WO1998036204A1

WO1998036204A1 - Hose coupling

Info

Publication number: WO1998036204A1
Application number: PCT/GB1998/000278
Authority: WO
Inventors: Victor Moody; Michael John Pendregaust; Brian Ellwood Purchon
Original assignee: Shand Engineering Limited
Priority date: 1997-02-14
Filing date: 1998-01-29
Publication date: 1998-08-20
Also published as: AU5872498A

Abstract

A hose coupling, for example for use with an oil drilling rig, comprises a tubular body (47) having a bore (44) therethrough and an annular socket (49) at one end thereof. The socket has inner and outer walls and opening at the end of the body, the inner wall presenting alternate circumferential peaks and troughs along its length and the outer wall presenting opposing troughs and peaks along its length. The external surface of the body is provided with circumferential ribs corresponding in position with the peaks on the outer wall of the socket such that, when an end portion of a hose is inserted into the socket in the coupling and the ribs are swaged inwardly, the hose end is firmly held in the socket.

Description

HOSE COUPLING Field of the Invention

This invention relates to a hose coupling, to a hose incorporating such a coupling, and to a method of connecting a hose coupling to a hose. The hose, hose coupling and method of the invention are particularly suited to high pressure applications such as conveying drilling mud to an oil well drilling string. Background to the invention

In oil drilling rigs, it is necessary to supply fluid, for example drilling mud, to the drill string as it rotates and moves axially. This is achieved by means of a flexible hose connected to a rotary fluid-tight connector on the string. Since very high pressures may be required to force the mud along the string to the drill bit, for example up to working pressures of 10,000 psi, not only does the hose itself have to be very strong, but also the coupling to the rotary connector. Typically, the hose will consist of steel wire reinforced rubber, and the coupling will comprise a steel member one end of which screws into the connector while the other end is moulded or clamped on to the hose.

Conventionally, the reinforced rubber hose is built up on a mandrel by wrapping rubber plies and reinforcing material around the mandrel and the coupling in such a manner that the coupling becomes an integral part of the hose. While this results in a satisfactorily strong hose, the cost of manufacture is very high. The present invention seeks to provide a hose coupling which can be attached to a length of preformed reinforced hose. Summary of the Invention

According to the invention, there is provided a hose coupling comprising a tubular body having a bore therethrough and an annular socket at one end thereof, the socket having inner and outer walls and opening at the end of the body, the inner wall presenting alternate circumferential peaks and troughs along its length and the outer wall presenting opposing troughs and peaks along its length, the external surface of the body being provided with circumferential ribs, each rib corresponding in position with one of the peaks on the outer wall of the socket such that, when an end portion of a hose is inserted into the socket in the coupling and the ribs are swaged inwardly, the hose end is firmly held in the socket. Advantageously, a portion of the bore adjacent to said end decreases progressively in diameter from said end whereby, after internal swaging the compression of the hose wall in the socket increases progressively from the said end along the coupling over the length of said portion. Preferably, at least some of the peaks on the inner wall are generally rounded and intersect with the next peak, and the corresponding troughs on the outer wall are of similar shape, intersecting at the peaks. More preferably, the longitudinal positions of the peaks on the outer wall are initially displaced longitudinally from the corresponding troughs in the inner wall such that after swaging they are substantially in alignment with each other.

In one preferred embodiment of the invention, at least one peak on the inner wall furthest from the opening has a greater diameter than the remaining peaks on the inner wall, so as to grip the hose especially firmly at a point adjacent to the end thereof.

The ribs preferably taper outwardly before they have been swaged, although straight-sided ribs and other shapes may be used instead.

The invention provides a method of connecting a hose to a hose coupling of the invention, comprising inserting an end portion of the hose into the socket and swaging the external ribs inwardly to hold the hose firmly in the socket.

The hose may comprise an elastomeric material encasing a tubular layer of a reinforcing material, and the method comprises removing at least a portion of the elastomeric material on the end portion before the end portion is inserted into the socket. The method preferably comprises removing the outermost elastomeric material from the end portion to expose the reinforcing material, and alternatively or additionally removing at least some of the innermost elastomeric material from the end portion so as to expose the reinforcing material. In a preferred method, substantially all of the outermost elastomeric material is removed from the outside of the reinforcing material on the end portion, but only an end part of the innermost elastomeric material is removed, preferably at a position corresponding to a peak on the inner wall larger than the other peaks. In some cases some of the external elastomeric material may be left on the end portion. Typically, the reinforcing material will consist of steel wires, for example two layers of wires, one wound over the other in opposing directions.

In a preferred method according to the invention, the inner wall is expanded outwardly after the hose end is inserted into the socket, more preferably before the outer wall is swaged. The inner wall is preferably expanded outwardly by drawing a die therethrough. The ribs on the outer wall are then suitably swaged inwardly by drawing the coupling through a die or drawing a die over the coupling.

