GB2132960A - Mobile scaffold apparatus - Google Patents

Abstract

A mobile scaffold apparatus for use on structures made of tubular elements (1), e.g. offshore oil rigs, comprises a platform (54) supported by a framework including uprights (41), transverse transoms (42,43), longitudinal ledgers (45) and support beams (46), and a first set of wheels or rollers (49) rotatably mounted on the framework and arranged to run on rails (21) secured on a tubular element (1) by means of a series of friction clamps. Each clamp consists of a bar (2) mounted over the element (1) and secured thereto by a belt (14) of flexible material passing round the element and secured to the bar (2) via a ratchet device (13). The uprights (41) of the framework are located on either side of the element (1) and serve to support the platform (54) below said element. A second set of wheels or rollers (59) rotatably mounted at the ends of rods (58) on the framework bear against opposite sides of the element (1) and serve to stabilise the framework and the platform with respect to the element. <IMAGE>

Description

SPECIFICATION Mobile scaffold structure This invention relates to scaffolding and is particularly concerned with a mobile scaffold platform for use on large diameter tubular structural elements such as, for example, those used on offshore oil production platforms.

The constructional elements of such platforms consist to a large degree of large diameter pipe-like structures. There is a frequent and recurring need to provide working platforms among these structural elements and on the underside of the decks. Much of the work that is carried out is routine inspection and maintenance and demands that either the whole of the underside of the structure be scaffolded or that a mobile scaffold be provided in order to provide workers with sufficient mobility to complete their work safely and economically.

The present invention aims to achieve this objective by providing a mobile scaffold structure which is capable of running on rails which can be fastened temporarily to large-diametertubularstructures.

According to the invention, there is provided a mobile scaffold structure comprising a platform supported by a framework, a first set of wheels or rollers rotatably mounted on the framework and a second set of wheels or rollers, said first set of wheels or rollers consisting of two pairs of wheels or rollers arranged to run on respective rails of a pair of rails secured on a tubular structural element and being so arranged that the framework surrounds the said structural element with the first set of wheels or rollers resting on rails located on the upper surface of the structural element and with the platform located below the structural element, and said second set of wheels or rollers being arranged to engage opposite sides of said structural element to stabilize the framework and platform with respect to the said tubular structural element.

The second set of wheels or rollers preferably comprises two pairs of wheels or rollers, one pair being located at or adjacent to each end of the platform with the wheels or rollers of each pair bearing against respective opposite sides of the tubular structural element. It is preferred that each wheel or roller of said second set is rotatably mounted at the end of a respective rod extending at an angle of approximately 45" to the plane of the platform.

Preferably, means are provided for immobilising at least one of said first set of wheels or rollers in order to secure the scaffold structure in a desired position. The immobilisation means may comprise a spring-loaded plunger engageable in a recess provided in a side wall of said one wheel or roller, means being provided to retract the plunger from the recess against the action of the spring.

The rails desirably consist of a plurality of rail sections, each section having a spigot at one end and being adapted to receive a spigot of another rail section at its other end, means being provided to fasten said section to clamping means on a tubular member.

According to a preferred embodiment of the invention, each rail section comprises a pair of tubular members braced apart by a series of plates and extending substantially parallel to one another, a spigot being provided at one end of each of said tubular members and being engageable in the other end of a respective one of the tubular members of another rail section.

The clamping means desirably comprise a friction clamp in the form of a bar and a belt of flexible material, the bar being adapted to be located over a tubular structural element and the belt being arranged to pass round the said structural element and to be fastened at each end to the bar, means being provided for tensioning the belt to make it grip the said tubular structural element. Preferably, the bar is provided at each end with a pair of tubes extending perpendicular to the longitudinal axis of the bar and terminating in transverse tubes which are adapted to rest on the said tubular structural element.

The bar may further be provided, at or adjacent to each end, with a pair of upstanding spigot tubes and each rail section may be provided with a tube adapted to receive a spigot tube on said bar whereby two rail sectionsforming a pair can be mounted on the friction clamp.

