GB2508215A - Lining of pipework with ferrules - Google Patents

Abstract

The invention relates to a method of lining a pipe 28 in which an existing ferrule 14 is located before the lining 26 is formed, and is machined to be suitable to receive a specific bush 20. After lining, the machined ferrule connection is located through the lining, and the bush is inserted into the machined ferrule opening through a hole cut in the liner. The ferrule may be located by a camera. The method is all carried out by apparatus (12 figure 1) within the pipe, wherein the apparatus may have a rotary head which carries different processing tools.

Description

LINING OF PIPEWORK WITH FERRULES

This invention relates to the lining of pipework, for example for refurbishment. The invention is of particular interest for water mains pipework, although the invention can applied to pipework for carrying other fluids such as gas.

The desire to be able to refurbish pipework with a minimum of disruption to users is well known.

Until recently, refurbishment of water mains pipes involved replacing the water main pipe, with the consequent disruption to the customers as well a significant amount of trench digging.

Trenchless technology is now being seriously considered by major water and gas utility companies with a view to negating the more traditional current open cut methods of practice in pipeline rehabilitation, repair or maintenance.

The cost benefit of enabling a trenchless operation to these utilities companies is significant when compared to existing methods of working. In view of this, a number of spray and pre manufactured liners are entering the market place. These methods provide an internal lining to the existing pipe, thereby extending the life before eventual replacement is needed. The lining can be applied either by spraying or by expanding a pre-formed liner within the pipe.

A water main typically comprises a pipe run with tap off points for customers. These tap off points are each formed using a ferrule which is screwed into the main pipe run to define a T-junction.

No matter what type of internal lining is used, the ferrules are covered by the lining, so that connections at the tap off points need to be reformed. This has in the past been achieved by an open cut method which involves digging trenches to the main pipe at each ferrule location, and externally fitting a new ferrule.

The lining techniques thus have problems of effectively sealing the ferrule take offs, and requiring significant works to providing the ultimate supply back to Co fl sum ers.

External drilling or other methods for exposing the main pipe run to enable the required service connections to be made can also cause breaching of the liner material. This creates further problems of water ingress behind the back of the liner material. This situation is unacceptable to utility owners as it is seen as a potential contamination void for future bacterial growth.

The issue of sealing ferrule take offs for customer or other services has thus not been resolved for relined pipes.

According to the invention, there is provided an apparatus and a method as claimed in the independent claims.

In one aspect, the invention provides a method of lining a pipe, comprising: locating a ferrule connection to the pipe wall; machining the ferrule opening to have a predetermined bore size and projection distance inside the pipe wall; lining the pipe; locating the machined ferrule connection to the pipe wall through the lining; cutting a hole in the liner at the ferrule location; and inserting a bush into the machined ferrule opening, wherein the two locating steps, the machining step, the cutting step and the inserting step are all carried out by apparatus within the pipe.

This method provides pipe lining as well as forming ferrule connections without any need for external trenches. Instead, the existing ferrules are located before the lining process, and they are then machined to make them suitable to receive a sealing bush. This sealing bush is applied over the lining so that it prevents ingress in the liner/pipe wall space. By accurately machining the existing ferrule before lining, the bush can be ensured to provide the required sealing. In a preferred example, it can simply be a push fit into the machined ferrule.

The projection distance can be zero, so that the ferrule is flush with the inner wall of the pipe, although an internal projection can instead be allowed.

Locating an existing ferrule connection to the pipe can comprise a visual location using a camera, which is carried by the apparatus.

The machining preferably comprises drilling with a left hand drill. This drilling cleans and sizes the ferrule opening for the bush to be inserted. The left hand drill avoids that the drilling loosens the ferrule.

After machining the ferrule opening, a location device can be inserted which emits a location signal, and locating the machined ferrule then comprises sensing the location signal. This location signal needs to be able to travel through the lining, and can for example comprise a laser or ultrasound signal. The is location device is preferably removed before inserting the bush.

Instead of using a locating device, locating the machined ferrule connection to the pipe wall through the lining can comprise performing an imaging step, for example an ultrasound step to locate cavity areas beneath the lining.

The apparatus can comprise a rotary head comprising a machining part, a bush insertion pad and a location part. The apparatus can thus perform the various steps without being moved between operations (other than being removed before the lining step).

The invention also provides an apparatus for forming ferrule connections to a lined a pipe, wherein the apparatus is adapted to be inserted into the pipe, and comprises: a first location part for locating a ferrule connection to the pipe wall before it is lined; a machining pad for machining the ferrule opening to have a predetermined bore size and projection distance inside the pipe wall; a second locating part for locating the machined ferrule connection to the pipe wall through the lining; a cutting part for cutting a hole in the liner at the ferrule location; and a bush insertion part for inserting a bush into the machined ferrule opening.

The apparatus enables the ferrule openings to be reformed after lining, from within the pipe, and therefore avoids the need for external trenches. The apparatus can comprise a rotary head to enable different operations to be carried out without moving the apparatus along the pipe.

