GB2229247A - Pipe cleaning pig - Google Patents

Abstract

A pipe cleaning apperatus (eg a pig 14) comprises a flexible (for example polyurethane) disc 12 comprising radially- extending cleaning fingers 19 removably secured (e.g. by a bolt 20) to removable anchor pins 17 connected to the disc 12 (e.g. by a cross-pin 21) radially inboard of its periphery. <IMAGE>

Description

PIPE CLEANING APPARATUS This invention relates to apparatus for cleaning pipelines, such, for example, as liquid or gas pipelines.

All pipelines, from time to time, become dirty due to the residual products of internal corrosion or ingress of foreign material which is usually introduced with the product being carried. However ingress of dirt can also occur during maintenance operations or following a burst or similar occurrence for whatever reason.

Dirt can be conveniently categorised into two forms, the first being loose material which tends to sit at the bottom of the pipeline either continuously or intermittently along its route. The second form of dirt is that which firmly adheres to the wall of the pipe usually at the bottom but sometimes on the entire circumference of the pipe wall. This build up of dirt which is often described as ta scale" can vary from being relatively soft to extremely hard and can be composed of ferrous and non-ferrous substances, or a combination of both. For instance, in water and sewerage pipelines, calcium carbonate is a particular problem; in crude oil pipelines, wax is the main problem; and in gas pipelines, it is usually hydrate formation.There are many types of scale, and it is to be noted that sometimes the scale build up does not actually adhere to the pipe wall but rather forms an integral "pipe" within the pipe.

Regardless of whether it does nor does not adhere to the pipe wall this scale is very difficult to remove, especially when the build up is very hard and/or thick, amounting, for example, to several inches.

The usual way of dealing with this scale build up together with its removal from the pipeline is to run pipe-cleaning pigs through the pipeline in order to break up the material.

Two types of pigs are usually used, the first being substantially made from cellular foam (grades vary from soft to very hard) coated with materials such, for example, as polyurethane containing or housing steel studs, abrasive grit, wire brushes and any other aggressive cleaning aids. The disadvantage with these foam pigs it that they have finite life since once they have been worn down they have to be thrown away. Also the cleaning action cannot be varied or adjusted since the cleaning aids of whatever form are permanently fixed into the pig.

The second type of pig has a steel body which is positioned in the pipeline by means of sealing discs and/or cups which are usually bolted to the pig body. Aggressive cleaning aids are then attached to the steel body, usually by bolting, and these aids include, inter alia, wire brushes, hardened steel plates and scraper blades. For most loose deposits and some softer deposits adhering to the pipewall, polyurethane discs have proved to be reasonably successful.

It is an object of the present invention to provide an improved and more versatile apparatus for cleaning pipelines compared with the aforesaid known pipe cleaning pigs.

According to the present invention there is provided apparatus for cleaning pipelines, the apparatus comprising a relatively flexible disc adapted for movement along a pipeline to be cleaned and mounting peripherally-extending replaceable and/or interchangeable cleaning elements.

Preferably the disc is mounted on, or constitutes, a pipe cleaning pig.

A plurality of pipe cleaning discs may be provided with or without spacer discs between adjacent pipe cleaning discs.

The pipe cleaning disc is preferably formed of polyurethane having radially inboard anchorages to which are releasably secured cleaning fingers housed in radial bores in the disc and extending radially outwardly of the disc.

The releasably anchoring of the cleaning fingers to their anchorages may be by screw-threading, bolting, pinning or any other convenient means.

The anchorages are preferably removably located within holes or other seatings within the polyurethane pipe cleaning disc to facilitate their removal when damaged for replacement purposes or for any other reason when they are not required.

Here, it should also be noted that the pipe cleaning disc instead of being made of polyurethane may alternatively be formed, inter alia, or neoprene, nitrile or rubber.

The cleaning fingers may, at their free ends, be fitted with plates or blades or other devices to increase the aggressive cleaning capacity of same. Additionally, the cleaning fingers may be hardened to increase wearability.

An embodiment of the present invention will now be described, by way of example, with reference to the accompanying drawing, in which: Fig. 1 is a transverse section through a pipeline to be cleaned showing a polyurethane cleaning disc in accordance with the present invention contained therein; Fig. 2 is a sectional view on the line II-II, to an enlarged scale; and Fig. 3 is a view similar to Fig. 2, but showing a multiple polyurethane cleaning disc arrangement.

