WO1993021389A1

WO1993021389A1 - Inflatable bridge, especially for rescue purposes, and hose for stiffening the bridge

Info

Publication number: WO1993021389A1
Application number: PCT/SE1993/000325
Authority: WO
Inventors: Ulf Jörgen JENSEN
Original assignee: Trelleborg Industri Ab
Priority date: 1992-04-16
Filing date: 1993-04-15
Publication date: 1993-10-28
Also published as: AU4043693A; SE9201234L; SE9201234D0; SE468992B

Abstract

An inflatable bridge comprises longitudinal, parallel hoses (10) which support or form a walkway (12) and can be inflated by inflating means. The bridge may further comprise a tunnel-forming cover (15) that can be raised and supported by means of arch-forming inflatable hoses (16). At least the longitudinal inflatable hoses (10, 16) have a sealing layer (20) of elastomeric material and a reinforcement (21; 22, 23; 25). The reinforcement comprises inner and outer reinforcing layers (21; 22, 23; 25). The inner reinforcing layer (21) takes up tensile stresses and is formed of substantially parallel, axial reinforcing threads. The outer reinforcing layer (22, 23; 25) comprises two sets of reinforcing threads running helically in opposite directions and at an obtuse angle to one another round the hose. The hoses (10) extending in the longitudinal direction of the bridge are juxtaposed in one or more layers and interconnected by transverse reinforcing layers (11) enclosing several adjacent hoses (10) to achieve flexural rigidity also in the transverse direction of the walkway.

Description

INFLATABLE BRIDGE, ESPECIALLY FOR RESCUE PURPOSES, AND HOSE FOR STIFFENING THE BRIDGE

Many types of plants require provisions for rapid as well as safe evacuation, in particular chemical indus¬ tries, oil refineries and oil extracting plants where accidents, e.g. fires, often take a violent and rapid course. When there is a fire or another serious accident in such a plant, it is necessary to rapidly evacuate the personnel, preferably while protecting them against fire, chemical fallout and toxic gases. This has to be done regardless of whether the. plant is surrounded by open ground or is situated by or on open water.

One object of the present invention is to meet these requirements and provide a bridge for the evacuation of personnel or equipment. Another object of the invention is to provide such a bridge for spanning surfaces which it is dangerous to set foot upon or which cannot be trod upon at all. A further object of the invention is to provide an inflatable bridge of such flexural rigidity and carrying capacity that it can hang freely between two spaced-apart abutments. Yet another object of the invention is to pro¬ vide an inflatable hose for stiffening such an inflatable bridge. It is known to form bridges and evacuation chutes from inflatable hoses. For instance, inflatable evacuation ramps or chutes are commonly used in aeroplanes. However, these ramps or chutes have but slight flexural rigidity and are so sensitive to mechanical damage that the pas- sengers have to take off their shoes or boots before being allowed to slide down the ramps or chutes.

DE-A-1,034,209 discloses an inflatable footbridge or driving bridge for spanning dangerous surfaces or surfaces that cannot be trod upon at all. This bridge has two or more inflatable hoses extending in the longitudinal direc¬ tion of the bridge and connected to transversre chambers arranged at regular intervals along the bridge to serve as pontoons.

SE-B-466,612 discloses a floating bridge of metal tubes which contain roadways and are immersed in a water mass to provide a connection between nearby shores. How¬ ever, this bridge is stationary and is kept floating by the displacement of the tubes as well as by separate floating pontoons connected thereto.

SE-B-327,430 discloses a floating device which can be used as a boom or pontoon bridge and which consists of a long strip with a plurality of transverse, closed or communicating pockets. These pockets contain gas-generat¬ ing substances which, when activated, generate gas for inflating the pockets so as to distend the boom or the pontoon bridge.

PCT Publication W090/01871 discloses a floating bridge whose walkway is supported by flexible hoses. The transverse rigidity of the bridge is achieved by designing the walkway so as to be flexurally rigid in the transverse direction of the bridge, but flexible in the longitudinal direction thereof to permit adapting the bridge to the waves which form on the water supporting the bridge.

The present invention relates to an inflatable bridge or escapeway, especially for evacuation purposes, which can be rapidly put out and which, in its preferred embodi¬ ment, protects the people being evacuated during at least a critical minimum period of time, so as to give them a chance to escape from the scene of the accident. The. invention further concerns an inflatable hose for stiffen- ing such a bridge.

