Bonding line attachment

Abstract

A bonding wire conductively connected to a pipe having a pipe body and a conductive tab mounted to the pipe and having a hole therein, the bonding wire being in the form of a braided conductive cable provided with a connector at each of its ends, the bonding wire being tightly wound around the pipe body and the ends both passing through the hole in the connector such that the ends of the bonding wire extend away from the pipe body after passing through the hole, while a portion of the bonding wire between the end portions is wrapped tightly around the pipe body; the bonding wire held under tension around the pipe body by a crimp around the two end portions where they pass through the hole.

Claims

1. An assembly comprising: a bonding wire; a pipe having a pipe body; and a conductive tab mounted to the pipe body and having a hole therein, wherein the bonding wire is conductively connected to the pipe and being in the form of a braided or twisted conductive cable provided with a connector at each of its ends, the bonding wire being tightly wound around the pipe body and having first and second end that both pass through the hole in the mounting tab and extend away from the pipe body; wherein the bonding wire is held under tension around the pipe body by a crimp around both the first and second two ends where they have passed through the hole.

2. The assembly of claim 1, wherein the first and second ends are provided with a tab or eyelet for connection to adjoining components.

3. The assembly of claim 1, wherein the bonding wire is a braided or twisted stainless steel cable.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is a perspective view of a conventional pipe and bonding wire arrangement.

(2) FIG. 2 is an end view of a pipe with a bonding wire attached according to this disclosure.

(3) FIG. 3 is a side view of the connection tab area of FIG. 2.

(4) FIG. 4 is a view similar to that of FIG. 3 but where two bonding wires are provided.

(5) FIG. 5 shows how the bonding wire can be wound twice around the pipe (the pipe not shown).

(6) FIG. 6 shows how a wire wound twice around the pipe could be crimped at two locations (the pipe again not shown).

(7) FIG. 7 is a perspective view of an embodiment of the bonding wire.

DETAILED DESCRIPTION

(8) Briefly referring to FIG. 1, as mentioned above, conventionally a bonding wire 1 is secured to a pipe 2, having an end fitting 3, by wrapping the wire around the pipe body several times while applying composite layers and then curing the entire structure. The wire ends 4 are attached to earthing rings by bolts and the fastening point is encased in a resin compound. The resulting pipe has a bulky, unprofessional appearance and the additional composite layers add to the size and weight of the pipe.

(9) According to the present disclosure, e.g. with reference to FIGS. 2 and 3, a twisted or braided cable 10 made, e.g. of strong, stranded conductive stainless steel, such as wires already known for securing fasteners against undesired rotation, is wound around the pipe body 20 under tension. The braid can be round or flat. This could be done while the composite layers are added or after they are cured. The crimping process applies appropriate tension to minimise movement through friction between the wire and pipe body. Conductive adhesive may also be applied to improve electrical flow but this is not essential. Put another way, the bonding wire can be installed “naked” over a finished pipe, i.e. after the composite layers have been cured, or it may be wrapped onto a layer of conductive adhesive provided over a cured or partially cured pipe, or it may be installed before the final layers of composite, and before curing. Where the ends of the cable 10 meet around the pipe, they pass through a hole 30 in a mounting tab 40 on the pipe 20. The tab 40 may be attached directly to the pipe body or can be attached to an end fitting that can be provided with the pipe or provided separately for attachment to the pipe. The attachment may be by, e.g., crimping, bonding, moulding or casting. Additive manufacture would allow complex shaped conductive tabs to be added.

(10) A crimp 50 is forced down or crimped tightly around the two parts of the cable where they meet coming through the hole 30 in the tab to secure the loop formed by the cable and hold it under tension around the pipe. The tension is needed to ensure conduction.

(11) The free ends of the cable can be provided with earthing rings, also referred to as connectors or eyelets, 70 for connection to other components.

(12) Whilst a single bonding wire will suffice to discharge built-up electricity, it can be preferable, where redundancy is required or desired, to wind two separate cables around the pipe, each secured by its own crimp at a respective hole in the tab (see FIG. 4) and/or for the cable(s) to be wound more than once around the pipe. FIG. 5 shows a double loop. FIG. 6 shows that even for one cable, wound as a double loop, two crimps may be provided.

(13) As shown in e.g. FIG. 7, the mounting tab 40 (here provided on the end fitting 3) may be formed with two (or more) openings 80 in the tab wall (a ‘bunny ears’ configuration). The ends of the bonding wire can, in embodiments, pass through the hole and then through the openings 80, where they can, again, be secured by crimps 90.

(14) The bonding wire formed from a braided or twisted wire such as known for locking wires will be securely attached under tension to the pipe. If desired, for extra security or to provide a smooth finish, a conductive gel coating can be provided over the outer surface of the pipe and bonding wire. Conductive epoxy may also be applied to increase conductivity between the wire and the pipe body.

(15) If desired, the free ends of the wire(s) can be shielded with additional tubing or flexible coatings to further increase corrosion resistance or service life.

(16) The ends of the wires and the places where they pass through holes or openings are preferably crimped to prevent sharp wire edges sticking out.

(17) Known crimp technology can be used to pull the wires taut and apply the crimps. If customised crimp fittings are used, some minor modifications to the tools may be needed.

(18) The crimps and tabs can be readily available parts or can be custom made.

(19) The pipes can be provided together with an end fitting or merely with a thread and an O-ring.

(20) The solution taught here will provide a quicker, smaller and neater bonding wire attachment and existing wire and tools can be used.

(21) The bonding wire solution will find application in many fields including aerospace, automotive, energy etc. fields.