CA2252785C - Pipeline storage - Google Patents

Abstract

A storage system for storing continuous lengths of rigid pipe, particularly for storage of pipe prior to the spooling of the pipe onto the pipe storage reel of a marine pipelay vessel. The system comprises a loop (1 2) of rail track (20) with a plurality of rail bogies (100) arranged around the circumference of the loop (12). The bogies (100) are adapted to retain and receive multiple turns of the length of pipe (102) extending around the loop (12). The radius of curvature of the loop (12) is selected such that the bending of the pipe (102) around the loop (12) does not result in plastic deformation of the pipe (102). Arrangements for loading and offloading the pipe (102) may include: a pipe guide (232) suspended from a gantry (230) spanning the track (20) and a pipe loading/offloading path (238); pipe tensioning means (234) located downstream of the pipe guide (232) in the offloading direction; and an "expansion arc" (216) extending from the loading/offloading point to allow variations in the length of the pipeline path (238) extending from the loop (12) to a vessel mooring location.

Description

1 "Pipeline Storage"

3 The present invention relates to methods and apparatus 4 for the storage of continuous lengths of rigid pipeline. The invention is most particularly intended 6 for use in the temporary storage of lengths of rigid 7 pipeline prior to said pipeline being spooled onto the 8 storage reel of a reel-type marine pipelaying vessel.

In reel-pipelaying operations, the pipeline to be laid 11 is spooled onto a reel, mounted on the pipelaying 12 vessel, and subsequently unspooled as the pipe is laid.
13 The pipe is plastically deformed during spooling, and 14 is straightened during unspooling prior to departure from the vessel.

17 The reel pipe-laying vessel "Apache" has a pipelay reel 18 with a capacity of approximately 2000 tonnes of rigid 19 pipeline up to 16 inches diameter. The pipeline is assembled by welding standard 40 foot pipe joints into 21 1 kilometre stalks which are stored on racks at an 22 onshore spoolbase. The stalks may be assembled and 23 stored whilst the vessel is away from the spoolbase on 24 pipelaying operations. When the vessel is at the spoolbase to receive a load of pipe, the pre-assembled WO 97!41054 PCT/GB97/01130 1 stalks are spooled onto the reel of the vessel with 2 tie-in welds between stalks being made during the 3 spooling process. The need to make, inspect and coat 4 the tie-in welds necessarily prolongs the non-productive time required to spool a load of pipe onto 6 the vessel. It would be desirable to reduce the length 7 of time occupied by the spooling operation, so as to 8 maximise the availability of the vessel for productive 9 pipelaying operations.
11 The present invention provides methods and apparatus 12 whereby a continuous length of rigid pipeline, up to a 13 length substantially equal to or greater than the 14 maximum capacity of the pipelay vessel, may be assembled and stored onshore, whereby a full load of 16 pipe may be spooled onto the vessel in a substantially 17 continuous manner so as to minimise the time required 18 for the spooling operation.

In accordance with a first aspect of the invention, 21 there is provided pipeline storage apparatus comprising 22 a closed loop of rail track (or equivalent) lying on a 23 substantially horizontal plane, a plurality of rail 24 bogies mounted on said track and distributed around said loop, and means for driving said bogies along said 26 track in synchronism with one another, said bogies 27 being adapted to receive and retain a plurality of 28 turns of a continuous length of pipeline extending 29 around said loop.
31 Preferably, the periphery of said loop is continuously 32 curved such that at every point around the periphery 33 thereof the radius of curvature of the loop is greater 34 than a predetermined minimum value. Preferably also, said minimum radius of curvature of the loop is 36 selected such that, fvr a pipeline having a 1 predetermined maximum diameter which is intended to be 2 capable of being stored on the apparatus, the elastic 3 yield limit of that pipeline will not be exceeded by 4 bending the pipeline for storage thereon. Most preferably, said minimum radius of curvature is 6 selected so that the stresses induced on said pipeline 7 do not exceed 72~ of its elastic yield limit.

