Access system

Abstract

An scaffolding access system (1, Fig 1) comprises an elongate scaffolding tube 81 having a longitudinal axis, a scaffolding accessory attachable to said tube, and a restraint system. The restraint sy

Description

Field This disclosure relates, in one aspect, to access systems, particularly but not exclusively to access systems that are designed to facilitate working above or below a support surface, such as the ground. Such systems are colloquially known as "scaffolding systems", or often just as "scaffolding". Background Access systems comprising interconnected poles and platforms have been in use for centuries. Modern access systems tend to employ lengths of, typically, galvanised steel tubes - colloquially known as scaffolding poles or supports - that are connected together by a variety of different types of metal couplers to form a frame on which (typically wooden) scaffolding planks can be laid to form platforms. The longest modern steel scaffolding poles tend to be around 21ft (approximately 6.4m) in length, and those manufactured to BS EN 10210 can weigh in the region of 4-5kg per metre, which equates to roughly 30kg for the longest poles. A typical steel scaffolding accessory, such as a coupler (which are used to join poles together), can weigh from 1.5 to 3kgs, and a typical 13ft (circa 4m) scaffolding board tends to weigh in the region of 20kg. As a typical installation can include a large number of poles, accessories and planks, it will be apparent that the total weight of the installation can quickly become quite significant. The magnitude of the weight of the installation has many ramifications. In the first instance, transporting the necessary components required to build a given installation carries with it a relatively high environmental cost, for example in terms of the carbon emissions required to transport such a significant load. The weight, in addition to other factors such as susceptibility to corrosion and electrical conductivity, can also limit the utility of the access system, in particular as the installation may not be suitable for use in certain circumstances, for example on weak or non-load bearing roofs, in marine environments, in high voltage environments, or on fragile or unstable support surfaces. It is also the case that manhandling the components necessary to construct a given installation requires a not insubstantial amount of human effort. There are also significant safety concerns associated with persons falling from height, or equipment being inadvertently dropped or falling from height, as well as the attendant potential lethality if that equipment should happen to hit someone on the ground. Lastly, the construction and deconstruction of systems is a noisy process, not only because of tubes banging together, but also because of the operating noise associated with the electric torque wrenches that are required to ensure that the couplers are tightened sufficiently to ensure that the poles are tightly gripped by the couplers. The construction process can also often lead to hearing damage as scaffolders often do not wear ear defenders when assembling access systems. To mitigate some of the issues associated with traditional steel scaffolding, it has previously been proposed to utilise aluminium scaffolding tubes and couplers. Such systems are advantageous, compared with traditional steel systems, as aluminium is more resistant to corrosion than steel, and also significantly lighter. For example, a 20ft aluminium tube weighs in the region of 10kg as compared with 30kg for a steel equivalent. One significant drawback, however, is that aluminium has lower load carrying capabilities, which means that such systems may not be suitable for supporting heavy loads at height or depth, or for systems that need to reach greater heights or depths (typically heights of more than 12 to 15m). In another attempt to address at least some of the issues associated with steel and aluminium scaffolding, it has previously been proposed to provide access systems that are of a composite material, predominantly plastics based. For example, United Kingdom Patent Application 2501614 discloses a scaffolding tube that comprises a fibre-reinforced polymer provided in layers, where the fibres of at least one layer are differently orientated to those of another. International PCT Patent Application no. 2013 / 132255 discloses a polymeric coupler that can be used with structural tubes, for example fire-reinforced polymer tubes of the type disclosed in the above-mentioned UK patent application. Another, more recent, polymeric coupler is disclosed in GB2578862. Whilst these composite tubes and couplers have similar load carrying abilities to conventional steel tubes and couplers and enjoy the weight advantages associated with aluminium systems (composite tubing tends to weigh in the region of 1.3 kg per metre), they suffer from the drawback that couplers clamped on tubes can tend to slide along the tubes, particularly if the tubes and couplers should become wet (as can often happen when they are used outside), as it can be difficult to achieve a sufficient clamping force for the coupler on the tube. This disadvantage has tended to limit the use of composite scaffolding systems to indoor installations. In an attempt to address this particular drawback, it has previously been proposed to use metal couplers with polymeric tubes, as metal couplers can be tightened to such a degree that they are less likely to slip along the tube. However, in so doing it is easy to tighten the couplers to such an extent that they cut into, and damage, the tubing. Such damage can, at worst, affect the structural integrity of the entire installation or, at best, mean that damaged tubes cannot be reused and must be discarded. Aspects of this disclosure have been devised with the foregoing in mind. Summary