie Breaker - a circuit breaker 901 that electrically connects two switch panels 902 or power distribution panels, thereby allowing electrical power to flow between the two switch panels or panels.

9. SCADA - Superior supervisory control and data acquisition 903

10. Distributed control system - A system characterized by the fact that real control processing takes place in several processing units. These distributed processing units receive digital and/or analog inputs, discretize these if analog, perform digital calculations, and output signals to control instruments, actuators, and systems.

CONTROL IN CONVENTIONAL PLUMBING CONDITION

The control system in the conventional state is exclusively line control. It includes load cells 570 connected to tensioner 500. The load cells 570 are mounted on the rear and front foundations for tensile stress manometer compression, as an example even any type of strain gauge may be used, which gives an output directly related to the stretch (pull) of the pipe 215 The load cell output, eight for each tensioner 500, is compared to the desired strain set point and the difference is sent as an error signal to a PID (proportional, integral, derivative) controller in each SCR operation, the output of which is connected to a -running motor 302 drive devices for each tensioner 500 which misdrives the motor torque to erase the fault.

The DC motor 302 drive devices will operate in the stretch state in all four quadrants (inverting or regenerating state) and allow the pipe 215 to be issued. The tensioners 500 should preferably be operated together, although spacing may be designed to allow only one tensioner to be required. The output of the load cells 570 goes to their respective SCR system 905, as illustrated above. The SCR systems can be in a master/slave arrangement or each SCR can individually control against its set point. In a master/slave arrangement, the set point will be given to the SCR system 905 by the master tightener 500. The master tightener system 905 will then allocate through a hierarchy the load for the master tightener system and the remaining load will then be distributed by the slave tightener 500 on the same the hierarchy way.

CONTROL IN COIL CONDITION

As set forth above, in a system arrangement it is desirable to have control of both the tightening and the speed of the pipe 215 during piping and coiling. It is required that with a horizontal coil 200 a minimum tension is always maintained on the coil 200 to prevent unwinding. Constant stretch and constant velocity conditions must both be implemented. Speed requires that loops are implemented for supplementary control when the predominant control is constant tension state and tension clamps are implemented for supplementary control when the predominant control is constant speed control. Master/slave logic determines which of the three devices 500, 400, 300 is in control and which motor 302 in each device is the master.

PID strain control is implemented by utilizing load cells 570 at tensioner 500's pivot points 506. The load cells 570 provide strain feedback to the Opto22 Mystic controllers. The Mystic controllers provide appropriate feedback signals to the SCR systems. Tachometers are installed on each engine 302 to provide feedback of engine speed to implement speed control. The PID controllers and system design logic are programmed into each SCR system. Open and closed loop control strategies for the coil 200 and tensioner 500 as an integrated system are programmed into the Opto22 Mystic controllers.

Master/slave logic has been developed in the Opto 22 controller using the Cyrano programming language. Algorithms are implemented for both pulling in and slacking out pipe 215. Configuration digital points indicate analog setpoints for speed and stretch and are input to the PCC 906 and handed over to the SCR system 905 by the distributed control system.

During normal coiling and laying operations, the primary control function of coil 200 is to maintain an adjustable minimum tension. This is accomplished by operating the SCR system 905 in current limit condition to provide adjustable control of motor torque. An overspeed/underspeed clamp is implemented to compensate for the moving mass of the coil 200.

Control of the speed of the coil 200 motor 302 is automatically varied to compensate for the winding diameter of the tube 215. A manual trim function is provided to adjust for the variations in the automatic variance. When the coil 200 has been used in conjunction with the tensioners 500, closed loop speed feedback is derived from the tensioner motor encoders 370 which transmit motor 302 speed.

Each tensioner 500 is provided with bi-directional load cells. This ensures stretch sensing in both directions. In the emission condition, the aft tightener 500 SCR systems are the control units. A tension setpoint is entered from the PCC 906. The front tensioner acts as a load-sharing conductor and receives tension inputs from the conductor through the Opto22 Mystic controller. Arrangements have been made in the control algorithms in both the SCR system 905 and Mystique controllers for operation with both speed and line control.

