GB2094679A - Method and apparatus for treating the internal surface of a pipe - Google Patents

Abstract

Apparatus for cleaning the internal surface of a pipe projects an annular stream of water containing abrasive particles from an outlet 13 onto the pipe. The device is propelled along pipe in one direction by the reaction of the water, the supply of abrasive is then turned off and water is delivered through an additional outlet into the pipe to wash the pipe. A valve having an operating member projecting from the apparatus controls the water supply to the additional outlet. <IMAGE>

Description

SPECIFICATION Method of treating a surface and device for use in the method Description of invention This invention relates to a method of treating a surface, for example to remove from the surface scale or particles adhering to the surface, and to a device for use in the method.

It is known to treat the surfaces ofworkpieces to remove therefrom scale or adherent particles by directing onto the surfaces a jet of water containing solid particles. This method can be used for cleaning both internal and external surfaces of workpieces.

The jet is directed from a nozzle along an axis defined by the nozzle with divergence of the jet to a greater extent or to a lesser extent from that axis. In a case where the surfaces of a chamber or passage within a workpiece are to be cleaned, the nozzle may be introduced into the chamber or passage.

According to a first aspect of the invention, there is provided a method of treating the internal surface of a pipe wherein there is directed onto said surface a stream of liquid, the kinetic energy of which has a maximum value away from and is distributed approximately evenly around a longitudinal axis of the pipe.

If the known procedure hereinbefore mentioned is used to clean the internal surface of a cylindrical pipe, and the nozzle is aligned with its axis coinciding with that of the pipe, the kinetic energy of the jet is not used efficiently because the liquid directed down the centre of the pipe has greater kinetic energy than that directed towards the wall of the pipe. If the axis of the nozzle is directed towards the wall of the pipe, a region of the wall around the axis of the nozzle is cleaned more effectively than are other parts of the wall. All parts of the internal surface of a pipe wall can be subjected to substantially the same treatment by a method in accordance with the invention.

In the preferred method, the stream impinges concurrently on substantially the whole of an annular region of the surface of the pipe and contains solid particles.

Alternatively or additionally, after the device has moved along the interior of the pipe from an end thereof to an abutment, flow of liquid from the device through a washing outlet may be commenced upon engagement of the device with the abutment and the device returned to said end of the pipe whilst the flow of liquid through the washing outlet is continued.

The kinetic energy of the stream may have a maximum value along the surface of a notional cone having an apex angle exceeding 40 and preferably within the range 90 to 140 .

According to a second aspect of the invention, there is provided a device comprising first and second inlets through which, in use, water and solid particles respectively enter the device, and an outlet communicating with both of the first and second inlets and being arranged to direct from the device a divergent, substantially annular stream of water containing the particles.

Preferably, the or each outlet is annular, in use, there emerges from the outlet a stream of water which is continuous around an axis of the outlet and the flow of water is distributed substantially evenly around the axis. However, it is within the scope of the invention for the stream to emerge from the outlet as a plurality of distinct jets. In normal use of the device for treating the internal surface of a pipe, these jets would intersect prior to impinging on the surface of the pipe.

The device may comprise a further outlet, called herein the washing outlet, and a valve for controlling the flow of liquid from the first inlet to the washing outlet, the valve having an operating member which protrudes from the body in and is movable relative to the body in the axial direction.

According to a third aspect of the invention, there is provided a device suitable for washing the interior of a pipe and comprising a body defining an inlet and an outlet through which a substantially annular divergent stream of liquid is directed, in use, onto the pipe from within same, the inlet and the outlet being spaced apart in a direction called herein the axial direction and the body containing a valve for controlling the flow of liquid from the inlet to the outlet, wherein the valve has an operating member which protrudes from the body in and is movable relative to the body in the axial direction.

The operating member is adapted by its relation with the body to be arrested by an abutment at an end of the pipe when the device moves along the pipe to that end, continued movement of the body after the operating member has been arrested bringing about movement of the body relative to the valve.

An example of a device embodying the second and third aspects of the invention and for use in the method according to the first aspect will now be described, with reference to the accompanying drawings, wherein Figures 1 and 2 show respectively opposite end portions of the device partly in diametral cross-section.

The device comprises a body 10 (shown in Figure 1) in which there is defined an annular chamber 11 which extends around but is spaced from an axis 12 of the device. An outlet 13 extends radially outwardly from the chamber 11 and is defined between two frusto-conical surfaces 14 and 15. These surface converge in the radially outward direction so that the outlet 13 tapers outwardly. The outer end of the outlet forms a continuous circumferential slot in the external surface of the body 10.

