Field of the Invention

The invention relates to a rigging deck module. This invention has particular application the a rigging deck module used for maintenance of offshore oil platforms and the like, and for illustrative purposes the invention will be further described with reference to this application. However, it is envisaged that this invention will find other applications, such as rigging decks for other structures such as buildings and bridges.

Prior Art

Rigging for oil rig maintenance and the like must be demountable for redeployment and storage, while providing as safe a working environment as possible in an inherently dangerous rigging situation. The sheer heights involved mandate either or both of securing rigging to the upright structure of the rig or suspending the rigging from the working platform of the rig. In the past there have been applied many technical solutions, some of which can be regarded as commonplace or standard and others of which are ad hoc solutions to local technical problems.

Fixed scaffolding represents the most conventional of temporary rigging for maintenance of structures generally. Oil platforms have widely spaced piers rather than a wall supported on the ground and so present fewer attachment points that are accordingly subjected to higher loadings. The complexity of the assembly increases as the distance from the fixed support increases. Accordingly, suspended apparatus is preferred.

Suspended rigid platforms are analogous to the working platforms suspended from davits and used for external maintenance and cleaning of high rise buildings and the like. The weight of these platforms and their attendant cages, cable winches and the like makes them difficult to move, and require specific overhead fixings. All suspended objects will tend to "wind up" in oscillation under wind loading. The massive nature of the platforms makes the oscillation difficult to control.

Harness arrangements provide limited tool carrying capacity, limited lateral scope, and lack of stability as a work platform. Safety nets are usually tensioned beneath a primary working arrangement and function as a secondary safety measure for the rope access technicians ("RATS"). The net is an engineered structure comprising spaced ropes or cables tensioned through respective spaced pockets provided in a rope mesh net. The ends of the net between the pockets are provided with a peripheral tensioning rope or wire, each end usually being tied off or shackled to the rigging ends of the respective rope or cable.

Safety nets are not suitable as primary work platforms or surfaces because of excess sagging, although they are relatively easy to rig.

WO 2009/1 17758 describes a different approach to rigging decks and wherein a deck is formed of modules, each including a deck body

substantially formed of flexible deck material bounded by a web-reinforced tensile edge. Suspension means are spaced about the edge whereby the deck body is tensionable to form a substantially flat deck surface. A lattice of tensile web members are secured to the flexible deck material and the web- reinforced tensile edge. Spaced tensile rigging strops are mounted in tension to a structure, each having securing points formed thereon. Tensionable connection means are located at each suspension means for securing and tensioning the deck body to respective securing points. The modules are configured for end to end connection to form a rigging deck assembly or walkway.

Summary of the Invention

In one aspect the present invention resides broadly in a rigging deck module including:

a deck body including flexible deck material bounded by a web- reinforced tensile edge, suspension means spaced about the edge whereby the deck body is tensionable to form a substantially flat deck surface, and a lattice of tensile web members secured to the flexible deck material and the web-reinforced tensile edge, at least part of said web-reinforced tensile edge including a hookless fastener element whereby the tensile edges of adjacent modules may be conjoined; tensile rigging strops adapted to be mounted in tension to a structure in maintained spaced relation to each other, and each having securing points formed thereon; and

tensionable connection means located at each suspension means for securing and tensioning the deck body to respective securing points.

The deck body may comprise a bonded arrangement such as high tensile polymer film or fibre or carbon fibre tapes sandwiched between layers of film or fabric. Alternatively the deck body may comprise a stitch-and-glued and/or thermally welded assembly of polymer film or polymer web or mesh, where the webbing lattice is entrapped in pockets.

The webbing may be natural or synthetic fibre webbing including but not limited to webbing of natural fibre, polyester, polyaramid, fibreglass or carbon fibre. The intersection points of the webbing may be stitched or bonded or both. The peripheral edge portions of the flexible deck may be further reinforced by a bolt rope. For example, the edge portion may be a laminate of functional parts, including but not limited to a bolt rope pocket, webbing pocket, hookless fastener binding web, stitched-in tabs, tapes and loops, and the like.

The flexible deck material may be selected from commercial grades of mesh or fabric such as that used for filtration or shade sails. For example, the flexible deck material may be a relatively stiff, flat PVC coated industrial mesh. The flexible deck material may be selected to enhance the inherent resistance to stretch of the lattice of tensile web members.