In one presently preferred implementation of the teachings of this disclosure there is provided an access system comprising: an elongate scaffolding tube having a longitudinal axis; a scaffolding accessory attachable to said tube; and a restraint system, said restraint system comprising a first part provided on at least part of an external surface of said scaffolding tube and a second part provided on a part of said accessory that is proximate the external surface of said tube when the accessory is attached to the tube, the first and second parts of said restraint system being configured to cooperate when the accessory is attached to the tube to inhibit relative movement of the accessory and the tube in a direction parallel to the longitudinal axis of the tube. An advantage of this implementation is that as the restraint system functions to inhibit relative movement of the accessory and tube, the likelihood of an accessory sliding along the tube is significantly reduced. This is particularly, but not exclusively, important for composite scaffolding systems as it enables such systems to be a viable alternative to aluminium or galvanised steel systems. In an implementation, said tube may comprise a composite material, including a plastics material. The tube may comprise a fibre-reinforced polymer. The fibre-reinforced polymer may be provided in layers. The fibres of at least one layer may be differently orientated to those of another. In one arrangement the first part of said restraint system may be integral with the tube. In one arrangement the second part of said restraint system may be integral with the accessory. In another arrangement the first part of said restraint system may comprise a sleeve securable around at least a portion of the tube. In another arrangement, the second part of said restraint system may comprise an insert for said accessory. In one implementation the first and second parts of said restraint system may be configured to interfere with one another when the accessory is attached to the tube. The first and second parts of said restraint system may be configured to interlock with one another when the accessory is coupled to the tube. The first and second parts may be shaped to have profiles that are complementary to one another. The first and second parts may have profiles that are the inverse of one another. The first and second parts may have complementary Whitworth profiles. The first and second parts of said restraint system may be shaped to have profiles that are similar to one another. The first and second parts of said restraint system may be shaped to have profiles that are different from one another. The accessory may comprise at least one connector, said connector comprising: a main body that includes a channel in a face thereof; a moveable component pivotally attached to the main body, and a latch assembly; wherein said moveable component comprises a channel that cooperates with the channel of the main body to provide an opening through the accessory for receiving a scaffolding tube, and the latch assembly is operable to draw the moveable component towards the main body to clamp the accessory to a scaffolding tube extending through the opening. In one implementation at least one of the main body and the moveable component may comprise the second part of said restraint system. The accessory may comprise a first connector for coupling the accessory to a first scaffolding tube and a second connector for coupling the accessory to a second scaffolding tube. The first and second connectors may be pivotally coupled to one another so that said first and second tubes may be arranged at any desired angle to one another (or in other words, can swivel relative to one another). The position of the first and second connectors relative to one another may be fixed. The accessory may comprise a connector and a bracket for holding a scaffolding plank or protective barrier. Another aspect of this disclosure relates to a scaffolding tube for an access system of the type disclosed herein, the scaffolding tube being elongate and having a longitudinal axis, said scaffolding tube further comprising a first part of a restraint system provided on at least part of an external surface of said scaffolding tube, said restraint system further comprising a second part provided on a part of a scaffolding accessory that is proximate the external surface of said tube when the accessory is attached to the tube, the first and second parts of said restraint system being configured to cooperate when the accessory is attached to the tube to inhibit relative movement of the accessory and the tube in a direction parallel to the longitudinal axis of the tube . A further aspect of this disclosure relates to a scaffolding accessory for an access system of the type disclosed herein, the scaffolding accessory being attachable to a scaffolding tube that has a longitudinal axis, said scaffolding accessory comprising a second part of a restraint system provided on a part of the scaffolding accessory that is proximate an external surface of said tube when the accessory is attached to the tube, said tube comprising a first part of said restraint system provided on at least part of the external surface of said scaffolding tube, the first and second parts of said restraint system being configured to cooperate when the accessory is attached to the tube to inhibit relative movement of the accessory and the tube in a direction parallel to the longitudinal axis of the tube. Another aspect of this disclosure relates to an access system comprising a plurality of scaffolding tubes of the type disclosed herein, and a plurality of scaffolding accessories of the type disclosed herein. Other advantages and aspects of the access system disclosed herein will be apparent from the detailed description provided below. Brief Description