The present invention relates to a cable handling chain for hoses and/or cables.

It is common in industry for a machine to reciprocate relative to a fixed point and for power hoses and/or cables to extend from the fixed point to the machine.

Cable handling chains are used to house the hoses and/or cables to ensure that the hoses and/or cables are protected from damage and are moved in a disciplined manner whilst the machine moves relative to the fixed point.

Cable handling chains usually comprise a series of rigid chain links which are pivotally connected to one another mechanically by hinge pins. The pivotal connections thereby enable the chain to flex laterally to loop upon itself and define a minimum loop diameter which is determined by the pivotal connections. This direction of lateral flexing is referred to hereinafter as the loop direction. However, such pivotal connections restrict lateral displacement of adjacent chain links longitudinally of the chain and in a direction perpendicular to the loop direction, ie. to the axis of the pivotal connections. Accordingly, in use such cable handling chains are able to freely flex along their length in the loop direction only.

In addition, in use the mechanical pivotal connection between adjacent links also prevents the cable handling chain to twist along its length. The above restrictions on movement of the cable handling chain normally dictate that cable handling chains be used only in environments where a linear path of travel of the chain can be maintained during movement of the machine relative to the fixed point.

It is a general aim of the present invention to provide a cable handling chain which is capable of flexing in the loop direction so as to determine the minimum diameter of loop for the chain and which is capable of flexing along its length in a lateral direction which is perpendicular to the loop direction. A further object is to provide a cable handling chain which is capable of twisting, by a predetermined amount, along its length.

According to one aspect of the present invention there is provided a cable handling chain for housing cables and/or hoses, the chain comprising a series of chain links interconnected by at least one elongate flexible support member, the, or all flexible support members in combination, being stiffer than the cables and/or hose to be housed in the chain so that in use, the flexible support member(s) define the minimum loop diameter of the chain when flexed along its length in a given lateral direction.

Preferably a pair of elongate support members are provided.

Preferably the pair of elongate support members extend side by side in a parallel relationship continuously along the length of the chain. Preferably the chain links are located inbetween the elongate members and are detachably attached thereto by clamp means. Preferably, the clamp means maintain the elongate members rigid over a predetermined length such that the elongate member is restricted to flexure inbetween adjacent clamp means.

According to another aspect of the present invention there is provided a cable handling chain for housing cables and/or hoses, the chain comprising a series of chain links interconnected by at least one elongate flexible support member arranged to control the amount of flexure of the chain along its length during use.

According to a further aspect of the invention there is provided a method of transferring a drill rig between a fixed well head and a movable platform, the method including connecting one end of a cable handling chain to the platform and the other end to the drill rig, and transferring the rig to or from the fixed well head from or to the platform respectively without disconnecting the cable handling chain from either the drill rig or platform.

According to another aspect of the invention there is provided a platfc m having a drill rig movably mounted thereon, and a cable handling chain as defined above connected between the drill rig and platform.

Various aspects of the present invention are hereinafter described, with reference to the accompanying drawings, in which :-

Figures la, lb and lc are schematic side views showing a succession of steps for transferring an oil drill rig onto a fixed well head platform;

Figures 2a and 2b are schematic plan views of the oil drill rig and fixed well head platform showing intermediate steps during the transfer process shown in Figure 1 ;

Figure 3 is a side view of a cable handling chain according to the present invention;

Figure 4 is an enlarged side view of a chain link according to the present invention;

Figure 5 is a sectional view taken along line N-N in Figure 4.

Figures 6a, 6b and 6c illustrate diagrammatically flexing of the chain of Figure 1 in the loop direction.

Referring initially to Figures 3 to 6 there is shown a cable handling chain 10 which comprises a series of chain links 12 secured together by a pair of elongate flexible support members 14. In the illustrated embodiment, the pair of support members 14 are located side by side in a parallel manner and extend continuously along the chain.

Each link 12 includes a pair of side walls 16 which are secured together and spaced from one another by an upper and lower cross-member 18.

