GB2136912A - Sealing pipes - Google Patents

Abstract

A damaged portion of underground pipe 12 is repaired without excavating to the pipe by wrapping a sleeve round a collapsible inflatable bag, impregnating the sleeve with resin, moving the bag and sleeve in collapsed condition down the pipe to the position of the damaged portion and expanding the bag to urge the sleeve under pressure against the pipe wall until the resin is set. The bag is then collapsed and removed. Preferably protective waterproof layers are located on opposite sides of the sleeve, the layer 16 being bonded to the resin.

Description

SPECIFICATION Sealing pipes This invention relates to sealing pipes. Pipes for example drainpipes or main water supply pipes, are normally located under the ground, often at a considerable depth. They are frequently located in positions to which it is awkward and disruptive to excavate, for example under a road or under a building.

When a pipe is broken or damaged it is conventional to dig down to the damaged portion, cut out the length of damaged pipe and replace it with a fresh length before filling in the hole excavated. This is expensive and time consuming and an object of the present invention is to provide means for mending a pipe from inside it without having to excavate.

One method of doing this has been previously proposed. In that method a sleeve of rigid material capable of fitting in the pipe to be mended is formed from six longitudinally separate sections, which are hinged together so that the sleeve can be partially collapsed to be pulled along the pipe to the required position. Two sets of hydraulic jacks have to be located in the collapsed sleeve and are then expanded in directions normal to one another to expand the sleeve within the damaged portion of pipe. While this avoids excavation, the use of a hinged sleeve of rigid material and solid jacks is itself complicated and since the pipe is never of exactly the nominal diameter a rigid sleeve does not produce a good seal with the pipe even when a foam layer is located outside the sleeve between the sleeve and the pipe wall.

The present invention uses a mouldable settable sleeve material which is expanded into contact with the pipe to conform with the pipe shape and form a good seal therewith.

In one form the invention provides a method of mending a pipe having a damaged portion which comprises locating a sleeve of flexible material around a cylindrical inflatable and collapsible flexible bag, impregnating the sleeve material with a settable resin, moving the sleeve and bag in a collapsed condition along the pipe to a position within the damaged section of pipe, inflating the bag to expand the sleeve into engagement under pressure with the damaged pipe portion, holding the sleeve in the expanded position until the resin has set, collapsing the inflatable bag and withdrawing this from the pipe.

Using a flexible sleeve material and a mouldable settable resin allows the sleeve to accommodate itself to the actual pipe shape which will never be accurately the nominal pipe diameter, particularly where the pipe is cracked or partially collapsed, and forms a good seal with the pipe.

Preferably the sleeve material is fibre-glass and, with advantage, is a laminate made from fibreglass of both woven and matt form. The resin is preferably a polyester resin and in any case must be resistant to what ever material is to pass along the pipe.

The final set sleeve may be for example five to ten millimeters thick. The diameter of the inflatable bag should be chosen to be approximately the nominal internal diameter of the pipes less twice the required thickness of the sleeve. Preferably the diameter of the inflatable bag is not more than 5% greater than the diameter of the pipe less twice the selected sleeve thickness.

Preferably after the sleeve material has been located on the bag and impregnated with resin, the whole of the sleeve material is wrapped in a protective sheet which is waterproof and tear resistant to protect the sleeve and resin during passage down the pipe. For example this may be a polythene sheet preferably of at least 300 gauge.

In the final repair this sheet remains between the resin and the pipe wall and forms part of the sleeve. While the resin will normally set within about one hour to sufficient hardness to allow removal of the inflatable bag after that period, the resin will not normally be completely cured or resistant to attack by water or chemicals for a considerable further period. We have found that if the resin is unprotected and the pipe reused too soon the resin may break up or flake off. If a protective sheet such as a polythene sheet is located on the inside of the sleeve material to protect the resin during final curing this tends to eventually come away and block the pipe.

According to a preferred embodiment of the invention the outside of the bag is first lined with a sheet of water-proof material to which the resin will stick before the sleeve is located on the bag. A metal foil has been found suitable for example aluminium foil of not less than 25 microns thickness. This protects the resin during final curing and allows the pipe to be reused as soon as the positioning and inflating means have been extracted from the pipe.

The invention extends to apparatus for carrying out the above method and to a pipe so mended.

One embodiment of a method and apparatus for mending a pipe will now be described, by way of example only, with reference to the accompanying drawings of which:~ Figure 1 is a diagrammatic perspective view of apparatus for mending a pipe, Figure 2 is a cross sectional view, not to scale, through a pipe in the process of being mended, and Figure 3 is a section on the line Ill-Ill of Figure 2.