Referring to the Figs. 1 and 2 the pipeline to be cleaned is indicated at 10 and the scale to be removed is indicated at 11.

The apparatus for cleaning the pipeline 10 comprises a flexible polyurethane disc 12 of solid construction centrally apertured as indicated at 13 for mounting on a convenient form of pipe cleaning pig generally indicated at 14 (see Fig. 2).

During forming of the disc 12 there is formed therein a number of equi-angularly spaced radial bores 15, each terminating in a seating hole 16 parallel with the central axis of the disc 12.

The holes 16 removably house anchor pins 17 by way of screwing, or a friction fit, or an interference fit, or by any other convenient means.

The anchor pins 17 are themselves formed with radial bores 18 aligned with the bores 15, and each of which releasably receives the inner end of a cleaning finger 19.

Each cleaning finger 19 extends radially outwardly of the disc 12 in order the contact the pipeline 10 to remove the scale 11.

In Figs. 1 and 2 each cleaning finger 19 is shown as being releasably secured by a bolt to its anchor pin 17 as indicated at 20, a removable retention cross-pin 21 extending through an axial extension of the anchor pin 17 and the bolt 20, but a preferred method of cleaning finger/anchor pin securement is by screw-threading.

The polyurethane cleaning disc 12 is formed adjacent its internal diameter with holes 22 to facilitate mounting of the cleaning disc on the body of the pig 14. On smaller sizes of pig only a single central hole may be required.

The diameter of the cleaning disc 12 will generally be smaller than the internal diameter of the pipeline 10 for initial cleaning, but it is envisaged that, in certain circumstances, an equal diameter or even an oversized diameter cleaning disc 12 may be utilised.

As can be seen from the drawing, the cleaning finger 19 extend beyond the circumference of the cleaning disc 12 and, in use, these cleaning fingers 19 will be sized to suit the type of deposit 11 being removed.

The cleaning fingers 19 may be undersized or oversized relative to the bore of the pipeline 10 depending on the operational cleaning requirements.

It will be manifest that the cleaning fingers 19 can be of any convenient cross sectional shape, for example circular, rectangular or square depending upon whatever shape is considered by the operator best to remove the particular form of scale 11 contained within the pipeline 10.

The aggressive cleaning capacity of these fingers 19 can be increased by welding or otherwise attaching to the end of the cleaning fingers 19 plates, blades or other cleaning devices. The cleaning fingers 19 may be hardened or have a hardening agent applied thereto to increase their wear resistance.

The cleaning disc 12 with associated cleaning fingers 19 is, as aforesaid, suitably secured to the body of the pig 14.

There may be more than one cleaning disc 12 provided as can be seen from Fig. 3 and in such an arrangement it is preferred that adjacent cleaning discs 12 are spaced apart by spacer discs 23 to ensure that the pack or assembly of cleaning discs 12 does not become too rigid thereby removing their flexing or bending capacity. It is to be noted that in this arrangement, the fixing holes 22 also traverse the spacer discs 23.

It will be noted in Fig. 3, that anchor pin 17A has both a foreand-aft axial extension to permit two retention cross pins 21A to traverse the bolt 20A securing the cleaning finger 19 to the anchor pin 17A.

It will also be noted that anchor pin 17B is formed with a blind bore 18A to receive the inner end of its cleaning finger 19 which is secured within the anchor pin by a bolt 20B, the anchor pin 17B being releasably pinned within its hole 16A as indicated at 21B.

The cleaning disc or discs 12 have a flexing or bending capacity which is or can be determined by the thickness and/or the hardness of the polyurethane used. This capacity is illustrated in Fig. 3. This flexing or bending capacity permits control of the cleaning action of the cleaning disc or discs 12.

The versatility of the pipe cleaning apparatus of the present invention is further increased by the ability to increase or reduce the number of cleaning finger 19 and/or to replace and/or change the cleaning fingers 19 to suit the cleaning requirements at site.

As the pig 14 travels through the pipeline 10 carrying with it one or more cleaning discs 12 with associated cleaning fingers 19, some or - all of the dirt of scale 11 is removed from the wall of the pipeline 10.