It has been found that, by swaging the external ribs inwardly, the hose can be locked in the socket substantially more securely than with conventional swaged hose couplings, permitting the combination of the hose and coupling to withstand operating pressure of the order of those experienced in the supply of drilling fluids to oil well drilling strings and the like. Since the coupling can be attached to any suitably- dimensioned length of standard hose, the cost of constructing the combination of hose and coupling for very high pressure use is substantially less than with the conventionally moulded combinations.

It has also been found that progressively reducing the grip on the hose towards the mouth of the socket in the coupling assists in ensuring that the hose can operate at high pressure reliably for a long time.

It has also been found that further improvements in seal strength and reliability can be achieved by placing a circumferential bead of a liquid sealant material on the inner part before introduction of the hose and swaging, such that the swaging tends to spread the sealant along the hose.

Another aspect of the invention provides a hose coupling comprising a tubular body having at one end thereof a socket having inner and outer walls with an annular space therebetween opening at the end of the body, the inner wall presenting alternate circumferential peaks and troughs along its length within the annular space and the outer wall presenting opposing troughs and peaks along its length within the annular space, the peaks (there can be several) on a first portion of the inner wall remote from the opening having a greater diameter than the peaks on the remaining portion of the inner wall. Brief Description of the Drawings

In the drawings, which illustrate exemplary embodiments of the invention: Figure 1 is a part-sectioned side elevation of the inner part of the coupling; Figure 2 is a part-sectioned side elevation of the outer part of the coupling which is welded on to the inner part;

Figure 3 is a sectional view of the coupling attached to a hose; and Figure 4 is a part-sectioned side elevation of an alternative embodiment of the coupling Detailed Description of the Illustrated Embodiment

In the first embodiment, the coupling is conveniently formed from two machined steel parts, a main inner part 1 (Figure 1 ) and an outer part 2 (Figure 2) which fits over one end of the inner part 1 and is welded thereto to define between them an annular socket opening at one end of the coupling. The main inner part 1 comprises a screw- threaded portion 10 for engagement in a threaded socket on the connecting assembly of a drill rig (not shown) and with an adjacent portion 1 1 being provided with spanner flats to facilitate tightening of the thread in the socket. A shoulder portion 12 provides the location for the outer part 2 to be welded on to the inner part 1 , and extending from the shoulder portion is the inner wall portion 1 3 of the socket. This has a cylindrical bore 14 therein, while the outer surface of the inner wall portion 13 is formed with a series of four circumferential peaks 1 5, 1 6, 17 and 1 8, the first three 1 5, 16 and 17 being of generally part-spherical shape intersecting in sharply-defined but smoothly-radiused troughs 1 . The fourth peak 1 8, which is the nearest to the shoulder portion 12, is of a greater external diameter than the others and leads into a region 18a of generally similar diameter with only a small trough between them. The profile of the fourth peak 18 is formed from several intersecting arcs, in cross-section. It will be seen that the internal diameter of the cylindrical bore 14 decreases over a tapered portion 14a. This is to permit a tapered die to be driven through the bore to expand the inner wall portion outwardly into contact with a hose end received in the socket, as hereinafter described.

The outer part 2, as may be seen from Figure 2, is generally cylindrical with internal circumferential troughs 21 , 22 and 23 whose shape mirrors the shape of the peaks 1 6, 17 and 18 on the inner part 1 , with relatively sharp (but smoothly-rounded) peaks protruding between them, corresponding to the troughs in the inner part. At one end, an inwardly-directed flange 24 is provided to fit on to the external surface of the inner part adjacent to the shoulder, the sloping profile of the flange and that of the shoulder resulting in a generally V-shaped gap, when assembled, defining the site for welding. At the other end, the internal bore of the part 2 increases slightly at a position approximately halfway along a fourth part-spherical trough 25 to provide a widening 26 of the socket to receive a portion of the resilient material of the hose as described hereinafter with reference to Figure 3.

Surrounding the second part 2 at intervals along its length are circumferential tapering ribs 27 whose positions correspond with the positions of the peaks between the troughs 21 , 22, 23 and 25 within the socket. Initially, the peaks, and thus the ribs 27, do not correspond exactly with the positions of the troughs in the surface of the inner wall portion 1 3, but are positioned such that, after swaging, the peaks coincide with the positions of the troughs precisely.

In use, the end portion of a steel wire reinforced rubber hose 30 (Figure 3) is prepared by stripping of the rubber outer sheath 31 to expose the steel reinforcing wire core 32 for a length substantially equal to the length of the portion 1 3 of the inner part 1 within the socket, and also stripping back the rubber inner layer 33 for a short distance from the end corresponding in length with that of the fourth peak 18 and the adjacent region 1 8a. The prepared end portion is then inserted fully into the socket and a tapered die is driven through the central bore of the inner part 1 of the coupling to expand the portion 13 outwardly into contact with the hose end.

