WO1995031665A1

WO1995031665A1 - Hose with wear indicator

Info

Publication number: WO1995031665A1
Application number: PCT/GB1995/001068
Authority: WO
Inventors: Michael John Riley
Original assignee: Btr Plc
Priority date: 1994-05-12
Filing date: 1995-05-11
Publication date: 1995-11-23

Abstract

In a system for the transportation of abrasive bearing fluid under high pressure use is made of a reinforced hose (10) comprising a body (12) of polymeric material having a lining layer (13) which lies inwards of the reinforcement structure (11) to define the bore of the hose (10), the lining layer (13) having associated therewith a conductor (14, 14') a conduction characteristic of which changes in the event of the conductor (14, 14') being subject to damage or degradation, and the hose (10) being arranged in association with monitoring means responsive to a change in a conductivity property of the conduction means (14, 14') upon damage or degradation thereof so as to provide a signal in response to which flow of pressurised fluid through the hose (10) may be halted.

Description

HOSE WITH WEAR INDICATOR

This invention relates to an elongate tubular article and in particular, though not exclusively, to a flexible type elongate tubular article such as a reinforced hose comprising a body of polymeric material having a reinforcement structure embedded therein. It relates also to a high pressure fluid system which incorporates said elongate tubular article.

In the case of reinforced hoses of the type commonly known as blast hoses, and which are required to deliver under high pressure a stream of fluid containing abrasive material, a problem arises of the abrasive material carried by the fluid transported through the hose causing damage to the internal surface of the hose.

Because of the high pressure of the fluid it is important to ensure that the hose does not become internally damaged to such an extent that it might burst or otherwise fail in a dangerous manner during use. Inspection of blast hoses is not easy firstly because it is necessary to remove them from service at relatively frequent intervals so as to monitor for any wear, and secondly, because wear is occurring at the internal surface of the hose wall due to the effect of the abrasive material, quick visual inspection is not possible.

More particularly, in order to ensure continuous safe operation of a blast hose it is desirable to be able substantially continuously to monitor the operation of a pressure system incorporating that hose. Monitoring for damage elsewhere in an elongate article than at a radially inner region may alternatively or additionally be desired.

The present invention seeks to provide an elongate tubular article, such as a hose, and a high pressure fluid system incorporating such an article adapted for monitoring wear of the article.

In accordance with one of its aspects the present invention provides an elongate tubular article comprising conduction means integral with the article to extend between end regions thereof, said conduction means having a conduction characteristic which changes in the event of at least a part of the structure of the elongate tubular article suffering damage or degradation.

Said conduction means may be provided at or in proximity to the radially inner surface of the article and be responsive to the effect of abrasive laden fluid transported by the article thereby to facilitate provision of a signal in the event of at least a part of the structure of the elongate tubular article suffering damage or degradation by the transported material.

The conduction means may be embedded, either wholly or partly, in the elongate tubular article or secured to an inner or outer surface of the article. It may be secured to an inwardly facing surface of a body portion of the tubular article so as to protrude into the bore defined by said body portion.

The conduction means may be wholly embedded in a body portion of the article but have a surface region which is exposed and contiguous with an inner or outer surface of said body portion.

For an elongate tubular article which is a reinforced hose, the conduction means may be provided for example radially inwardly of the main reinforcement structure of the hose. If the hose has a lining layer inwards of the main reinforcement structure, the conduction means may be embedded wholly or in part in said lining layer.

The conduction means may extend non-linearly between end regions of the elongate article. It may extend helically, the angle of lay being selected such that the pitch of successive turns is sufficiently close to ensure that the conduction means is able to respond adequately quickly to damage or degradation initiating at any position between said successive turns.

Alternatively the conduction means may be of a kind which extends or comprises a part which extends substantially directly between end regions of the elongate article.

Two or more conduction members may be provided. One may extend helically, at a pitch sufficient to ensure an adequate response to damage or degradation initiating between successive turns, and another may extend substantially directly between end regions, or at a pitch angle less than that of said one helically extending conductor. In another configuration two or more conduction members may be arranged to extend helically in a manner analogous to that of a multi-start thread.

Two conduction members may be interconnected at one end region, or they may be comprised by lengths of a single conductor which extends to and fro along the tubular article.

Two conduction members may be interconnected directly to one another at an end region or interconnected indirectly. They may be interconnected by an end fitting of the tubular article, e g a discharge nozzle at the end of a hose. In that case both ends of the conduction members at an opposite end region of the tubular article may be arranged to facilitate connection to monitoring means.

