EP0745436A1

EP0745436A1 - Pipe cleaning pig

Info

Publication number: EP0745436A1
Application number: EP95303784A
Authority: EP
Inventors: Peter John c/o Shell Research Ltd. Collins; Vyvian Anthony c/o Shell Research Ltd. COX
Original assignee: Shell Internationale Research Maatschappij BV
Current assignee: Shell Internationale Research Maatschappij BV
Priority date: 1995-06-02
Filing date: 1995-06-02
Publication date: 1996-12-04

Abstract

A pipe cleaning device (1) comprises a central body (3) and articulated scraper elements (5). The articulated shape of the scraper elements (5) serves to enhance the cleaning performance of the device (1).

Description

The invention relates to a pipe cleaning device. Pipe cleaning devices are widely used for cleaning the interior of pipes. These devices typically contain a sponge type body, bristles and/or scraper plates which remove debris from the inner surface of the pipe when the device is moved in an axial and/or tangential direction through the pipe.
The device may be moved through the pipe by pulling or pushing it therethrough by a wire or a rod, as is done if the device is a chimney-sweep, or by pumping fluid through the pipe, as is done if the device is a cleaning pig.
A pipe cleaning device in the form of a pig is disclosed in UK patent application GB 2273543. In the known device radially extending flexible scraping fingers are present which are slightly oversized relative to the internal diameter of the pipe so as to make resilient scraping contact with the inner surface of the pipe.
A disadvantage of the known device is that when it is moved through the pipe the scraping fingers will deflect such that debris which may be present on, or in pits in, the pipe wall is pressed against the wall by the finger and is therefore trapped and not removed.
An object of the present invention is to provide a pipe cleaning device which does not have this disadvantage and which is able to clean the pipewall to a high degree, even if the wall has an irregular surface.
The device according to the invention thereto comprises a central body and a plurality of scraper elements extending away from the central body, wherein at least some of the scraper elements have an articulated shape.
The device may form part of a cleaning pig which is transported through a pipeline by pumping fluid therethrough, which pig has a tubular central body that carries one or more sets of articulated scraper elements.
In such case it is preferred that

a rear cup surrounds the tubular body at its rear end and a front cup surrounds the tubular body at its front end, which cups at least partly seal off the annular space between the central body and pipe wall when the device is in use;
an internal disc baffle is mounted within the tubular body at a location between said discs such that said baffle at least partly seals off the interior of the tubular body;
at least one set of articulated scraper elements is carried by the tubular body at a location between the rear cup and internal disc baffle; and
a series of circumferentially spaced bypass openings are provided in the tubular central body between said rear cup and set of articulated scraper elements and between said internal disc baffle and said front cup.

If the device forms part of a cleaning pig it is furthermore preferred that, in order to rotate the pig when it is pumped through a pipe, the outer surface of the front cup is provided with a plurality of helical grooves and the tubular body further carries a series of helical scraper blades.
These and other features, objects and advantages of the present invention will become apparent from the accompanying claims, abstract and drawings, in which

Fig. 1 shows a schematic, partly side and partly longitudinal sectional view of a cleaning device according to the present invention within a pipe;
Fig. 2 shows a cross-section of part of the cleaning device of Fig. 1, taken along line II-II and seen in the direction of the arrows; and
Fig. 3 shows a longitudinal section of part of the cleaning device of Fig. 1 and 2, taken along line III-III and seen in the direction of the arrows.