of the Drawings The teachings of this disclosure, and arrangements embodying those teachings, will hereafter be described only by way of illustrative example with reference to the accompanying drawings, in which: Fig. 1 is a schematic perspective view of an access system installation that embodies the teachings of this disclosure; Fig. 2 is a schematic perspective view of an accessory, in this particular example a 90-degree coupler, that embodies the teachings of this disclosure; Fig. 3 is a schematic representation of two accessories of the type shown in Fig. 2 that are employed to couple together three scaffolding tubes; Fig. 4 is a schematic perspective view of another accessory, in this particular example a multi-angle coupler, that embodies the teachings of this disclosure; Fig. 5 is a schematic representation of an accessory of the type depicted in Fig. 4 coupling together two scaffolding tubes at a non-orthogonal angle to one another; Fig. 6 is schematic representations of another scaffolding accessory, in this instance a scaffold board retaining clamp, used to couple scaffolding boards to horizontal tubes to form a platform; Fig. 7 is a view of the accessory of Fig. 6, used in this instance as a toeboard clamp; Fig. 8 is a photograph of part of a scaffolding tube that embodies the teachings of this disclosure; Fig 9 is a diagrammatic lateral cross-sectional view of the tube depicted in Fig. 8; Fig. 10 is an enlarged perspective view of the accessory of Fig. 2 arranged to orthogonally couple together two scaffolding tubes of the type depicted in Figs. 8 and 9; Figs. 11a, 11b and 11c are schematic cross-sectional views of parts of illustrative scaffolding tubes; Fig. 12a is a schematic representation of two co-operating surfaces; Fig. 12b is a diagrammatic representation of a profile of the surfaces of Fig. 12a; Figs. 13a, 13b and 13c are schematic cross-sectional views of other illustrative arrangements; Fig. 14 is a photograph of a coupler with one open connector, showing a movable component, and Fig. 15 is a photograph of the coupler shown in Fig. 14 showing a main body. Detailed Description Although preferred implementations of the teachings of this disclosure are described below in detail with particular reference to composite scaffolding tubes and accessories, it will be appreciated that these implementations are merely illustrative and hence should not be construed as limiting the scope of the present disclosure solely to composite scaffolding systems. For example, the teachings of the present disclosure could equally be applied to wooden, graphene or metal scaffolding systems. That said, it is the case that the advantages associated with the teachings provided herein are most apparent when those teachings are implemented in composite scaffolding systems. As noted above, composite scaffolding systems have previously been proposed. The tubes disclosed herein may be manufactured by means of techniques and processes similar to those that are disclosed in United Kingdom Patent Application 2501614. In particular, the composite scaffolding tubes disclosed herein may be of a fibre-reinforced polymer that is provided in layers, where the fibres of at least one layer are differently orientated to those of another. Likewise, the techniques disclosed in International PCT Patent Application no. 2013 / 132255 for the manufacture of a polymeric coupler that can be used with structural tubes, for example fibre-reinforced polymer tubes of the type disclosed herein and in the above-mentioned UK patent application, may also be employed to manufacture couplers and other scaffolding accessories of the type disclosed herein. Referring now to Fig. 1, there is provided a schematic front perspective view of an access system installation 1 that embodies the teachings of this disclosure. The installation 1 comprises - in this example - six longer scaffolding tubes that function as risers 3 and extend substantially vertically from the support surface on which the installation has been built. A first pair 5 of risers forms one end of the installation and the risers of that first pair are connected by four shorter tubes 7. Likewise, a second pair 9 of risers that form the other end of the installation are similarly interconnected by four shorter tubes 11 (only two of which are visible). The shorter tubes co-operate to provide a support for a platform consisting of a plurality of scaffolding planks 13 laid side-by-side, and to form a guardrail that is intended to stop persons on the platform from falling off either end of the installation. A third pair 15 of risers is provided roughly midway between the first and second pairs 5, 9 of risers. The third pair 15 of risers are connected to one another by a shorter scaffolding tube 17 that forms part of the support for the platform, and to the first and second pairs by means of a pair of longer tubes 19 (only one of which is visible) at the front and rear of the installation. Additional longer tubes 21 coupled to each of the first, second and third pairs of tubes form a guardrail that is intended to stop persons on the platform from falling from the front of the installation. Tubes are not provided on the opposite back side of the installation, as this side will abut against the building, for example, that the installation is built against. The installation also comprises, in this instance, three angled bracing tubes 23 that have been coupled between tubes to enhance the structural rigidity of the installation. Referring now to Figs. 2 and 3, there is depicted a scaffolding accessory, known as a coupler 25, that can be employed to couple two scaffolding tubes together at right angles to one another. As shown in Fig. 3, a first coupler 25(i) may be employed to couple a first tube 27 to a second 29, and a second coupler 25(ii) may be employed to couple the first tube 27 to a