The invention will now be further described, by way of example, with reference to the drawings, in which: Figure 1 is a side elevation of one embodiment of a scaffold structure according to the invention showing said structure suspended from rails secured on a substantially horizontal tubular structural element; Figure 2 is an end elevation of the scaffold structure, rails and structural element shown in Figure 1; Figures 3 is a side elevation, to an enlarged scale, of one embodiment of a friction clamp for use in mounting the rails onto a structural element; Figure 4 is a plan view of the friction clamp shown in Figure 3; Figure 5 is a side elevation, to an enlarged scale, of one embodiment of a section of the rail shown in Figure 1; Figure 6 is an end elevation of the rail section shown in Figure 5;; Figure 7 is a side elevation of an end support bracket for use in conjunction with the rail section shown in Figure 5; Figure 8 is an end elevation of the end support bracket shown in Figure 7; Figure 9 is a part-sectional view, to an enlarged scale, of an embodiment of a device for immobilising the wheels of the mobile scaffold structure shown in Figure 1; and Figure 10 shows an example of a fixing pin which can be used to fasten together various components of the scaffold structure according to the invention.

In the drawings, like parts are denoted by like reference numerals.

Reference will first be made to Figure 1 of the drawings in which a pair of rails are secured in position on a substantially horizontal structural element 1. The rails consist of a plurality of sections which are mounted on friction clamps secured to the structural element 1. As shown more clearly in Figures 3 and 4, each friction clamp consists of a bar 2, which may be hollow or solid, having a pair of tubes 3 welded at its ends. The tubes 3 are braced to the ends of the bar 2 by means of bracing plates 4. A further short tube 5 is secured, e.g. by welding, to the end of each respective tube 3 and extends substantially at right angles to the associated tube 3.

The tubes 5 are designed to rest on the tubular structural element 1 as shown in Figure 2.

A hook 6 is mounted at one end ofthe bar 2 and a pair of plates 7 are secured, e.g. by welding, at the other end of the bar. A roller 8 is rotatably mounted on a pin 9 which extends between the plates 7 and is secured in bores in said plates by means of split pins 11. The bar 2 is further provided, intermediate its ends, with a further short tube 12 which is welded to the bar on the side remote from the tubes 3, that is the upper side of the bar as shown in the drawings.

This tube 12 serves as a pivot mounting for a ratchet mechanism 13 (Figure 2).

In order to secure a friction clamp on the tubular structural element 1, it is first laid on the structural element so that the tubes 5 rest on said element as shown in Figure 2. A belt 14 having a loop at one end is then fitted by hooking the loop over the hook 6 and passing the belt under the structural element to the other end of the bar 2. The belt is then passed over the roller 8 and engaged in the ratchet mechanism 13. The ratchet mechanism is then operated to tension the belt until the clamp is firmly secured on the tubular structural element 1.

A series of friction clamps are secured to the structural element 1 in like manner and then the rails can be fitted. In order to fit the rails, each friction clamp is provided with a pair of spigot tubes 15 extending from adjacent the ends of the bar 2 in a direction opposite to that of the tubes 3. The spigot tube 15 adjacent the end of the bar at which the hook 6 is provided is secured, e.g. by welding, directly to the bar 2 but the spigot tube 15 adjacent the other end of the bar 2 is secured, e.g. by welding, to the plates 7. This leaves a space between the end of the spigot tube 15 and the bar 2 between the plates 7 through which the belt 14 can pass from the roller 8 to the ratchet mechanism 13.Each spigot tube 15 is provided with two pairs of bores 16 and 17 the axes of which extend at right-angles to one another and at right angles to the axis of the tube 15 in which they are provided.

Each rail consists of a plurality of rail sections each of which comprises a pair of tubular members 21 and 22 which are braced apart by a series of plates 23. The plates 23 are secured, e.g. by welding, to the tubular members 21 and 22 at spaced apart intervals and maintain said tubular members substantially parallel to one another at a predetermined distance apart. As shown in FigureS, each tubular member 21,22 is provided at one end with a pair of aligned bores 24 in its side walls and, at the other end, with a spigot 25 likewise provided with a cross-bore 26.The spigots 25 of one rail section are adapted to fit into the ends of the tubular members 21, 22 of an adjacent rail section with the bores 24 and 26 in alignment with one another so that the two rail sections can be secured together by passing pins or bolts through the aligned bores 24 and 26 and securing them in position.