The internal space defined between the side walls 16 and the upper and lower cross members 18 is preferably divided into compartments 20 by vertical partition members 19 extending between the upper and lower cross members 18 and a horizontal partition member 24 extending between the side walls 16. Preferably the partition member 24 rotatably supports a series of rollers 25.

In use hoses and cables (not shown) are located within compartments 20 of adjacent chain links 12 and so are held in a disciplined manner along the length of the chain 10.

Each side wall 16 is secured to a respective support member 14 by a clamp member 30 which is preferably made from a rigid material, such as metal. The clamp member 30 preferably co-operates with the flexible member 14 over a predetermined length to prevent flexure of the flexible member 14 over that length.

In the illustrated embodiment, the clamp member 30 comprises an

elongate body 31 having a channel 32 extending longitudinally of the body. The channel 32 has an open top facing the adjacent side wall 16. A plurality of bolts 34 are provided, passing through the body 31 and side walls 16 to enable an elongate member 14 passing through channel 32 to be gripped between the body 31 and side wall 16. Preferably, grub screws (not shown) threadedly received in threaded bores 36 formed in body 31 and communicating with the channel 32 are provided. The grub screws are tightened onto the flexible member 14 and provide added resistance to movement of the chain link 12 along the flexible members 14.

The flexible members 14 are constructed so that, in combination they are stiffer 'than the stiffness of the hoses and/or cable assembly to be carried by the cable handling chain 10. In this way, the stiffness of the flexible members 14 controls the flexing of the chain 10 particularly when flexing in the loop direction.

An example of flexing of the chain 10 in the loop direction is shown in Figures 6a, 6b and 6c. In Figure 6 the chain 10 is suspended at both ends to form a hanging loop 60. The stiffness of the flexible members 14 inbetween adjacent links determines the resistance of the chain 10 to flexure in the loop direction and so determines the minimum loop diameter D as shown in Figure 6b.

In order to vary the mimmum loop diameter D, using elongate members 14 of a given stiffness, the spacing between adjacent links 12 and/or the length over which the clamps 30 hold the flexible member 14 rigid may be adjusted.

In practice, the minimum loop diameter D is chosen to be at least as great

as the minimum loop diameter required by the largest cable/hose in the cable/hose assembly.

The flexible members 14 are also preferably constructed so as to have less stretch, when in tension, than any of the cables/hoses in the cable/hose assembly. In this way, pulling of the chain 10 will not cause stretching of the housed cables/hoses. Also, should the chain 10 be suspended as shown in Figures 6a, 6b and 6c, then the flexible members 14 will support the weight of the chain and cable/hose assembly without subjecting the cable/hose assembly to stretch.

If desired, the inherent stiffness of the flexible elongate members 14 and/or the stiffness imparted by the spacing and/or clamping of the elongate members 14 is chosen to enable the chain 10 to be pushed or pulled in a longitudinal direction.

Preferably the elongate flexible members 14 are formed from a multi- strand metal rope, the metal preferably being steel.

For a chain link having a width of 800 mm and height of 450 mm the diameter of the metal rope may vary between 10 to 100 mm. The metal ropes used may be for example a 26 mm steel rope having a 6 x 36 strand construction ie. six minor ropes twisted together, each minor rope having 36 strands. The minor rope may be twisted about a fibre or steel core. Alternative combinations may be 6 x 41 or 6 x 49. If stainless steel is used, the ropes may be 7 x 7, 7 x 19 or 1 x 19 configuration.

In the illustrated embodiment, the pitch spacing between adjacent links is about 600 mm, although this spacing could be varied as desired.

Since the adjacent links 12 are interconnected by a pair of flexible support members 14, the chain 10 is able to flex along its length in a lateral direction which is perpendicular to the loop flexing direction.

The degree of lateral flexing permitted in the direction perpendicular to the loop direction can be adjusted by altering the pitch spacing of adjacent links 12 and/or the distance over which the clamps 30 hold rigid the flexible members 14 and/or the inherent stiffness of the flexible members 14. These factors need to be adjusted bearing in mind the degree of flexure required in the loop direction.

