GB2032043A

GB2032043A - A method of lining a pipe

Info

Publication number: GB2032043A
Application number: GB7931023A
Authority: GB
Original assignee: Oakes ET Ltd
Current assignee: Oakes ET Ltd
Priority date: 1978-10-11
Filing date: 1979-09-07
Publication date: 1980-04-30
Also published as: ES484919A1; AU5135279A; JPS5551531A; BR7906484A; GB2032043B; DE2938790A1; IT7925896A0; FR2438787A1; ZA794701B; IT1123264B

Abstract

In a method of lining a pipe 10 an adhesive layer is formed on the inner surface of the pipe which layer can be activated at a first temperature value, an adaptor 11 including a tubular member having an internal diameter at least equal to that of the pipe and a recess 16 in one end in which the pipe can be engaged is provided and a tube 25 of thermoplastic material is inserted into the pipe to overlie the adhesive layer and extends out beyond the end of the pipe. The tube 25 is passed into the tubular member and the end of the pipe is engaged in the recess. Thereafter radial force is applied to the thermoplastic film and the assembly is heated by relative axial displacement between the pipe and a source of heat, whereby the source of heat moves relatively towards the adaptor so as to raise the temperature to a value below the said first value, to render the thermoplastic film to a plastic state, and the entrapped gases are allowed to vent between the pipe and the recess. Finally the assembly is heated at least to the first temperature value to activate the adhesive. Alternatively the adhesive layer may be applied to the tube. <IMAGE>

Description

SPECIFICATION A method of lining a pipe The present invention relates to a method of lining a pipe and an adaptor for use therein.

It has already been proposed to line a pipe by applying an adhesive layer to the inner surface of the pipe, the adhesive layer being capable of being activated at a first temperature value, inserting in the pipe a tube of thermoplastic material to overlie the adhesive layer on the inner surface of the pipe, applying a uniform, purely radial force to said thermoplastic film, heating the assembly in an axially progressive manner, by effecting relative axial displacement between the pipe and the source of heat to raise the temperature to a value below said first value, to render the thermoplastic film to a plastic state and then heating the assembly at least to said first value to activate the adhesive. In a modification the adhesive is applied to the exterior surface of the tube before inserting in the pipe.These methods have proved very satisfactory except that there is some difficulty in ensuring a good bond between the pipe and the thermoplastic tube at the end of the pipe because it is difficult to eliminate all the vapours and/or gases from between the pipe and the tube.

It is now proposed, according to the present invention, to overcome this difficulty by providing an adaptor which includes a tubular member having an internal diameter at least equal to the internal diameter of the pipe and a recess in one end in which one end of the pipe can be engaged, inserting the tube of thermoplastic material in the pipe so that it not only overlies the adhesive layer on the inner surfaces of the pipe but also extends beyond the end of the pipe, passing the tube into the tubular member and engaging one end of the pipe in the recess, and effecting the relative axial displacement between the pipe and the source of heat whereby the source of heat moves relatively towards the adaptor, so that the thermoplastic material is rendered to a plastic state while allowing the entrapped gases and/or vapours to vent between the pipe and the recess.The assembly is subsequently heated to the first value to activate the adhesive.

The provision of the adaptor in this manner and the subsequent described operations ensures that the gases and/or vapours are vented reqdily and this enables the operation to be carried out in a fully satisfactory manner.

Preferably the thermoplastic material extending into the adaptor is clamped to the adaptor and the purely radial force is effected by producing a pressure differential between the inner surface of the pipe and the outer surface of the film. The adaptor may be rotatably mounted and the pipe rotated about its longitudinal axis during the heating.

The venting may be carried out simply by the pipe being a loose fit in the recess or it may be effected by providing a vent communicating between the end of the recess and the exterior of the tubular member.

The invention also provides an adaptor for mounting a pipe of a given diameter to be lined during the lining process, said adaptor comprising a tubular member having an internal diameter at least equal to the internal diameter of the pipe, a recess in one end of the tubular member in which the end of the pipe can be engaged and at least one vent communicating between the end of the recess and the exterior of the member.

In order that the invention may more readily be understood, the following description is given, merely by way of example, reference being made to the accompanying drawings, in which:~ Fig. 1 is a schematic cross-section through one embodiment of adaptor according to the invention; and Fig. 2 is a similar view of a second embodiment of adaptor.

In the construction of Figure 1, a metal pipe 10 is shown mounted in an adaptor 11 according to the invention. The pipe 10 has an internal diameter substantially corresponding to the internal diameter of the adaptor which is mounted for rotation in stationary arms 13. A conical plug 14 co-operates with a conical widening of the bore of the adaptor, the plug being held in place by a nut 15 inserted on to the adaptor at 12. The adaptor is provided with a recess 16 having a projecting part 1 7 extending over the exterior of the pipe 10. The recess 16 has an end wall 18 abutting the end of the pipe 10 and vents, in the form of radial grooves 19 and axial grooves or slots 20, extend from the end of the adaptor to the radial grooves 19. The grooves are preferably arranged at circumferentially spaced locations, to provide all round venting. In one construction there are four grooves.

