GB2247444A - Lowerator - Google Patents

Abstract

Conveying apparatus intended especially for the escape of people from an elevated structure e.g. oil rig in an emergency comprises an endless chain (2) located in a releasable receptacle (18), one end (upper) of the chain (2) passing around toothed wheels (7A - 7C) while the other chain end (lower) hangs free on release of the receptacle (18). The chain includes means (24) e.g. blocks carrying holding elements to enable persons to be carried by the endless chain the elements being released at the lower end of the chain, so that the chain, moving due to the weight of persons thereon, transports the carried persons to a lower zone to permit their escape. The toothed wheels (7A-7C) run in viscous fluid to limit the speed of movement of the chain, and brake means (12, 15) are provided to halt chain movement. <IMAGE>

Description

CONVEYING APPARATUS Description The present invention relates to conveying apparatus, especially but not exclusively for lowering personnel from an elevated location in a structure, for example in an off-shore oil or gas rig in an emergency.

The platform defining the work and accommodation sections in an off-shore oil or gas rig is necessarily located at a considerable height above water level, and consequently there is the problem of providing adequate measures to enable personnel to be evacuated quickly from the platform in an emergency for example in a fire situation. Evacuation may be achieved by lifeboats releasably carried on the rig but in a severe fire situation there may be difficulty in releasing these lifeboats and satisfactory personnel mustering at the lifeboats may not be achievable. Ladders or stairways can be provided but in an emergency situation movement via this ladder/stairway may be extremely hazardous.

It is the principal object of the present invention to provide conveying apparatus of an economic nature which enables oil/gas rig personnel to be evacuated from the rig platform in a satisfactory manner.

According to the present invention conveying apparatus comprises an endless cable; and support means for locating said endless cable in a vertical orientation; said support means being adapted to permit movement of the cable; said endless cable including holding means for personnel or objects. Preferably said endless cable comprises a chain.

Preferably the bottom of the cable is freely positioned. The suspended portion of the cable can be located in a receptacle which is movable for release of the cable to place the apparatus in an in-use condition.

Preferably restraining means are provided for limiting the speed of movement of the cable, and in an preferred embodiment these restraining means comprise a viscous damper system.

Preferably the support means comprises a set of carrying wheels.

Preferably the holding means comprises blocks, and these blocks preferably carry holding elements preferably in such a way that the elements are released automatically when the blocks are at the lower end of the cable.

Preferably brake means are provided to stop movement of the cable. Thus, by the present invention personnel can be lowered conveniently under restrained gravity effect from an elevated position such as an oil-gas rig platform to a lower automatic-release position eg at sea level.

An embodiment of the present invention will now be described by way of example with reference to the accompanying drawings wherein: Fig 1 is a schematic view of conveying apparatus in the "stored" condition for evacuating personnel in an oil/gas rig; Fig 2 shows the apparatus in the in-use condition, with the personnel carrying endless chain released so as to be suspended freely; Fig 3 shows a front view of the chain support means; Figs 4 and 5 are side and plan views respectively of the support means of Fig 3; Fig 6 shows the chain brake means in greater detail; Fig 7 shows a side view of a personnel holding block as in the descending run of the endless chain; Fig 8 shows a plan view of the block of Fig 7; and Fig 9 shows the block of Fig 7 moving into the rising run of the endless chain.

Referring to the drawings, conveying apparatus 1 constituting a descending chain escape system especially for use in an off-shore gas or oil rig comprises an endless link chain 2 supported in a free vertically suspended operative-mode by a chain support assembly 3 which has loops 4 whereby the assembly 3 is carried by a suitably positioned gantry 5. The assembly 3 comprises a casing 6 housing, in a central section 6A, a set (three) of sheaved wheels 7A-C (or wildcats as they are known around which the chain 2 passes in pockets 7D for chain driving, the wheels 7A-C being carried by shafts 8 journalled in the casing 6. An outer section 6B of the casing defines an oil chamber, having oil fill and drain plugs 9A, 9B, and portions of shafts 8 in the section 6B carry vanes 10 rotating with the wheels 7A-C for reaction with the oil in the section 6B.Hence the speed of the chain 2 when descending loaded under gravity effect is limited by a viscous damping action created by the vanes 10 rotating in the oil. Movement of the chain 2 can be stopped by a brake 11 in an outer casing section 6C, the brake 11 shown being of internal expanding type (see Fig 6) having a drum 12 coupled to the wheel 7B, brake shoes 13, and an operating cam 14 actuated by lever 15 and rope 15A, appropriate biasing springs 16, 17 being present.