In the overtaking condition, the rolls are reversed with the forward tightener 500 in the leading condition and the aft tightener 500 in the tacking condition.

In both modes of operation, control loops are implemented to ensure that a constant tension is maintained between the coils 200 and the tensioners 500. This is required to support the tube 215 over the span from the output of the u/i' 400 at the preset profile. Stretch is monitored by a PID controller loop to ensure that it remains in an acceptable range for the size and metallurgy of the pipe 215.

Control loops are implemented to accept a "velocity along track" analog input from the dynamic positioning system 1000. These control loops are capable of driving pipe 215 either onto or off spool 200 at the same speed as the barge 100 moves along the track .

Operating conditions will change the water depth and tube 215's characteristics. In shallower water, maintenance of pipe runs is more critical than in deeper water, likewise the angle of attack of the laying ramp is 800.

In shallower applications, the pipeline stretch will be the controlling parameter for discharge of pipe 215. As the dynamic positioning system 1000 moves the barge 100 down track, the pipeline stretch will rise to the top of the predetermined deadband for pipe 215. When this occurs, pipe 215 will start and go out. When the barge 100 decelerates to a stop, the stretch will drop to the point where the system stops and releases pipe 215.

In deeper water, the majority of the pipeline route is in the vertical plane. Movement down track 2000 adds tension in the horizontal plane. Because the increase in tension is functionally less after the barge 100 moves down the track, it takes longer to build up tension. Because of these factors, it is possible to safely set the tension in the system for an acceptable minimum level and release pipe 215 directly equivalent to the length in feet moved along the track. A control loop is implemented to drive the pipe 215 layout to match the velocity along the track from the dynamic positioning system.

Control of the level winding functions of the system is carried out through the use of the PID controller in the Opto22 Mystic controllers. LCDTer provides positional feedback for each of the components. Control logic is implemented to adjust the radius of the pipe extending from the u/i 400 based on the elevation of the u/i 400. As discussed above, this is implemented using a curve fit built into the system. Parameters for these curves have been developed based on the requirements of each pipeline.

There are three control states for elevation of the u/i'en 400 independent, manual and automatic. In the independent state, each unit can be powered and lowered individually from either the PCC or its local control panel. In the manual condition, the platform is raised and lowered by the operator to align it with the elevation of the pipe 215's starting point on the spool 200.1 the automatic condition, a model of the spool 200 is implemented in control software that remembers where the pipe 215's starting point is based on the diameter of the pipe 215 and the length in feet away on or off the coil 200. Operator intervention is programmed into the system to compensate for slippage and to design the point where the pipe layers change. The brakes on all equipment are software controlled to only release when a minimum level of engine torque has been established to keep the pads ready and when torque loading the engine at start to have a smooth transition.

FLUSHED PIPES

The tube 215 is held lightly on the coil 200 by the tensioners 500 which operate in a tensioned state to provide a pullback as discussed above. The tension control setting for the tensioner 500 closest to the spool 200 and the spool 200 is set, as well as the speed, and is illustrated to compensate for the varying drag provided by the length of pipe 215 if pipe 215 is recovered from the seabed 2000. The tensioner brakes 551 are released only when sufficient motor-302 torque has been developed. Coil 200 is operated in the speed condition to provide full torque to overcome coils 200's inertia, both static ("stiction") and dynamic ("load") at startup, as discussed above. During operation, the spool 200 rotates at the constant speed setting on the set point control scale. When stopping, the coil 200 is regeneratively braked. The coil 200's speed is interfaced with the dynamic positioning system 1000 to match the speed of the pipe 215's laying to the vessel 100's speed at e.g. cascade control. The SCR system controls the motors 302 to remove the torque after the pipe 215 slows to a stop. The output of the tightener code 570 which encodes such output to speed is used as the feedback to the spool speed controller to provide a true line speed regardless of the layer on the spool 201 being wound.