Referring now to Fig. 1, there is shown a longitudinal section of a pipe 1 through which a cleaning device 2 according to the invention is moved in the direction of the arrows I by pumping fluid through the pipe 1 in the direction of these arrows I.
The device 2 comprises a tubular central body 3 on which a rear cup 4, two sets of articulated scraper elements 5 according to the invention, a set of helical scraper vanes 6, a front cup 7 and a set of conventional scraper elements 8 are mounted.
The conventional scraper elements 8 and the articulated scraper elements 5 are both slightly oversized with respect to the internal pipe diameter. The resulting deflection of the conventional scraper elements 8 will cause any debris which may be present on, or in pits of, the inner surface of the pipe 1 to be trapped between the tips of the elements 8 and the pipe wall, which reduces the cleaning performance.
The length of the articulated scraper elements 5 is selected such that primarily the foot sections 5A thereof are induced to deflect such that the tip sections 5B thereof engage the inner surface of the pipe 1 in a substantially radial direction. As a result of the radial orientation of the tip sections 5B no debris is trapped between these tip sections 5B and the pipe wall and the tip sections 5B will penetrate even into small pits in the pipe wall.
The cleaning performance of the device 1 is further enhanced by allowing some of the fluid to bypass the device 1 such that the fluid flushes any debis from the surface of the scraper elements 5 and 8.
This is accomplished by providing the rear cup 4 with an open or perforated centre (not shown) through which fluid enters the interior of the tubular central body 3. Furthermore an internal disc baffle 9 is mounted between the sets of articulated scraper elements 5 and the front cup 7 and perforations 10 are present between the rear cup 4 and each of the sets of articulated scraper elements 5 and between the baffle 9 and the front cup 7. As can be seen in Fig. 1 the perforations 10 and baffle 9 induce fluid to flow in the direction of the arrows IV thereby flushing and cleaning the scraper elements 5.
The outer surface of the front cup 7 is provided with a series of helical grooves 11. During operation of the device 1 some of the fluid will flow through these helical grooves 11 and between the helical scraper blades 6 in the direction of arrows V in a swirling motion, which enhances the cleaning of the pipe wall.
Figures 2 and 3 show the upper part of one set of articulated scraper elements 5 in an expanded position.
The elements 5 consist of elongate metal strips which are folded in a U-shape and stabbed through openings 12 in a scraper carrier ring 13 which is welded co-axially around the tubular central body 3 of the device.
The openings 12 are drilled in a regular pattern through the ring 13 such that the scraper elements 5, when seen in the direction of the central axis VI of the central body 3 as shown in Fig. 2, are located at regular tangential spacings.
Furthermore, the openings 12 are drilled in a slant orientation through the ring 13 such that, when seen in a cross-axial direction as shown in Fig. 3, the foot sections 5A of the scraper elements 5 are oriented at an acute angle of between 70 and 80 degrees relative to the central axis VI and point towards the rear cup 4.
The articulated scraper elements 5 are each pre-shaped by bending the element 5 during the manufacturing process of the device 1 and before the device is inserted in a pipeline such that a tip section 5B is defined which is oriented at an angle of between 40 and 50 degrees with respect to the foot section 5A of the element in question and such that the tip section 5B points towards the front cup 7.
The articulated shape of each scraper elements 5 causes the elements to deflect into the position shown in Fig. 1 when the device is pumped through the pipe 1 such that the tip sections 5B engage the pipe wall in a substantially radial direction.
It will be understood that instead of using metal strips for forming the articulated scraper elements any other resilient material may be used as well. If desired, the scraper elements may consist of articulated rods of a plastic material.
Furthermore instead of pumping the device through a pipe it may pulled or pushed therethrough by a rope or a rod.
These and other modifications and alternative embodiments will become apparent to those skilled in the art of pipeline maintenance and inspection upon reading this description and accompanying claims. Accordingly, it is to be understood that the embodiment of the pipe cleaning device depicted in the accompanying drawings is illustrative only and should not be construed as a limitation to the appended claims.

Claims

A pipe cleaning device comprising a central body and a plurality of scraper elements extending away from the central body, wherein at least some of the scraper elements have an articulated shape.
The pipe cleaning device of claim 1, wherein the length of the articulated scraper elements is selected such that when the device is located within a pipe the elements are induced to deflect such that tip sections of the scraper elements engage the inner circumference of the pipe in a substantially radial direction.
The pipe cleaning device of claim 2, wherein the articulated scraper elements, when seen in the direction of a central axis of the central body, are located at regular tangential spacings and, when seen in a cross-axial direction, have each a tip section which is oriented at an angle with respect to a foot section of the scraper element in question.
The pipe cleaning device of claim 3, wherein the angle between said tip section and foot section is between 40 and 50 degrees.
The pipe cleaning device of claim 3 or 4, wherein the foot sections of the articulated scraper elements are when seen in a cross-axial direction, oriented at an angle between 70 and 80 degrees relative to said central axis.
The pipe cleaning device of claim 2, 3, 4 or 5, wherein the foot section is about three to four times longer than the tip section of each articulated scraper element.
The cleaning device of any one of claims 1-6, wherein the articulated scraper elements consist of elongate flexible strips which are each bent at about the same distance from the central axis of the central body.
The cleaning device of any one of claims 1-7, wherein the device forms part of a cleaning pig which is transported through a pipeline by pumping fluid therethrough, which pig has a tubular central body that carries one or more sets of articulated scraper elements.
The cleaning device of claim 8, wherein
- the tubular central body has a front end and a rear end;

- a rear cup surrounds the tubular body at said rear end and a front cup surrounds the tubular body at said front end, which cups at least partly seal off the annular space between the central body and pipe wall when the device is in use;

- an internal disc baffle is mounted within the tubular body at a location between said discs such that said baffle at least partly seals off the interior of the tubular body;

- at least one set of articulated scraper elements is carried by the tubular body at a location between the rear cup and internal disc baffle; and

- a series of circumferentially spaced bypass openings are provided in the tubular central body between said rear cup and set of articulated scraper elements and between said internal disc baffle and said front cup.
The cleaning device of claim 9, wherein the outer surface of the front cup is provided with a plurality of helical grooves and the tubular body further carries a series of helical scraper blades.