There extends from an inlet 16 at one end of the body 10 along the axis 12 to a position situated radially inwardly of the chamber 11, a first inlet duct 1 6a. Adjacent to the end of the body, this inlet duct is provided with a female screw thread 17 whereby a hose (not shown) can be connected to the duct 1 6a to convey water thereto.

The body defines a second inlet duct 18 which is offset from the axis 12 and lies beside the 1 6a. In use, a second hose (not shown) is connected to the duct 18 at an inlet thereof to convey thereto solid particles, for example sand.

In a wall of the body which separates the chamber 11 from the first inlet duct 16, there is formed a number of passages 19 which provide communication between the first inlet and the chamber. In each passage 19 there is secured a nozzle 20 of known form defining an orifice from which a jet of water can be directed through the outlet 13. Each orifice is elongated and is arranged with its longer dimension extending circumferentially of the chamber and its shorter dimension extending along the axis 12.

As shown in the drawing, each nozzle 20 is arranged with its axis inclined to the axis 12 at an angle which exceeds 20 and is preferably within the range 45 to 700. In the particular example illustrated, the angle is 600. The axis of the nozzle passes close to or intersects with surface 15 at the periphery of the outlet and diverges from the axis 12 in the axial direction towards the inlet 16.

In use, there emerges from each nozzle 20 a jet of water which is markedly divergent, as viewed along the axis 12, and may subtend at the orifice an angle of approximately 90". As viewed in the drawing, each jet is only slightly divergent. In the particular example illustrated, there are six nozzles 20 spaced equally around the axis 12 and the jets from these nozzles intersect with one another within the outlet 13 so that there emerges from the outlet a divergent, annular stream of water which is continuous around the axis.

Communication between the second inlet duct 18 and the chamber 11 is provided by an annular passage 21 and a plurality of orifices 22. The passage 21 surrounds a part of the inlet duct 1 6a and diverges towards the orifices 22.

The number of orifices 22 is equal to the number of nozzles 20 and each orifice 22 is aligned with the orifice defined by a respective nozzle 20. The orifices 22 extend from one end of the annular passage 21 through a wall of the chamber 11 and emerge at the surface 15 at a position within the chamber 11, spaced somewhat from the outlet 13 and spaced also from the wall of the chamber in which the nozzles 20 are disposed. The axis of each orifice 22 is inclined to the axis 12 and intersects with the axis of the corresponding nozzle 20 at an angle which is or is approximately a right angle.

As shown in Figure 1,the body 10 may be assembled from a number of components, including a spider 40 disposed in the chamber 11 and having arms lying between adjacent nozzles 20. The surfaces 14 and 15 are formed on separate components which are spaced apart by the spider.

The body 10 is extended in a direction away from the inlet 16 by a tubular housing 23 having a diameter somewhat less than the maximum diameter of the body 10. In the end of the housing 23 remote from the body 10, there is secured a plug 24 to which there is secured a further body 25 lying mainly outside the housing. At respective positions which are spaced apart equally around the axis 12 and are near to the body 25, there is mounted on the housing 23 a plurality of wheels 26. The wheels are arranged for rotation about respective axes which are perpendicular to the axis 12. A diameter of each wheel intersects the axis 12 at right angles. Each wheel is arranged for limited movement towards and away from the axis 12 relative to the housing and is urged outwardly of the housing by an associated spring 27.As shown, the peripheries of the wheels extend somewhat further from the axis 12 than does the body 10.

The body 25 is of somewhat smaller overall diameter than is the body 10. In the body 25, there is formed an annular chamber 28 from which a number of passages 29 lead to the periphery of the body 25, these passages being inclined to the axis 12 at an angle which exceeds 20 and is preferably within the range 45" to 70". In each passage 29, there is secured a nozzle 30 which may be of the same form as the nozzles 20. The elongated orifices of the nozzles 30 are arranged with their longer dimensions extending circumferentially of the body 25 and with their shorter dimensions extending along the axis 12. The nozzles 30 collectively constitute a washing outlet of the body 25.

The first inlet duct 16a communicates with the annular chamber 28 via a tube 31 disposed within the housing 23 and screwed onto each of the bodies 10 and 25, a duct 32 which extends through the body 25 in a direction parallel to the axis 12 but offset from that axis, an annular outer chamber 33 and an inner chamber 34 defined by the body 25. Communication between the chambers 33 and 34 is provided by an annular series of apertures and communication between the inner chamber 34 and the annular chamber 28 is controlled by a valve 35 which is urged by spring 36 against a seat 37 provided in the body 25.

