GB2482220A

GB2482220A - Sealing of Coiled Pipe

Info

Publication number: GB2482220A
Application number: GB201108359A
Authority: GB
Inventors: Martin Stuart Denning; David John Hill
Original assignee: Glynwed Pipe Systems Ltd
Current assignee: Glynwed Pipe Systems Ltd
Priority date: 2010-07-20
Filing date: 2011-05-18
Publication date: 2012-01-25
Anticipated expiration: 2031-05-18
Also published as: GB2482220B; GB201108359D0; GB201012138D0; GB2482132A

Abstract

A method of providing a sterile, coiled pipe 1 with a sealed sterile bore comprises; extruding molten polymer to form a pipe 1, sterilising the bore of the pipe, cutting the pipe to a required length, capping or plugging 5 a first end of the pipe and coiling to leave a trailing edge of the pipe 1, while the bore is still sterile, bonding a towing head 2 or towing head socket 32 onto the trailing end of the pipe thereby to seal the sterile bore.

Description

Sealing of Coiled Pipe The present invention relates to a method of sealing a coiled pipe to maintain sterility in the bore of the pipe during storage and transit. The invention further provides a sealed pipe product which can be delivered sterilised and ready for installation.

The Applicant's earlier filed Patent Application publication number GB2431611 describes one method for sealing a coiled pipe and maintaining the sterility of the pipe bore. That publication describes a method for manufacturing polymeric pipe coils and effectively sterilising, capping and sealing the bore in a continuous process.

In order to minimise disruption when replacing damaged pipes, it has become common practice to use "No-Dig" methods. In such methods the existing in situ pipe is lined or replaced with a new, typically polyethylene pipe without the use of a trench. Typically, a pit is dug at the starting point and another at the required end point of the replacement pipeline. The existing pipeline may then be lined by towing a smaller diameter pipe through its bore. In an alternative, the existing pipe might be replaced by means of a pipe bursting tool, immediately followed by a replacement pipe in the channel vacated by the destroyed pipe.

It is known to clamp metal towing heads to pipe ends and use cables or ropes or rods to tow the pipe through the bore of an existing pipe or channel vacated by a destroyed pipe. Ordinarily such a towing head is a re-usable metal device (of which there are numerous variants) which may be firmly clamped into the pipe coil end, has a flush * external surface, a tapered or rounded nose and a towing eye for the attachment via a metal shackle of a rope or cable. The Applicant's product as described in GB2431611 may be installed by this method but such installation requires the sealing cap to be removed before mechanically clamping the towing head in place. Such a process S.., compromises the sterility of the pipe coil, especially as conventional towing heads may not be fully sealed against the ingress of dirty water from the surround. In which case the inserted pipe must be sterilised throughout after insertion -a time consuming process after which the sterilising solution must also be disposed of thoughtfully.

The present invention addresses the same practical issues addressed by the method of GB2431611 but provides an improved end product with further practical applications.

In accordance with the present invention there is provided a method of providing a sterile, coiled pipe with a sealed sterile bore comprising; extruding molten polymer to form a pipe, sterilising the bore of the pipe, cutting the pipe to a required length, capping or plugging a first end of the pipe and coiling to leave a trailing edge of the pipe, while the bore is still sterile, welding a towing head or a towing head socket onto the trailing end of the pipe thereby to seal the sterile bore.

Conveniently, sterilisation of the bore can be achieved through extrusion of the polymer material through a heated die and admission to the bore of a sterilised gas, for example as applied in the method of GB2431611.. The die preferably comprises a hollow cylinder with a central mandrel, the mandrel having at least one aperture through which a sterilising gas can be passed. Conveniently, the sterilising gas is gas heated at a temperature of about 170 to 250°C. For example or without limitation, the gas may be * air or nitrogen.

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In one option the plug or cap is a cylindrical plug. Alternatively, the plug is tapered. S...

A towing head may be either directly welded or an adaptor in the form of a socket suited for receiving a conventional (eg metal) towing head may be directly welded to S...

allow separate mechanical attachment of a conventional towing head. An advantage of the latter is that sterility of the bore is maintained but conventional towing head devices and attachment methods may still be adopted.

The socket may optionally be configured to serve the dual purpose of providing a positive attachment means for locating the fitting in the spin welding machine. In this case, the socket is provided with a cylindrical recess configured to receive an end of a towing head and one or more additional smaller recess at the base of the cylindrical recess which engage with complimenting protrusions on the spin welding machine to provide rotary motion. For example, the additional smaller recesses may comprise multiple smaller cylindrical holes arranged equidistantly at a common radius from the centre of the base of the cylindrical recess.

The towing head or socket may be made from a polymeric material compatible with the pipe coil material. Preferably, the towing head or socket is welded into position by spin welding thereby providing a joint that is generally as strong as the pipe and provides a full seal.

Spin welding is a well-known jointing process in the assembly of consumer products, automotive applications, etc., but hitherto not widely used for plastics pipes and fittings for utilities application. The process can, however be easily adapted to welding towing heads to the trailing end of the pipe coil in a factory based manufacturing process.

In one suitable method of the invention, the pipe is extruded continuously and cut to make the required coil length. After the cut is made the coiler is sped up to wind up the trailing end of the pipe just before completion of the winding, the coiler is stopped and * **.S.

* the towing head or socket welded to it. In the case of spin welding, this step takes just a few seconds. Winding of the pipe coil with welded towing head is then completed and retaining straps applied. The coil is then removed from the coiler. In order to maintain continuity of manufacture, extruded pipe (terminating where the coil was cut) continues S...

to be directed inexorably toward the coiler to provide the next coil. This newly extruded pipe is capped before winding onto the now vacant coiler.