9 Preferably also, the loop is substantially circular, having a substantially constant radius of curvature.

12 Preferably also, said bogies are spaced substantially 13 equidistantly around the loop.

Preferably, the minimum radius of curvature is at least 16 150 metres so that the maximum diameter of pipe which 17 may be stored on the apparatus without stresses 18 exceeding 72~ of the elastic yield limit is at least 16 19 inches.
21 The apparatus preferably further includes pipe handling 22 apparatus for loading and offloading pipe to and from 23 said loop. The pipe handling apparatus preferably 24 includes: a pipeline path extending from a loading/offloading point on the loop for guiding the 26 pipe towards a firing line extending towards a mooring 27 location for a pipelay vessel; pipe guide means 28 suspended from a gantry traversing said track and said 29 pipe path at or adjacent to said loading/offloading point, said pipe guide means being mounted for 31 transverse movement along said gantry; and pipe 32 tensioning means located on said pipe path downstream 33 of said pipe guide means in the direction of pipe 34 offloading.
36 The pipe path preferably also includes an expansion arc 1 portion of sufficient width to allow the length of the 2 pipe path to vary in response to differential movements 3 of the bogies around the track and of a reel of a 4 pipelay vessel onto which the pipe is being spooled.
6 The expansion arc preferably comprises a series of pipe 7 supporting roller members arranged along an arcuate 8 path, the rollers having substantially horizontal axes 9 of rotation extending substantially radially with respect to said arcuate path.

12 In accordance with a second aspect of the invention, 13 there is provided a rail bogie for use in apparatus 14 according to the first aspect of the invention, said bogie including pipe supporting means and pipe 16 restraining means located on one side of the pipe 17 supporting means which faces the interior of the 18 storage loop, in use.

The pipeline contacting surfaces of the supporting 21 means and restraining means are preferably formed from 22 or faced with protective material, such as elastomer or 23 polymer material.

Preferably also, bogies in accordance with the second 26 aspect of the invention are connected together, in use, 27 by rigid, elongate coupling members connected to close 28 tolerance coupling assemblies on the ends of the 29 bogies.
31 In accordance with a third aspect of the invention, 32 there is provided a method of storing a continuous 33 length of pipeline, comprising the steps of:
34 providing a closed loop of rail track (or equivalent) lying on a substantially horizontal plane;
36 mounting a plurality of rail bogies on said track 1 such that said bogies are distributed around said loop, 2 said bogies being adapted to receive and retain a 3 plurality of turns of a continuous length of pipeline 4 extending around said loop;

5 securing a first end of a pipeline to one of said 6 bogies;

7 driving said bogies along said track in 8 synchronism with one another such that said pipeline 9 extends around said loop, supported by said bogies.
11 Preferably, said pipeline is wound onto pipeline 12 supporting means of said bogies, the first wrap of the 13 pipe abutting pipe restraining means located on one 14 side of the pipe supporting means which faces the interior of the storage loop, and subsequent wraps 16 lying side by side on said pipeline supporting means, 17 forming a first layer of pipe. Additional layers of 18 pipe my be wound on top of the first layer, the layers 19 being separated by battens. The additional layers may comprise lengths of pipe of differing diameters.

22 Embodiments of the invention will now be described, by 23 way of example only, with reference to the accompanying 24 drawings, in which:
26 Fig. 1 is a schematic plan of an onshore spoolbase 27 incorporating a pipe storage loop in accordance 28 with the first aspect of the invention;

Fig. 2 is a schematic plan view of a portion of 31 the storage loop of Fig. 1;

33 Fig. 3 is a plan view of a portion of the storage 34 loop of Fig. 1, incorporating wagon sidings;
36 Figs. 4(a), 4(b) and 4(c) are, respectively, side, 1 end and plan views of a rail bogie in accordance 2 with the second aspect of the invention;

4 Fig. 5 is a plan view of a preferred embodiment of a pipe storage loop in accordance with the 6 invention;

8 Fig. 6 is a perspective view illustrating a pipe 9 loading/offloading area of the pipe storage loop of Fig. 5; and 12 Fig. 7 is a plan view of an expansion arc forming 13 part of the storage loop of Fig. 5.

Fig. 1 illustrates the layout of one example of a 16 conventional spoolbase, located onshore adjacent a 17 coastline 10, having a pipe storage loop 12 in 18 accordance with the invention superimposed thereon.