The valve 35 is provided with an operating member 38 in the form of a stem which extends through the inner chamber 34 and through an end wall of the body 25 to protrude from the free end of the body.

The stem and valve can undergo together limited sliding relative to the body 25 along the axis 12.

The stem 38 is of stepped form, having a shoulder 39 disposed within the inner chamber 34 and facing in a direction towards the valve 35. The area of this shoulder, as projected onto a plane perpendicular to the axis 12, is at least approximately equal to the area projected onto the same plane of that part of the valve 35 which lies radially inwardly of the seat 37.

Accordingly, when the valve is closed, the valve and stem are not urged along the axis 12 in either direction by pressure within the chamber 34.

There are exposed to the contents of the annular chamber 28 respective surfaces of the valve 35 which face generally in opposite directions along the axis 12. The areas of these surfaces, when projected onto a plane which is perpendicular to the axis 12, differ, that of the surface which faces generally towards the seat 37 and the inner chamber 34 being larger. Accordingly, any pressure to which the contents of the annular chamber 28 are subjected when the valve is open tends to maintain the valve open and opposes the action of the spring 36.

In order to treat the internal surface of a pipe (not shown) to remove scale or other material adhering thereto, the device shown in the drawing is introduced into the pipe with the stem 38 leading so that the inlets 16 and 1 8a are adjacent to one end of the pipe. When the device is not in use, the valve 35 is closed by the spring 36 and the valve remains closed during an initial stage of use of the device. The wheels 26 maintain the tubular housing 23 clear of the wall of the pipe and assist with maintaining a substantially coaxial relation between the device and the pipe. Water under high pressure is fed to the first inlet 16 and sand, either dry or as a slurry, is fed to the inlet 18a. The water passes from the inlet duct 16a through the nozzles 20 and the outlet 3 to impinge on the walls of the pipe.Emergence of the jets of water from the nozzles into the chamber 11 establishes a relatively low pressure in that chamber so that atmospheric pressure acting on the sand in the inlet duct 18 causes the sand to flow through the orifices 22 into the chamber 11 where the sand is entrained in the jets of water. A stream of water containing particles of sand is projected at high velocity onto the walls of the pipe.

The kinetic energy of the stream of water which is projected onto the walls of the pipe from the outlet 13 is distributed approximately evenly around the axis 12so that the whole of an annular region of the wall is subjected to substantially the same treatment concurrently.

It will be noted that no part of the stream is directed from the device along the axis of the pipe.

The kinetic energy of the stream has a maximum value along the surface of a notional cone containing the axes of the nozzles 20.

The reaction on the device of the stream of water which is projected from the device causes the device to move away from the adjacent end of the pipe along the pipe. The device automatically traverses the length of the pipe until the stem 38 engages an abutment at a second end of the pipe. The stem 38 is thereby arrested and continued movement of the remainder of the device results in opening of the valve 35 so that water can flow from the first inlet duct 16a through the body 25 and the washing outlet. Opening of the valve 35 is accompanied by a sudden reduction in pressure in the first inlet duct 16a and at the source of the water supplied thereto.

The source would include a pressure-sensing device (not shown) which provides a control signal indicating that the device illustrated in the drawings has traversed substantially the entire length of the pipe.

This control signal may be fed to the device feeding sand to the second inlet 18a to terminate the feeding of sand and may also be fed to drive means for a reel on which hoses connected to the inlets 16 and 18 are coiled. The control signal is used to initiate coiling of the hoses and thus withdrawal of the device shown in the drawings from the pipe.

As the device shown in the drawings moves away from the abutment along the interior of the pipe, water is projected onto the pipe from the outlets 13 and 30 without abrasive, thereby washing from the interior of the pipe all of the loose solid matter remaining therein. If required, the control signal may also be used to bring about a further reduction in the pressure at which water is supplied to the inlet 16.

In addition to the second inlet 18a which is offset to one side of the axis 12, there may be provided an additional inlet for sand or other abrasive material, this additional inlet being diametrically opposite to the inlet 18a and communicating also with the annular passage 21. It will be appreciated that the body 10 may be used in a device without the body 25 and tube 31. Also, the body 25 and associated parts may be used in a device having means alternative to the body 10, for example rotating brushes, for removing material adhering to the interior of the pipe.