PLUMBING

Coil 200 and tensioner 500's operation is as set forth above. One

constant tension is maintained between coil 200 and u/i 400 by a controller with input 570 and output to SCR system 905 with a PID algorithm. The spool drive 300 either drives the motors 302 or regenerates after the pipe 215 is pulled from the spool 200 at the speed set by the tensioners 500, as described above.

Compensation is applied for coil 200's inertia upon speed feedback and upon manual input for the layer on coil 201 which is in operation. As the vessel 100 moves down the route or track for pipe laying, the integrated control system 900 senses the rise in tension and releases pipe 215 to maintain the tension within the dead band set by the operator around the tension set point. The dynamic positioning system 1000 may be coupled with the control system 900 to synchronize the amount of movement with the track with the piping speed.

Determination of the departure angle (stretch) of the pipe 215 in relation to the tip

of the laying ramp 800 is also an important parameter. The horizontal component (thrust) in addition to maintaining the vessel 100's position determines the tension on the pipeline set at the tensioners 500 and the spool 200. It should be noted that different methods have been used to determine the lift of the pipe 215 from

the loading roller to the lay-out ramp 800. This confirms that the pre-calculated tightening parameters have been met by the system for pipes 215. Different methods can be used which include measuring distance with a sonar device, measuring pipe pressure on the end roller at load cells, visual television confirmation etc.

COIL CONTROL LOOPS

Positioning control of vessel 100 becomes less critical as vessel 100 moves towards deeper water, and the change in pipe 215's departure angle (stretch) in relation to the change in vessel position becomes less severe. As the water depth increases, there is a corresponding reduction in the resolution and accuracy requirements of the dynamic positioning system 1000.1 reality with increasing water depth the stretch ceases to be the controlling factor and the length of pipe 215 laid on the route and the water depth determines the position of the vessel 100 as presented above.

Claims (10)

1. Barge for laying pipes, comprising: a hull (100); a deck (101) mounted on said hull (100); a spool (200) holding the pipe (215), the pipe (215) is wound on the spool (200), and the spool (200) is rotatable, horizontally mounted on and secured by fastening means (211) to the tire (101), characterized by that: the coil (200) is divided into parts (201, 202, 203, 213, 214) which are adapted to be removed separately from the tire (101). 2. Barge according to claim 1, characterized in that said parts comprise a top flange (202) which is screwed to a drum (201) which is screwed to a lower flange (203), the drum (201) resting on a middle grating (213) which is screwed to an outer sprinkler works (214). 3. Barge according to claim 1 or 2, characterized in that the sprinkler system (215, 214) includes rails (105) connected to the deck (101), the middle sprinkler system being removably attached to the rails (105). 4. Barges according to one of the preceding requirements, characterized in that the sprinkler (213) for removal includes rails (105) connected to the deck (101), the middle sprinkler (213) being removably attached to the rail (105). 5. Barges according to one of the preceding requirements, characterized in that the sprinkler system includes t-slide rails (115) positioned on said barge deck (101) transverse to the length of said barge and said coil (200) can slide off said barge deck (101) along said T-rails (115). 6. Barge according to one of the preceding requirements, characterized in that the rotation axes (219) of all said parts (201, 202, 203, 213, 214) are coaxial. 7. Barge according to one of the preceding requirements, characterized in that it further includes at least one drive set (306) and the coil (200) is driven by the drive set (306) and the device for removal includes a further device for removing (301) the drive set (306) with the coil (200). 8. Barges according to one of the preceding claims, characterized in that it further includes a stretching device (500) for coiling by level winding of tube (315) on the coil (200). 9. Barge according to one of the preceding claims, characterized in that the coil (200) further includes a foundation (213, 214), the foundation (213, 214) stores said coil (200) and uniformly distributes the load of the coil (200) on the tire (101). 10. Barge according to one of the preceding claims, characterized in that it further includes a power source (302), removable drives (320), the drive (320) is driven by said power source (302), a retracting gear (204), driven by the drive (320), said bull gear (204) is mounted on the spool (200) to rotate the spool (200) through the drives (320).