The conventional spoolbase comprises a main pipe 21 fabrication plant 14, where individual joints of pipe 22 are welded together to form stalks. The stalks are 23 conventionally stored vn pipe racks 16, which extend 24 between the welding plant 14 and a tie-in welding station 18 adjacent the coastline 10. In this example, 26 the pipe racks are approximately 1 km in length. In 27 accordance with conventional practice, the stalks are 28 spooled onto the storage reel of the pipelaying vessel 29 (not shown) in the direction of the arrow A, tie-in welds being formed between subsequent stalks, at 31 station 18, as spooling progresses. The pipe racks 16 32 of the conventional spoolbase are rendered redundant by 33 the present invention.

The storage loop 12 in accordance with the invention 36 comprises a closed loop of rail track, having a 1 plurality of interconnected rail bogies (or wagons or 2 carriages) 100 (Figs. 2, 3 and 4) distributed about its 3 circumference. The loop is preferably circular, as in 4 this example, but may be non-circular so long as its radius of curvature is nowhere less than a 6 predetermined minimum value selected to suit the 7 maximum diameter of pipe which is to be accommodated.

9 As noted above, it is preferred that the minimum radius of curvature is selected such that the elastic yield 11 limit of the pipe is not exceeded when the pipe is bent 12 around the storage loop, and preferably such that the 13 stresses imposed on the pipe do not exceed 72$ of its 14 yield limit. For a 16 inch diameter pipe, this requires a loop approximately 300 meters in diameter 16 (ie. a radius of curvature not less than 150 meters).
17 In the illustrated example, the loop has a diameter of 18 450 meters. It will be noted however that the 19 invention is not restricted to non-plastic bending of the stored pipe. It is also possible for the pipe to 21 be bent plastically when wound onto the storage loop 22 and to be straightened on removal, allowing the minimum 23 radius of curvature of the loop to be reduced for a 24 given pipe diameter. Straightening apparatus and methods for this purpose are well known from reel 26 pipelay systems and will not be described further 27 herein.

29 Figs. 2 and 3 illustrate portions of the 450 meter diameter loop 12 of Fig. 1 in greater detail. Fig. 1 31 shows the location of two wagons 100 on the rail track 32 20. The wagons 100 will be spaced substantially 33 equidistantly around the length of the loop. In this 34 example the wagons 100 have a spacing of 18 meters between wagon centres. This would require seventy 36 seven wagons for a 450 meter diameter loop. Fig. 2 1 shows an optional arrangement for sidings 22 extending 2 into the interior of the loop 10, allowing wagons 100 3 to be taken out of the loop for servicing etc. The 4 arrangement includes two individual sidings 24, 26 with points 28, 30 at the track junctions, as will be 6 readily understood by those skilled in the art.

8 In use, pipeline fabricated in the main plant 14 is fed 9 towards the storage loop 10. As shall be described further below, the wagons 100 are adapted to receive 11 and retain the pipeline such that, when the pipeline is 12 secured to one of the wagons, the wagons may be driven 13 around the loop 12 so as to wind the pipe onto a 14 supporting surface provided by the wagons, so that multiple turns of the pipeline may be wrapped around 16 the length of the loop. This is best seen in Fig. 4, 17 which illustrates the configuration of the wagons 100 18 and the disposition of the pipe 102 thereon, in use.

The wagons 100 may be purpose built or may be converted 21 from existing rolling stock, such as conventional 22 hopper wagons. Each consists of two pairs of flanged 23 wheels 104, mounted on respective axles 106 beneath a 24 chassis 108, which engage the rails 109 of the track 20 in a well known manner. A horizontal pipe supporting 26 deck 110 is mounted on the chassis, and vertical pipe 27 retaining struts 112 are mounted on that side of the 28 chassis 108 which will face the interior of the loop 29 12, in use.
31 The struts 112 restrain inward movement of the pipe 102 32 when the pipe is wound onto the loop. As best seen in 33 Fig. 4(b), the wraps of pipe 102 lie side by side on 34 the deck 110. In this example, the wagon 100 accommodates 8 wraps of 16 inch pipe 102. For a 450 36 meter loop, this corresponds to a total pipeline length 1 of about 11 km. The pipeline contacting surfaces of 2 the deck 110 and struts 112 may be faced with 3 protective material, such as polymers or elastomers, to 4 protect the pipe against damage. In this example, the deck 110 is faced with a 25mm thickness of UHMW
6 polyethylene 114, and the struts 110 with 'D' rubber 7 116.