During the cleaning operation it is necessary to ensure that too much debris will not be removed which could lead to a massive accumulation ahead of and/or around the cleaning pig 14 thereby causing it to become stuck within the pipeline 10.

As a result of the present invention it is possible to select cleaning fingers 19 which will permit a relatively light initial cleaning action by using, for example, short length cleaning fingers 19 and/or by omitting some of the cleaning fingers 19. This relatively light cleaning action can be enhanced by using a cleaning disc 12 formed of a soft grade polyurethane which, due to its increased flexibility would allow the cleaning fingers 19 to bend back easily if required. The aggressiveness of the cleaning operation can be increased by changing the cleaning fingers 19, employing end plates, blades or other devices at the ends thereof, and/or using a more rigid grade of polyurethane for the cleaning disc or discs 12.

A cleaning pig can be formed entirely of cleaning discs 12 and associated cleaning fingers 19 in accordance with the present invention, the pig being formed of a multiplicity of cleaning discs 12 secured together with either a central shaft or bolted to a tubular body having retained flanges such as indicated at 24 in Fig. 3.

An articulated pig with a multiplicity of cleaning discs may also be used.

To ensure a 3600 cleaning action when employing a plurality of cleaning discs 12, each disc 12 will be offset relative to the other discs 12 by a pre-set amount to avoid the cleaning fingers 19 of one disc 12 tracking those of another. When pre-setting the orientation of each disc 12, the disc will be clearly marked to indicate where on the pig body it is to be fitted, or (if no pig per se is provided)how it is to be orientated relative to the other discs, to avoid two likeorientated discs being provided. The pipe cleaning action, according to this invention, can be varied from light to severe by selecting a cleaning disc or discs 12 of a soft or hard grade of polyurethane and/or by a selection of the kind and/or size of cleaning fingers 19 employed.

As a result of the present invention it is possible to use the cleaning disc 12 repeatedly and to replace and/or change the cleaning finger format to suit the requirements at site.

The pig may be self-propelled through the pipeline 10 by fitting sealing cups and/or discs or it may be towed through the pipeline 10 using a tow pig, or it may be pushed forwards by a pushing pig.

Claims (12)

1. Apparatus for cleaning pipelines, the apparatus comprising a relatively flexible disc adapted for movement along a pipeline to be cleaned and mounting peripherally-extending replaceable anchor interchangeable cleaning elements.

2. Apparatus as claimed in claim 1, in which the disc comprises radially inboard anchorages to which are releasably connected cleaning fingers which extend radially beyond the disc periphery.

3. Apparatus as claimed in claim 2 in which the anchorages are removably mounted in the disc.

4. Apparatus as claimed in claim 3 in which the disc is formed with angularly-spaced holes for removably housing the anchorages each hole communicating with the disc periphery through the intermediary of a radial bore within which one of the cleaning fingers is received.

5. Apparatus as claimed in claim 3 or 4 in which each anchorage is an anchor pin having a bore aligned with its respective disc bore and within which is received the inner end of its cleaning finger.

6. Apparatus as claimed in claim 5 in which each anchor pin is screw or otherwise releasably connected into its respective hole.

7. Apparatus as claimed in claim 5 or 6 in which each cleaning finger is pinned, bolted, screwed or otherwise releasably connected to its respective anchor pin.

8. Apparatus as claimed in any one of claims 1 to 7 in which the cleaning disc has a central hole to permit it to be mounted on a pipe cleaning pig.

9. Apparatus as claimed in claim 8 in which the cleaning disc is formed with a ring of holes radially inboard of the anchor pin holes to facilitate its securement to the pipe cleaning pig.

10. Apparatus as claimed in claim 8 or 9 comprising a plurality of discs mounted on the pipe cleaning pig with or without the intervention of spacers between adjacent discs and with respective discs orientated to stagger the cleaning fingers of respective discs to provide 3600 cleaning of a pipeline.

11. Apparatus as claimed in claim 9 or 10 in which the pipe cleaning pig is omitted and the assembly of discs with or without the intervention of spacers constitute a pipe cleaning pig per se.

12. Apparatus for cleaning pipelines, substantially as hereinbefore described with reference to the accompanying drawing.