Examples of suitable conduction means are an electrical wire, which may be of mono or multi-filament type construction, or an optical fibre. These types of conduction means are particularly suitable for provision helically or in other non-linear manner. The conduction means may comprise electrically conductive material provided in a form other than a conventional metallic wire. It may, for example, be a band of electrically conductive carbon or other such material which, in the case of a hose, may be embedded within a lining layer; it may be positioned to be exposed to transported fluid only when an innermost portion of the lining layer has been worn away by transported fluid.

The conduction means may be a tubular passage provided within the wall of the tubular article to extend between end regions and arranged normally to be isolated from fluid flowing through the bore of the article by part, e g an inner region, of the article. Thus it may be arranged to be exposed to transported fluid only when an inner region of the article has been worn away. The passage may be in the form of a void extending along at least part of the length of the elongate article, or may be pre-filled with a material which is dissolved or becomes otherwise removed when exposed to the transported fluid, e g to be carried away by that fluid.

The conduction means may be of a material and/or dimension selected to result in it being more susceptible to damage or degradation by abrasive containing fluid than other parts of the elongate article exposed to that fluid.

The invention provides in another of its aspects an assembly of the elongate article of the invention and an end fitting secured thereto.

In an assembly of the elongate article of the invention and an end fitting secured thereto, said end fitting may comprise contro^! -πeans for control of fluid through a bore of the elongate article, and said conduction means may be operatively associated with said control means.

The conduction means may be an electrical conductor which is operatively associated with the control means in a manner in which it is electrically insulated from a body portion of the end fitting, or at least an outer surface region of that body portion may be of a material which is an electrical insulator.

The conduction means may be an electrical conductor and the end fitting may comprise a body portion of electrically conductive material to which the conductor is connected to enable static charge at the end fitting to be conducted along the length of tubular article, for example for connection to earth potential. In an assembly in which two or more electrically conductive conduction means extend along the length of the elongate tubular article in which one conductor has a lower electrical resistance than the other, for example by virtue of having an angle of lay which results in it being of a shorter total length, that conductor of lower resistance is connected to the end fitting for discharge of static. The discharge conductor may connect to a second end fitting at the other end of the elongate tubular article.

It will be understood therefore that in the case of conduction means in the form of an electrical conductor that conductor may be multi¬ functional. In addition to enabling the hose to be monitored for damage or degradation it may be used for discharge of static from e g a fluid outlet nozzle and/or it may be part of a control circuit including a control means at the nozzle and whereby flow of fluid through the hose or like tubular article may be controlled.

The invention provides also an assembly of the elongate article of the invention and an end fitting secured thereto, said article comprising a body or reinforcement of electrically conductive material and said conduction means being electrically conductive, the assembly comprising insulation means whereby the conduction means is isolated electrically from said body or reinforcement and from any metallic material of the end fitting.

If the conduction means is electrically conductive and arranged to extend helically, successive turns typically may be spaced. In contrast, in the case for example of an optical fibre, said fibre may be arranged to extend helically with successive turns at touch pitch.

The invention teaches that in a system for the transportation of abrasive bearing fluid under high pressure an elongate tubular article in accordance with the present invention is provided in association with monitoring means responsive to a change in a conductivity property of the conduction means upon damage to or degradation of the article to provide a signal in response to which, either manually or automatically, flow of pressurised fluid through the elongate tubular article may be halted.

The invention further teaches a method for control of flow of abrasive containing fluid through a hose in which an assembly of the present invention is connected to monitoring means arranged to provide a warning signal or cause termination of the flow of fluid in the event of the monitoring means detecting the occurrence of potentially unacceptable damage or degradation. Flow may be under control of a switch in the hose nozzle, and that switch may be arranged operatively in series with the conduction means.

Embodiments of the present invention are shown, by way of example only, in the accompanying drawings in which:-

Figure 1 is a perspective view of part of a reinforced rubber hose of the invention;

Figure 2 is a cross-sectional view of the hose; and

Figure 3 is a schematic view of a system according to the invention for delivery of abrasive containing fluid.

A hose 10 comprises a wire braided reinforcement structure 1 1 surrounded by a rubber cover layer 12 and having an internal lining layer 13 each of a type known per se.

The lining layer has embedded therein a pair of helically extending conduction means in the form of wires 14,14' of electrically conductive material such as aluminium each arranged to extend helically between ends of the hose. The wires are embedded in the hose lining layer to lie just below the radially inner surface region of the lining layer. The wires are provided in this position during manufacture by applying an inner sub-layer of the lining layer 13 around a hose building mandrel, spiralling the wires around the sub-layer, and then extruding the remainder of the rubber lining layer 13 followed by subsequent construction of the reinforcement 1 1 and outer cover layer 12 in conventional manner.