9 More than one layer of pipe may be wrapped on the loop.
Additional layers may be continuations of the first 11 layer, or may be comprise separate pipelines. In Fig.
12 4(a), a second layer 118 is shown comprising a separate 13 4 inch pipeline, separated from the first layer by 14 means of timber battens 120.
16 The wagons are preferably interconnected by means of 17 rigid, elongate connecting members 122, such as lengths 18 of steel pipe, connected to the wagons by suitable 19 couplings 124. The conventional "instanter" rolling stock coupling is preferably replaced with a close 21 tolerance coupling such as a clevis pin assembly, to 22 prevent relative movement between wagons which might 23 damage the pipe or pipe coatings.

Conversion of standard rolling stock preferably also 26 includes increasing the overall width and the track 27 width, and lowering the suspension and deck height.
28 The wagons may further be modified in view of the fact 29 that they will always be travelling on a closed loop with in which the inside track is shorter in length 31 than the outside track. For example, the wheels of the 32 wagons may be mounted on individual stub axles, rather 33 than in pairs on conventional through-axles.

The wagons 100 may be driven by a locomotive which may 36 be purpose built or converted from an existing 1 locomotive (the power sources of most commuter trains 2 are below floor level, allowing a clear deck area above 3 for supporting the pipe), preferably including 4 conversion to an hydraulic power source.
5 Alternatively, drive means may be incorporated into 6 some of the wagons. For example, hydraulic motors 7 could be fitted to, say, every sixth wagon, each pump 8 being electrically controlled from a central station 9 communicating with each driven wagon via an RS 232 10 interface. Speed control would be achieved using a 11 closed loop feedback system.

13 The pipeline can be wound onto the storage loop as the 14 pipeline fabrication proceeds. This could be done by assembling stalks and making tie in welds as the stalks 16 are wound onto the loop, or directly from the main 17 welding plant 14. When the pipeline is to be 18 transferred from the loop onto the reel of a pipelaying 19 vessel, the end of the pipeline which was the trailing end during winding onto the storage loop becomes the 21 leading end for spooling onto the vessel. In the 22 illustrated example, the pipe supporting wagons would 23 be driven in the same direction (counter-clockwise) 24 for both winding the pipeline onto the loop and for spooling the pipeline from the loop onto the vessel.

27 Figs. 5 to 7 illustrate a preferred embodiment of the 28 invention. A circular storage loop 212 is located 29 adjacent the coastline 210. The main storage loop 212 may be substantially the same as that described above 31 with reference to Figs. 1 to 4. In this case the 32 sidings 22 have been omitted.

34 In this embodiment the storage facility includes a pipe loading/offloading area 214 and an "expansion arc" 216, 36 both of which are described in greater detail below.

WO 97141054 PCTlGB97/01130 1 The expansion arc 216 leads from the loop 212 to a 2 firing line 218 which extends along causeway 220 to the 3 location where the pipelay vessel 222 is moored for 4 loading.
6 Fig. 6 illustrates the loading/offloading area 214 of 7 Fig. 5 in greater detail. Fig. 6 shows a portion of 8 the storage loop 212 comprising track 224 with bogies 9 or wagons 226 supporting multiple turns of pipe 228. A
gantry 230 spans the track 224, extending outwith the 11 loop 212 so as to overlie a pipe approach path which is 12 approximately tangential to the track 224 at the point 13 of loading/offloading. Suspended beneath the gantry 14 230 for transverse movement along the length thereof is a "roller box" 232 through which the pipe 228 passes 16 during loading or off loading.

18 The roller box acts as a guide for the pipe and may 19 include sensors for monitoring the position and orientation of the pipe. Pipe guides of this type are 21 used in the laying of pipe from reel-type pipelay 22 vessels such that as disclosed in US-A-4,269,540, and 23 will not be described in greater detail herein.
24 Transverse movement of the roller box 232 on the gantry 230 permits the pipe to be guided accurately during 26 loading and unloading.

