GB2108172A - A tunnel for supporting cables on racks - Google Patents

Abstract

A cable tunnel for supporting and protectively enclosing long runs of cable of an industrial complex, such as a nuclear power station or an oil refinery, instead of being constructed in situ, is merely assembled on site from prefabricated modules fitted with cable racks which have been manufactured elsewhere. Each module, comprising opposed walls 12 & 13 which may be two or three metres high and five or six metres long and a roof 14 spanning across between the walls. <IMAGE>

Description

SPECIFICATION Electrical-cable enclosure and support means This invention relates to enclosure and support means for electrical cables of an industrial complex. In an industrial complex, such as a nuclear power generating installation or an oil refinery, for example, different units of the complex may have to be interconnected by many electrical cables, some carrying electrical power, some serving to transmit monitoring or controlling signals or connected to safety devices and emergency alarms, and all requiring to be adequately supported and protected, for example, from fire or other possible environmental hazards, both during construction of the complex and subsequently during its operational life-time, over what may be long runs of cable, extending over a wide area, if the complex occupies a large site.

The on-site construction of suitable cable racking and enclosure means is laborious and time-consuming, and presents difficulties in checking the quality of the work; and it is an object of the present invention to offer an improved method and means, by which such disadvantages and difficulties are much reduced, of providing the required support and protective enclosure for such electrical cables of such a complex.

According to one aspect of the invention there is provided a cable-tunnel module comprising a pair of protective longitudinal walls facing and spaced from one another, a protective roof secured to the walls and extending over the space between them, and a plurality of longitudinally extending cable support racks mounted one above another on or adjacent at least one of the walls and projecting therefrom towards the other wall, the module being constructed to be transportable as a unit whereby it can be constructed on one site and used on another.

According to another aspect of the invention, there is provided a method of building a cable tunnel of an industrial complex, for supporting a run of electrical cables of such complex, which comprises the steps of constructing a plurality of modules each as referred to in the preceding paragraph, transporting each module to its required position on the site of such complex, in end-to-end relationship with at least one other such module, and securing each module in position and to each adjacent module with which it is in such end-to-end relationship.

The invention will be more fully understood and appreciated from the following description of an illustrative embodiment of it with reference to the accompanying drawings, in which Figure 1 is a general perspective view, partly cut away to show details, of a cabletunnel module according to the invention; Figure 2 is a transverse sectional view, on a larger scale, of a module such as is shown in Fig. 1; Figure 3 is a detail transverse sectional view showing a modified construction for a module such as is shown in Fig. 1; and Figure 4 is a detail sectional view, similar to Fig. 3 but showing a further modification.

The cable-tunnel module indicated generally in Fig. 1 by the reference numeral 11 has a pair of opposed longitudinal walls 1 2 and 1 3 and a roof 14 secured to the walls 1 2 and 1 3 at their upper ends and extending over the space between them. Both the roof and the walls are fabricated as framework structures fitted with panels which fill the apertures of the framework.Thus each of the walls 1 2 and 1 3 has a footing rail 1 5 which, preferably, extends in one continuous piece over the whole length of the module, uprights 1 6 secured at their lower ends to the footing rail 15, and a top rail 1 7 to which the upper ends of the uprights 1 6 are secured.The rails 1 5 and 1 7 and the uprights 1 6 are preferably cut to appropriate length from suitable standardsection steel channels such as those available under the trademark "Unirax", or similar products, offering open-channel longitudinal grooves to receive the edges of wall panels 18, of suitable sheet material such that available under the trademark ''Durasteel", which are assembled with the framework member to form the walls. Similarly, the roof 14 is formed of joists 1 9 and roof panels 20, suitably of the same materials as the uprights 1 6 and wall panels 18, respectively, and the opposite ends of each joist being secured to the top rails 17 of the two walls 12 and 13.If desired, stiffening braces 21 may be fitted, as shown, between the upper ends of the uprights 1 6 and the adjacent ends of the joists 19.

The walls 1 2 and 1 3 are fitted at their lower edges with anchoring means, such as fixing-down plates 22, by means of which the module 11 can eventually be secured in its intended final position; and these anchoring means may be used for fitting cross braces (not shown) temporarily between the lower ends of the walls 1 2 and 1 3 so as to provide the module temporarily with extra stiffening and rigidity before it is located in its final position.

