GB2442010A

GB2442010A - An adaptor for externally connecting a CIPP-lined pipe to a replacement pipe

Info

Publication number: GB2442010A
Application number: GB0618796A
Authority: GB
Inventors: Stephen John Taylor
Original assignee: PLANNED MAINTENANCE
Current assignee: PLANNED MAINTENANCE
Priority date: 2006-09-23
Filing date: 2006-09-23
Publication date: 2008-03-26
Also published as: GB0618796D0; WO2008035104A1; GB0904111D0; GB2454157A

Abstract

An apparatus suitable for providing an outer seal around a CIPP(cured-in-place-pipe)-lined pipe comprises a tubular body 30 having an internal dimension which is slightly larger than the external dimension of the CIPP-lined pipe, said tubular body being adapted at one end to be connected to a section of replacement pipe, and at the other end to receive a CIPP-lined pipe so as to form an airtight seal around its outer surface. Means 37, 51 may be provided for positioning the CIPP-lined pipe axially and centrally. The end 31 which receives the CIPP-lined pipe may be tapered outwardly, while the end to be connected to the replacement pipe ideally comprises a flange 32. The CIPP-lined pipe is preferably engaged by a stuffing-box connection, wherein a rubber seal 46 is urged against its outer surface by two flanges 35, 43 forced together. Preferably, an inner rubber seal 20 connects the two pipes 21, 23; see figure 2. A kit and method are also disclosed.

Description

Apparatus and Method The present invention relates to an apparatus and

method for use in forming a joint, in particular for forming a joint with a pipe which contains a cured-in-place lining. The invention is suitable for use in pipes which are used to transfer any type of fluid, for example water, oil or natural gas, at low or high pressures, for example up to 25 Bar.

Traditionally, gas pipelines in many parts of the world, for example the UK, US and Japan have been laid comprising sections made from cast iron and sections made from ductile iron.

Ductile iron sections of pipeline have eroded much more quickly than the cast iron sections and following a recent explosion resulting from this erosion, the Health and Safety Executive recommended that all ductile iron be removed from pipelines located within 30 metres of any property. When a cast iron section is simply bolted to a ductile iron section, it is a relatively simple operation to remove the ductile iron section and replace it with, for example, a polyethylene pipe which bolts onto the remaining cast iron section. However, problems arise when the pipes in question are CIPP-lined. A CIPP (cured in place pipe) lining is well known to those skilled in the art.

To CIPP line a pipe, a long, flexible lining tube is drawn through the pipe. Air or water under pressure is then fed into the tube which causes it to fit tightly to the wall of the pipe. The liner comprises on its outer surface when fitted an epoxy resin which is thus distributed between the liner and the internal surface of the pipe. Once the liner is in place, hot water or air is circulated through the pipe. This cures the thermo-setting epoxy resin and secures the pipe in place. A continuous lining may be applied throughout the interior of a pipeline thus lining with a single liner adjoining sections made from cast iron and ductile iron.

When it is desired to replace a section of ordinary ductile iron pipe which is connected to a cast iron section of pipe when the pipes are not CIPP lined, a simple operation is involved. The ductile section is simply replaced by a polyethylene pipe which is bolted onto the remaining cast iron section of pipe. The joint may be internally sealed using any suitable method as will be known by those skilled in the art. A preferred method of sealing such a joint is by the use of a seal such as that sold under the trade mark AMEX-lU, produced by Meyer and John of Hamburg, Germany and supplied in the UK by PMP Limited of Lancashire. Details of the AMEX-lO seal can be found at www.pmp-ltd.co.uk.

The AMEX-b seal is typically used to fit pipes having a diameter of at least 24 inches and into which an engineer is able to climb if necessary.

A typical AMEX-lU seal is shown in Figure 1A in which the seal is located across the joint of pipes 1 and 2.