28 Downstream of the roller box 232 in the direction of 29 offloading is a tensioning unit 234 for controlling the tension on the pipeline during loading and offloading 31 operations. The tensioning unit comprises a pair of 32 roller track assemblies located on either side of the 33 pipe and mounted for transverse movement with the 34 roller box 232. Pipe tensioning apparatus of this type is well known in the field of marine pipelaying and 36 will not be described in greater detail herein. The 1 tensioner applies a degree of back tension to the pipe 2 during loading and unloading and while the pipe is 3 stored on the loop, so as to oppose the tendency of the 4 bent pipe to spring outwardly. Typically, one or two tonnes of tension might be required.

7 If the storage loop is configured such that the pipe is 8 plastically deformed when wound thereon then the 9 tensioning unit 234 may also include means for straightening the pipe during offloading. The 11 straightening means may comprise a three-point 12 straightener of the type which is also well known in 13 the field of marine pipelaying. The straightener and 14 tensioner may be integrated into a single unit, as is also well known. A control cabin 236 houses the 16 personnel and apparatus required to control the 17 operation of the storage facility.

19 During offloading of the pipe, it will be necessary for the rotation of the pipe storage reel on the pipelaying 21 vessel to be coordinated with the movement of the 22 wagons 226 around the loop 212. Clearly, if the 23 movements of the reel and the wagons are not 24 coordinated with sufficient precision then it is possible that the pipe will be damaged as a result of 26 excessive tensile or compressive forces being applied.
27 For this reason, the loading/offloading arrangement 28 preferably includes an expansion arc 216 as seen in 29 Fig. 5 and further illustrated in Figs. 6 and 7.
31 The expansion arc 216 consists of a series of pipe 32 supports defining an arcuate path of sufficient width 33 to allow a nominal pipeline path 238 along the centre 34 of the path to be lengthened or shortened in response to differential movements of the reel and the wagons.
36 In this example, the expansion arc comprises a series 1 of rollers 240 having their axes of rotation extending 2 at right angles to the nominal pipeline path 238. In 3 the present example the rollers 240 are suitably about 4 10 metres in length (i.e. the path is about 10 metres wide). The rollers 240 might be reduced in length 6 towards either end of the expansion arc 216. Fig. 7 7 illustrates the maximum and minimum pipeline excursion 8 routes 242 and 244 respectively along the expansion arc 9 216.
11 It will be understood that, in the embodiment of Figs.
12 5 to 7, the pipe is loaded and offloaded along the same 13 path, so that the direction of movement of the wagons 14 is reversed in each case. The fabrication of the 15 pipeline for loading onto the loop may be carried out 16 at a welding station (not shown) at any suitable 17 location along the firing line 218. Alternatively, 18 lengths of pipe may be assembled into stalks away from 19 the firing line 218 prior to being transported to the 20 firing line, tie-in welds being made between successive 21 stalks before being spooled onto the storage loop.

23 The embodiments of the invention described herein 24 utilise conventional rail track and converted rolling stock. However, it will be appreciated that a similar 26 storage facility might be constructed using purpose-27 built tracks etc, which might differ in configuration 28 from conventional track and rolling stock.

Improvements and modifications may be incorporated 31 without departing from the scope of the invention.

Claims (23)

Claims

1. Pipeline storage apparatus comprising a closed loop of rail track lying on a substantially horizontal plane, a plurality of rail bogies mounted on said track and distributed around said loop, and means for driving said bogies along said track in synchronism with one another, said bogies being adapted to receive and retain a plurality of turns of a continuous length of pipeline extending around said loop, and further including means for loading and offloading said pipeline to and from said bogies, said pipe loading/offloading means being arranged so as to define a substantially horizontal pipe approach path which is approximately tangential to said loop at the point of loading/offloading.

2. Apparatus as claimed in claim 1, wherein the periphery of said loop is continuously curved such that at every point around the periphery thereof the radius of curvature of the loop is greater than a predetermined minimum value.

3. Apparatus as claimed in claim 2, wherein said minimum radius of curvature of the loop is selected such that, for a pipeline having a predetermined maximum diameter which is intended to be capable of being stored on the apparatus, the elastic yield limit of that pipeline will not be exceeded by bending the pipeline for storage thereon.