To enable the apparatus 1 to be placed in a compact stand-by condition, the suspended chain 2 is received in folded manner in a receptacle or tray 18 which, in the stand-by condition (Fig 1) is pulled up to be positioned juxtaposed, the casing 6 by means of cables 19 wound on drums 20 in the casing 6, the drums 20 being driven by a ratchet wheel 21 which co-operates with a control pawl 22 for uni-directional movement of wheel 21. Guide plates 23 assist the passage of the chain 2 onto the wheel set 7A-C.

The chain 2 serves to lower personnel or objects from an elevated position eg platform P (Fig 2) to a lower position eg water level L, and to facilitate this function the chain 2 includes carrying blocks 24 (shown in detail in Figs 7-9) located at appropriately spaced positions along the chain 2, bifurcations 25 on the blocks serving for the fitting of the blocks 24 to adjacent chain links.

It is a feature of the arrangement that a release element is present in each block 24 operable to cause the conveyed person or object to fall automatically from the chain 2 at the chain lower end, and more specifically this element comprises a holding hook 26A articulated to a pin 26B which is located in a socket 27 in the block 24. Chain reversal at the lower chain end causes the socket 27 to reverse (see Fig 9) so that the pin 26B falls from the socket.

Normally the chain is held in the tray beneath the casing 6 (see Fig 1) to safeguard the chain against weathering. To place the apparatus 1 in an operative condition the pawl 22 of the drive wheel 21 is released to allow the tray 18 to descend in a controlled release through a suitable retarding mechanism. When the chain 2 is fully released (Fig 2) the tray 18 is jettisoned, and the chain 2 is now free to run and rotate wheels 7A-C.

Escapees E (personnel) can grasp a holding hook 26A of the descending chain run and hold on until they reach the chain turning zone at water level L, or if they are unable to grip the hook 26A a harness with a tumbling pin can be inserted into the socket 27 of a carrying block 24.

Likewise, a stretcher case or other object eg inflatable liferaft can be lowered to water level. To facilitate pin insertion into the block 24, the chain 2 can be stopped by pulling rope 15A to apply the brake 11. Descent is achieved by restrained gravity effect, by virtue of the viscous damping action created by the rotary vanes 10 in the oil chamber 6B, and is therefore comfortably controlled. A number of the apparatus 1 could be employed and positioned at suitable locations on the rig.

Whereas the above apparatus 1 was described in terms of an escape system, the apparatus could find use in other areas, in particular as a general conveying apparatus for articles. Modifications are of course possible. Thus instead of a chain some other form of endless cable, such as a rope, could be used, and it would be possible for some form of flexible endless ladder to be used in place of the chain.

Claims (14)

Claims

1. Conveying apparatus comprising an endless cable; -and support means for locating said endless cable in a vertical orientation; said support means being adapted to permit controlled movement of the cable; said endless cable including holding means for personnel or objects.

2. Conveying apparatus as claimed in claim 1, wherein said endless cable comprises a chain.

3. Conveying apparatus as claimed in claim 1 or 2, wherein the bottom of the cable is freely positioned.

4. Conveying apparatus as claimed.in any one of the preceding claims, wherein a receptacle is provided for releasably housing the suspended portion of the cable, the receptacle being settable to release the cable for placement of the apparatus in an in-use condition.

5. Conveying apparatus as claimed in any one of the preceding claims, wherein restraining means are provided to control movement of the cable by limiting the speed of movement of the cable.

6. Conveying apparatus as claimed in claim 5, wherein the restraining means comprise a viscous damper system.

7. Conveying apparatus as claimed in any one of the preceding claims, wherein the support means comprises a set of carrying wheels.

8. Conveying apparatus as claimed in claim 4, wherein the holding means are located in housing means which support said receptacle.

9. Conveying apparatus as claimed in claim 8, wherein hoist means are located between the housing means and the receptacle, the receptacle being capable of falling from said housing means to place the cable in the extended in-use condition, said hoist means serving for return of the receptacle with said cable portion to the housing means.

10. Conveying apparatus as claimed in claim 8 or 9, wherein the housing means include a chamber in which said support means are housed, said chamber containing viscous fluid serving to restrain movement of the support means.

11. Conveying apparatus as claimed in any one of the preceding claims, wherein the holding means comprises blocks.

12. Conveying apparatus as claimed in claim 11, wherein the blocks carry holding elements arranged in such a way that the elements are released automatically when the blocks are at the lower end of the cable.

13. Conveying apparatus as claimed in any one of the preceding claims, wherein brake means are provided to stop movement of the cable.

14. Conveying apparatus substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.