The characteristic features of the bridge or escape- way and the inflatable hose are recited in, respectively, appended claim 1 and appended claim 10. Especially pre¬ ferred embodiments are defined in the dependent claims. An inflatable bridge according to the invention com¬ prises longitudinal, parallel hoses which support or form a walkway and which can be inflated by inflating means. The bridge may also comprise a tunnel-forming cover that can be raised by means of arch-forming inflatable hoses. At least the longitudinal inflatable hoses have a seal¬ ing layer of elastomeric material and a reinforcement. The reinforcement comprises inner and outer reinforcing layers. The inner reinforcing layer takes up tensile stresses and is formed of substantially parallel rein¬ forcing threads or cords extending in the longitudinal direction of the hose. The outer reinforcing layer has two sets of reinforcing threads or cords running helically in opposite directions and at an obtuse angle to one another round the hose. The hoses which extend in the longitudinal direction of the bridge are juxtaposed in one or more layers and are interconnected by transverse reinforcing layers or reinforcing strips enclosing several adjacent hoses to make the walkway flexurally rigid also in the direction of its width.

The invention will be described in more detail below with reference to the accompanying drawings schematically illustrating embodiments of the inflatable bridge and the inflatable hose according to the invention. In the draw¬ ings,

Fig. 1 illustrates an opened, stationary or mobile con¬ tainer for an inventive inflatable bridge which is being pulled out or extended from a storage drum; Fig. 2 illustrates an extended inflatable bridge after the walkway and a tunnel-forming cover have been distended; Fig. 3 illustrates an embodiment of an inflatable hose according to the invention for use as a longitu¬ dinal and/or as an arch-forming distending element in a bridge according to the invention; Fig. 4 illustrates another embodiment of such an inflat- able hose according to the invention; Fig. 5 illustrates from above the interconnection of a number of juxtaposed hoses in the walkway or road¬ way of the bridge shown in Fig. 1, for imparting transverse rigidity to the bridge construction; and Fig. 6 illustrates in perspective a similar interconnec¬ tion of several juxtaposed hoses. An inflatable bridge according to the invention has a walkway formed by a number of juxtaposed, parallel and specially-reinforced hoses 10. These hoses are intercon- nected, preferably by transverse strips 11 (see Figs 5 and 6). The strips 11 are suitably arranged in .such a.pattern that the flexural rigidity of the interconnected hoses in the transverse direction of the bridge is optimised.

Conveniently, the interconnected hoses 10 are enclos- ed by an outer covering of flexible cloth or fabric mate¬ rial 12, e.g. a woven-fabric-reinforced plastic or rubber cloth. This outer covering may form the walkway or roadway of the bridge. On the outside of the covering, or some place else, lifting eyes 13 or other fastening means can be arranged to facilitate handling of the bridge in the deflated as well as the inflated state. Also, the bridge may be provided with pullropes 14 facilitating extension of the bridge (see Fig. 1).

In the embodiment shown, the bridge is also equipped with a tunnel-forming cover 15, which can be made of any suitable cloth or fabric material, e.g. a woven-fabric- reinforced plastic or rubber cloth. If the bridge is to be used where there is a risk of fire, the cloth material is preferably surface-coated with a material of high heat- reflective ability, such as a shiny metal layer, to increase the resistance of the bridge to heat radiation, thereby enhancing the protection for the people using the bridge as a means of escape.

The tunnel-forming cover 15 is connected to trans- verse, arch-forming hoses 16 for distending and supporting the cover. The ends of the hoses are anchored to the side edges of the bridge. As illustrated schematically in Fig. 5, the hoses are connected to a gas-supply unit 17, which may be a high-performance pump or a diesel engine whose fumes are used for the inflation. Preferably, however, the gas- supply unit or units 17 consist of gas generators of the type used in airbags for motor vehicles, in which case the gas-supply means can be actuated electrically. Each inflatable hose or set of hoses may also be provided with separate gas-supply means, e.g. of the type described in the above-mentioned Swedish Publication SE-B-327,430, where .the gas-generating substances are a carbonate and an acid in aqueous solution. The carbonate and the acid are kept in separate plastic bags or other containers, or the one component is kept in the inflatable hose while the other is kept in one or more plastic bags or other containers enclosed therein. When this technique is applied to the present invention, the two gas-generat¬ ing substances may be brought together by explosive car¬ tridges and electric actuators. The inflatable bridge according to the invention can be produced in lengths of e.g. 40 m and have a width of 1.2-1.5 m and an arch height of e.g. 1.9-2.1 m, if a tun¬ nel-forming cover is used. In its deflated state of pre¬ paredness, the bridge may be stored on a large hose drum 18 in a container 19. Then, such containers can be stra¬ tegically positioned in the plants requiring safe ways of evacuation.

