Sleeves often need to be secured to the ends of pipes for various reasons such as for use as an end cap with one end of the sleeve closed or to provide for the joining of pipes by the provision of a flange on the sleeve or where the sleeve itself forms part of another pipe.

End caps are often secured to one or both ends of a pipe to isolate a section of pipe to perform a pressure test to check for leaks in the isolated section of pipe or to temporarily seal a section of pipe when work is interrupted at the end of a day. It is known to use end caps with an annular elastomeric seal to be secured onto and tightened around the outside surface of the end of a pipe. However, it is a burdensome and time consuming task to fit such an end cap because the end of the pipe must be cut to be substantially perpendicular to its axis and the pipe must be carefully prepared and cleaned to receive and form an adequate seal with the annular elastomeric seal of the end cap. Furthermore, the use of such an end cap is limited to situations where the pipe is subject to only a relatively low internal pressure whilst the end cap is fitted because of the limited friction provided by the annular rubber seal.

The end cap can be used in situations where the pipe to be capped is subject to higher pressures by placing heavy blocks against the end cap or by installing a transverse beam adjacent to the end cap with the ends of the beam in lateral excavations prepared on each side of a trench containing the pipe to be capped. If a section of pipe has end caps at both ends, a torsion bar or strap may be provided around both end caps and the length of the pipe to hold the end caps against the ends of the pipe.

However, it is burdensome and inconvenient to position heavy blocks or a beam against an end cap or to provide torsion bars and/or straps around the pipe and end caps.

It is often desirable to join lengths of pipe together, or to join flanges to pipes.

However, it is often undesirable to perform welding when in the vicinity of fuel gas conveying pipes or installations because of the risk of explosion. Furthermore, it can be difficult to join together pipes of particular materials such as Reinforced Thermoplastic Pipe (RTP) as is well known in the art.

It is an object of the present invention to securely attach a sleeve to an end of a pipe whilst overcoming or alleviating at least some of the above problems.

According to a first aspect of the present invention, there is provided a method of securely joining a sleeve to an end portion of a pipe, the method comprising positioning at least a portion of a sleeve over an end portion of a pipe to form an annular space between the outer surface of the pipe and the inner surface of the sleeve, inserting grout into the annular space and allowing the grout to cure to secure the sleeve to the end portion of the pipe.

The use of grout to secure the sleeve to the outside surface of the pipe produces a robust joining of the two.

According to a further aspect of the present invention there is provided a sleeve for joining to an end portion of a pipe, the sleeve comprising a tubular section to be positioned around the outside surface of an end portion of a pipe and an inlet through which grout may be inserted into an annular space formed between the inside surface of the tubular section of the sleeve and an outside surface of the pipe when in use.

Examples of the present invention will now be described with reference to the accompanying drawings in which:- Figure 1 shows a perspective view of a sleeve; Figure 2 shows a cross-sectional view of a sleeve, in this example with a flange and end plate, positioned over the end portion of a pipe; Figure 3 shows a cross-sectional view of a sleeve with a flange attached to an end portion of a pipe; and Figure 4 shows a cross-sectional view of a sleeve forming the end portion of one pipe attached to an end portion of another pipe.

The sleeve 10 shown in Figure 1 is made of carbon steel and has a tubular portion 11 with a flange 12 at one end. The flange 12 has an end plate 13 secured to it by a plurality of nuts 14 and bolts 15 passing through the flange 12 and end plate 13. The end plate 13 closes one end of the tubular portion 11 making the sleeve 10 an end cap in this example.

The tubular portion 11 of the sleeve 10 has two annular elastomeric seals 16,16a arranged on its inside surface. The seals 16,16a may be made from any suitable material such as rubber or polymer. The seals 16, 16a are of an appropriate size to be able to seal against the outside surface of a pipe to be received within the sleeve 10.

Clearly the annular seals 16,16a may be selected to be of an appropriate size to be able to seal against any diameter of pipe to be received within the sleeve 10.

An inlet 17 is provided in the wall of the tubular portion 11 between the seals 16,16a.

Grout may be introduced into the interior of the sleeve 10 through the inlet 17. An outlet 18 is provided in the wall of the tubular portion 11 through which displaced air and excess grout may be expelled. In this example, the inlet 17 and outlet 18 are arranged diametrically opposite to each other on the wall of the tubular portion 11. A plurality of series of so called"tell-tale"holes 19 are provided in the wall of the tubular portion 11. Each series of tell-tale holes 19 comprises a number of holes arranged in the direction of the axis of the tubular portion 11 between the seals 16, 16a. Each series of"tell-tale"holes 19 is spaced circumferentially around one or both sides of the tubular portion 11 between the inlet 17 and outlet 18.