Internally of the module 11, at least some of the uprights 1 6 are fitted with horizontally projecting struts 23 which support, and to which are secured, longitudinally extending runs of racking 24, which may (as shown) be in the form of ladder racking and which is suitable to provide support for runs of cable laid along it. In a module 11 which is, say, six metres long, the walls 1 2 and 1 3 may be two or three metres high and spaced two metres apart, and both walls 12 and 1 3 may be fitted internally with struts 23 and racking 24 while still, as best seen in Fig. 2, leaving space for a central walkway between them.

In providing an industrial complex with a cable tunnel using modules like that described above, the modules are first fabricated, individually, at some convenient location which may be totally separate from the site of the complex and at which, for example, the fabrication and subsequent quality assurance testing can be carried out under factory conditions. The modules, with their racking 24 already fitted (in accordance, as will be understood, with the eventual onsite requirements), are transported to their required positions on the site and there secured (preferably on a concrete or other base prepared there to receive them) in position in the required end-toend relationship with one another.

A base prepared on site to receive the modules 11 may be provided with cast-in channel members 25 to which the fixingdown plates 22 (after removal of any temporary cross-bracing which may have been attached to them) are then bolted to secure the modules in their desired positions. To facilitate the assembly of the modules together in end-to-end relationship, each module may at one end (the nearest end as viewed in Fig. 1) have the end edges of its wall panels 1 8 and roof panel 20 exposed and ready for insertion (by longitudinal movement of the whole module) into receiving channels of the uprights 1 6 and roof joist 1 9 at the "other" end of an adjacent module to which it is to be secured.

Once it is so positioned and secured, a module is then ready to receive, in the appropriate channels of the uprights 1 6 and joist 1 9 at its other end, the exposed panel edges at the one end of the next module to be positioned. A module which is to form an end of a cable tunnel as just described may be provided with an end wall 26 fitted, if desired, with a door 27, as shown in Fig. 2.

Once the modules 11 have been assembled together on site to provide the required cable tunnel, the tunnel itself provides a protected environment in which the work of installing the cables in the tunnel can proceed almost independently of other work being done on the site. The racking 24 is already fitted in accordance with the eventual cabling requirements before the modules are brought on site, but the cables themselves, which will be long compared to the module length, are installed after the tunnel has been built (in layers 30 supported by the racking 24, as represented in Fig. 2).Similarly, lighting fittings such as fluorescent tube fittings 28 may be installed in the individual modules 11 as they are fabricated, but the wiring for such fittings may be installed after the tunnel has been built; and a fire4ighting main 29 may also be fitted after erection of the tunnel, though associated monitoring devices and smothering-gas outlet nozzles may be installed during fabrication of the individual modules. Alternatively, of course, fire-fighting pipework, lighting, vent systems and any other intended support services may all be installed completely during construction of the modules, leaving only the connecting-up to be done as the modules are assembled together on site.

Any of the modules 11, but particularly end modules (as shown in Fig. 2) which may serve as termintion or marshalling rooms for the cables, may be provided during fabrication (i.e. before being brought on site and assembled together) with other auxiliary fittings for use with the cables which will eventually be installed. For example, wall or roof panels may be formed with apertures 31 for eventual connection of the ends of external cable ducts 32, and such apertures may be provided with temporary covers 33 which can be discarded when the duct is to be connected.Cross racks 34 may be provided, preferably along an end wall of an end module, to carry cables from one side of a module to the other; for crosspatching, terminal boards 35 may be provided (secured, for example, to vertical struts 35' as shown in Fig. 2) for connection thereto, and any desired interconnection, of the ends of cables.

Within the scope of the invention, the details of construction of the modules 11 may, of course, be different from that shown in Figs. 1 and 2. For example, if enhanced fire protection is required, the construction may be such as to replace the single-thickness panels 1 8 and 20 by a double-skin arrangement of sheets 36 of suitable 1-hour fire-rated material as shown in Fig. 3, and the space between the sheets may, if desired, be filled by a suitable fire-resistant filler material 37.