Pipe 2 is shown in a cut away view so that the seal can be clearly seen. A cross section of the seal and the joint along the line A-A' is shown in Figure lB. The AMEX-b seal comprises a tube 3 of substantially cylindrical cross-section. It is made from a rubber material, for example EPDM (ethylene propylene diene monomer) rubber or NBR (nitrile rubber) To join pipes using an AMEX-b seal, the joint is first cleaned to ensure a smooth surface on which to seat the seal. In high pressure systems, an MDPE (medium density polyethylene) backing band may be applied to protect the rubber seal. The rubber tube is then placed in position across the joint. Each end of the internal surface of the rubber seal is provided with an annular recess 6 designed to receive a stainless steel retaining ring 7. Two such rings are provided. Each is fitted in place loosely at first, and then hydraulically expanded and secured with stainless steel retaining wedges. The underside of each end of the rubber ring seal is provided with three double sealing ribs 8 between inner and outer sealing lips 9 and 10. To ensure a secure compression seal, the engineer applying the seal will repeatedly hit the retaining ring once in position, for example using a metal rod. This vibration ensures that the rubber forms a strong seal with the pipe surface. The effectiveness of the seal can be tested via test nipple 11. Soap solution is applied to the edge of the seal and nitrogen is delivered to the test nipple. The presence of a leak is indicated if bubbling is seen around the edge of the seal.

As many gas pipes are too small to accommodate an engineer, the repeated hitting to ensure a good seal is not possible. Gas pipes may have a diameter of for example 8", 12", 16", 18", 20" or 21", although pipes of larger diameter are known.

Further, the method of sealing a joint using an AMEX-seal as shown in Figures 1A and lB is not suitable for completely sealing a CIPP-lined section of pipe to a section of new replacement pipe.

Figure 2 shows a problem which can arise when an AMEX-seal 20 is used to seal the joint of a CIPP lined pipe 23 to an ordinary pipe 21. The seal 20 is held in place by steel retaining rings 25. Pipe 23 is provided with a CIPP lining 22. If there is a tear in the lining at a different location, which could be distant from the joint, gas could enter the space behind the CIPP lining 24. Thus gas could travel along the pipe behind the lining and would be able to escape via the joint at B, behind the seal. This leakage would be both costly and potentially dangerous. Thus although the AMEX-b seal provides an effective internal seal, external leackage is still possible when it is used with a CIPP-lined pipe.

It is an aim of the present invention to provide a method and apparatus for use in forming a joint with a CIPP lined pipe which overcomes a disadvantage of the prior art whether specifically mentioned herein or not, for example by preventing any external leakage from the pipe and its lining.

According to a first aspect of the present invention, there is provided an apparatus for providing an outer seal around a CIPP-lined pipe, the apparatus comprising a tubular body, the internal dimension of which is slightly larger than the external dimension of the CIPP-lined pipe, the tubular body being adapted at one end to be connected to a section of replacement pipe and at the other end to receive a CIPP-lined pipe so as to form an airtight seal around the outer surface of said CIPP-lined pipe.

Preferably the tubular body comprises a cylindrical body.

The apparatus for providing an outer seal may be made from any suitable material. Preferred materials are stainless steel and especially, mild steel. The material must be strong, tough, non brittle, durable and corrosion resistant or provided with a corrosion resistant coating.

The apparatus may be made from a single casting or may be manufactured from a plurality of pieces welded together.

Provided within the interior of the cylindrical body is a positioning means which ensures that the CIPP-lined pipe is correctly positioned within the apparatus. This typically comprises a projection which extends into the internal cavity and prevents the pipe from being pushed through the apparatus. Suitably the positioning means comprises an annular projection which extends into the internal cavity of the cylindrical body. The positioning means may comprise an inner cylinder which, is coaxial with the outer cylindrical body and of shorter length.

The internal diameter of the inner cylinder is substantially identical to the internal diameter of the CIPP-lined pipe. In use, the CIPP-lined pipe is inserted into the apparatus until it reaches the internal edge of the inner cylinder. The other end of the inner cylinder is suitably appended to the main outer cylindrical body of the apparatus at the end adapted to be connected to a section of replacement pipe.

Extending from the end to be connected to the section of replacement pipe, there is preferably provided an outer flange which extends substantially perpendicularly from the wall of the cylinder. The flange is preferably provided with a number of apertures which enable a new section of replacement pipe having a corresponding flange to be bolted thereto.

The end of the apparatus adapted to receive the CIPP lined pipe preferably tapers outwardly so that it may accommodate, in use, a sealing ring between the outer surface of the OIPP lined pipe and the inner surface of the apparatus.

The apparatus may be provided with a further flange in the region immediately below the tapered end of the cylinder, said second flange being adapted to be releasably connected to a further external annular member, such that in use, the connection between the flange and the external annular member can be adjusted to effect a seal around the external edge of a CIPP-lined pipe positioned within the apparatus. Preferably the second flange is provided with a plurality of apertures which can be aligned with a plurality of apertures on the external annular member so that a system of nuts and bolts can be used to tighten and loosen the engagement of the apparatus with the pipe.

