GB2387833A

GB2387833A - A mobile access system and method of access thereof

Info

Publication number: GB2387833A
Application number: GB0308643A
Authority: GB
Inventors: Daniel Alexander Constantinis
Original assignee: E M & I
Current assignee: E M & I
Priority date: 2002-04-15
Filing date: 2003-04-15
Publication date: 2003-10-29
Anticipated expiration: 2023-04-15
Also published as: GB0208601D0; GB0308643D0; GB2387833B

Abstract

A mobile access system to enable personnel to gain access to an elevated position at a workface or within an enclosed site for example in marine environments such as the enclosed cargo tanks of a vessel, comprising a platform 15 which is demountable from individual components and may be assembled within the tank and suspended on cables 18 and 20 the latter being attached to the tank roof at generally horizontally spaced positions thereon so that the platform 15 is movable along the cables 20 as required. A flexible protective enclosure 30 may surround the platform 15 to provide a protective and an enclosed working environment which can be maintained at a constant pressure in excess of ambient air pressure thus allowing hot work to be performed and ensuring that undesirable residues can be contained, collected and disposed of. The whole assembly may be introduced in component form through a small opening in the tank roof and assembled and manoeuvred therein as required. A method of gaining personnel access to a elevated position at a workface or within an enclosed site, is also disclosed.

Description

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A MOBILE ACCESS SYSTEM AND METHOD

THIS INVENTION concerns a mobile access system and a method of assembling and operating same to enable personnel to gain access selectively to a range of elevated positions at a workface or within an enclosed site for example in marine environments such as the hull or cargo tanks of a vessel. The system is designed to provide a safe alternative to scaffold staging and must be made ready with minimum time and personnel involvement and be readily movable from place-to-

place at the site to provide a working stage for personnel.

For work on a vessel, the system is designed to be transported thereto and may need to be introduced into a cargo tank through a confined or restricted opening for example in the deck of the vessel, in the form of Remountable components which can then be readily assembled within the tank to form a platform which can then be elevated to a position in which work is to be carried out by personnel to be located on the platform.

Once assembled, the system can be raised and lowered and may be traversed horizontally along pre-tensioned suspension lines thus

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enabling it to be located anywhere along the lines as required. The system is not specifically designed for working personnel to ride upon the platform during its movements from one position to another but is preferably assembled and manoeuvred by experienced installation personnel prior to occupation by working personnel.

According to the present invention, there is provided, a mobile access system comprising a platform for supporting personnel, the platform consisting of Remountable components which can be transported to site and assembled thereat, a line and pulley assembly to elevate the assembled platform to an elevated position, flexible suspension lines adapted for attachment to fixed means at generally horizontally spaced positions at the site, means to suspend the assembled platform from the suspension lines thus to be transportable generally horizontally there-

along, and supporting means to attach the suspension lines to fixed means at the site at further positions between said spaced positions.

Also according to the invention, there is provided a method of gaining personnel access to an elevated position at a workface or within an enclosed site, comprising the steps of providing a personnel-supporting platform in demountable component form, a line and pulley assembly, suspension lines and supporting means therefor; transporting same to

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said workface or enclosed site; assembling the platform; elevating same by the line and pulley assembly to an elevated position at the site; attaching the suspension lines at spaced positions at or in the region of said elevated location; suspending the assembled platform from the suspension lines at a selected location therealong; and attaching the suspension lines to fixed means thereabove at the site by means of the supporting means at further positions between said spaced positions.

An embodiment of the invention will now be described, by way of example only, with reference to the accompanying drawings, in which: Fig. 1 schematically illustrates the upper internal structure of a cargo tank in a vessel, and having a mobile access system in accordance with the invention located therein; Fig. 2 is an enlarged view of the platform positioned in readiness for work to be carried out in the enclosure; Fig. 3 is a plan view illustrating the manner of suspension of the platform at opposed ends thereof;

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Fig. 4 is a partly broken perspective view from above the platform illustrating an enclosure for use therewith; and Figs. 5a to 5d schematically illustrate the manner of assembly of the enclosure with the platform.