Increased strength, for example to meet seismic-resistance requirements, may be imparted to the structure if, within the framework of walls and roof of the module, the cable-supporting means is supported not directly by that framework but by separate steelwork, such as additional uprights 38 as shown in Fig. 4, which is however, secured to the structure of the walls and roof and provides reinforcement therefor. If desired, the additional uprights 38 may be secured to the module framework by links 39 which are fusible at some predetermined temperature so that in the event of a serious and persistent fire (which would be sufficient to destroy the cables in any event) the link 39 will fuse and allow the cables and their supporting steelwork to fall away from the walls and roof of the module 11, thereby to increase the chance of the walls and roof maintaining their physical integrity and of their containing the fire damage within the tunnel.

Claims (20)

1. A cable-tunnel module comprising 2 pair of protective longitudinal walls facing and spaced from one another, a protective roof secured to the walls and extending over the space between them, and a plurality of longitudinally extending cable support racks mounted one above another on or adjacent at least one of the walls and projecting therefrom towards the other wall, the module being constructed to be transportable as a unit whereby it can be constructed on one site and used on another.

2. A module as claimed in Claim 1 and fitted with cross-bracing extending between the lower edges of the walls.

3. A module as claimed in claim 1 or claim 2, wherein the walls and roof are each formed as a frame-work of rails with panels of sheet material filling apertures of the framework.

4. A module as claimed in claim 3, having, at one of its ends, end edges of panels of its walls and roof exposed and having, at its opposite end, framework rails formed with receiving channels adapted to receive similarly exposed end edges of panels of another such module.

5. A module as claimed in claim 3 or claim 4, wherein the sheet material of the panels has a double-skin composite construction comprising spaced-apart sheets of fireresistant sheet material and a fire-resistant filler material between the spaced-apart sheets.

6. A module as claimed in any of claims 1 to 5, and provided at one end with an end wall.

7. A module as claimed in any of claims 1 to 6, wherein the cable support racks are supported on struts mounted on and projecting from the module walls.

8. A module as claimed in any of claims 1 to 6 and provided with additional upright members spaced inwardly from the walls, wherein the cable support racks are supported on struts mounted on and projecting inwardly from the additional upright members.

9. A module as claimed in claim 8, wherein the additional upright members are secured to the module framework by links which are fusible at temperatures to which they would be subjected in the event of a serious fire within the module.

10. A module as claimed in any of claims 1 to 9 and provided internally with a crosspatching terminal board in association with the cable racks.

11. A module as claimed in any of claims 1 to 10 and fitted with light fittings or other support-service components.

1 2. A cable-tunnel module substantially as described herein with reference to and as illustrated in the accompanying drawings.

1 3. A method of building a cable tunnel of an industrial complex, for supporting a run of electrical cables of such complex, which comprises the steps of constructing a plurality of modules each as claimed in one or more of claims 1 to 12, transporting each module to its required position on the site of such complex, such position being in end-to-end relationship with at least one other such module, and securing each module in position and to each adjacent module with which it is in such end-to-end relationship.

14. A method as claimed in claim 13 and, the modules being as claimed in claim 4, including the step of inserting exposed end edges of panels of one module into receiving channels of framework rails of an adjacent module in end-to-end relationship therewith.

1 5. A method as claimed in claim 1 3 or claim 14 and, the modules being as claimed in claim 2, including the steps of preparing on the said site a base incoporating module anchorage means and, after locating each module in its said required position on such base, removing the cross-bracing from the lower edges of the module walls and securing such lower edges to the said module anchorage means.

16. A method as claimed in any of claims 1 3 to 1 5 and, the modules being as claimed in claim 11, including the step of connecting up the support-service components of the modules.

1 7. A method of building a cable tunnel of an industrial complex, substantially as described herein with reference to the accompanying drawings.

18. A method of installing a cable run of an industrial complex, comprising the steps of building a cable tunnel by the method as claimed in any of claims 1 3 to 1 7 and laying the required cables along the said support racks of the modules of the assembled cable tunnel.

19. A method as claimed in claim 18 and, at least one of the modules being as claimed in claim 10, including the step of terminating a plurality of the cables on the terminal board thereof.

20. A method of installing a cable run of an industrial complex, subsantially as described herein with reference to the accompanying drawings.