When the apparatus is provided in a ready-to-use position, the external annular member is preferably loosely connected to the second flange by a plurality of bolts so that it is possible for a pipe to be positioned within the core of the apparatus. A rubber seal may also be loosely placed in the interior of the apparatus in preparation for use.

The apparatus is preferably provided with one or more means for positioning the main cylindrical body centrally around a pipe. These means suitably comprise a plurality of bolts spaced around the cylindrical surface of the apparatus such that each bolt extends tangentially through the surface of the apparatus and can be screwed into the apparatus such that the tip of the bolt contacts the outer surface of a pipe positioned within the apparatus.

Adjustment of the different bolts enables the relative position of the pipe and the apparatus to be adjusted so that the pipe lies substantially centrally within the apparatus.

Each of the bolts is suitably located within a housing. The housing may comprise a small cylindrical body extending from the surface of the apparatus. The housing is preferably sealed with a cap which must be removed in order to access the bolt. A suitable cap may be a threaded cap used with a Dowty washer to ensure an airtight seal.

The apparatus may comprise a further housing, for example a further cylindrical housing having an airtight seal. Through this housing it may be possible to supply a gas, for example, air or nitrogen, into the housing to test whether the seal is effective: soap solution is applied around the edge of the seal and any escaping gas will cause visible bubbling.

According to a second aspect of the invention there is provided a kit for use in forming a seal with a CIPP-lined pipe, the kit comprising an apparatus for providing an outer seal as defined in accordance with the first aspect and an apparatus for providing an inner seal.

Preferably, the apparatus for providing an inner seal comprises a rubber tube of substantially cylindrical cross-section, two retaining rings and two corresponding retaining wedges to hold the rings in place. In the region of the outer edges of the internal surface of the rubber tube there are provided grooves to accommodate the retaining rings.

Preferably, on the external surface of the rubber tube' there is provided one or more sealing ribs. Preferably the sealing ribs are located in the region of the outer edges of the external surface, on the opposite side of the tube to the grooves for accommodating the retaining rings.

There is preferably provided at each end a region comprising one or more sealing ribs, for example 2, 3 or 4 sealing ribs. Around each of these regions of sealing ribs, there is preferably provided inner and outer lips, the outer lips provided at the edges of the seal.

The seal may be made from any suitable material.

However, preferred materials are EPDM (ethylene propylene diene monomer) or NBR (nitrile rubber) . The retaining rings and retaining wedges are preferably of stainless steel.

The apparatus for providing an inner seal around said joint is preferably a seal of similar construction to the seal known under the trade mark AMEX-b.

According to a third aspect of the invention, there is provided a method of providing an outer seal around a CIPP-lined pipe, the method comprising providing an apparatus comprising a tubular body, the internal dimension of which is slightly larger than the external dimension of the CIPP-lined pipe, the method comprising connecting one end of the tubular body to a section of replacement pipe and connecting the other end of the tubular body to a CIPP-lined pipe so as to form an airtight seal around the outer surface of said CIPP-lined pipe.

The third aspect of the invention further provides a method of forming a seal with a CIPP-lined pipe, the method comprising: (a) placing the end of the CIPP-lined pipe within the outwardly tapered end of an apparatus for providing an outer seal as described in accordance with the first aspect, such that the end of the CIPP-lined pipe rests against positioning means of the apparatus; wherein the apparatus has been fitted with a rubber sealing ring and an external annular member has been loosely connected to a flange of said apparatus; (b) adjusting the axial alignment of the pipe within the apparatus so that it lies in a substantially central position; (c) tightening bolts connecting the flange of the apparatus to the external annular member to provide a seal to the outside of the pipe; (d) internally sealing the joint of the CIPP-lined pipe to the apparatus of the first aspect using an apparatus for providing an inner seal as defined in the second aspect; and (e) connecting a portion of replacement pipe to the end of the apparatus of the first aspect adapted to be so connected.

As explained above, it is usually necessary for engineers to repeatedly hit the retaining rings to force the rubber to form a good seal with the pipe. However, this is not possible with pipes of small diameter.

The present invention also provides a method of providing a secure seal of a rubber sealing tube to the internal surface of the pipe by expanding a retaining ring and retaining wedge using a hydraulic ramp attached to a vibrating machine, thus applying continuous vibrations to the rubber as the ring is expanded. Suitably the vibrating machine vibrates at a frequency of 1000 cycles per minute. A suitable vibrating machine is a K-series ball vibrator available from K Supplies Limited of Waterside Industrial Estate, BB4 5EN, United Kingdom.