In the embodiment illustrated, the deflated bridge is to be unrolled from a hose drum. However, the deflated bridge may also be loosely stored in a container, in which case an ejector of harpoon-gun type is used for rapidly laying out the bridge. In this case, explosive cartridges can be electrically actuated to bring the gas-generating substances in the different hoses together just before, or just after, the bridge has been fully extended. An important component of the bridge according to the invention are the hoses used for forming at least the bridge way proper, i.e. the hoses 10, but preferably also the arches, i.e. the hoses 16. These hoses are made of a special material imparting flexural rigidity and stability to the inflated hose. An instance of such a hose is illu¬ strated in Fig. 3. This hose has an inner sealing layer 20, e.g. of synthetic rubber material. On the inner layer, there is provided an axial reinforcement 21 of a material capable of taking up tensile stresses in the hose. Use is preferably made of .aramid threads which are -arranged at a reinforcing angle of V=0° (by reinforcing angle is meant the angle between the centre line of the deflated hose and the reinforcement projected perpendicular thereto). On the layer 21, there is provided an additional reinforcing layer 22 which preferably is also made of aramid fibres and which is helically wound in one direction round the hose (reinforcing angle V=60-70°, preferably V=63-68°, V=65°). On the layer 22, there is provided a further rein- forcing layer 23 having the same construction and rein¬ forcing angle as the layer 22, but being helically wound in the opposite direction. The two layers 22, 23 are thus wound at an obtuse angle to one another. Finally, an outer tube or outer layer 24, suitably made of synthetic rubber as well, is also provided. If so desired, an intermediate rubber layer may be inserted between the layers 21 and 22 and/or the layers 22 and 23.

Fig. 4 illustrates an alternative to the hose con¬ struction described above. This alternative differs from that of Fig. 3 only in that the layers 22 and 23 have been replaced with a single layer 25 which is braided on the hose at an obtuse braiding angle (the reinforcing angle V=60-70°, preferably V=63-68°, most preferred V=65° for each set of reinforcing threads or cords). Also in this case, an intermediate rubber layer may be inserted between the layers 21 and 25. In this hose construction, the layers 22, 23 and 25 will strive to change their angle towards 54.7° (i.e. the so-called neutral angle), when the construction is exposed to an internal overpressure. At the same time, the hose will strive to increase its length, which is largely pre¬ vented by the inner layer 21. As a result, two forces are acting in opposite directions, thereby imparting rigidity to the hose and making it able to support forces directed perpendicular to it (i.e. downward flexion caused by people walking or running across the bridge). Since the arch-forming hoses, which are manufactured in straight condition, are maintained in a curved state by the cloth material 15 and the fixation to the bridge edges, addi¬ tional rigidity is imparted to these hoses. Owing to the increased rigidity obtained, in accor¬ dance with the invention, in the longitudinal hoses 10, and preferably also in the arch-forming hoses 16, the bridge and the tunnel will retain their shape much better when in use. If the arches are formed by hoses of the type shown in Figs 3 and 4, they will, in addition, help stif¬ fen the footbridge or driving bridge in the transverse direction.

In an inflatable bridge according to the invention, the hoses 10 may have a diameter of e.g. 0.3-0.8 m, and the hoses 16 may have a diameter of e.g. 0.15-0.3 m.

As appears from the foregoing, a bridge according to the invention can be rapidly laid out by using quick-act¬ ing pumps or, which is preferred, by generation of gases in the different hoses. The bridge is so designed that, when collapsed, it can be stored on large hose drums or in containers, whence it is ejected by harpoon-gun tech¬ niques. If a tunnel-forming cover is employed, the escap¬ ing personnel can be protected against poisonous or other¬ wise harmful chemicals as well as against heat radiation. If the cloth material 12 round the hoses 10 and the cloth material 15 in the tunnel-forming cover are properly designed, the bridge may provide effective protection for several minutes in the case of violent fires that may arise in refineries or in other places where toxic and combustible chemicals are handled. If the cloth material consists of heat-resistant rubber containing suitable fire-protecting additives and fillers, protection can be further enhanced.

By a suitable interconnection of the juxtaposed hoses 10 in two or more layers, the bridge will have a bearing capacity in the longitudinal as well as the transverse direction such that it can serve as suspension bridge between two stationary abutments. As a result, the bridge may also be used at sea as a rescue bridge e.g. between two ships, in which case it may additionally serve as a life raft.