The outer ribbed surface of the coupling is then passed through a tapered die to swage it on to the outer surface of the hose end. Because of the ribs 27, the swaging pressure is directed inwardly at the peaks on the internal surface of the outer part 2, while the longitudinal displacement of the metal of the outer part 2 caused by passage through the die is accommodated by ensuring that the peaks initially do not correspond in position with the troughs on the inner part 1. After swaging, the ribs have been compressed inwardly, driving the peaks into the hose end at positions corresponding with the troughs in the inner part , locking the hose end firmly in the coupling. It has been found that the pressure-resisting capacity of the coupling and hose is at least equal to those fabricated by moulding the hose and coupling together, while the cost of the resultant assembly is substantially smaller than that of the fabricated hose. Referring now to Figure 4, the coupling body of the second embodiment differs from that of the first embodiment in having an extended portion 41 remote from the mouth 42 of the socket adapted to grip the reinforcing wires only of the hose, after removal of the inner and outer elastomeric material along the corresponding portion of the hose, the remainder 43 of the socket being of greater width to receive the hose with the inner and outer elastomeric layers still in place. The wider portion 43 of the socket is designed to provide a progressively decreasing grip on the hose towards the mouth 42 of the socket by providing the bore 44 through the centre of the coupling body with a portion 45 adjacent to the mouth 42 whose diameter increases progressively towards the free end 46 of the inner part 47 of the coupling. As a result, after internal swaging, the grip exerted by the inner part 47 on the hose decreases slightly in a progressive manner over the length of the portion 45, being least at the mouth 42.

In addition, the portion 48 of the external surface of the outer part 49 of the coupling corresponding to the wider portion 43 of the socket is not externally ribbed or ridged like the first portion, but instead simply increases in diameter by a shoulder 50, so that there is less concentration of pressure at the inwardly directed peaks in the outer wall of the socket. It has been found that this configuration is especially effective in providing a secure coupling in high pressure hoses.

Claims

1. A hose coupling comprising a tubular body having a bore therethrough and an annular socket at one end thereof, the socket having inner and outer walls and opening at the end of the body, the inner wall presenting alternate circumferential peaks and troughs along its length and the outer wall presenting opposing troughs and peaks along its length, the external surface of the body being provided with circumferential ribs, each rib corresponding in position with one of the peaks on the outer wall of the socket such that, when an end portion of a hose is inserted into the socket in the coupling and the ribs are swaged inwardly, the hose end is firmly held in the socket.

2. A hose coupling according to Claim 1 , wherein a portion of the bore adjacent to said end decreases progressively in diameter from said end whereby, after internal swaging the compression of the hose wall in the socket increases progressively from the said end along the coupling over the length of said portion.

3. A hose coupling according to Claim 1 or 2, wherein at least some of the peaks on the inner wall are generally rounded and intersect with the next peak, and the corresponding troughs on the outer wall are of similar shape, intersecting at the peaks.

4. A hose coupling according to Claim 1 , 2 or 3, wherein the longitudinal positions of the peaks on the outer wall are initially displaced longitudinally from the corresponding troughs in the inner wall such that after swaging they are substantially in alignment with each other.

5. A hose coupling according to any preceding claim, wherein at least one peak on the inner wall remote from the opening has a greater diameter than the remaining peaks on the inner wall closest to the opening.

6. A method of connecting a hose to a hose coupling as defined in any preceding claim, comprising inserting an end portion of the hose into the socket and swaging the ribs inwardly to hold the hose firmly in the socket.

7. A method according to Claim 6, wherein the hose comprises an elastomeric material encasing a tubular layer of a reinforcing material, and the method comprises removing at least a portion of the elastomeric material on the end portion before the end portion is inserted into the socket.

8. A method according to Claim 7, comprising removing the outermost elastomeric material from the end portion to expose the reinforcing material.

9. A method according to Claim 7 or 8, comprising removing at least some of the innermost elastomeric material from the end portion so as to expose the reinforcing material.

10. A method according to Claim 7, 8 or 9, wherein the reinforcing material comprises steel wires.

1 1. A method according to any of Claims 6 to 10, comprising expanding the inner wall outwardly.

12. A method according to Claim 1 1 , wherein the inner wall is expanded outwardly before the outer wall is swaged inwardly.

1 3. A method according to Claim 12, wherein the inner wall is expanded outwardly by drawing a die therethrough.

14. A method according to any of Claims 6 to 13, wherein the ribs are swaged inwardly by drawing the coupling through a die or drawing a die over the coupling.

15. A hose coupling comprising a tubular body having at one end thereof a socket having inner and outer walls with an annular space therebetween opening at the end of the body, the inner wall presenting alternate circumferential peaks and troughs along its length within the annular space and the outer wall presenting opposing troughs and peaks along its length within the annular space, the peaks on a first portion of the inner wall remote from the opening having a greater diameter than the peaks on the remaining portion of the inner wall.

16. A hose having secured to one end thereof a hose coupling device according to any of Claims 1 to 5.