According to a fourth aspect of the present invention there is provided the use of the apparatus of the first aspect or a kit of the second aspect to form a seal around a CIPP-lined pipe.

The apparatus, kit and method of present invention may be used to form a joint to CIPP-lined pipes of all sizes.

However, it is particularly useful for sealing a joint to pipes having a diameter of less than 30", for example less than 24". The invention may be used on pipes carrying any fluid but is especially suitable for pipes carrying natural gas (methane) The invention will now be further described by way of example by reference to the accompanying drawings in which: figure 3 shows an apparatus for forming an outer seal in accordance with the first aspect of the invention; figure 4 shows a cross-section of the apparatus of figure 3 along the line B-B'; figure 5 shows a perspective view of an apparatus for forming an outer seal in which a rubber sealing ring and an external annular member are placed in position so that the apparatus is ready to use; figure 6 is a perspective view of the side of the apparatus of figure 5; figure 7 is a cross-sectional view of a bolt located in a cylindrical housing; figure 8 is a cross-sectional view of an additional housing provided to allow the seal to be tested; and figure 9 shows a rubber sealing ring for use with the invention.

The apparatus will be described as if sitting in a vertical position as shown in the figures. However, it will be appreciated that in use when joining a pipe, the apparatus may be located in a substantially horizontal position.

As shown in figures 3 and 4 the apparatus comprises an outer cylindrical body 30 which is flared at its upper end 31. At its lower end the body comprises an outer flange 32 having a plurality of apertures 33 spaced around the flange. The flange extends slightly into the internal cavity of the outer cylindrical body to join an inner cylinder 34, the top of which extends to just under half of the height of the outer cylindrical body. In the region near to the top of the outer body, but below the flared region there is provided a further flange 35 extending from the outer surface of the body and having a plurality of apertures 36.

Extending through the outer surface of the main cylindrical body are six bolts 37 located in pairs approximately equidistantly around the surface of the cylinder in the upper region above the top of the inner cylinder 34. These bolts are surrounded by a cylindrical housing 38 and sealed with caps 39. An additional cylindrical housing is provided next to one pair of bolts to cover an aperture 40 which is open to the interior of the main cylindrical body.

The additional outer cylinder 41 can be more clearly seen in figures 5 and 6.

Figures 5 and 6 show the apparatus ready to be fitted to a pipe in which an external annular member 42 and a rubber sealing ring 46 have been roughly positioned in place.

The external annular member 42 comprises an outer flange 43 of similar external diameter to flange 35 and a depending internal skirt 44, which is shaped to fit just outside the outer tip of the outer upper edge of the main cylindrical body. Flange 43 is provided with a plurality of apertures which are aligned with the apertures on 46 on flange 35 of the main cylindrical body. A plurality of nuts and bolts 45 are used to loosely attach flanges 35 and 43. Between these flanges there is positioned a rubber ring 46 which is shaped to fit into the flared internal surface of the outer cylindrical body. This rubber ring is shown in perspective view in figure 9.

Figure 7 shows a cross-section through the cylindrical housing 38, which is welded to the outer surface of main cylindrical body 30. The surface of the main cylindrical body 30 comprises a threaded aperture so that bolt 37 may be screwed in and out of the body. Cylindrical housing 38 is sealed by a threaded cap 39 and a dowty washer 47 to ensure an airtight seal.

In figure 8 it can be seen that the additional cylindrical housing 41 is closed by similar cap 48 and a further washer 49. However, in this case aperture 40 within the housing remains open so that it allows air to flow into the body of the housing when cap 48 is removed.

In use, the prepared apparatus as shown in figures 5 and 6 is slid onto the end of a CIPP-lined pipe until the end of the pipe registers with the top edge 51 of inner cylinder 34. Due to the weight of the apparatus there will be at the bottom a larger gap between the interior of the outer cylindrical body and the exterior of the CIPP-lined pipe than there will be at the top. Thus caps 39 are removed from housing 38 to provide access to bolts 37 which are suitably adjusted to centralise the position of the pipe within the apparatus.

Bolts 45 are then tightened to provide a compression seal of ring 46 around the outer edge of the pipe. Once the outer seal is in place, the internal joint of the pipe with internal cylinder 34 is sealed using, for example, a standard AMEX-lO seal as is well known by those skilled in the art. However, as the diameter of this is not sufficient to allow an engineer to bang the rubber to improve the seal, a hydraulic ram attached to a vibrating member is used to secure the seal in place by expanding retaining rings and fixing with retaining wedges.