third 31. As shown in Fig. 3, in the resulting arrangement, all three tubes 27, 29, 31 are orthogonal to one another. The coupler 25 comprises a main body 33 that includes a first channel 35 in a first surface and a second channel 37 in a second surface opposite the first. The first and second channels, as shown in Fig. 2, are orthogonal to one another. A first moveable component 39 is coupled by a pivot 41 to one side of the main body 33 (the upper side, in the depicted orientation), and a second moveable component 43 is coupled by a pivot 45 to an opposite side of the main body 33 (the lower side, in the depicted orientation). The first and second moveable components include channels 42, 44 that co-operate with the first and second channels 35, 37, respectively, in the main body to form openings through the coupler - which openings are generally circular in cross-section when the moveable components are in the position shown in Fig. 2 and extend orthogonally to one another. A first latch assembly 47 is pivotally coupled to the main body and can be tightened, in the arrangement shown in Fig. 2 to draw the first moveable component 39 towards the main body and into clamping engagement with a scaffolding tube - not shown - extending through the opening defined by the first moveable component and the main body. Likewise, a second latch assembly 49 is pivotally coupled to the main body and can be tightened, in the arrangement shown in Fig. 2 to draw the second moveable component 43 towards the main body and into clamping engagement with a scaffolding tube - not shown - extending through the opening defined by the second moveable component and the main body. The main body, first moveable component and first latch assembly form a first connector 51 that enables the accessory to be coupled to a first tube; and the main body, second moveable component and second latch assembly form a second connector 53 that enables the accessory to be coupled to a second tube. All of the accessories herein disclosed include at least one connector. Referring again to Fig. 2, for each connector 51, 53 at least part of at least one of the main body and moveable component surfaces that co-operate to provide an opening through the coupler includes a plurality of ribs, ridges or projections that extend from the main body or moveable component, respectively, into the opening. In a preferred implementation, the ribs, ridges or projections that extend into the opening comprise the above mentioned second part of the restraint system. In one envisaged arrangement, both the surface of the main body that forms the first channel 35 and the surface of the first moveable component 39 that forms channel 42 include a plurality of projections, for example ribs or ridges, that project from the main body and the first moveable component into the opening through the accessory. Likewise, it is envisaged that both the surface of the main body that forms the second channel 37 and the surface of the second moveable component 43 that forms channel 44 include a plurality of projections, for example ribs or ridges, that project from the main body and the second moveable component into the opening through the accessory. Referring now to Figs. 4 and 5, there is depicted another scaffolding accessory, known as a multi-angle coupler 55, that can be employed to couple together two scaffolding tubes at any desired angle to one another. As shown in Fig. 5, one such coupler 55 may be employed to couple a first tube 57 to a second 59 so that the second tube 59 is at an angle, in this instance roughly 30 degrees, to the first. As shown in Fig. 4, the coupler 55 - in common with the coupler 25 shown in Fig. 2 - comprises first and second connectors 61, 63 that enable it to be connected to two scaffolding tubes. The connectors 61, 63 of the accessory shown in Fig. 4 are the same as and operate in the same way as the connectors 51, 53 of the accessory shown in Fig. 2, and hence - for brevity and to avoid unnecessary repetition - will not be further described herein. The difference between the coupler 55 shown in Fig. 4 and the coupler 25 shown in Fig. 2 is that the main body 33 of the coupler in Fig. 2 comprises a single body, whereas the main body 33 of the coupler of Fig. 4 comprises a first main body component 67 (in the orientation shown, the upper component) and a second main body component 69 (in the orientation shown, the lower component) that are pivotally coupled to one another by a pivot hinge (not visible) so that one body component (and hence connector) can pivot (swivel) relative to the other thereby enabling two scaffolding tubes to be coupled together at any desired angle. Of particular note, for the purposes of this disclosure, is that for each connector 61, 63 at least part of at least one of a main body component and moveable component surfaces that co-operate to provide an opening through the coupler includes a plurality of ribs, ridges or projections that extend from the main body component or moveable component, respectively, into the opening. In one envisaged implementation, the ribs, ridges or projections that extend into the opening comprise the above mentioned second part of the restraint system. In one envisaged arrangement, both the surface of the first and second main body components 67, 69 and the co-operating moveable components that define the openings include a plurality of projections, ribs or ridges, that extend into the respective openings through the accessory. Figs. 14 and 15 are photographs of a coupler with one connector open. Fig. 14 is a view of the moveable component of the coupler and Fig. 15 is a view of the main body. In both instances the projections, ribs or ridges on the moveable component and main body, respectively, are clearly visible. Referring now to Figs. 6 and 7, there is depicted another scaffolding accessory 71, in