GB2306257A

GB2306257A - Cable spacer device

Info

Publication number: GB2306257A
Application number: GB9621387A
Authority: GB
Inventors: Andrew Charles Ratcliffe Tyrer
Original assignee: CRP GROUP Ltd; CRP Group Ltd
Current assignee: CRP GROUP Ltd; CRP Subsea Ltd
Priority date: 1995-10-14
Filing date: 1996-10-14
Publication date: 1997-04-30
Anticipated expiration: 2016-10-14
Also published as: GB9521093D0; GB2306257B; GB9621387D0

Abstract

A cable spacer assembly for use with underwater oil or gas pipelines, is formed from interconnected hollow cable spacer elements (10 Figures 1 and 2) having apertures 40 to allow ingress of water. Each element (10) is formed from two conjoined, semicylindrical halves 10' (Figures 3 to 5), the halves being held together by titanium bands 46, 48 in grooves 42, 44. One element (10) connects to an adjacent element by means of an internal socket 18 which is adapted to receive the flange 16 of an identical adjacent element. The inter-engagement of the socket 18 and flange 16 permits longitudinal and/or annular play of spacers which enables the assembly as a whole to flex. The neck 24 corresponds closely to the outside diameter of the cable to be positioned within the assembly and centres the cable. A clamp (50 Figure 2) may be secured to the cable in the recess 26 to prevent the assembly moving longitudinally along the cable.

Description

DESCRIPTION CABLE SPACING DEVICE The present invention relates to cable spacing devices and in particular, but not exclusively, to devices for ensuring that a cable is held at a fixed minimum spacing from a pipeline lying on the seabed to prevent any corrosion effect from abrasion or electrolytic action.

The increasing number of cables being laid on the seabed presents difficulties when they are required to cross existing oil or gas pipelines. It is normal for the owner of the existing pipeline to require the owner of a cable which is intended to cross the pipeline to ensure that the cable is spaced from the pipeline by a minimum distance which may typically be 300mm.

Such spacing can be achieved either by preinstalling "bridges" onto the seabed over the existing pipelines and subsequently laying the cable on the bridges or by firstly laying the cable directly onto the existing pipelines and subsequently using divers to position grout bags between the laid cable and the existing pipeline.

If pre-installed "bridges" or "mattresses" are laid, a lift barge or a dynamically positioned construction vessel with suitable craneage is required in order to lift the bridges into position. Close control of the subsequent cable laying operation is required in order to ensure that the cable is actually located on the pre-installed bridges, which is virtually impossible in deep water with current cableship technology. The alternative scenario of positioning grout bags between the cable and the existing pipeline is inherently expensive as a result of the requirement for divers, especially if in saturation.

It is thus an object of the present invention to provide a spacing device which may be easily and reliably positioned between a cable and an existing pipeline.

In accordance with the present invention, a cable spacer comprises two spacer halves which in use are coupled together to form a spacer, the spacer comprising a longitudinally extending cable passage, support means for retaining a cable at a substantially fixed radial position within the cable passage, a female connector portion at one end and a male connector portion at the opposite end adapted to fit into the female connector portion of an identical spacer to prevent longitudinal disengagement, but to permit longitudinal and/or angular play, of adjacent connected spacers, the spacer halves additionally being hollow and comprising an aperture to allow the ingress of water when submerged.

Several such cable spacers can be connected together over a cable, which may then be laid such that the assembled spacers will be located over a pipe positioned on the seabed, in the knowledge that the cable will always be held at a predetermined distance from the pipe.

Preferably, each cable spacer is generally cylindrical and the spacer halves are substantially identical. Preferably, each spacer half is generally semi-cylindrical and has a diametric planar abutment face which, in use, abuts an identical abutment face of an associated spacer half.

The means for retaining the cable at a substantially fixed radial position may comprise a neck portion forming part of the cable passage, the diameter of the neck portion corresponding to the outer diameter of the cable.