At this stage the seal is tested to ensure there can be no leaks. A soap solution is applied around the edges of the internal and external seals. Cap 48 is removed from housing 41 exposing aperture 40. A positive pressure of nitrogen is then introduced into the apparatus and the presence or absence of bubbling around the edges indicates the presence or absence of a leak.

Finally a replacement polyethylene pipe or the like may be bolted onto outer flange 32. When the pipe in question is a gas pipe, flange 32 is suitably a PN-16 flange, which is able to be easily connected to a similar such standard fitting on a replacement pipe.

Claims

Claims 1. An apparatus for providing an outer seal around a CIPP-lined

pipe, the apparatus comprising a tubular body, the internal dimension of which is slightly larger than the external dimension of the CIPP-lined pipe, the tubular body being adapted at one end to be connected to a section of replacement pipe and at the other end to receive a CIPP-lined pipe so as to form an airtight seal around the outer surface of said CIPP-lined pipe.
2. An apparatus according to claim 1 wherein the tubular body comprises a cylindrical body.
3. An apparatus according to claim 2, which further comprises positioning means to locate the CIPP lined pipe within the apparatus.
4. An apparatus according to claim 3 wherein the positioning means comprises an inner cylinder coaxial with the outer cylindrical body and of shorter length.
5. An apparatus according to any of claims 2 to 4 which comprises an outer flange which extends substantially perpendicular from the wall of the tubular body at the end which is to be connected to the section of replacement pipe.
6. An apparatus according to any of claims 2 to 5 wherein the apparatus tapers outwardly at the end adapted to receive CIPP-lined pipe.
7. An apparatus according to any of claims 2 to 6 which comprises one or more means for positioning a CIPP-lined pipe centrally within the cylindrical body.
8. An apparatus according to any of claims 2 to 7 which is provided with a second flange adapted to be connected to an external annular member at the end for receiving the CIPP-lined pipe.
9. An apparatus according to claim 8 which is provided in combination with an external annular member adapted to be connected to said apparatus.
10. An apparatus according to any of claims 2 to 9 which is provided in combination with a rubber sealing ring adapted to fit into the end of the apparatus which receives the CIPP-lined pipe.
11. A kit for use in forming a seal with a CIPP-lined pipe, the kit comprising an apparatus for providing an outer seal as claimed in any preceding claim arid an apparatus for providing an inner seal.
12. A kit according to claim 11 wherein the apparatus for providing an inner seal comprises a rubber tube of substantially cylindrical cross-section, two retaining rings and two retaining wedges for holding said retaining rings in place.
13. A kit according to claim 11 or claim 12 wherein the apparatus for providing an inner seal around said joint comprises a seal of the type sold under the trade mark AMEX-b.
14. A method of providing an outer seal around a CIFP-lined pipe, the method comprising providing an apparatus comprising a tubular body, the internal dimension of which is slightly larger than the external dimension of the CIPP-lined pipe, the method comprising connecting one end of the tubular body to a section of replacement pipe and connecting the other end to a CIPP-lined pipe so as to form an airtight seal around the outer surface of said CIPP-lined pipe.
15. A method of forming a seal with a CIPP-lined pipe, the method comprising: (a) placing the end of the CIPP-lined pipe within the outwardly tapered end of an apparatus for providing an outer seal as defined in claim 3 and claim 6, such that the end of the CIPP-lined pipe rests against positioning means of the apparatus; wherein the apparatus has been fitted with a rubber sealing ring and an external annular member has been loosely connected to a flange of said apparatus; (b) adjusting the axial alignment of the pipe within the apparatus so that it lies in a substantially central position; (c) tightening bolts connecting the flange of the apparatus to the external annular member to provide a seal to the outside of the pipe; (d) internally sealing the joint of the CIPP-lined pipe to the apparatus as defined in claim 3 and claim 6 using an apparatus for providing an inner seal as defined in claims 11 to 13; and (e) connecting a portion of replacement pipe to the end of the apparatus as defined in claim 3 and claim 6 adapted to be so connected.
16. The use of a apparatus or kit as claimed in any of claims 1 to 13 to form a seal with a CIPP-lined pipe.
17. An apparatus for use in forming an outer seal with a CIPP-lined pipe substantially as hereinbefore described with reference to figures 3 to 9.