GB2274699A

GB2274699A - Lining pipes

Info

Publication number: GB2274699A
Application number: GB9401191A
Authority: GB
Inventors: Peter John Rose
Original assignee: AMEC UTILITIES Ltd
Current assignee: AMEC UTILITIES Ltd
Priority date: 1993-01-29
Filing date: 1994-01-21
Publication date: 1994-08-03
Anticipated expiration: 2014-01-21
Also published as: GB9401191D0; GB9301767D0; GB2274699B

Abstract

A method of lining lead service pipe (3), comprises providing a plug (4) of viscous lining material which fills the cross-section of the pipe (3) to be lined. A foam pig (1) is inserted in the pipe behind the plug (4); and the plug (4) is forced along the pipe (3) by applying fluid pressure to the foam pig (1) such that material (5) from the plug (4) is deposited on the inner surface of the pipe to reduce lead contamination of water flowing in the service pipe (3). In use, the cross-section of the foam pig (1) varies with the cross-section of the pipe (3). <IMAGE>

Description

A METHOD OF LINING PIPE This invention relates to a method of lining lead service pipe.

Conventionally, lead pipes which may cause contamination of the potable water which passes through them must be removed from their existing sites and replaced with non-contaminating pipes. Where the pipes in question are buried in streets or pavements this causes considerable disruption which it is desirable to avoid. A known method of lining lead pipes which avoids moving them from their sites is to insert a smaller bore pipe within the existing pipe. However, this has the effect of decreasing the flow rate of the fluid which passes through the pipe which is also undesirable. An alternative, particularly where the user is concerned with obtaining an uniformly smooth layer is to use a solid body or spray head. This may be pulled on a wire through the pipe. However these arrangements are inappropriate where the pipe has numerous bends and an uneven bore.This is a particular problem with lead pipes due to the softness of the material which easily distorts under external forces.

In accordance with the present invention, a method of lining lead service pipe comprises providing a plug of viscous lining material which fills the cross-section of the pipe to be lined; inserting a foam pig in the pipe behind the plug; and forcing the plug along the pipe by applying fluid pressure to the foam pig such that material from the plug is deposited on the inner surface of the pipe to reduce lead contamination of water flowing in the service pipe, and wherein, in use, the cross-section of the foam pig varies with the cross-section of the pipe.

The present invention provides a method of lining lead service pipe in situ in order to reduce contamination of the fluid in the pipe due to the material of the pipe itself, without causing disruption or causing any substantial alteration in the characteristics of the pipe.

The present invention also overcomes the problems of lining lead service pipe encountered in the prior art by providing a foam pig which varies its cross-section in use with the varying internal cross-section of the pipe.

In accordance with a second aspect of the present invention, apparatus for lining lead service pipe in accordance with the method of the first aspect of the invention comprises means to generate a fluid pressure to force the foam pig along the pipe such that material from the plug is deposited on the pipe.

Preferably, the thickness of the material deposited from the plug is controlled by controlling the speed at which the foam pig forces the plug through the pipe.

Typically, the lining material comprises a solvent free epoxy resin.

An example of a method and apparatus according to the present invention will now be described with reference to the accompanying drawings, in which: Figure 1 shows a section through a pipe being lined; and, Figure 2 is a sectional view of a pipe which has been lined by the method of the present invention.

A plug of lining material 4 is inserted into a pipe 3 to be lined. The plug 4 is forced along the pipe by a foam pig 1. The foam pig is driven by pressure of compressed air 2 at its end remote from the plug of material 4. As can be seen from Figure 1 the plug of material 4 is directly in contact with an inner wall of the pipe 3. A layer of lining material 5 is deposited in the pipe as the plug is pushed along by the foam pig 1. To accommodate this, the diameter of the foam pig is slightly reduced relative to the diameter of the plug of material 4. As the plug of material is forced further down the pipe its volume is reduced although it's cross-sectional area remains substantially the same until it is finally used up. The foam pig is driven out through an open end of the pipe.As the plug and foam pig encounter narrowed or non-uniform diameter sections of pipe their respective cross-sections expand and contract or change shape to allow the lining process to proceed.

If the length of pipe to be lined is already known it is possible to calculate within tolerances the amount of lining material 4 which would be required to line the inside of the pipe. In this case there will not be spare lining material which could form a blockage in the pipe when the end of the pipe is reached.

This would be calculated using the formula V = A.d Where V is the volume of material required, A the surface area of the pipe and d the desired thickness of living.

Preferred material for the lining material is drinking water inspectorate approved 2 part solvent free epoxy resin also conforming to BS6920 which is made up by mixing a base resin and hardener under controlled temperatures and then pumping a predetermined amount in front of the foam pig 1.

The resin is chosen for its rapid curing qualities which allow the water supply to be reconnected in a relatively short time eg. 24 hours.

Figure 2 shows a sectional view of a lead pipe which has been lined in accordance with the invention. The thickness of the lining 5 is typically of the order of a few microns.

The invention is typically applicable to lining pipes having diameters in the range of i" to 1".

Claims

1. A method of lining lead service pipe, the method comprising providing a plug of viscous lining material which fills the cross-section of the pipe to be lined; inserting a foam pig in the pipe behind the plug; and forcing the plug along the pipe by applying fluid pressure to the foam pig such that material from the plug is deposited on the inner surface of the pipe to reduce lead contamination of water flowing in the service pipe, and wherein, in use, the cross-section of the foam pig varies with the cross-section of the pipe.

2. A method according to claim 1, wherein the thickness of the material deposited from the plug is controlled by controlling the speed at which the foam pig forces the plug through the pipe.

3. A method according to claim 1 or claim 2, wherein the lining material comprises a solvent free epoxy resin.

4. Apparatus for lining lead service pipe in accordance with the method of claim 1, the apparatus comprising means to generate a fluid pressure to force the foam pig along the pipe such that material from the plug is deposited on the pipe.