this instance a scaffold board retaining clamp that can be used, as shown in Fig. 6, to couple boards 73 to a tube 75 to form a platform; or, as shown in Fig. 7, as a clamp for securing a toeboard 77 to the platform (the "toeboard" being the plank that runs along the front of the installation in Fig. 2, and is orientated so as to be orthogonal to the platform). Unlike the accessories previously described, the accessory shown in Figs. 6 and 7 comprises only a single connector 79, and hence can only be coupled to a single scaffolding tube. Otherwise, the connector 79 of the accessory shown in Figs. 6 and 7 is the same as the connectors of the other accessories herein described, and hence - for brevity and in order to avoid unnecessary repetition - will not further be described. That said, it is of particular note for the purposes of this disclosure, that in one envisaged implementation at least part of at least one of the surfaces which co-operate to provide an opening through the accessory include a plurality of ribs, ridges or other projections that extend into the opening. In one envisaged implementation these ribs, ridges or projections that extend into the opening comprise the above mentioned second part of the restraint system. Fig. 8 is a schematic perspective view of a length of composite scaffolding tube 81. As shown the tube 81 includes an outer surface, a portion 83 of which has been profiled (or in other words, shaped or formed) so as to comprise a plurality of parallel grooves 85 that - in this particular implementation - extend around the entire circumference of the tube. In one implementation these grooves form the first part of the aforementioned restraint system. Fig. 9 is a cross-sectional view of the tube depicted in Fig. 8. In this particular example, the tube has an internal diameter of 35 mm, and an external diameter of 48.3 mm (which outside diameter is the standard size for scaffolding that meets BS1139 EN39). The grooves 85, denoted by the dashed line in Fig. 9, are each 3 mm deep, so that the diameter of the tube at the base of each groove is 45.3 mm. In this instance the wall of the tube is in the region of 13mm thick. In other envisaged arrangements the wall of the tube is at least 4 mm thick and up to 15 mm thick. Other dimensions for the tube are envisaged. For example, it might be that tubing which is intended to provide a guardrail (and hence will not be as heavily loaded) might have a thinner wall than tubing that is intended for use as risers (and hence will be more heavily loaded). In one envisaged arrangement, the tubing could be colour coded by application with tubing that is suited for heavy loading bearing a different colour to tubing that is not suitable for heavy loading. In one implementation the grooves are formed in a second step of a two-step process, the first step being the extrusion, pultrusion or pull winding of the tube, and the second step being machining the tube to form the grooves. In accordance with the teachings of this disclosure, the grooves in the tube are shaped to co-operate with the ribs of the accessories herein disclosed to resist movement of the accessory along the tube and thereby provide the aforementioned restraint system. In one arrangement the ribs in the accessories interfere with the grooves in the tube, and in other arrangements the ribs in the accessories mechanically engage or otherwise inter-engage or interlock with the grooves in the tube. Fig. 10 is a schematic representation of two scaffolding tubes 81 that have been coupled together with an accessory 25 of the type shown in Fig. 2. As the ridges inside the accessory co-operate with the grooves in the tube, movement of the accessory along the tube is inhibited. This means that composite tubes and accessories of the type disclosed herein can be used outside, as the accessories are restrained from sliding along the tubing when wet. Another advantage is that the mechanical coupling, co-operation and / or interference is such that the accessories do not need to be tightened to such a high torque value as traditional steel scaffolding - lessening the time taken and noise associated with the build of a given installation, as well as the likelihood of composite tubing being damaged by excessive tightening. Referring now to Figs. 11a to 11c, there is depicted a schematic longitudinal cross sectional view of a length of tubing illustrating three contemplated shapes for the grooves in the tubing. In each of the examples depicted, the tubes have been shaped so that the grooves provide a Whitworth profile - which profile can mechanically engage with a like complementary inverse profile (and potentially with a similar profile) on the inside of an accessory (not shown) that is clamped on the tube. Whitworth profiles are normally associated with screw-threads, and indeed were the subject of a British standard for screw-threads. The British Standard Whitworth (BSW) is a, now superseded, screw thread standard that used imperial (inch-based) units. It was devised and specified by British engineer Joseph Whitworth in 1841, making it the world’s first national screw thread standard. When employed as a screw-thread, a Whitworth Profile provides a plurality of continuous parallel helical peaks and troughs that are orientated diagonally relative to the length of the screw. However, in this implementation of the teachings of this disclosure the Whitworth profile has been rotated from the diagonal to provide a plurality of discrete peaks and troughs which run in parallel to one another around the circumference of the tube, and perpendicularly to the length of the tube. Surprisingly, re-orientating a Whitworth profile in the manner taught in this disclosure can provide complementary Whitworth profiled surfaces that mechanically engage and interlock when brought together. In Fig. 11a the Whitworth profile