[0001] This invention concerns a device for scraping the internal surface of fluid conducting
pipes. The device will be chiefly described in relation to water pipes made of metal
but it will be understood that pipes used in oil and chemical installations may equally
be cleaned physically by the device. Concrete pipes may also be treated.
[0002] Water mains are particularly troublesome in areas where the water contains ferric
and ferrous salts in appreciable concentration. The iron content of these salts is
sometimes visible in water samples as a flocculated sludge. This. material may adhere
to the surface of reticulation pipes and ultimately prevents valves in the pipes from
sealing fully.
[0003] In one known method this is removed by subjecting section after section of pipe to
a rodding technique or with hydraulic pressure using a dumbell-shaped device with
a rigid shaft, pairs of steel discs and rubber washers clamped between the discs.
Such devices proved unreliable in use. They jammed on bends which were not plotted
on official records of reticu- .lation layouts or on minor obstructions such as protruding
maincocks or stopvalve doors. Moreover the whole pipe section had to be drained before
rodding began.
[0004] This invention seeks to provide a device which will negotiate bends and obstacles
easily. This invention provides a device for scraping the internal surface of a fluid
conducting pipe comprising at least one pair of preferably mutually parallel discs
made of resilient material which are a push fit into the pipe, said discs being mutually
connected by a resilient support the separation of the discs being such as to permit
the device to pass around bends without undue interference between the edges of the
disc as the bend is passed. There may be 3, 4, 5, 6, 7, 8, 9, 10, 11, 12 or more discs
but we find 5 or 6 discs perform acceptably. The discs may taper in thickness toward
the periphery to assist flexing during their passage. We have found that if the discs
have a single radially directed slit, the whole device flexes better in use (kerfs
allow unwanted liquid pressure drop). The slits may be mutually aligned in an axial
direction. Alternatively, the slits in successive discs may lie at 90° to each other
and this is the preferred arrangement, the reason being that the alternate discs provide
baffles to the passage of liquid.
[0005] Conveniently the article will be moulded in one piece or as a double article being
divided after moulding. In order to open and close the mould easily, the discs are
moulded in parallel conformation but this relationship is not critical and the discs
may be in planes which are at an angle to each other providing they do. not, interfere
with the ability of the device to negotiate bends. The Shore "A" hardness of the rubber
may be about 80.
[0006] One embodiment of the invention is now described with reference to the accompanying
drawings in which:
Fig.l is a sectional side elevation of the device.
Fig.2 is an end view thereof.
Fig.3 is a fragmented sectional side view of another embodiment.
[0007] Referring now.to the drawings, the device for a 150 mm. nominal bore main consists
of a one piece rubber moulding which. is having having a shaft 2,325 mm. long and/a
diameter of 35 mm. There are five integral discs, 4 of 155 mm. diameter. Each disc
tapers in thickness from the shaft to the periphery in the manner shown, the thickness
A being 10 mm. or less, B being 15 mm. which improves the deformation characteristics.
Each disc is spaced from the next by a distance of 80 mm. measured flat face to flat
face. Radial slits 6 extend from periphery to shaft in each disc in a north/south
direction.
[0008] In another embodiment, which is used for cleaning four-inch diameter water mains,
the shaft is 230 mm. long with a diameter of 35 mm. There are six discs each of 106
mm. diameter. Each disc tapers to the periphery as illustrated, thickness A being
2.mm., B being 77 mm. and adjacent discs are separated by a distance of 42 mm. measured
flat face to flat face.
[0009] In Fig..3 discs 4 are not tapered in thickness, instead . they have cruciform ribs
8. A length of multistrand wire cable 10 acts as the shaft and the discs 4 are separated
by collars 12. These are all held together by a pair of bronze collars 14,loosely
enough to permit flexure.
[0010] When a pipe,for example a water main, is to be cleaned the procedure is as follows.
In the street to be cleaned the pipe is cut 3 metres from the valve and also at the
dead end or 3 metres from another valve. All house services are isolated and a 750
mm. section of pipe removed. The cleaner is inserted in the pipe, ensuring a firm
fit (tapering of the cleaner is required), and the pipe reconnected using gibault
couplings. A flexible hose may be connected to the receiving end to avoid property
damage from the water. The valve is then opened (about four turns depending on head),
and water (and/or air) pushes the cleaner through the pipe. When the cleaner exits
from the open end the main is flushed clean, then the pipe is reconnected and chlorinated
prior to returning to service.
[0011] We have found the advantages of the embodiment described above to be a good scouring
action in one pass; the ability to flex around pipe bends to pass through valves and
to move past obstructions within the pipe; the resistance to undue-deformation tending
to cause the device to stick in the pipe.
[0012] Although the device has been described in relation to its use for cleaning water
mains, clearly it may also be used in chemical plant, petrochemical installations,
gas pipelines and the like.
1. A device for scraping the internal surface of a fluid- conducting pipe comprising
at least one pair of ganged discs made of resilient material which discs are a push
fit into the pipe, the discs being mutually connected by a flexible central support,
the separation of the discs being such as to permit the device to pass around bends
without undue interference between the disc edges as the bend is passed.
2. A device as claimed in Claim 1 wherein the discs are mutually parallel and perpendicular
to the axis of the support.
3, A device as claimed in Claim 1 or 2 wherein there are multiple discs mutually separated
by a distance of the order of a half of the disc diameter, the supportbeing of the
order of a quarter of the disc diameter.
4. A device as claimed in any one of the preceding Claims wherein the discs taper
in thickness toward the periphery.
5. A device as claimed in any one of the preceding claims wherein at least some of
the discs have a slit extending from near the support to the periphery.
6. A device as claimed in Claim 5 wherein the slit extends diametrically across the
discs from the support to mutually opposite loci on the disc periphery.
7. A device as claimed in Claims 5 and 6 wherein the slits of successive discs lie
at 90° to each other.
8. A device as claimed in any one of the preceding claims wherein the support is a
shaft which together with the discs constitutes a one piece moulding.
9. A device as claimed in any one of the Claims 1 to 7 wherein the support is a flexible,
elongated tie upon which the discs are threaded, but separated by spacers and urged
together by a pair of abutments, one anchored at mutually opposite ends of the tie.
10. A device as claimed in Claim 8 when moulded in urethane rubber.
11. A device for scraping the internal surface of a fluid- conducting pipe, constructed
and adapted for use substantially as herein described, with reference to and as illustrated
in Figs. 1 or 2 or as modified in Fig.3 of the accompanying drawings.