A lining tube 25 is passed through the pipe and extends beyond the end of the pipe and is secured between the adaptor and the plug 14. Air is expelled from between the pipe 10 and the tube 25 by moving a heat source relative to the pipe in an axially progressive manner towards the end adaptor 12. An annular bubble of air is formed as the heater moves along and this bubble of air, which may include entrained gases or vapours, is allowed to escape through the vents formed by the grooves.

The lining is urged against the inner bore of the pipe by a radial force which may be produced by air under pressure fed to the interior of the lining by way of an inlet line 22 and a rotating coupling 21.

The construction of Fig. 2 is used when the lining tube is formed of a rigid material, for example of polypropylene. Like parts have been ilustrated by like reference numerals. In this construction, by way of illustration, the grooves and slots 19 and 20 are omitted and the air and gases or vapours can escape simply due to a slack fit of the pipe 10 in the recess 16. The plug 14 is of a different structure having an annular tapered groove 30 to accommodate the end of the lining tube 25, and being externally threaded at 31 to engage in a co-operating internal thread on the tubular body 1 1 of the adaptor. As the plug 14 is screwed in it will clamp the tube 25. A gas tight seal is made by means of an O-ring 32.

Claims

1. A method of lining a pipe, comprising applying an adhesive layer to the inner surface of the pipe, the adhesive layer being capable of being activated at a first temperature value, providing an adaptor which includes a tubular member having an internal diameter at least equal to the internal diameter of the pipe and a recess in one end in which one end of the pipe can be engaged, inserting in the pipe a tube of thermoplastic material to overlie the adhesive layer on the inner surface of the pipe and to extend beyond the end of the pipe, passing the tube into the tubular member and engaging one end of the pipe in the recess, applying a uniform, purely radical force to said thermoplastic film, heating the assembly in an axially progressive manner, by effecting relative axial displacement between the pipe and the source of heat, whereby the source of heat moves relatively towards the adaptor, and so as to raise the temperature to a value below said first value, to render the thermoplastic film to a plastic state, allowing the entrapped gases and/or vapours to vent between the pipe and the recess and then heating the assembly to said first value to activate the adhesive.

2. A method of lining a pipe comprising coating one surface of a film of thermoplastic material with an adhesive, the adhesive being capable of being activated at a first temperature value, forming the thermoplastic material to a tubular film, with the adhesive on the exterior, providing an adaptor which includes a tubular member having an internal diameter at least equal to the internal diameter of the pipe and a recess in one end in which one end of the pipe can be engaged, inserting the tubular film into the pipe so as to extend on the end of the pipe, passing the tubular film into the tubular member and engaging said pipe in said recess, applying a purely radial force to the thermoplastic material, heating the assembly in an axially progressive manner, by effecting relative axial displacement between the pipe and a source of heat, whereby the source of heat moves relatively towards the adaptor, so as to raise the temperature to a value below the first value, to render the thermoplastic film to a plastic state, allowing the entrapped gases and/or vapours to vent between the pipe and the recess, and then heating the assembly at least to said first value to activate the adhesive.

3. A method according to Claim 1 or 2, wherein the thermoplastic material extending into the adaptor is clamped to the adaptor and wherein the purely radial force is effected by producing a pressure differential between the inner surface of the pipe and the outer surface of the film.

4. A method according to Claim 1, 2 or 3, wherein the adaptor is rotatably mounted and the pipe is rotated about its longitudinal axis during the heating.

5. A method according to any preceding claim, wherein at least one vent is provided communicating between the end of the recess and the exterior of the tubular member.

6. An adaptor for mounting a pipe of a given diameter to be lined during the lining process, said adaptor comprising a tubular member having an internal diameter at least equal to the internal diameter of the pipe, a recess in one end of the tubular member in which the end of the pipe can be engaged and at least one vent communicating between the end of the recess and the exterior of the member.

7. An adaptor according to Claim 6, wherein the vent comprises a number of axially extending grooves formed in the pipe from one end into the recess to a location beyond the end of the recess.

8. An adaptor according to Claim 6, wherein the vent comprises one or more radial holes communicating with internal grooves which extend inwardly from the recess.

9. An adaptor according to Claim 6, 7 or 8, wherein the end of the adaptor remote from the recess is tapered, and further comprising a plug with a complementary external surface to the taper and engageable thereon to clamp the tube to the adaptor and a fluid passage in said plug for applying fluid under pressure into the interior of the tube.

10. An adaptor according to Claim 6, 7 or 8, and further comprising a plug insertable into the tubular member from the end thereof remote from the recess, and having an annular tapered groove facing said recess to accommodate and clamp a rigid lining tube, and a passage through said plug to permit the passage of fluid under pressure.

11. Methods of lining a pipe substantially as hereinbefore described with reference to and as Illustrated in the accompanying drawings.

12. An adaptor for use in lining a pipe substantially as hereinbefore described with reference to and as illustrated in Figure 1 of the accompanying drawings.

13. An adaptor for use in lining a pipe substantially as hereinbefore described with reference to and as illustrated in Figure 2 of the accompanying drawings.