The female connector portion preferably comprises a socket having an aperture defined by an inturned peripheral lip. The male connector portion preferably comprises a flange whose outer diameter exceeds the inner diameter of the inturned peripheral lip, thereby preventing longitudinal disengagement but permitting longitudinal and/or angular play.

The present invention also includes a cable spacer assembly formed from a plurality of interconnected cable spacers in accordance with the present invention.

By way of example only, a specific embodiment of the present invention will now be described, with reference to the accompanying drawings in which: Fig. 1 is a side elevation of an embodiment of cable spacing device in accordance with the present invention, fitted on a cable; Fig. 2 is a side elevation, partly in cross section illustrating an end portion of the cable spacer of Fig. 1; Fig. 3 is a side elevation, partly in cross section, of a spacer section half which is used to construct the cable spacer illustrated in Fig. 1; Fig. 4 is an end elevation of the cable spacer section half illustrated in Fig. 3; and Fig. 5 is an inverted plan view of the section half illustrated in Fig. 3.

A cable spacer assembly comprises a plurality of interconnected hollow cable spacer elements 10.

Each cable spacer element 10 is formed from two conjoined, generally semi-cylindrical element halves 10'. Each half has a planar abutment face 12 which abuts the corresponding abutment face 12 of an opposed element half to form a spacer element which is externally generally cylindrical. One end of the spacer section is formed into a male connector by means of a reduced diameter cylindrical portion 14 and an enlarged flange 16 located at the outer end of the reduced diameter portion 14. The opposite end of the spacer element is provided with a female connector in the form of an internal socket 18 which is adapted to receive the flange 16 of an identical adjacent spacer section.The longitudinally outer end of the generally cylindrical socket 18 is provided with a continuous, inturned peripheral lip 20 which defines an opening 22 of greater diameter than the diameter of the flange 16 of the male connector but of smaller diameter than the reduced diameter portion 14. Thus, as the flanges 16 of identical spacer sections are inserted into the socket 18 of an adjacent spacer section, a certain amount of longitudinal and/or angular 'play" is permitted which, as illustrated in Fig. 1, enables the completed cable spacer to flex to a certain extent.

As best seen in Figs. 4 and 5, a continuous pathway for a cable extends through each spacer section, through the socket 18 and passing along the longitudinal axis of the spacer. The through passage is provided with a neck 24 which is chosen to correspond very closely with the outside diameter of the cable upon which the spacing device is to be positioned. Adjacent to the neck 24 is a clamp recess 26 (to be explained hereinafter) and an outwardly flared passage portion 28 extending from the clamp recess to male connector end.

As explained previously, each spacer 10 is formed from two identical halves 10' illustrated in Figs. 3 to 5, each half having a planar abutment face 12 adapted to engage an identical abutment face of an identical spacer half to form a spacer section.

Location of the spacer halves with respect to one another is achieved by means of lugs 30, 32 adapted to sit in complementarily-shaped recesses 34, 36 of an identical section half.

As shown in Fig. 3, the body of each section half is hollow, having a 12mm thick wall 38. Water is allowed to enter the body voids by means of a plurality of apertures 40 (and/or additional ballast can be added co the interior void of one or more of the spacer halves) in order to control or adjust the buoyancy of the cable spacer, normally to ensure that the spacer will not become buoyant in use. It will also be observed that the spacer is provided with 3 equally spaced peripheral groves 42 and the reduced diameter portion 14 is provided with two peripheral grooves 44, each for receiving a respective metal securing band 46,48 to hold together adjacent section halves to form a section.