Each rail section is further provided with a short tube 27 secured to one of the plates 23 as well as to the tubular members 21 and 22. A pair of aligned bores 28 are provided in the wall of the tube 27 and said tube is adapted to fit over one of the spigot tubes 15 of one of the friction clamps. If the rail section is to extend substantially parrallel to the tubular structural element 1 as shown in Figure 1, the bores 28 are aligned with the bores 17 in the spigot tube 15 and a pin or bolt or the like is passed through the aligned bores and secured to fasten securely the rail section on the friction clamp.

The tubular structural element 1 will normally be accessible from a fixed structure at one end and a friction clamp will be fitted on the structural element at this end, the right hand end in Figure 1. A pair of end support brackets 31 will be fitted over the spigot tubes 15 of this friction clamp. As shown in Figures 7 and 8, each end support bracket comprises a tube 32 adapted to fit over a spigot tube 15 and provided with a pair of bores 33 which can be aligned with the bores 17 in the spigot tube whereby the tube 32 can be secured on the spigot tube 15 by passing a pin, bolt or the like through the aligned bores and securing the pin, bolt or the like in position.A further pair of tubes 35,36 are secured to one side of the tube 32 at its ends, the axes of the tubes 35 and 36 extending substantially parallel to one another and substantially perpendicular to the axis of the tube 32.

The tubes are held firmly together by means of a bracing plate 34 which is welded to all three tubes 32,35 and 36. The tubes 35 and 36 are each provided with a pair of aligned bores 37 and said tubes are adapted to receive the spigots 25 at the ends of the tubular members 21,22 of a rail section.

In order to mount the first pair of rail sections over the tubular structural element 1, a second friction clamp is fitted on the structural element 1 and the tubes 27 of a pair of rail sections are fitted over the respective spigot tubes 15. At the same time, the spigots 25 are fitted into the tubes 35 and 36. The bores 26 in the spigots 25 are aligned with the bores 37 in the tubes 35, 36 and pins, bolts or the like are passed through the aligned bores and secured in position to fasten the rail sections to the end supporting brackets 31. Similarly, the bores 28 in the short tubes 27 are aligned with the bores 17 in the spigot tubes 15 and pins, bolts orthe like passed through the aligned bores and secured in position to fasten the rail sections to the friction clamp. The first rail sections are now securely mounted on the structural element 1.

The second rail sections can now be mounted on the structural element 1 in a similar manner two the first rail sections except that, in this case, the spigots 25 of the second rail sections are inserted in the ends of the tubular members 21 and 22 of the first rail sections instead of in the tubes 35 and 36 of the end supporting brackets. The bores 26 in the spigots 25 are aligned with the bores 24 in the first rail sections and pins, bolts or the like are passed through the aligned bores and secured in position to fasten the second rail sections to the first rail sections.

Successive rail sections can be mounted in a similar manner to form the rails shown in Figures 1 and 2 of the drawings. As shown in Figure 1, the upper tubular members 21 of the left hand rail sections are provided with end stops 29 adapted to be secured to the members 21 by providing said end stops with spigots having cross-bores which can be aligned with the bores 24 in the tubular members.

Pins, bolts or the like can then be passed through the aligned bores and secured in position to fasten the end stops 29 to the end rail sections.

A mobile platform can now be suspended from the rails. As shown in Figures 1 and 2, the platform is supported by a framework comprising four main vertical scaffold tube 41 which are secured together by horizontal transverse transoms 42 and 43 and horizontal longitudinal ledgers 45 and longitudinal beams 46. Further, upper transverse transoms 44 may also be provided if desired as shown in Figure 2.

Secured to the transoms 42 are a pair of rods 47, each rod terminating at each end in a pair of plates 48 between which a respective wheel or roller 49 is rotatably mounted on an associated pin 51 extending through the roller and bores in the plates 48 and secured in position by split pins or the like (not shown). The rods 47 are so positioned on the transoms 42 that the rollers 49 are arranged to rest on the upper tubular members 21 of the rails. The rollers are desirably V-shaped so that the tubular members 21 can enter the V and prevent the rollers from falling off the rails.