In addition, since the links 12 are joined by flexible members 14, the chain 10 is able to twist along its length. This is particularly advantageous where it is necessary for the chain 10 to undergo a change in feed direction.

As indicated above, the clamp means 30 act to hold a flexible member 14 rigid over a predetermined length. Accordingly the clamp means 30 not only secure the chain links 12 to flexible member 14, they also act as flexure resistance means.

It is envisaged that, as an alternative, or in addition, the flexure resistance means may be comprised by other members, for example rigid sleeves which may be located in between links 12.

It is also envisaged that the pitch spacing between the flexure resistance means (including clamps 30) may be constant or may vary along the length of the chain. The spacing between the flexure resistance means may vary, for example between 400 mm to 2000 mm in the example shown in Figure 3.

It is also envisaged that the stiffness of one of the flexible members 14 may be different to that of the other flexible member 14. This would give the chain 10 different asymmetric flexure characteristics.

The chain 10 illustrated in Figures 3 to 6 is particularly suited for use in drilling operations where a drill rig is temporarily sited on a fixed well head but is fed with power cables and hoses from an adjacent movable platform. This is illustrated in Figures 1 and 2.

In Figure la there is shown an oil or gas drill rig 50 which is mounted on a mobile platform 51. In the position shown, the rig 50 is located in board of the platform 51 for transport purposes. In Figure la it will be noted that the chain 10 according to the present invention is attached at one end to one side of the platform and extends along an upper surface of the platform to the oil rig 50.

The platform 51 is initially positioned adjacent a fixed well head 54. A cantilever beam assembly 55 is then extended toward the fixed well head 54 and is adjusted in height so as to be on the same level as the fixed well head 54. The drilling rig 50 is then skidded on rails 56 across the cantilever beam assembly 55 (as illustrated in Figure lb) prior to being moved across and onto rails 57 on the fixed well head 54. The rig 50 is then skidded along rails 57 to a drilling position (as illustrated in Figure lc).

As seen in Figures 2a, 2b, when the platform 51 is positioned adjacent the well head 54, and the cantilever beam assembly 55 is extended, it is not normally possible to accurately align rails 56 and 57. Accordingly, it is possible for the rails 56, 57 to be laterally displaced relative to one another by ± 1 meter and to be angularly displaced relative to one another

by ± 5°.

It will be noted however that during the entire transfer sequence, the chain 10 according to the present invention remains connected to the drilling rig 50 and platform 51. Accordingly, once the drilling rig 50 has been positioned on the well head 54 for drilling, the drilling operation can be commenced immediately.

The chain 10 according to the present invention may remain connected to the platform 51 and rig 50 during the transfer sequence since the chain 10 is not only able to flex in the loop direction but is able to twist longitudinally and flex in a lateral direction perpendicular to the loop direction so as to accommodate for the lateral and angular displacements of the rails 56, 57.

The chain 10 of the present invention may be used in other applications, for example as a festoon chain wherein selected chain links are provided with rollers to run in an overhead rail; a chain for use in top drive applications wherein the machine to which the chain is connected reciprocates in a vertical path; or a skid chain wherein the chain is constrained to run in a guide channel.

The chain of the present invention is not restricted to any cross-sectional size.

The chain 10 of the present invention has several additional advantages over conventional cable handling chains having chain links interconnected by mechanical pivots.

In this respect, the present invention requires fewer chain links per length

of chain and so is considerably lighter. Adjustment of the minimum loop diameter may be easily performed on site by adjusting the pitch spacing of the chain links.

Maintenance of the chain is substantially reduced since it is no longer necessary to lubricate/maintain a mechanical pivotal connection. Wear on the chain due to shock loadings on the pivotal connections and metal fatigue are not experienced with the present invention since driving forces for moving the chain 10 are transmitted through the entire length of each of the elongate support members 14.

It is envisaged that only one elongate support member 14 may be used in certain circumstances. In addition, 3 or more support members 14 may be used by attaching additional side walls 16 to the link 12.

If 3 or more support members 14 are used, they are arranged side by side in the same plane to thereby enable flexure in the loop direction.