Figure 2 shows a cross-sectional view of the sleeve 10 positioned substantially concentrically over the end portion of a pipe 20. The pipe 20 may be buried in the ground with the end portion exposed by an excavation to enable the sleeve 10 to be mounted onto the end portion of the pipe 20. In this example, the sleeve 10 is slide over the end of the pipe 20. The outside surface of the end portion of the pipe 20 may be roughened, for example by being grit blasted, to ensure that there is a good key for the grout. The inside surface of the sleeve 10 may also be roughened to provide further keying for the grout. The sleeve 10 may be positioned onto the end of the pipe 20 using a suitable support or jacking means (not shown). The sleeve 10 is positioned over the pipe 20 such that both seals 16,16a seal around the pipe 20 to provide an annulus 21 between the outside surface of the pipe 20, the seals 15,16 and the inside surface of the tubular portion 11. Grout is then inserted through inlet 17, in this example using a delivery pipe 22 attached to a suitable pump (not shown), to fill the annulus 21. As the grout fills the annulus 21 from below, it reaches the lowermost series of tell-tale holes 19. When grout is seen to be discharged from all of the tell- tale holes 19 of the lowermost series, indicating that there are no voids at that level in the annulus 21, the tell-tale holes of that series are blocked to prevent further discharge. This procedure is repeated with each series of tell-tale holes 19 as the grout progresses up the annulus 21 during filling.

As the grout fills the annulus 21, displaced air is discharged from the outlet 18.

During filling with grout, the outlet 18 is arranged at the uppermost portion of the sleeve 10 to enable air to be discharged from the annulus 21 without creating trapped air pockets which would create voids in the grout and thus weaken the affixing of the sleeve 10 to the pipe 20. A funnel 23 is positioned on the outlet 18 to accommodate grout discharged from the outlet 18 when the annulus 21 is full. The funnel 23 is provided with a marking 24 indicating the minimum level to which grout should be filled to ensure that when the inserted grout cures and shrinks, the annulus 21 is still full of grout. When the sleeve 10 with the annulus 21 filled with grout has been left for a suitable period of time for the grout to cure, the delivery pipe 22 and funnel 24 are removed leaving the sleeve 10 securely fixed onto the end of the pipe 20.

In the example shown in Figures 1 and 2, the sleeve 10 and end plate 13 form an end cap. If it is subsequently decided to remove the end cap, the end plate 13 may simply be unbolted from the flange 12 and the flange joined to another flange or section of pipe (not shown) with the secure attachment of the tubular section 10 to the pipe 20 via the grout left intact for permanent use.

If it were desired to secure a flange 12 to an end of a pipe 20, then the sleeve 10 shown in Figures 1 and 2 could be secured to an end of a pipe 20 as described above except without the need for end plate 13 or nuts 14 and bolts 15. A cross-sectional view of a flange 12 attached to an end portion of a pipe 20 is shown in Figure 3.

Figure 4 shows a sleeve 100 secured to the outside of an end of a pipe 20 as in the previous examples except that in this example, the sleeve is the end portion of another pipe 30 to be joined to pipe 20. The further pipe 30 may have the same diameter along its length as the sleeve 100 which has a slightly larger diameter than pipe 20 or the further pipe 30 may have a slightly enlarged diameter at the end comprising the sleeve 100.

This method of joining a sleeve to the end portion of a pipe is particularly applicable to use with cast iron and ductile iron pipes which suffer from corrosion pits over the course of time, since these corrosion pits provide a roughness to the outside surface of the pipe 20 which assists the grout in adhering to the pipe.

The grout may, for example, be selected from the following range :- urethanes, polyesters, acrylics, epoxies and cemtatious compounds. It will be appreciated that each should be selected to satisfy the operating temperature, humidity and curing rate which then leads to the different adhesion strengths for different applications.

Different grout material provides a different exothermic reaction which will determine the volume change after installation. Different markings 24 may be provided on the funnel 23 for grouts which contract to different extents upon curing. It will also be understood that the volume change of epoxy grout should be optimised to minimise the internal stress that the grout exerts upon the end cap 10 as it contracts.

Various modifications may be made to the example described above whilst still falling within the scope of the invention. For example, the end cap 10 may not have a flange 12 and a removable end plate 13 at its closed end but may instead have a permanent end plate affixed thereto, which may be welded on in advance.

Furthermore instead of a funnel 23 a tube or any other suitable receiving means may be used.