The position and length of damaged portion of a pipe 12 is first ascertained, preferably using a closed circuit television camera which is passed down the pipe. An inflatable and collapsible cylindrical bag 13 of flexible but not stretch material for example nylon fabric coated internally with Neoprene (for water proofing) and externally with Hypalon (Trade Mark) is selected to have a length greater than the length of the damage portion and a diameter substantially equal to the internal diameter of the pipe 12 minus twice the selected sleeve thickness for example 5 mm. A laminate 14 of glass-fibre material is prepared having a width slightly greater than the length of the damaged portion of the pipe and a length at least equal to and preferably slightly greater than the internal circumference of the pipe portion to be mended.This laminate is preferably made up from three to five layers of glass-fibre for example chopped strand matt layers.

The bag 13 is inflated via a connecting air line 1 5 and is first coated with a release agent. A protective sheet 1 6 of waterproof material which will bond to the resin to be used, for example aluminium foil not less than 25 microns thick is then wrapped round the bag. The foil has a width greater, in the direction of the axis of the bag, than the width of the laminate 14. The laminate 14 is then wrapped round the bag on top of the foil sheet 16 and is impregnated with a resin, preferably a polyester resin, which is resistant to water and chemicals likely to be found in sewers.

One suitable resin is Leguval W45R sold by Bayer.

The edges 17 of the aluminium foil sheet 16 are then folded over the edges of the laminate and the whole is covered with a water proof sheet 18 for example a polythene sheet, the edges of which are secured to the bag by tape 20.

The bag is then collapsed and the protective sheets and laminate also collapsed into concertina like folds around the collapsed bag. If desired they may be held in this state by breakable or expandable ties at intervals along the length of the bag outside the polythene sheet.

The prepared sleeve and bag are attached to the pulling line 21, are entered into the pipe through one manhole and pulled along the pipe to the required position which is preferably detected using a closed circuit television camera also attached to the pulling line. When the bag is correctly positioned it is inflated through line 15 to a pressure of 10 to 15 pounds per square inch (0.69 to 1.03 bar) to expand the protective layers and resin impregnated laminate into pressurised contact with the pipe wall. The pressure is maintained for sufficient time for the resin to set for example for one hour, after which the bag is uninflated and withdrawn from the pipe together with the television camera.

During insertion down the pipe to the required position the polythene sheet forms a protective layer which is water proof and tear resistant and this layer is pressed into contact with the pipe to form part of the set sleeve. The aluminium foil layer provides a protective sheet on the inside of the set sleeve and allows the pipe to be reintroduced into service as soon as the bag is removed since it provides a protective waterproof and chemically resistant layer to the resin while its final curing takes place.

The bag beyond the sleeve expands sufficiently to contact the pipe wall and produce tapered ends to the sleeve so there is no stepped edges in the pipe. The ends of the bag may be tapered to assist extraction.

This sytem is applicable to pipes of considerable diameter and down as small as 100 mm diameter. Sleeve lengths of up to about 1 metre are easily handled and a complete pipe liner can be made using a plurality of sleeves end to end or overlapping one another.

Claims (16)

1. A method of mending a pipe having a damaged portion which comprises a sleeve of flexible material around a cylindrical inflatable and collapsible flexible bag, impregnating the sleeve material with a settable resin, moving the sleeve and bag in a collapsed condition along the pipe to a position within the damaged section of the pipe, inflating the bag to expand the sleeve into engagement under pressure with the damaged pipe portion, holding the sleeve in the expanded condition until the resin is set and then collapsing and withdrawing the inflatable body.

2. A method according to Claim 1 in which the sleeve has a thickness between 4 and 10 mm.

3. A method according to Claim 1 or Claim 2 in which the inflatable bag has a diameter selected to be no less than and not more than 5% greater than the internal diameter of the pipe minus twice the selected sleeve thickness.

4. A method according to any of Claims 1 to 3 in which the inflatable bag is inflated to a pressure in the range of 0.69 to 1.03 bar.

5. A method according to any of Claims 1 to 4 which includes locating a waterproof protective sheet around the outside of the sleeve material and resin on the bag to protest the material during its movement along the pipe to the required position, this sheet remaining between the sleeve and pipe in the finished repair.

6. A method according to Claim 5 in which the edges of the protective sheet are taped to the bag to provide the required waterproof seal.

7. A method according to Claim 5 or Claim 6 in which the sheet is a polythene sheet of at least 300 gauge.

8. A method according to any of Claims 1 to 7 which includes locating on the inflatable bag, between the bag and sleeve material and resin, a sheet of material which is waterproof and will bond to the resin.

9. A method according to Claim 8 in which the sheet is a metal foil.

10. A method according to Claim 9 in which the sheet is an aluminium foil of at least 25 microns thickness.

11. A method according to any of Claims 1 to 10 in which the sleeve material is fibre-glass.

12. A method according to Claim 1 1 in which the sleeve material is a laminate.

13. A method according to any of Claims 1 to 12 in which the bag material is a flexible non stretch material.

14. A method of mending a pipe substantially as described herein with reference to the accompanying drawings.

15. A pipe having a sleeve formed therein according to the method of any of Claims 1 to 1 3.

16. A pipe having a sleeve formed therein from a fibre-glass and resin material.