In another aspect, the invention provides a novel pipe coil, comprising a coiled plastic pipe having a sterilised bore, a first sealed end which is enclosed by a cap and a second trailing end which has a plastic towing head or towing head socket welded thereto.

Desirably the cap and/or towing head/socket comprise the same plastic as the pipe and the towing head or socket is welded to the second pipe end.

The novel pipe coil is conveniently a product of the method already described herein.

The provision of an integral, sealed towing head avoids the need for sterilisation after the pipe is installed. After the new pipe is inserted into the existing pipeline the sealed towing head may be left in place until a joint is about to be made to an adjacent pipe end. The towing head can then be sawn off, a rapid cleaning process undertaken with a minimal volume of sterilising solution in the pipe ends only, and the joint made. This process is advantageous not only in that it is rapid but also does not generate a large volume of used sterilising solution to be disposed of. Furthermore the sawn off towing head may be recycled and reused in the production of new pipe coils.

Some embodiments of a coiled pipe in accordance with the invention are now described with reference to the accompanying Figures in which: Figure 1 shows in three views an end of a first novel coiled pipe in accordance with the *...S * invention which incorporates a welded towing head.

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Figure 2 shows a pipe coil with sealed end and towing head end.

Figure 3 shows in three views an end of a second novel coiled pipe in accordance with the invention which incorporates a welded towing head socket.

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Figure 1(a) shows an end view of the pipe 1 to which has been welded the towing head 2. Figure 1(b) shows a side view of the pipe end with the pipe cut away for better visibility of the towing head/pipe join. Figure 1 (c) shows a view from a cut end of the pipe 1 to the plug 3 of the towing head 2. The towing head 2 further comprises an eye 4 through which a shackle can be fastened allowing a cable or tow rope to be attached, for the pipe to be towed.

As can be seen from Figure 2, a first pipe section 1, having been cut from a continually extruding previous section 1' is coiled onto a coiler 6. A towing head 2 has been spin welded to the trailing end of the pipe 1 and meanwhile the end of pipe section 1' is capped by cap 5. Once the coiler 6 has been vacated, pipe 1' is coiled using the same method. The method is continuous, new pipe being extruded and capped as older pipe is coiled and its trailing end welded to a towing head.

Figure 3(a) shows an end view of the pipe 31 to which has been welded the towing head socket 32. Figure 3(b) shows a side view of the pipe end with the pipe cut away for better visibility of the towing head socket/pipe join. Figure 3(c) shows a view from a cut end of the pipe 1 to the plug 33 of the towing head socket 32. The towing head socket 32 comprises a main socket 34 which has an inside diameter substantially similar to that of the inside diameter of the pipe 31 and a depth suited to receive the plug of conventional towing head (not shown). At the base of the main socket 34 are two additional, smaller sockets 35a and 35b which are configured for attaching the socket to S..

* : the spin welding machine during manufacture of the coiled pipe. * .

Prior to installation of the coiled pipe, a conventional towing head is inserted into the socket 32 and secured by conventional mechanical means used for attaching a towing head to a pipe end. Typically the mechanical means is an expanding clamp. * * 0Ss*

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Claims

Claims 1. A pipe coil, comprising a coiled plastic pipe having a sterilised bore, a first end which is sealingly enclosed by a cap or plug and a second trailing end which has a plastic towing head or towing head socket welded thereto.
2. A pipe coil as claimed in claim 1 wherein the cap and/or towing head/towing head socket comprise a plastic which is weld compatible with the plastic of the pipe and wherein the towing head or towing head socket is welded to the trailing pipe end.
3. A pipe coil as claimed in claim 1 or claim 2 wherein the pipe material is polyethylene.
4. A pipe coil as claimed in any of claims 1 to 3 wherein the plug or cap is a heat shrinkable cap.
5. A pipe coil as claimed in any of claims 1 to 3 wherein the plug or cap is a cylindrical plug.
6. A pipe coil as claimed in any of claims 1 to 3 wherein the plug is tapered.
7. A method of providing a sterile, coiled pipe with a sealed sterile bore the pipe having the configuration of any of claims 1 to 6 comprising; *ISs** * extruding molten polymer to form a pipe; ::::. sterilising the bore of the pipe; cutting the pipe to a required length; capping or plugging a first wrapped end of the pipe and coiling to leave a trailing end of **** the pipe; and characterised by, while the bore is still sterile, bonding a towing head or towing head socket onto the trailing end of the pipe thereby to seal the sterile bore.
8. A method as claimed in claim 7 wherein the joining step involves spin welding the towing head or towing head socket to the pipe end.
9. A method as claimed in claim 8 wherein the sterilisation step is achieved by extrusion of the pipe through a die which allows exposure of the bore to a sterilising gas.
10. A method as claimed in claim 9 utilising a die which comprises a hollow cylinder with a central mandrel, the mandrel having at least one aperture through which a sterilising gas can be passed.
11. A method as claimed in any of claims 7 to 10 wherein the sterilising gas is heated at a temperature from about 170 to 250°C.
12. The method of claim 11. wherein the gas is selected from air or nitrogen.
13. The method of any of claims 7 to 12 utilising cap and/or towing head/towing head socket materials which comprise a plastic which is weld compatible with the plastic of the pipe.
14. A pipe coil, comprising a coiled plastic pipe having a sterilised bore substantially as described herein with reference to either of the accompanying Figures 1 and 3.*.S... * S::5:.
15. A method of providing a sterile, coiled pipe with a sealed sterile bore substantially as described herein and with reference to the accompanying Figure 2. S... * S S...S S.... * S