A further pair of transoms 52 are secured to the ends of the beams 46 which transoms, together with the transoms 43, serve to support the platform which is composed of planks 54. Uprights 55 are secured to the ends of the transoms 53 and safety hand rails 56 and 57 are secured to the uprights 55. Finally, in order to stabilize the platform, rods 58 each having a respective wheel or roller 59 at one end are clamped to the hand rails 56 or 57 in such a manner that the rollers bear against the lower sides o the tubular structural element 1. The rods 58 preferably extend at an angle of 45" to the main vertical tubes 41, and hence also at 45" to the platform, and may be secured to the side hand rails 56 and/orthe end hand rails 57 in order to achieve this desired angle.Two pairs of rods 58 with associated rollers 59 are desirably provided - one pair at each end of the platform.

It will be seen that the platform can be moved along the rails on the tubular member 1 in a safe manner, the end stops 29 ensuring that the rollers 49 will not run off the ends of the rails. However, it may be desired to immobilise the platform intermediate the ends ofthe rails. Forthis purpose, one roller 49 on each rail is desirably provided in a side wall with a recess 61 in which a spring-loaded plunger 62 is engageable as shown in Figure 9. The plunger 62 is slidably mounted in a tubular housing 63 which is secured, e.g. by welding, to one of the plates 48 at the end of the associated rod 47. One end of the housing 63 is located in a bore in the plate 48 and the other end is closed by a plug 64.A coil spring 65 located in the housing bears at one end against the plug 64 and at the other end against the plunger 62 to urge said plunger against the side of the roller 49.

One end of the inner core 66 of a Bowden cable 67 is secured to the plunger 62 and passes axially through the plug 64. The other end of the Bowden cable is attached to a brake operating lever 69 which is clamped by a clamp 70 to one of the scaffold tubes 41. The brake lever 69 is also arranged to operate an identical braking mechanism on a wheel or roller on the other rail (not shown) via a cable 68.

When the brake lever 69 is operated, each plunger 62 is drawn out of the associated recess 61, against the force of the associated spring 65 and the rollers 49 are free to rotate. The platform may then be moved along the rails. However, as soon as the brake lever 69 is releaed, the plungers 62 are returned by the springs 65 to the position in which they can engage in the recesses 61 in the associated rollers 49 in orderto immobilisethe platform.

While the invention has been described with reference to a substantially horizontal tubular structural element, it should be noted that use of the mobile scaffold structure according to the invention is not limited to horizontal structural elements but can cope with quite steep angles.

The mobile scaffold structure according to the invention is safe and convenient to use. Moreover, additional rail sections can be simply fitted on the tubular structural element 1 by workmen working from the mobile platform and, in this way, the platform can be advanced, rail section by rail section, along the entire length of the structural element 1 ora like tubular structural element.

The main vertical scaffold tubes 41 of the scaffold structure preferably take the form of adjustable drop scaffold tubes as described in British Patent Specification No. 1 600 696 although other forms of tube may be used if desired.

The belts 14 are preferably made of polyester webbing material although other materials may be utilised if desired. The friction clamp is desirably made of steel with the exception of the roller 8 which is preferably made of nylon. The hand rails 56 and 57 are preferably made of aluminium tubing in the interests of lightness. The other components of the scaffold structure according to the invention are desirably made of mild steel with the exception of the rollers 49 and 59 which are preferably made of nylon.

The pins, bolts or the like for passing through the aligned bores in the components in order to fasten the various components together may take the form of spring-loaded sword pins of the type shown in Figure 10 of the drawings. As shown in Figure 10, this form of pin comprises a shank 71 having a head 72 at one end and a leaf 73 pivotally mounted on a pin 74 at the other end. A spring 76 is mounted on the shank. In order to fit the pin, the leaf 73 is pivoted into a position in which it extends parallel to the axis of the shank 71 and forms, in effect, an extension of the shank. In this position, a portion 75 of the leaf 73 is located in a slot (not shown) in the shank. The pin can now be passed through the aligned bores of a pair of components which are to be fastened together. The spring 76 is compressed until the slot in the shank is clear of the components. The leaf 73 is then pivoted to the position shown in Figure 10 of the drawings when the components and the pin will be held in position by the action of the spring 76 which serves to urge the leaf 73 against the fastened components.

It shoud be noted that the invention is not restricted to the above-desribed embodiments but modifications and variations may be made without departing from the scope of the invention as claimed in the appended claims.

