GB2217423A

GB2217423A - Inflatable pipe-cleaning pig

Info

Publication number: GB2217423A
Application number: GB8809567A
Authority: GB
Inventors: Edward Alan Cattenach Jennings
Original assignee: PIPELINE PIGGING SERVICES LIMI
Current assignee: PIPELINE PIGGING SERVICES LIMI
Priority date: 1988-04-22
Filing date: 1988-04-22
Publication date: 1989-10-25
Anticipated expiration: 2008-04-22
Also published as: GB8809567D0; GB2217423B

Abstract

An inflatable or expandable pipe-cleaning pig moulded from flexible, non-permeable material is shown with a round nose and a concave rear having an inflation/deflation connection (1). Many variations are shown in the other figures. The pig may be expanded by a gas, a liquid, a gel or semi-solid or combinations thereof to vary the overall density of the pig. <IMAGE>

Description

INFLATABLE PIPE-CLEANING PIG Description This invention relates to inflatable pipecleaning pig.

The term "pig" is widely used to describe devices whose prime function is to clean internally pipeworks or pipelines by either a wiping or abrasive action.

There are two principal types in existence at present, namely "mechanical pigs" and "polly-pigs".

Mechanical pigs comprise a metal body to which semi-rigid urethane cups or discs are affixed to give an outside diameter which is slightly larger than the internal diameter of the pipe. In order to insert the mechanical pig into the pipe to be cleaned, it is necessary to affix a pig launcher or oversize spool piece onto the end of the line, in order that the pig may then be propelled by liquid, gaseous or semi-solid pressure into the pipeline. -Once the pig is inside the pipe the frictional interface between the cups or discs and the internal pipe wall cannot be adjusted to provide maximum cleaning efficiency.

Polly-Pigs comprise a moulded open-cell polyurethane bullet-shaped body, which can have urethane coatings permanently fixed to the outside diameter, to permit the scraping action for removal of deposits.

Some models also incorporate abrasive helical straps to permit a scratching action for removal of harder substances adhered to the internal pipe wall. Poly- pigs are also manufactured to be radially oversized, relative to the internal diameter of the pipe and thus also require a pig launcher to propel them into a pipeline. Althoughpolly pigs are much more flexible than mechanical pigs, once they are inside the pipe the frictional interface with the internal pipe wall cannot be adjusted.

An object of the invention is to obviate or mitigate the disadvantages of the mechanical pigs and the Polly-Pigs.

According to the invention there is provided an inflatable pipe-cleaning pig moulded from flexible, non-permeable material, the pig comprising a hollow generally cylindrical body having an inflation/deflation connection at least at one end.

With the inflatable pig according to the invention there is no necessity for a pig launcher to be used.

The inflatable pig can be inserted easily by hand into the pipe in its deflated state, whereupon it can be inflated in situ. In addition, the operative can adjust the degree of frictional interface between the outside diameter and the internal diameter of the pipe, by increasing or decreasing the pressure within the inflatable pig, before the pipe cleaning operation commences.

The inflatable pig according to the invention also permits the operative to select and vary the overall density of the pig to match the specific gravity of the propellant medium and/or the product to be recovered or removed from the line to be cleaned, since the inflatable medium may be gaseous, liquid, gel, semisolid or in any combination thereof. This enables the pig to perform optimum cleaning, by assisting even wear around its circumference which also extends the operational life of the pig. Mechanical pigs, due to the weight of their metal body, tend to create greater frictional interface on the bottom of the pipe, than the top. Consequently, their cleaning efficiency diminishes over a distance as the bottom part of the cups or discs are worn away.Conversely, Polly-Pigs are extremely light weight and are unable to negotiate hatch or inspection boxes due to their buoyancy, which floats them out of pipe alignment.