Claims

1. An inflatable bridge comprising longitudinal, parallel and inflatable hoses (10) arranged in the lon¬ gitudinal direction of the bridge to support or form a walkway (12) and connected to or comprising inflating means (17), c h a r a c t e r i s e d in that the inflatable hoses (10) have a sealing layer (20) of elas- tomeric material and a reinforcement (21; 22, 23; 25) comprising a tensile-stress-absorbing inner reinforcing layer (21) made up of substantially parallel reinforcing threads or cords extending in the longitudinal direction of the hose, and a hose-expansion-limiting outer reinforc- ing layer (22, 23; 25) comprising two sets of reinforcing threads or cords running helically in opposite directions and at an obtuse angle to one another round the hose, and that the hoses (10) are juxtaposed in one or more layers and interconnected by transverse reinforcing layers (11) enclosing several adjacent hoses (10).

2. A bridge as set forth in claim 1, c h a r a c ¬ t e r i s e d in that it further comprises a tunnel- forming superstructure (15) made of flexible cloth or fabric material and connected to arch-forming inflatable hoses (16) arranged transversely of the bridge and con¬ nected to the long side edges thereof, said arch-forming inflatable hoses (16) being connected to or comprising inflating means (17) .

3. A bridge as set forth in claim 2, c h a r a c - t e r i s e d in that also the arch-forming hoses (16) have a sealing layer (20) of elastomeric material and a reinforcement (21; 22, 23; 25) comprising a tensile- stress-absorbing inner reinforcing layer (21) made up of substantially parallel reinforcing threads or cords extending in the longitudinal direction of the hose, and a hose-expansion-limiting outer reinforcing layer (22, 23; 25) comprising two sets of reinforcing threads or cords running helically in opposite directions and at an obtuse angle to one another round the hose.

4. A bridge as set forth in any one of claims 1-3, c h a r a c t e r i s e d in that the outward layer of material (12, 15) of the bridge is, or is provided with, a surface layer of a fireproof material which preferably is heat-reflective.

5. A bridge as set forth in any one of the preceding claims, c h a r a c t e r i s e d in that the two sets of reinforcing threads or cords of the hose-expansion- limiting outer reinforcing layer (22,.23) extend as sepa¬ rate partial layers (22, 23) one outside the other.

6. A bridge as set forth in any one of claims 1-4, c h a r a c t e r i s e d in that the two sets of rein- forcing threads or cords of the hose-expansion-limiting outer reinforcing layer (25) together form a braided rein¬ forcing layer (25).

7. A bridge as set forth in any one of claims 1-5, c h a r a c t e r.i s e d in that the reinforcing threads or cords of the hose-expansion-limiting outer reinforcing layer (22, 23; 25) run helically round the hose at a rein¬ forcing angle of 60-70°, preferably 63-68°, most preferred 65°, measured in the deflated state of the hose.

8. A bridge as set forth in any one of the preceding claims, c h a r a c t e r i s e d in that the bridge in the deflated state is rolled up on a hose drum (18) to enable it to be paid out for evacuation purposes.

9. An inflatable hose (10, 16) adapted to reinforce an inflatable bridge as set forth in any one of the pre- ceding claims and comprising a sealing layer (20) of elas- tomeric material and a reinforcement (21; 22, 23; 25), c h a r a c t e r i s e d in that the reinforcement (21; 22, 23; 25) comprises a tensile-stress-absorbing inner reinforcing layer (21) made up of substantially parallel reinforcing threads or cords extending in the longitudinal direction of the hose, and a hose-expansion-limiting outer reinforcing layer (22, 23; 25) comprising two sets of reinforcing threads or cords running helically in opposite directions and at an obtuse angle to one another round the hose.

10. A hose as set forth in claim 9, c h a r a c - t e r i s e d in that the two sets of reinforcing threads or cords of the hose-expansion-limiting outer reinforcing layer (22, 23) extend as separate partial layers (22, 23) one outside the another.

11. A hose as set forth in claim 9, c h a r a c - t e r i s e d in that the two sets of reinforcing threads or cords of the hose-expansion-limiting outer reinforcing layer (25) together form a braided reinforcing layer (25).

12. A hose as set forth in any one of claims 9-11, c h a r a c t e r i s e d in that the reinforcing threads or cords of the hose-expansion-limiting outer reinforcing layer (22, 23; 25) run helically round the hose at a rein¬ forcing angle of 60-70°, preferably 63-68°, most preferred 65°, measured in the deflated state of the hose.