Claims (20)

1. A mobile scaffold structure comprising a platform supported by a framework, a first set of wheels or rollers rotatably mounted on the framework and a second set of wheels or rollers, said first set of wheels or rollers consisting of two pairs of wheels or rollers arranged to run on respective rails of a pair of rails secured on a tubular structural element and being so arranged that the framework surrounds the said structural element with the first set of wheels or rollers resting on rails located on the upper surface of the structural element and with the platform located below the structural element, and said second set of wheels or rollers being arranged to engage opposite sides of said structural element to stabilize the framework and platform with respect to the said tubular structural element.

2. A mobile scaffold structure according to claim 1, wherein said second set of wheels or rollers comprises two pairs of wheels or rollers, one pair being located at or adjacent to each end of the platform with the wheels or rollers of each pair bearing against respective opposite sides of the tubular structural element.

3. A mobile scaffold structure according to claim 2, wherein each wheel or roller of said second set is rotatably mounted at the end of a respective rod extending at an angle of approximately 45 to the plane of the platform.

4. A mobile scaffold structure according to any preceding claim, wherein the framework includes four main substantially vertical members, said members serving to support the platform at or adjacent to one end by means of transverse members and said first set of wheels or rollers being mounted at or adjacent to the other end of said members.

5. A mobile scaffold structure according to claim 4, wherein said four main members are connected to one another at or adjacent to said other end by two pairs of transverse members.

6. A mobile scaffold structure according to claim 5, wherein said first set of wheels or rollers are rotatably mounted at the ends of a pair of rods and wherein said rods are secured to one pair of said transverse members at or adjacent to said other end of the four main members.

7. A mobile scaffold structure according to any preceding claim, wherein said first set of wheels or rollers are each provided with a V-shaped groove around the circumference adapted to receive a rail.

8. A mobile scaffold structure according to any preceding claim, wherein means are provided for immobilising at least one of said first set of wheels or rollers.

9. A mobile scaffold structure according to claim 8, wherein the immobilisation means comprise a spring-loaded plunger engageable in a recess provided in a side wall of said one wheel or roller, means being provided to retract the plunger from the recess against the action of the spring.

10. A mobile scaffold structure according to claim 9, wherein the plunger retracting means comprise a cable arranged to be operated by a lever mounted on the framework.

11. A mobile scaffold structure according to any preceding claim, wherein the rails consist of a plurality of rail sections, each section having a spigot at one end and being adapted to receive a spigot of another rail section at its other end, means being provided to fasten said section to clamping means on a tubular member.

12. A mobile scaffold structure according to claim 11, wherein each rail section comprises a pair of tubular members braced apart by a series of plates and extending substantially parallel to one another, a spigot being provided at one end of each of said tubular members and being engageable in the other end of a respective one of the tubular members of another rail section.

13. A mobile scaffold structure according to claim 11 or claim 12, wherein the clamping means comprises a friction clamp in the form of a bar and a belt of flexible material, the bar being adapted to be located over a tubular structural element and the belt being arranged to pass round the said structural element and to be fastened at each end to the bar, means being provided for tensioning the belt to make it grip the said tubular structural element.

14. A mobile scaffold structure according to claim 13, wherein the bar is provided at each end with a pair of tubes extending perpendicular to the longitudinal axis ofthe bar and terminating in transverse tubes which are adapted to rest on the said tubular structural element.

15. A mobile scaffold structure according to claim 13 or claim 14, wherein the bar is provided at one end with a hook adapted to receive one end of the belt and at the other end with a roller over which the belt is arranged to pass, the belt tensioning means being mounted on the bar intermediate its ends.

16. A mobile scaffold structure according to claim 15, wherein the belt tensioning means comprise a ratchet mechanism.

17. A mobile scaffold structure accordingto any one of claims 13 to 16, wherein the bar is further provided at or adjacent to each end with a pair of upstanding spigot tubes and wherein each rail section is provided with a tube adapted to receive a spigottube on said bar whereby two rail sections forming a pair can be mounted on the friction clamp.

18. A mobile scaffold structure according to any one of claims 11 to 17, wherein the rail sections at one end of the rails are provided with end support brackets mounted on clamping means.

19. A mobile scaffold structure according to claim 18, wherein the rail sections at the other end of the rails are provided with end stops.

20. A mobile scaffold structure substantially as described herein with referrence to the drawings.