Embodiment of the invention will now be described, by way of example, with reference to the accompanying side elevation drawings, in which: Fig. 1 shows an inflatable pig with a round nose and a concave rear having an inflation/deflation connection; Fig. 2 shows a pig similar to that in Fig. 1 but with a chamfered nose having an accessory attachment; Fig. 3 shows a pig similar to that in Fig. 2 but including an internal flexible longitudinal expansion restrictor; Fig. 4 shows a pig similar to that shown in Fig. 1 except that the round nose is replaced by a concave one and so that the pig can be propelled in both directions; Fig. 5 shows a modified form of the bi-directional pig in Fig. 4 with both ends chamfered; Fig. 6 shows another modified form of the bidirectional pig in Fig. 4 but with both ends flat;; Fig. 7 shows a pig similar to that in Fig. 2 but with an external surface formed with raised lattice pattern of intersecting helical strapping; Fig. 8 shows a pig similar to that in Fig. 2 but with an external surface formed with a pattern of diamond-shaped raised pads of abrasive grit and/or wire bristles; Fig. 9 shows a pig similar to that in Fig. 2 but with raised discs of flexible, non-permeable material; Fig. 10 shows a pig similar to that in Fig. 2 but with raised cups of flexible non-permeable material; Fig. 11 shows a flexible jacket of permeable material and designed to slip over an inflatable pig; Fig. 12 shows a pig similar to that in Fig. 2 but including front and rear tow loops; Fig. 13 shows a pig similar to that in Fig. 2 but with front and rear housings for transmitter and instrumentation devices;; Fig. 14 shows a-pig similar to that in Fig. 2 but including a internal flexible hose with a nozzle for jetting, flushing, cleaning and other in-line applications; Fig. 15 shows a pig similar to that in Fig. 2 but including in its front end an emergency in-line deflator operated by a remote control or timing device; Fig. 16 shows a pig similar to that in Fig. 2 but including at its rear end a thin aluminium gauging plate for investigating or proving the bore of the pipeline; and Fig. 17 shows a pig similar to that in Fig. 2 but including at its rear end deformable non-resilient wire whiskers for indentifying in-line obstructions.

In Figs. 1 to 6 an inflation/deflation connector is shown at 1. The connector 1 can be provided at either end or, indeed, both ends of the pig. In Fig. 2 and 3 an accessing attachment is shown at 2.

In Fig. 3 an internal flexible longitudinal expansion restrictor is shown at 3. This is of great benefit when pigging a multi-dimensional pipeline since the restriction on longitudinal expansion makes the pig capable of great radial expansion. Under certain applications, especially in larger diameter pigs, the internal longitudinal expansion restrictor may be made of rigid or semi-rigid material to house instrumentation said / or automatic inflation deflation controls and associated equipment.

n Figs. 7 to 10 the external surface is formed with a raised lattice pattern 4 of intersecting helical strapping, a pattern of diamond-shaped raised pads 5 of abrasive grit and/or wire bristles, raised discs 6 of flexible, non-permeable material, and raised cups 7 similarly of flexible, non-permeable material.

Fig. 11 shows a flexible jacket 8 of permeable material into which a pig can be inserted and thereafter inflated.

Fig. 22 shows a pig having front and rear tow loops 9. This is useful when application of pressure on the pig by any propellant medium is impracticable. The most obvious example of this is in the cleaning and removal of grease desposits from sewer lines. In such applications the insertion of a mechanical pig or a polly-pig is impossible, due to their rigid or semi-rigid physical properties, in as much as access to mainline sewers is through narrower diameter manholes. because the inflatable pig can be deflated entirely, it can be lowered easily down the manhole and inflated insitu, after a winch cable has been connected to the front loop 9 from the next man hole. The inflatable pig can then be winched along the sewer, cleaniiig as it goes. Because the inflatable pig is being towed by its nose, any obstructions can be bypassed as any extra radial pressure on the pig will result in elongation thereof. This, in turn, descreases the radial frictional interface of the pig, resulting in it bypassing the obstruction. This would not be possible with a polly-pig since all polly-pig tow loops are affixed through the body of the pig. Thus, when meeting an obstruction the pig would be shortened longitudinally and thus expanded radially making it impossible for the polly-pig to pass the obstruction.

Fig. 13 shows front and rear housings 10 for transmitter and instrumentation devices. Fig. 14 shows an internal flexible hose 11 with a nozzle 12 for jetting, flushing, cleaning and other in-line operations.

Fig. 15 shows in its front end an emergency in-line deflator 13 which may be operated by a remote control timing device.

Fig. 16 shows at the rear end a thin aluminium gauging plate 14. This is manufactured from 1 mm thick plate to 95 of the internal diameter of the pipe for investigating or improving its bore.

Fig. 17 shows also at the rear end deformable nonresilient wire whiskers. These are distributed over the full circumference and are slightly oversize relative to the bore of the pipe. An obstruction met by the whiskers produce a deformation thereof which can be identified.

The various accessories can be used in different combinations to suit different applications.

Claims

1. An inflatable pipe-cleaning pig moulded from flexible, non-permeable material, the pig comprising a hollow generally cylindrical body having an inflation/deflation connection at least at one end.

2. A pig according to claim 1, including an internal longitudinal expansion restrictor.

3. A pig according to claim 2, wherein the restrictor houses instrumentations and/or automatic inflation/deflation controls and associated equipment.

4. A pig according to claim 1, wherein the outer cylindrical surface thereof has raised portions.

5. A pig according to claim 1, including an internal flexible base with a nozzle.

6. A pig according to claim 1, wherein deformable means are provided at one end thereof.

7. An inflatable pipe-cleaning pig substantially as hereinbefore described with reference to any one of Figs. 1 to 10 or any one of Figs. 12 to 17 of the accompanying drawings.