The deck body may be a unified assembly of may comprise a plurality of join-together sub-panels. For example the deck body may include deck body portions incorporating a portion of the tensile edge structure and having zip element edge portions adapted to conjoin the body portions in assembly. Alternatively, deck body portions may be bordered all-round with continuous hook-less fastening such as a zip portion and adapted to be joined to form a deck body assembly which is then edged by a tensile edge portion secured to the body assembly by the hook-less fastening. In this embodiment the tensile edge portion bears also the hookless fastener element whereby the tensile edges of adjacent modules may be conjoined. The body portions may be configured whereby a portion may be zipped open when the deck is in use to provide an access or inspection hatch through the deck module. In this embodiment the openable body portions preferably do not incorporate the tensile edge portions.

The plurality of suspension means describes a polygonal tensioned deck surface. The polygon will be at least a triangle and is preferably a rectangular shape. It is envisaged that any number of suspension means may be used to form polygonal shapes up to an approximation of a circular shape. For example, wherever elements of the lattice intersect the periphery there is potential for a suspension means. In the case of relatively long rectangular shapes, there are preferable provided intermediate suspension means. For example, for a given end length L of a deck body, intermediate suspension means may be provided along the side edges of the deck at, for example, 1 .5-2.0 L spacing.

The suspension means are preferably reinforced to provide for secure mounting of the tensionable connection means.

The tensile rigging strops may be selected from high-tensile, low stretch media such as one or more of wire rope, chain, low stretch webbing or braided line such as SPECTRA ^® or other polyaramid or polyester braid. The choice of the tensile rigging strops and the means of securing them to the structure will be determined at least in part by the structure itself. In the case of offshore oil rig platforms and like structures it is envisaged that the tensile rigging strops will be permanently or removably installed to tensioning lugs or structure formed on the platform legs or cross members. The tensile rigging strops each may be a single length or alternatively may include discrete securing points for the deck bodies. For example, the tensioned mounting members may be formed with high tensile rings to which selected ones of the tensioning means may be secured.

The spaced relation of the rigging strops may be maintained by any suitable means. For example, where the relevant pair of respective securing points will be close to the fixed structure, the spacing will be maintained by the structure. However, when the rigging strops are distant from the fixed structure, such as interposed in extended tension members, then the spacing may be maintained by compression struts disposed between the spaced rigging strops.

The compression strut may be disposed between the spaced rigging strops at the ends of the deck and having the ends of the strut shackled or otherwise affixed between the pair of securing points securing an end of the deck. The compression strut may be a fixed or adjustable strut. The compression strut may be tubular. For example the tube may be of a heavy- wall, high strength aluminium alloy such as 75mm OD by 7.0mm wall, tempered 6061 alloy tube. The tube may be fabricated to suitable end pieces. The end pieces may include high strength mounting means. For example, the end pieces may be fabricated in stainless steel. The end pieces may include a horizontal pivot to allow the strut to find an equilibrium position in use.

The tensionable connection means located at each suspension means for securing the deck body to a respective securing point on the rigging strop structure may include a winch arrangement for providing the tension.

Preferably the winch arrangement is located at the deck body so final tensioning can be done from the rigging deck. For example the rigging deck may include a mounting for a load strap ratchet winch, the strap of which may be adapted to be secured to a rigging cable from which the rigging deck is to be deployed. The tensionable connection may be terminated by fixed or removable means. For example, the connection may be by conventional rigging links such as carabineer.

The mounting base may be secured to webbing integral with the deck body and disposed generally in line with the tensioning direction. The mounting base may for example comprise a pair of metal plates bolted together to capture the deck body at the suspension point. The mounting base is preferably of a metal that is strong relative to its weight. For example the mounting base may be of titanium or of an aluminium alloy such as 6061 plate, preferably tempered. The winch arrangement may be secured to the mounting base by any suitable means. For example, the winch arrangement may be secured to the mounting base by a swivel pin or bolt to enable alignment of the winch tension with the centre of effort on the deck.

Alternatively the winch arrangement may comprise a pair of metal swaged eyes secured to the webbing structure with their centres aligned along the load direction and adapted to receive bolts passing through a load spreader plate. The outer bolt also acts as a pivot for a winch assembly such as a strap winch providing the tensioning means.

Some or all of the termini of the webbing integral with the deck body and adjacent the suspension means may be provided with a metal eye of the like providing a mounting point for a shackle. The shackle may be used for initial deployment of the deck module before tensioning. The shackle may also be used as an anchor point for equipment.

There may be provided means for attachment of life lines or the like.

The lifelines may be passed through loops or eyes formed at the module periphery. In the alternative or in addition to loops, the shackles may be used as anchors for life lines. In particular embodiments of the present invention an edge portion of the decking module is associated with a toe rail in the form of a tensioned cable running though web loops, super ring wire attachments or the like secured to an edge portion of the rigging deck.