has an angle of 66 degrees, a radius of 0.25 mm and a pitch of 2 mm. In Fig. 11b the Whitworth profile has an angle of 43 degrees, a radius of 0.5 mm and a pitch of 4 mm. In Fig. 11c the Whitworth profile has an angle of 60 degrees, a radius of 0.5 mm and a pitch of 4 mm. Fig. 12a is a schematic representation of two lengths of material with co-operating Whitworth profiles, as one might observe were one to look at a longitudinal cross-section of a tube secured in one of the aforementioned accessories. Fig. 12b is a diagrammatic representation of the Whitworth profile of the material shown in Fig. 12a. As shown in Fig. 12b, in the example depicted in Fig. 12a the profile on each length of material has an angle of 55 degrees, a radius of 1.5 mm and a pitch of 5.36 mm. As will be apparent to persons of skill in the art, the lengths of material depicted in Fig. 12a can be fitted closely together, for example with the profiles mechanically interengaging, so that movement of one length relative to the other in a direction parallel to the lengths of material is resisted. In general terms, in the context of a Whitworth profile in accordance with the teachings of this disclosure, it is preferred for the profile to have an angle of between 40 to 70 degrees inclusive, a radius of between 0.2 to 2.0 mm inclusive and a pitch of 2 to 7 mm inclusive. In a particularly preferred arrangement, the profile may have an angle of between 40 and 70 degrees inclusive, a radius of between 0.2 and 1.5 mm inclusive, and a pitch of between 1.5 and 6 mm inclusive. More preferably, the profile may have an angle of between 43 and 66 degrees inclusive, a radius of between 0.25 and 1.5 mm inclusive, and a pitch of between 2 and 5.5 mm inclusive. Figs. 13a, 13b and 13c are schematic cross-sectional views of other illustrative arrangements for the accessory surface 89 and tubing surface 91. In Fig. 13a two surfaces with a triangular profiled region are depicted, the profiles having roughly the same shape so that the two surfaces will mate when brought together. Fig. 13b shows two surfaces that have very different profiles, but which will nevertheless mate to resist movement of either surface in the directions indicated by the arrow when the two surfaces are brought together. Fig. 13c depicts yet another pair of surfaces which have different profiles but will nevertheless co-operate to resist movement of either surface in the directions indicated by the arrow. In general terms, a key aspect of the teachings of the disclosure is the concept of addressing the issue of accessories moving along scaffolding tubes by profiling at least part of the tube and at least part of the accessory so that the tube and accessory cooperate when coupled together to resist such movement. In principle, any profile that provides this functionality may be adopted. Another advantage of composite access systems, in particular those formed from polymer layers, is that it is relatively easy to incorporate functional components into the tubing. For example, it is contemplated that the tubing may be provided with one or more spirit levels incorporated into the body of the tubing to assist with vertical and / or horizontal arrangement of the tubing. It will be appreciated that whilst various aspects and embodiments of the present invention have heretofore been described, the scope of the present invention is not limited to the particular arrangements set out herein and instead extends to encompass all arrangements, and modifications and alterations thereto, which fall within the scope of the appended claims. It should also be noted that whilst the accompanying claims set out particular combinations of features described herein, the scope of the present invention is not limited to the particular combinations hereafter claimed, but instead extends to encompass any combination of features herein disclosed. For example, whilst it is envisaged for the accessory and tubing to each be profiled to interfere, it is anticipated that the accessory may be provided with a profiled liner (that locates within the accessory) and the tube may be provided with a profiled sleeve (that could be secured to the tube by grub screws, or adhered to the tube), the liner co-operating with the sleeve to inhibit sliding movement of the accessory along the tube. In this way conventional composite scaffolding, or indeed any other type of scaffolding, could be provided with a restraint system of the type disclosed herein to resist relative movement of an accessory along a pole. It is also the case that whilst the arrangements disclosed herein have a region of the tube that is profiled, it is anticipated that multiple regions may be profiled. It is also anticipated that the entire length of the tube could be profiled if desired. In addition, whilst in the foregoing the main body and moveable component of the accessory are both profiled to provide the aforementioned second part of the restraint system, it will be apparent to persons of skill in the art that it may be sufficient to profile one or the other instead of both of them. It will also be apparent to persons of skill in the art that whilst in one illustrative arrangement the tube is provided with grooves and the connector is provided with ribs, projections or ridges that cooperate with the grooves, this arrangement could be swapped around so that the connector comprises the grooves and the tube comprises the ribs, projections or ridges. Finally, it should be noted that any element in a claim that does not explicitly state "means for" performing a specified function, or "steps for" performing a specific function, is not to be interpreted as a "means" or "step" clause as specified in 35 U.S.C. Sec. 112, par. 6. In particular, the use of "step of" in the claims appended hereto is not intended to invoke the provisions of 35 U.S.C. Sec. 112, par. 6.