Referring now to the drawings, the tank or internal enclosed site comprises side walls 10 and 11, a strengthening bulk head 12 and a deck or roof 13. Typically, access to the tank is by a restricted opening generally indicated at 14 in the deck 13.

A mobile access system in accordance with the invention comprises a platform generally indicated at 15 having a platform base 16 and guard rails 17 upstanding therefrom.

The platform is supported at its respective ends by cables 18 mounted by pulleys 19 on respective suspension lines 20, one above each end region of the platform 15 and attached in a generally horizontal attitude to the upper internal region of the deck 13 by means of fixed hooks 21 within the enclosure at spaced positions across the deck.

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The platform 15 with its component parts and cables 18 and lines 20 are passed through the opening 14 into the tank. After assembly from its component parts, the platform is first elevated by a line and pulley assembly (not shown) to a position in which the cables 18 and pulleys 19 are mounted on the suspension lines 20. The platform 15 may be attached to the suspension lines 20 at any position therealong, and with reference to Fig. 2 it will be seen that the lines 20, at spaced positions between their ends, and in the region where the platform 15 is to be located, are attached to adjacent fixed hooks 21 by means of cable strops 22. These strops support the suspension lines to prevent them from sagging unduly under the weight of the platform 15 and also to prevent the latter from swinging on the lines 20.

The platform may then be occupied by working personnel.

When the platform is required to be moved along the suspension lines, the strops 22 are moved to new locations adjacent the position attained by the platform. The spacing of the hooks 21 is typically in the region of 2. 6 metres where the platform with personnel working thereon may weigh typically 300kg. The rating of the suspension lines 20 is typically 1.6 tonnes.

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If the system is to be used, for example, in a ship under way then it may be necessary to provide means to secure the pulleys 19 in position on the suspension lines 20 to prevent the platform from travelling locally along the suspension lines as a result of movements of the ship.

The cables 18 suspending the platform from the suspension lines 20 may be adjustable in length as required using a pulley system thus to raise and lower the cradle to the appropriate work height. Indeed, the cables 18 may be long enough to be used to elevate the platform from the bottom of the tank to any required height therein.

Referring now to Figs. 4 and 5a to 5d, in some applications it is desirable to provide shelter for working personnel and to enclose the platform 15 within an enclosure providing a protective environment in which work may be carried out on, for example, an upright bulkhead.

In Fig. 4 it can be seen that the platform 15 is surrounded by an enclosure 30 having top and bottom walls 31 and 32 respectively, side walls 33 and 34 and a back wall 35. The walls are of a flexible material. Thus the enclosure has an open front and is bounded by a sealing flange 36 which may be held against the bulkhead or other workface.

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The enclosure 30 includes a clean air ventilation system comprising an inlet duct 37, an outlet duct 38 and an extractor fan 39.

The environment bounded by the enclosure 30 may thus be maintained at a desired moisture and temperature with clean air slightly in excess of the ambient pressure thus to prevent ingress of ambient air or moisture.

Baffles or other devices may be provided within the enclosure to ensure that the flow of clean air between the inlet duct 37 and the outlet duct 38 passes through the entire enclosure in order to scavenge any contaminants from the interior. The enclosure 30 is particularly useful, if not necessary, when carrying out hot work working within an environment which may be contaminated with hazardous gases or vapours. If required, stiffening struts 40 may extend outwardly from the enclosure 30 to rest against the bulkhead and provide additional stability for the assembly.

The enclosure 30 is suspended upon cables 41 attached to the upper corner regions of the enclosure, and sealed slots 42 may be provided for the passage of the suspension cables 18 supporting the platform 15.

The floor or bottom wall 32 of the enclosure 30 may be form ed (as at 50) to serve as a sump with drainage means 51 to enable liquids

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and other waste products to be collected, i.e. drained or pumped from the enclosure. Thus it is possible to prevent waste products from being discarded into the tank bottom or to the external environment.

Figs. 5a to 5d illustrate schematically the manner of location of the enclosure 30 over the platform 15. Fig. 5a shows the platform suspended adjacent a bulkhead or other vertical wall 50 by its suspension cables 18.

