GB2253023A

GB2253023A - Preventing hose burst

Info

Publication number: GB2253023A
Application number: GB9201570A
Authority: GB
Inventors: David Surman
Original assignee: BOC Group Ltd
Current assignee: BOC Group Ltd
Priority date: 1991-02-23
Filing date: 1992-01-24
Publication date: 1992-08-26
Anticipated expiration: 2012-01-24
Also published as: GB9201570D0; GB2253023B; GB9103806D0

Abstract

A high pressure hose assembly 1 comprises an inner tube 4 and outer braid 6 and also includes a cable 14 extending through the hose 2 and anchored to a termination 8 at each end of the hose for preventing or inhibiting whip-like movement of the hose should the hose burst when in use. <IMAGE>

Description

IMPROVED HOSE ASSEMBLY The present invention relates to high pressure hose assemblies and in particular to high pressure hose assemblies which include means to prevent or inhibit the damage caused by a hose which when burst during use is propelled in a whip-like motion by a jet of the escaping fluid.

The problem of hose whip is of particular importance when flexible hoses are used to fill cylinders of industrial gases at very high pressures in the order of 3000 lb/in2.

To prevent or inhibit the whip-like motion of a flexible high pressure, substantially non-extensible hose used for gas cylinder filling when it bursts, it is known to run a cable externally of the length of the hose and attach it to the hose end fittings. Alternatively, the cable may have fittings provided at its end which enables it to be anchored to a suitable structure adjacent to the hose connection. Such a cable is usually attached to the metallic braided outer jacket of the flexible hose by clips and should the hose suffer a burst then its movement is restrained by the cable. It is found that the hose no longer whips but will quiver in a relatively safe manner.

The problems associated with these known means for preventing or inhibiting the whip-like motion of a flexible high pressure hose are as follows:1) The cost of the hose assembly is increased; 2) the hose looks cumbersome; 3) dirt and corrosion and finger traps are created at the cable attachment and anchoring positions; 4) there is a safety hazard in that the cable is easily caught during hose handling; and 5) the cable is exposed and can therefore itself be damaged.

6) if the fluid escape is prolonged there is the risk that the hose will progressively work free of the clips and the whiplash effect will develop.

It is an aim of the present invention to provide a high pressure hose assembly which includes a member passing through the interior of a hose for preventing or inhibiting the whip-like motion of the high pressure flexible hose should the hose burst which obviates the various disadvantages referred to above.

According to the present invention a high pressure hose assembly comprises a flexible hose including an impermeable inner tube surrounded by at least one braided sheath, a termination attached to each end of the flexible hose and a member extending through the hose and itself attached to each termination.

Preferably, the member is a high tensile strength cable.

An embodiment of the invention will now be described by way of example, reference being made to the Figure of the accompanying diagrammatic drawing which is a longitudinal cross-section through one end of a flexible hose.

As shown, a high pressure hose assembly 1 includes a flexible hose 2 for the passage therethrough of high pressure gases, typically in the range of 50 to 500 bar. The flexible hose 2 consists of a smooth, impermeable inner tube 4 of polytetrafluroethylene which is surrounded by a braided sheath 6, e.g. of stainless steel. The braided sheath 6 provides longitudinal stability and contains the high pressure gas held by the inner tube 4 when passing through the hose 2. In addition, an outer jacket 16 of elastomeric material may be included which affords abrasion resistance and enhances handlability.

At each end (only one illustrated) the hose 2 is firmly attached to a termination 8. Each termination 8 is designed to enable the hose assembly to interface with, for example, a gas cylinder to be filled and a source of gas at high pressure. Each termination 8 includes an insert 10 and a ferrule 12. As is well known in the art, when connecting the flexible hose 2 to the termination 8 a portion at least of the insert 10 is pushed into the hose and the ferrule is threaded over the hose and deformed such that the end of the hose 2 is crimped to the termination 8.

Typically, the flexible hose 2 has a cross-section of between 20mm2 and 200mm2 and is substantially inextensible.

A high tensible strength cable 14 e.g. in the order of 1000 to 3000 N/mm2 extends through the flexible hose 2 and is firmly anchored at each end to an insert 10. The cable 14 is thin in order to minimise its resistance to high pressure gas flow within the flexible hose 2.

It is perceived that the end of the cable 14 can be anchored to the insert 10 at the time the termination 8 is crimped to the end of the hose 2.

In use, a gas under high presure passes through the flexible, inextensible hose 2 from a source to, for example, a gas cylinder. A fitting connects each termination 8 respectively to the source and the gas cylinder in a manner known per se. Should the hose 2 burst then the cable 14 will prevent any whip-like motion of the hose since it is firmly anchored to each termination 8 which in turn is held by a fitting to the source or gas cylinder. The cable 14 prevents lateral separation of the high pressure hose either side of a rupture.

The advantages of the embodiment described above over similar hose assemblies for preventing or inhibiting the whip-like motion of a high pressure flexible hose when it is burst are:1) Enhanced handlability, that is, the cable cannot be caught since it is arranged within the flexible hose; 2) it is cheaper to produce than known hose assemblies whose design incorporates a feature of hose burst whip restraint; 3) the hose itself is not deformed or damaged by cable attachments; 4) the cable is held automatically when a fitting is connected and no separate operation is required; 5) any static electrical build-up in the fluid is eliminated; and 6) there are no problems of dirt and corrosion or finger traps.

7) it is safer because the cable is protected by the hose and, furthermore, a hose which has failed cannot work itself free of the cable as time progresses.

8) the adiabatic heating of the working fluid associated with pressurisation can be dissipated into the cable by the selection of appropriate materials such as copper or phospher bronze.

It will be apparent that the cable 14 can be anchored to the termination 8 by means other than those disclosed in the above described embodiment.

The above described embodiment is particularly suitable when filling gas cylinders with industrial gases at high pressures. In these situations the cable material would need to be selected for compatibility with the gas passing through the hose and should present a minimal resistance to gas flow.

It is possible that the cable passing through the bore of the hose could itself be a hollow cable or it could consist of several small cables arranged around the hose tube inner circumference.

Claims

1. A high pressure hose assembly comprising a flexible hose including an impermeable inner tube surrounded by a braided sheath, a termination attached to each end of the flexible hose and a member extending through the hose and itself attached to each termination.

2. A high pressure hose assembly as claimed in Claim 1, in which the member is a high tensile strength cable.

3. A high pressure hose assembly as claimed in Claim 2, in which each termination includes an insert, a portion at least of which extends into the associated end of the hose, one end of the cable being anchored to said insert.

4. A high pressure hose assembly as claimed in claim 3, in which each termination includes a ferrule extending over the associated end of the hose, said ferrule crimping the end of the hose to the insert and anchoring the associated end of the cable to said insert.

5. A high pressure hose assembly constructed and arranged substantially as hereinbefore described with reference to and as illustrated in the Figure of the accompanying drawing.