Whilst the particular example of apparatus illustrated in the accompanying drawings is arranged to direct an annular jet of water containing abrasive particles onto the inner wall of the pipe to impinge on that wall at an acute angle, it is within the scope of the invention for the device to be arranged to direct the jet so that it impinges at right angles on the wall of the pipe. In this case, it would be necessary to provide additional means for pushing or pulling the device along the interior of the pipe or to provide drive means, for example driven rollers, in the device itself.

Claims (25)

1. A method of treating the internal surface of a pipe wherein there is directed onto said surface a stream of liquid, the kinetic energy of which has a maximum value away from and is distributed approximately evenly around a longitudinal axis of the pipe.

2. A method according to Claim 1 wherein said stream contains solid particles.

3. A method according to Claim 1 or Claim 2 wherein the stream impinges concurrently on substantially the whole of an annular region of said surface.

4. A method according to any preceding claim wherein the kinetic energy of said stream has a maximum value along a surface of a notional cone having an apex angle exceeding 40".

5. A method according to Claim 4 wherein the apex angle is within the range 900 to 1400.

6. A method according to any one of Claims 1 to 5 wherein said stream is directed onto the surface by a device disposed within the pipe and wherein the device is moved along the pipe by the reaction of the liquid on the device.

7. A method according to Claim 6 as appendant to Claim 2 wherein, after the device has been moved in a first direction along the pipe by the reaction of the liquid, the device is moved along the pipe in the opposite direction and a stream of liquid substantially free of particles is directed by the device onto said surface.

8. A method according to Claim 7 wherein move mentofthe device in said first direction istermin- ated, flow of liquid from the device through a washing outlet is commenced and movement of the device in the opposite direction is commenced, all automatically when the device reaches the limit of its intended travel in said first direction.

9. A method according to Claim 1 wherein a device from which said stream of liquid is directed is caused to move along the interior of the pipe from an end thereof to an abutment, flow of liquid from the device through a washing outlet is commenced upon engagement of the device with the abutment and the device is returned to said end thereof whilst the flow of liquid through the washing outlet is continued.

10. A device comprising first and second inlets through which, in use, water and solid particles respectively enter the device, and an outlet communicating with both the first and second inlets and being arranged to direct from the device a divergent, substantially annular stream of water containing abrasive particles.

11. A device suitable for washing the interior of a pipe and comprising a body defining an inlet and an outlet though which, in use, a substantially divergent stream of liquid is directed onto the pipe from within the pipe, the inlet and the outlet being spaced apart in a direction called herein the axial direction, and the body containing a valve for controlling the flow of liquid from the inlet to the outlet, wherein the valve has an operating member which protrudes from the body in and is movable relative to the body in the axial direction.

12. A device according to Claim 10 or Claim 11 wherein the outlet is annular.

13. A device according to any one of Claims 10 to 12 comprising an annular chamber and a plurality of primary orifices which provide communication between the chamber and the first inlet, the outlet leading from the chamber

14. A device according to Claim 13 as appendant to Claim 10 comprising, for each primary orifice, a secondary orifice which provides communication between the second inlet and the chamber.

15. A device according to Claim 14 wherein each primary orifice is arranged to direct through the chamber to the outlet a divergent jet of water which intersects jets from adjacent primary orifices and the corresponding secondary orifice lies nearer two the primary orifice than do the positions at which the jet from the primary orifice intersects the adjacent jets.

16. A device according to any one of Claims 13 to 15 wherein the primary orifices are elongated in a direction circumferentially of the chamber.

17. A device according to any one of Claims 13 to 16 wherein each primary orifice defines an axis of a jet which issues from the primary orifice in use and the axis defined by the orifice is inclined at an angle in the range 45" to 70" to an axis of the device.

18. A device according to Claim 17 as appendant to Claim 10 wherein the second inlet is offset from the axis of the device and the axis passes through the first inlet.

19. A device according to Claim 11 wherein the valve is biased towards a closed position and movement of the operating member inwardly of the body opens the valve.

20. A device according to Claim 19 wherein the valve and operating member present to liquid flowing through the outlet when the valve is open respective surfaces having areas such that pressure exerted on the valve by the liquid flowing past the valve tends to maintain the valve in an open position.

21. A device substantially as herein described with reference to and as illustrated in Figure 1 of the accompanying drawings.

22. A device substantially as herein described with reference to and as illustrated in Figure 2 of the accompanying drawings.

23. A device substantially as herein described with reference to and as illustrated in Figures 1 and 2 of the accompanying drawings.

24. A method substantially as herein described of treating the internal surface of a pipe.

25. Any novel feature or novel combination of features disclosed herein or in the accompanying drawings.