In Fig. 5b the enclosure 30 can be seen being lowered over the platform 15 on its suspension cables 41. Fig. 5c shows the enclosure 30 in position over the platform 15, and Fig. 5d shows the enclosure in a closed condition with its top wall 31 and air ducts 37 and 38.

Preferably, at least a part of the top wall 31 may be hinged or rolled back to permit working tools and the like to be lowered into the enclosure. This arrangement is particularly useful when replacing a wall panel on the bulkhead 50 such that a damaged panel may be raised from the enclosure and replaced by a new panel lowered into place.

Claims

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1. A mobile access system comprising a platform for supporting personnel, the platform consisting of Remountable components which can be transported to site and assembled thereat, a line and pulley assembly to elevate the assembled platform to an elevated position, flexible suspension lines adapted for attachment to fixed means at generally horizontally spaced positions at the site, means to suspend the assembled platform from the suspension lines thus to be transportable generally horizontally therealong, and supporting means to attach the suspension lines to fixed means at the site at further positions between said spaced positions.

2. A mobile access system according to Claim 1, wherein the

demountable components of the platform comprise a platform base and guard rails upstanding therefrom.

3. A mobile access system according to Claim 1 or Claim 2, wherein the means to suspend the assembled platform from the suspension lines comprises cables mounted, by way of pulleys, on the respective

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suspension lines with the latter located respectively above opposed end regions of the assembled platform.

4. A mobile access system according to any preceding claim, wherein the supporting means to attach the suspension lines to fixed means at the site, comprises cable strops removably attachable to the suspension lines at said further positions between said spaced positions.

5. A mobile access system according to Claim 3, including means to secure the pulleys in position on the suspension lines to prevent the platform from travelling locally along the suspension lines between said further positions.

6. A mobile access system according to any preceding claim, wherein the means to suspend the assembled platform from the suspension lines comprises cables of adjustable length.

7. A mobile access system according to Claim 6, wherein said adjustable cables are comprised by the line and pulley assembly to elevate the assembled platform to an elevated position.

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8. A mobile access system according to any preceding claim, further including an enclosure to surround the platform and enclose same against an upright wall, the enclosure being supported on one or more additional suspension lines.

9. A mobile access system according to Claim 8, wherein the enclosure has flexible walls and includes means for introducing an air supply into the interior thereof such as to maintain therein an air pressure slightly in excess of ambient pressure.

10. A mobile access system according to Claim 8 or Claim 9, wherein the enclosure has an open front and includes means to seal the enclosure against a workface, and a removable or retractable wall part to permit working tools or repair materials to be introduced into/removed from the enclosure.

11. A mobile access system according to any one of Claims 8 to 1O, wherein the enclosure has a part formed to serve as a sump and drainage means therefor.

12. A method of gaining personnel access to an elevated position at a workface or within an enclosed site, comprising the steps of providing

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a personnel-supporting platform in demountable component form, a line and pulley assembly, suspension lines and supporting means therefor; transporting same to said workface or enclosed site; assembling the platform; elevating same by the line and pulley assembly to an elevated position at the site; attaching the suspension lines at spaced positions at or in the region of said elevated location; suspending the assembled platform from the suspension lines at a selected location therealong; and attaching the suspension lines to fixed means thereabove at the site by means of the supporting means at further positions between said spaced positions.

13. A method according to Claim 12, further comprising the step of utilising the line and pulley assembly, after elevating the platform, to suspend the assembled platform from the suspension lines at said selected location.

14. A method according to Claim 12 or Claim 13, further comprising the step of removing the supporting means from the fixed means and reattaching the suspension lines to further fixed means at still further positions between said spaced positions.

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15. A method according to any one of Claims 12 to 14, including the step of permitting movement of the platform between said further positions by means of pulleys acting to suspend the assembled platform from the suspension lines.

16. A method according to any one of Claims 12 to 15, including the step of providing an enclosure; positioning same over the platform to create a protective working environment therearound; and placing the enclosure with an open front against a workface for work to be carried out thereon by personnel on the platform.

17. A method according to Claim 16, including the step of ventilating the interior of the enclosure at a pressure slightly in excess of ambient pressure.

18. A method according to Claim 16 or Claim 17, including the step of collecting waste products from the lower region of the enclosure.