In use of the hose, in the event of erosion of the inner sub-layer of the rubber lining material 13 in the vicinity of the wires 14,14' that wire becomes exposed to wear by the abrasive material. By appropriate selection of the cross-sectional size of the wires, it is arranged that at least one of the wires will break and thus become electrically non-conductive between its ends prior to the remainder of the hose lining layer 13 and other structure of the hose being exposed to a degree of further erosion that would risk the occurrence of hose failure.

In use of the hose in a high pressure hose blast system the ends of the wires normally are to be connected to a monitor which provides a warning signal in the event of change of conductivity of the wires. That warning signal is used to provide a visual/audible warning to an operative as well as simultaneously and automatically closing down the supply of pressurised fluid. Preferably the system also automatically depressurises fluid in the hose.

An example of a monitoring system and method is described now in conjunction with Figure 3. A pump 20 for abrasive containing fluid has an outlet 21 to which is connected an end coupling 22 of a blast hose 23 having a control nozzle 24 at its other end.

The blast hose is of a construction as described above with reference to Figures 1 and 2. The coupling 22 and nozzle 24 have metal bodies and these are connected electrically by one of the wires 14'. The pump body and outlet 21 to which the metal coupling 22 is secured are all of metal and are grounded so that the wire 14' can serve to discharge from the nozzle any static charge which might otherwise build up, particularly in consequence of flow of fluid therethrough.

The pump 20 is powered by mains voltage electricity controlled by a relay 25 which is part of a low voltage control circuit. The relay 25 is connected by wire 28 to an insulated terminal 26 of the coupling 22, and that terminal is at an end of the other wire 14 which runs the length of the hose to a control switch 27 on the nozzle 24.

In normal operation, when the operator closes switch 27, current flows through the wire 14' and closes the relay, allowing the pump to operate. If the wire 1 or wire 14' is damaged there will be a discontinuity in the low voltage relay circuit and the relay will open, thus switching off the pump 20. —

It may be desired to prevent operation of the pump when either of the wires 14,14' is significantly degraded, rather than wait for a wire to wear to such an extent that it becomes electrically discontinuous. In that case a current sensing meter 29 may be provided, e g in the connecting wire 28 and be linked to a monitoring device (not shown) which switches off the low voltage supply in the event of the current flow being above zero but below a predetermined value associated with a tolerable level of degradation of one of the wires 14,14'. In that event, switching off of the low voltage supply will also cause the relay 25 to open and the pump 20 to switch off.

Claims

CLAIMS:

1. A system for the transportation of abrasive bearing fluid under high pressure comprising an elongate tubular article in the form of a reinforced hose comprising a body of polymeric material having a reinforcement structure embedded therein, said body of polymeric material comprising a lining layer of polymeric material which lies inwards of the reinforcement structure to define the bore of the hose, said lining layer having associated therewith a conductor a conduction characteristic of which changes in the event of the conductor being subject to damage or degradation, and the elongate tubular article being arranged in association with monitoring means responsive to a change in a conductivity property of the conduction means upon damage to or degradation of the tubular article to provide a signal in response to which flow of pressurised fluid through the elongate tubular article may be halted.

2. An elongate tubular article for use as a hose in the system of claim 1 and comprising conduction means integral with the article to extend between the end regions thereof, said conduction means having a conduction characteristic which changes in the event of at least a part of the structure of the elongate tubular article suffering damage or degradation.

3. An elongate tubular article according to claim 2 wherein the conduction means is embedded at least in part in the elongate tubular article.

4. An elongate tubular article according to claim 2 or claim 3 wherein said conduction means is provided at or in proximity to the radially inner surface of the article.

5. An elongate tubular article according to claim 2 or claim 3 wherein the conduction means is secured to a surface of the article.

6. An elongate tubular article according to any one of the preceding claims wherein the conduction means extends non-linearly between end regions of the elongate article.

7. An elongate tubular article according to claim 6 wherein the conduction means extends helically.

8. An elongate tubular article according to any one of the preceding claims wherein the conduction means comprises two or more conduction members.

9. An elongate tubular article according to claim 8 wherein one conduction member extends helically and the other conduction member extends substantially directly between end regions or at a pitch angle less than that of said one helically extending conductor member.

10. An elongate tubular article according to any one of claims 1 to 8 wherein the conduction means comprises two conduction members which extend helically in the manner of a multi-start thread.