In particular embodiments of the present invention, the deployed deck is associated with tensioned safety members deployed at or about waist height above one or more of the peripheral edges of the decking module. The tensioned safety members may be connected to the decking module by cable droppers, fabric panels or the like. The droppers or panels may be secured to the deck module periphery by any suitable means, including the aforementioned lifelines.

Apart from the optional compression strut, there may be provided one or more spreader bars disposed between the spaced rigging strops intermediate the ends of the deck and having an end located between an adjacent pair of intermediate suspension points. The spreader bar may be captured to the rigging strop by common attachment with a supplementary link connecting the deck body to the rigging strop.

The spreader bar may be a fixed or adjustable strut. Typically the spreader bar operates in compression. The disposition of the spreader substantially in the plane of the rigging deck means that the spreader bar is preferably of a material having a high transverse strength with light weight.

For example the spreader bar may be of a heavy-wall, high strength aluminium alloy such as 75mm OD by 7.0mm wall, tempered 6061 alloy tube.

The spreader bar may be captured to the tensioned rigging struts by shackling or other attachment to the securing points for intermediate suspension means.

The tempered tube may be fabricated to suitable end pieces with high strength mounting means. For example, the end pieces may be fabricated in stainless steel. The end pieces may be secured to the deck body by any suitable means and may include terminal attachments for carabineers or the like for supplementary attachment to cables or the like. The end pieces may include a horizontal pivot to allow the spreader to find an equilibrium position in use.

The at least part of said web-reinforced tensile edge including a hookless fastener element will usually comprise a straight edge although it is envisaged that complementary curved edges may be so joined. The hookless fastener element may be selected from metal or plastic-toothed hookless fasteners of the zipper kind. Preferably, the hookless fastener is a plastic fastener having sufficient tensile strength across the line of the join to maintain the join between deck modules without further reinforcing in use. Alternatively the zipped join may be reinforced by lacing or other web joining means.

Preferably, a protective flap covers the hookless fastener element and extends from one or both faces of said deck body. The protective flap preferably covers at least the top of the assembled join between deck modules in use. The protective flap is preferably selected to increase the fire rating of the hookless fastener join. Rectangular decks present a particular form of the present invention may be configured particularly. Rectangular deck bodies may be adapted to be deployed in end to end relation. In one preferred embodiment the lattice of webs comprising the body may include a pair of peripheral edge portions interconnected by a plurality of spaced, transverse web portions. The transverse web portions interconnecting the ends of the peripheral edge portions may form a continuous peripheral tensile web with the peripheral edge portions. The end to end join may be by securing the respective end corner suspension means to common tensionable connection means.

The deck body may include one or more medial webs parallel to and spaced from the peripheral edge portions and interconnecting each of the transverse web portions. Each of the four corners of the rectangular deck portion may provide a suspension means having tensionable connection means. The ends of the medial web may be configured to accept joining plates to secure the decks in end to end relation, or mount a tensionable connection means if at the end of run. The medial web may be provided with additional suspension points whereby stabilizing lines may be attached from below or overhead. The additional suspension points may be located at the intersections of the medial web and the transverse web portions.

A compression strut may be shared between adjacent decks in end to end relation. The respective rigging strop end securing points may be secured to the respective end fitting of the preferred compression strut, the common attachment formed thereby also attaching the tensionable connection means.

There may be provided a webbing load distributor extending from the suspension means to a distributor point on the medial web away from the peripheral transverse web portions. For example for a substantially symmetric deck the distributor point may be about 25% of the medial web length away from the peripheral transverse web portion. Both webbing load distributors of the suspension means at an end of the deck may share a common distributor point. Brief Description of the Drawings

The invention will be further described with reference to preferred embodiments of the present invention, and wherein:

Figure 1 is a plan view of a deck module in accordance with the present invention;

Figure 2 is a central pocket detail of the apparatus of Figure 1 ;

Figure 3 is a typical edge detail at internal seam location of the apparatus of Figure 1 .