In order to assemble the cable spacer, the lower half 10' of each of the cable spacers is laid out, with the half-flange 16 of the male connector end being received in the half-socket 18 of an adjacent cable section half (apart from the two end cable sections) . The cable C is then laid on the interconnected section halves such that it lies along the continuous longitudinal passageway formed by the communicating socket 18, neck portion 24, clamp recess 26 and outwardly flaring passage portion 28 of each section half. The upper half 10' of each section is then located on the respective lower half, whereupon the flange 16 of all but one of the sections is retained in an associated socket of an adjacent section. Titanium bands 46,48 are then applied in the recesses 42,44 in order to secure the cable section halves together.There is no need to secure together adjacent cable sections since the flange 16 is unable to move beyond the peripheral inturned lip 20 leading to the socket 18 of the female connector.

As shown in Fig. 2, one of the sections 10 receives a clamp 50 secured to the exterior of the cable to be protected, the clamp recess 26 being complementarily-shaped to the clamp. The assembled spacer is thus securely held in its longitudinal position along the cable. Any of the sections may be chosen for this purpose, but it may be most convenient to use an end section.

When the spacer is assembled on a cable as illustrated in Fig. 1, the engagement of the flanges 16 in the sockets 18 of adjacent sections permits a degree of longitudinal and/or angular movement, which enables the spacer as a whole to flex. Thus, as seen in Fig.

1, it is possible for the cable to be held away from a pipeline 44 with the spacer in engagement with the upper surface of the pipeline. Moreover, the neck portion 24 of the through passage ensures that a minimum spacing is always maintained between the cable and the pipe whereas the outwardly flared portion of the through passage leading from the clamp recess permits the cable to flex to the necessary extent.

The invention is not restricted to the details of the foregoing embodiment.

Claims

1. A cable spacer comprising two spacer halves which in use are coupled together to form a spacer, the spacer comprising a longitudinally extending cable passage, support means for retaining a cable at a substantially fixed position within the cable passage, a female connector portion at one end and a male connector portion at the opposite end adapted to fit into the female connector portion of an identical spacer to prevent longitudinal disengagement, but to permit longitudinal and/or angular play, of adjacent connected spacers, the spacer halves additionally being hollow and comprising an aperture to allow the ingress of water when submerged.

2. A cable spacer as claimed in claim 1, wherein each cable spacer is generally cylindrical.

3. A cable spacer as claimed in claim 2, wherein the support means retains the cable at a substantially fixed radial position within the cable passage.

4. A cable spacer as in any of the preceding claims, wherein the spacer halves are substantially identical.

5. A cable spacer as claimed in claim 4, wherein each spacer half is generally semi-cylindrical.

6. A cable spacer as claimed in claim 5, wherein each spacer half has a diametrical planar abutment face which, in use, abuts an identical abutment face of an associated spacer half.

7. A cable spacer as claimed in any of the preceding claims, wherein the means for retaining the cable at a substantially fixed position comprises a neck portion forming part of the cable passage.

8. A cable spacer as claimed in any of the preceding claims, wherein the female connector portion comprises a socket having an aperture defined by an inturned peripheral lip.

9. A cable spacer as claimed in claim 8, wherein the male connector portion comprises a flange whose outer diameter exceeds the inner diameter of the inturned peripheral lip.

10. A cable spacer as claimed in claim 8 or claim 9, wherein the longitudinal length of the socket exceeds the longitudinal length of the flange of the male connector portion.

11. A cable spacer as claimed in any of the preceding claims, comprising means for securing a cable longitudinally or axially with respect to the cable spacer.

12. A cable spacer as claimed in claim 11, wherein the securing means comprises a clamp securable onto a cable, the clamp being receivable in a complementarily-shaped recess.

13. A cable spacer as claimed in claim 12, wherein the recess forms part of the cable passage.

14. A cable spacer as claimed in any of the preceding claims, comprising ballast to adjust the buoyancy of the spacer.

15. A cable spacer as claimed in claim 14, wherein the additional ballast is located within the void of one or more spacer halves.

16. A cable spacer substantially as herein described, with reference to, and as illustrated in, the accompanying drawings.

17. A cable spacer assembly comprising a plurality of interconnected cable spacers as claimed in any of the preceding claims.