11. An elongate tubular article according to any one of claims 8 to 10 wherein said two conduction members are interconnected at one end region.

12. An elongate tubular article according to claim 11 wherein said two conduction members are interconnected at an end region by an end fitting of the tubular article.

13. An elongate tubular article according to any one of claims 8 to 10 wherein said two conduction members are comprised by lengths of a single conductor which extends to and fro along the tubular article.

14. An elongate tubular article according to any one of the preceding claims wherein the conduction means is selected from one of a metallic wire of electrically conductive material, an optical fibre, a band of electrically conductive carbon.

15. An elongate tubular article according to any one of claims 1 to 13 wherein the conduction means comprises a tubular passage which extends between end regions of the article and is arranged normally to be isolated from fluid flowing through the bore of the article.

16. An elongate tubular article according to claim 15 wherein said passage is pre-filled with a material which is dissolved or becomes otherwise removed when exposed to fluid transported through the bore of the hose.

17. An elongate tubular article according to any one of the preceding claims wherein, in use, the conduction means is more susceptible to damage or degradation by abrasive containing fluid flowing through the bore of the elongate article than other, surrounding parts of the elongate article.

18. An elongate tubular article according to any one of claims 2 to 17 and comprising a body of polymeric material having a reinforcement structure embedded therein, said body of polymeric material comprising a lining layer of polymeric material which lies inwards of the reinforcement structure to define the bore of the hose and said lining layer having associated therewith said conduction means.

19. An elongate tubular article according to claim 2 and constructed and arranged substantially as hereinbefore described with reference to the accompanying drawings.

20. An assembly for use in the system of claim 1 and comprising an elongate article according to any one of claims 2 to 18 and an end fitting secured thereto, said article comprising a body having a reinforcement of electrically conductive material and said conduction means being electrically conductive, the assembly comprising insulation means whereby the conduction means is isolated electrically from said body of reinforcement and from any metallic material of the end fitting.

21. An assembly according to claim 20 wherein the conduction means is electrically conductive and extends helically with successive turns spaced.

22. An assembly according to claim 20 or claim 21 wherein the end fitting comprises control means for control of fluid through a bore of the elongate article.

23. An assembly according to claim 22 wherein said conduction means is operatively associated with the control means.

24. An assembly according to claim 23 wherein the conduction means is an electrical conductor which is operatively associated with the control means and electrically insulated from a body portion of the end fitting.

25. An assembly according to claim 23 wherein the conduction means is an electrical conductor which is operatively associated with the control means and at least an outer surface region of a body portion of the end fitting is of a material which is an electrical insulator.

26. An assembly according to any one of claims 20 to 25 wherein the conduction means comprises two or more electrically conductive conduction means and one conductor has a lower electrical resistance than the other.

27. An assembly according to any one of claims 20 to 26 wherein the elongate tubular article comprises a body portion of electrically conductive elastomeric material.

28. An assembly according to claim 27 wherein said body of electrically conductive elastomeric material serves as one of two or more electrically conductive conduction means.

29. An assembly according to claim 20 and constructed and arranged substantially as hereinbefore described with reference to the accompanying drawings.

30. A system according to claim 1 and constructed and arranged substantially as hereinbefore described with reference to the accompanying drawings.

31. Method for control of flow of abrasive containing fluid through a hose wherein an assembly according to any one of claims 20 to 29 is connected to monitoring means arranged to provide a warning signal or cause termination of the flow of fluid through the tubular article in the event of the monitoring means detecting the occurrence of potentially unacceptable damage or degradation.

32. A method according to claim 31 wherein control of flow of abrasive containing fluid is under the control of a switch associated with an end fitting discharge nozzle. AMENDED CLAIMS

[received by the International Bureau on 6 November 1995 (06.11 .95) ; original claim 20 amended; remaining claims unchanged ( 1 page) ] claims wherein, in use, the conduction means is more susceptible to damage or degradation by abrasive containing fluid flowing through the bore of the elongate article than other, surrounding parts of the elongate article.

20. An assembly for use in the system of claim 1 and comprising an elongate article according to any one of claims 2 to 18 and an end fitting secured thereto, said article comprising a body or reinforcement of electrically conductive material and said conduction means being electrically conductive, the assembly comprising insulation means whereby the conduction means is isolated electrically from said body of reinforcement and from any metallic material of the end fitting.

25. An assembly according to claim 23 wherein the conduction means is an electrical conductor which is operatively associated with the control means and at least an outer surface region of a body portion of the end