4. Apparatus as claimed in claim 2, wherein said minimum radius of curvature is selected so that the stresses induced on said pipeline do not exceed 72% of its elastic yield limit.

5. Apparatus as claimed in any one of claims 1 to 4, wherein the loop is substantially circular, having a substantially constant radius of curvature.

6. Apparatus as claimed in any one of claims 1 to 5, wherein said bogies are spaced substantially equidistantly around the loop.

7. Apparatus as claimed in claim 6, wherein said bogies are spaced apart from one another and adjacent bogies are connected to one another by a rigid, elongate coupling member.

8. Apparatus as claimed in claim 7, wherein each of said coupling members is connected at each end to a respective bogie by a pivot arrangement having a substantially vertical pivot axis.

9. Apparatus as claimed in any one of claims 1 to 8, wherein the minimum radius of curvature is at least 150 metres so that the maximum diameter of pipe which may be stored on the apparatus without stresses exceeding 72% of the elastic yield limit is at least 16 inches.

10. Apparatus as claimed in any one of claims 1 to 9, wherein said pipe loading/offloading means includes pipe handling apparatus for loading and offloading pipe to and from said loop.

11. Apparatus as claimed in claim 10, wherein said pipe handling apparatus includes a pipeline path extending from a loading/offloading point on the loop for guiding the pipe towards a firing line extending towards a mooring location for a pipelay vessel.

12. Apparatus as claimed in claim 11, wherein said pipe handling apparatus includes pipe guide means suspended from a gantry traversing said track and said pipe path at or adjacent to said loading/offloading point, said pipe guide means being mounted for transverse movement along said gantry.

13. Apparatus as claimed in claim 11 or claim 12, wherein said pipe handling apparatus further includes pipe tensioning means located on said pipe path downstream of said pipe guide means in the direction of pipe offloading.

14. Apparatus as claimed in any one of claims 11 to 13, wherein said pipe path includes an expansion arc portion of sufficient width to allow the length of the pipe path to vary in response to differential movements of the bogies around the track and of a reel of a pipelay vessel onto which the pipe is being spooled.

15. Apparatus as claimed in claim 14, wherein said expansion arc comprises a series of pipe supporting roller members arranged along an arcuate path, the rollers having substantially horizontal axes of rotation extending substantially radially with respect to said arcuate path.

16. Apparatus as claimed in claims 1 to 15, wherein at least some of said bogies include pipe supporting means and pipe restraining means located on one side of the pipe supporting means which faces the interior of the storage loop, in use.

17. Apparatus as claimed in claim 16, wherein the pipeline contacting surfaces of the supporting means and restraining means are formed from or faced with protective material.

18. Apparatus as claimed in claim 17, wherein the protective material is an elastomer or a polymer.

19. Apparatus as claimed in any one of claims 16 to 18, wherein a plurality of said bogies are connected together, in use, by rigid, elongate coupling members connected to close tolerance coupling assemblies on the ends of the bogies.

20. A method of storing a continuous length of pipeline, comprising the steps of:

providing a closed loop of rail track lying on a substantially horizontal plane;

mounting a plurality of rail bogies on said track such that said bogies are distributed around said loop, said bogies being adapted to receive and retain a plurality of turns of a continuous length of pipeline extending around said loop;

securing a first end of a pipeline to one of said bogies; and driving said bogies along said track in synchronism with one another such that said pipeline extends around said loop, supported by said bogies;

wherein said pipeline is loaded onto and offloaded from said bogies along a substantially horizontal pipe approach path which is approximately tangential to said loop at the point of loading/offloading.

21. A method as claimed in claim 20, wherein said pipeline is wound onto pipeline supporting means of said bogies, the first wrap of the pipe abutting pipe restraining means located on one side of the pipe supporting means which faces the interior of the storage loop, and subsequent wraps lying side by side on said pipeline supporting means, forming a first layer of pipe.

22. A method as claimed in claim 21, wherein additional layers of pipe are wound on top of the first layer, the layers being separated by battens.

23. A method as claimed in claim 22, wherein said additional layers comprise lengths of pipe of differing diameters.