Claims

1. An access system comprising:an elongate scaffolding tube having a longitudinal axis;a scaffolding accessory attachable to said tube; anda restraint system, said restraint system comprising a first part provided on at least part of an external surface of said scaffolding tube and a second part provided on a part of said accessory that is proximate the external surface of said tube when the accessory is attached to the tube, the first and second parts of said restraint system being configured to cooperate when the accessory is attached to the tube to inhibit relative movement of the accessory and the tube in a direction parallel to the longitudinal axis of the tube.

2. An access system according to Claim 1, wherein said tube comprises a composite material, said composite comprising a plastics material.

3. An access system according to Claim 2, wherein said tube comprises a fibre-reinforced polymer.

4. An access system according to Claim 3, wherein said fibre-reinforced polymer is provided in layers.5 An access system according to Claim 4, where the fibres of at least one layer are differently orientated to those of another.

6. An access system according to any preceding claim, wherein the first part of said restraint system is integral with the tube.

7. An access system according to any preceding claim, wherein the second part of said restraint system is integral with the accessory.

8. An access system according to any of claims 1 to 5, wherein the first part of said restraint system comprises a sleeve securable around at least a portion of the tube.

9. An access system according to Claim 8 or any of Claims 1 to 5, wherein the second part of said restraint system comprises an insert for said accessory.

10. An access system according to any preceding claim, wherein the first and second parts of said restraint system are configured to interfere with one another when the accessory is attached to the tube.

11. An access system according to any preceding claim, wherein the first and second parts of said restraint system are configured to interlock with one another when the accessory is coupled to the tube.

12. An access system according to any preceding claim, wherein the first and second parts are shaped to have profiles that are complementary to one another.

13. An access system according to Claim 12, wherein said firstand second parts have profiles that are the inverse of one another.