Figure 4 is a typical edge detail of apparatus of Fig. 1 ;

Figure 5 is a toe rail typical panel plan;

Figure 6 is a detail of a corner portion of the apparatus of Fig. 1 ;

Figure 7 is a plan view of a strut for use with the apparatus of Figure 1 ; Figure 8 is a detail of the end of the strut of Fig. 7;

Figure 9 is a detail of a swivel lug for use at the termini of the struts of Figure 7;

Figures 10 and 1 1 are custom fastener options for the apparatus of the invention;

Figure 12 is a plan view of a deck assembly incorporating rigging deck modules body construction through section F of Figure 2;

Figure 13 is a sectional end elevation showing hand and toe rail safety configuration for use with the rigging deck module if Figure 1 ;

Figure 14 is a detail of the toe rail region of the set up of Figure 13;

Figure 15 is a detail of a shackle connection between the main wire and webbing margin of the deck assembly of Figure 12;

Figure 16 is a typical wire rope termination detail; and

Figure 17 is a typical end-of-strut ratchet connection.

Description of an Embodiment

In the Figures there is provided a rigging deck module including a deck body 10 comprising a webbing lattice 1 1 and an industrial PVC mesh deck surface members 12. The lattice 1 1 is formed by assembly from 50 m wide, low-stretch, high modulus webbing 13 rated to 2500kg and comprising respective edge stringer 14 and medial webbing 15 interconnected by end webbing members 16 and transverse webbing members 17. Distributor webbing members 18 extend from the region of the corners and are secured to the medial webbing 15. The lattice 1 1 is secured to the deck surface members 12 by pocketing with 1000g/m ² PVC pockets 20 secured by thermal welds 21 to the deck surface members 12. The edges of the deck body 10 are further reinforced by a bolt rope 19.

Corner suspension means 24 comprises a pair of spaced superring eyelets 22 interconnected by a plate 23 secured by bolting through at the inner eyelet and by bolting through both the plate and a tensioning means comprising a ratchet strap winch assembly 30 supported at the outer eyelet on a special swivel lug 57, the winch assembly pivoting about the vertical on this outer bolt and about the horizontal on a pin 34 securing the winch body 35.

Bonded in assembly with each edge stringer 14 and end webbing members 16 are zipper elements 36 extending beyond the deck body corners at zipper strip extensions 37. These zipper elements 36 permit the interconnection of respective deck assemblies in either or both end-to-end and side-by-side relation.

Figs 10 and 1 1 include illustration of alternative forms of the pin superring eyelet fasteners for the swivel lug 57, either fabricated on a stud stock or made from a bolt with a ground down head.

Similarly, supplementary suspension means 46 are supported by bolting through a plate 47 and spaced superring eyelets 22. The

supplementary suspension means 46 may selectively mount a tensioning means comprising a ratchet strap winch assembly 30 as before. Otherwise, the supplementary suspension means 46 may be a static suspension point for securing to a substrate or to rigging strops by means such as a carabineer. The locations of the corner 24 and supplementary 46 suspension means are a location for webbing loop tabs 38 through which a toe rail cable 39 may pass.

The intersections of the medial webbing member 15 and the transverse webbing members 17 are provided with supering eyelet attachment holes 52 permitting selective stay attachment from above or below.

Rigging strops 53 comprise steel wire cable 54 secured by multiple cable clamps 55 to form a terminal eye about a thimble 25. The rigging strops 53 are tensioned in mutually spaced relation by Tirfor ^® winches 64 to a structure (not shown), via a load/strain gauge 65 and webbing straps secured to rings 66.

A compression strut 56 is disposed between the spaced rigging strops 53 at the ends of the deck bodies 10 and having the ends of the strut 56 affixed by a shackle 33 to the wire 54. The compression strut 56 is formed of 75mm OD by 7.0mm wall, tempered 6061 alloy tube 60 fabricated to stainless steel end pieces 61 . The end pieces 61 include a horizontal pivot

62 to allow the strut to find an equilibrium position in use. Similar spreaders

63 are disposed intermediate the ends of the deck body 10.

The struts 56 spread the cables 53 and provide a primary support via a wire rope clip 29 for a toe rail 26 the outer end of which is secured to a truss 27 via a wire rope clip 28. Intermediate the struts 56, the transverse webs are provided with a superring eyelet 31 which is shackled to the support cable 54 via a bow shackle 32 with nut and split pin.

The rigging deck of the above embodiment is a tensioned platform which is a primary support for work to replace aluminium scaffold, but used in a similar way to aluminium scaffold and also may be used where scaffolding has no access. The platform is versatile. Strength and minimal deflection are advantages. Whereas a safety net would deflect approx 1 m to 1200mm, a deck in accordance with the present invention will only deflect 200mm -

400mm with an applied weight of 250 kilo per square metre, approximating a semi rigid floor. It will of course be realised that while the above has been given by way of illustrative example of this invention, all such and other modifications and variations thereto as would be apparent to persons skilled in the art are deemed to fall within the broad scope and ambit of this invention as defined in the claims appended hereto.