14. An access system according to Claim 12 or 13, wherein said first and second parts have complementary Whitworth profiles.

15. An access system according to Claim 14, wherein the Whitworth profiles provide a plurality of discrete peaks and troughs which run in parallel to one another around the circumference of the tube, and perpendicularly to the length of the tube.

16. An access system according to Claim 15, wherein the Whitworth profiles have an angle of between 40 to 70 degrees inclusive, a radius of between 0.2 to 2.0 mm inclusive and a pitch of 2 to 7 mm inclusive.

17. An access system according to Claim 16, wherein the Whitworth profiles have an angle of between 40 and 70 degrees inclusive, a radius of between 0.2 and 1.5 mm inclusive, and a pitch of between 1.5 and 6 mm inclusive.

18. An access system according to Claim 17, wherein the Whitworth profiles have an angle of between 43 and 66 degrees inclusive, a radius of between 0.25 and 1.5 mm inclusive, and a pitch of between 2 and 5.5 mm inclusive.

19. An access system according to Claim 18, wherein the Whitworth profile has an angle of 66 degrees, a radius of 0.25 mm and a pitch of 2 mm.

20. An access system according to Claim 18, wherein the Whitworth profile has an angle of 43 degrees, a radius of 0.5 mm and a pitch of 4 mm.

21. An access system according to Claim 18, wherein the Whitworth profile has an angle of 60 degrees, a radius of 0.5 mm and a pitch of 4 mm.

22. An access system according to Claim 18, wherein the Whitworth profile has an angle of 55 degrees, a radius of 1.5 mm and a pitch of 5.36 mm.

23. An access system according to Claim 12, wherein the first and second parts of said restraint system are shaped to have profiles that are similar to one another.

24. An access system according to Claim 10 or 11, wherein first and second parts of said restraint system are shaped to have profiles that are different from one another.

25. An access system according to any preceding claim, wherein said accessory comprises at least one connector, said connector comprising:a main body that includes a channel in a face thereof;a moveable component pivotally attached to the main body, anda latch assembly;wherein said moveable component comprises a channel that cooperates with the channel of the main body to provide an opening through the accessory for receiving a scaffolding tube, and the latch assembly is operable to draw the moveable component towards the main body to clamp the accessory to a scaffolding tube extending through the opening.

26. An access system according to Claim 25, wherein at least one of the main body and the moveable component comprise the second part of said restraint system.

27. An access system according to Claim 25 or 26, wherein said accessory comprises a first connector for coupling the accessory to a first scaffolding tube and a second connector for coupling the accessory to a second scaffolding tube.

28. An access system according to Claim 27, wherein said first and second connectors are pivotally coupled to one another so that said first and second tubes may be arranged at any desired angle to one another.

29. An access system according to Claim 27, wherein the position of the first and second connectors relative to one another is fixed.

30. An access system according to Claim 25 or 26, wherein said accessory comprises a connector and a bracket for holding a scaffolding plank or protective barrier.

31. A scaffolding tube for an access system according to any preceding claim, the scaffolding tube being elongate and having a longitudinal axis, said scaffolding tube further comprising a first part of a restraint system provided on at least part of an external surface of said scaffolding tube, said restraint system further comprising a second part provided on a part of a scaffolding accessory that is proximate the external surface of said tube when the accessory is attached to the tube, the first and second parts of said restraint system being configured to cooperate when the accessory is attached to the tube to inhibit relative movement of the accessory and the tube in a direction parallel to the longitudinal axis of the tube .

32. A scaffolding accessory for an access system according to any of Claims 1 to 30, the scaffolding accessory being attachable to a scaffolding tube that has a longitudinal axis, said scaffolding accessory comprising a second part of a restraint system provided on a part of the scaffolding accessory that is proximate an external surface of said tube when the accessory is attached to the tube, said tube comprising a first part of said restraint system provided on at least part of the external surface of said scaffolding tube, the first and second parts of said restraint system being configured to cooperate when the accessory is attached to the tube to inhibit relative movement of the accessory and the tube in a direction parallel to the longitudinal axis of the tube.

33. An access system comprising a plurality of scaffolding tubes according to Claim 31 and a plurality of scaffolding accessories according to Claim 32.A

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