The rotary head can have two configurations, a first configuration for use before pipe lining, with the first location part and machining part, and a second configuration for use after pipe lining, with the second locating part, the cutting part and the bush insertion part. The apparatus is thus positioned once before lining to carry out all the required steps before lining and once after lining to carry is out the required steps after lining.

The apparatus can have an insertion part for inserting a location device which emits a location signal and the second locating part then comprises a sensor part for sensing the location signal and for removing the location device.

Alternatively, the second locating part can comprise an imaging apparatus.

The bush can be part of the apparatus, and it can comprise a push fit component with a sleeve part for sealing to the machined ferrule and a cover part for sealing over the cut lining opening. This bush design comprises a top hat type bush, which can be rubber coated to effectively seal the liner/ferrule exposed interfaces.

An example of the invention will now be described in detail with reference to the accompanying drawings, in which: Figure 1 shows the various steps carried out by the apparatus of the invention, which together form one example of the method of the invention; and Figure 2 shows the final ferrule configuration at the end of the method.

The invention provides a method of lining a pipe in which an existing ferrule is located before the lining is formed, and is machined to be suitable to receive a specific bush design. After lining, the machined ferrule connection is located through the lining, and the bush is inserted into the machined ferrule opening through a hole cut in the lining. The method is all carried out by apparatus within the pipe.

The invention provides a new design of liner to ferrule sealing method and bushes, and an apparatus to install them. The apparatus is carried by a crawler unit which is advanced within the pipe to the ferrule locations to perform the required processing.

A range of sealing bushes can be provided to enable the apparatus to accommodate all liner products on the market irrespective of manufacturer, thickness or type (sprayed or manually inserted into the pipework infrastructure).

Figure 1 shows the various steps carried out by the apparatus of the invention, which together form one example of the method of the invention.

Figures 1A to 10 show sequential steps.

Figure IA shows an existing pipe 10 in which the apparatus 12 of the invention has been inserted. The pipe 10 is to be lined. At various locations along the pipe, there are existing T-connections formed by screw threaded ferrules 14 which are screwed into the pipe wall. These ferrules have a standard opening diameter, but the amount by which they extend into the pipe internal space is not standardised and thus may vary between different ferrules.

The apparatus 12 has a rotary head, which carries different processing tools. The apparatus is positioned at each ferrule location in turn and carries out pre-lining processes described below. It is removed for pipe lining, and then re-inserted to carry out post-lining processes also described below.

The apparatus can thus be reconfigured during lining and can thus have two configurations. Figures lAto iF show pre-lining operations, and Figures 1H to 10 show post-lining operations.

In Figure IA, the crawler unit carrying the apparatus 12 travels in the empty pipeline and is positioned at the first ferrule location. The approximate location can be known from information about the infrastructure. The exact location can be determined visually by a camera carried by the apparatus, and by an operator receiving the visual information. Of course, the visual identification could potentially be automated.

An optional feature is for the apparatus to undertake a push test to establish that the pipe to ferrule fitting is acceptable i.e. there is sufficient structural integrity, and the pipe is not heavy corroded or the ferrule loose.

If the push test establishes that the connection is not sufficient for machining, the position is recorded and a conventional dig will be required to replace the ferrule at this position. It is envisaged that this situation will be very infrequent (2% to 4% of cases).

In Figure IB, the apparatus drills out the ferrule to both clean and slightly oversize the internal bore of the ferrule. In addition to this, the ferrule thread protrusions, which will all be of different lengths, are machined back to the pipe wall. This results in the structure shown in Figure 10. This machining is to ensure the ferrule protrusions are all at the same height so that a single bush design can be used.

In the example of Figure 1, the apparatus head is then rotated to the position shown in Figure 10, and a location device 16 in the form of a laser, ultrasound emitter or other signal emitting device is inserted into the internal bore of the ferrule. This is shown in Figure 1 E and Figure 1 F. The design of this location device will have a retaining feature which centres the signal within the centre of the bore of the ferrule internal diameter.

The crawler unit then moves onto other ferrules and repeats the operations of Figures 1A to IF at all the other ferrule locations.

The lining is shown in Figure 1G. The crawler unit is retracted out of the pipework infrastructure for the lining process. Any known lining process can be used, which will typically be a spray or sleeve process.

The crawler unit is then inserted back into the newly lined pipe and moves to position the rotating head directly below the covered ferrule.

In the example shown, the location of the ferrules is found by using the location device, and in particular using a sensor carried by the apparatus.

However, in an alternative arrangement, there is no need for the locating signal device 16. Instead, imaging can be used to locate the ferrule openings, as they will have a circular void behind the lining, in contrast with all other pipe areas. The approximate location will be known from the infrastructure information or from information gathered during the ferrule machining operation, so the imaging can be used for a fine tuning of the exact location of the ferrule bore.

The locating function is shown in Figure 1 H. The apparatus has a cutter 18 which then machines away the liner material to form an opening into the ferrule, as shown in Figure 11. The cut liner is part is removed when the cutter is retracted as shown in Figure IJ.

The exposes the location device 16 when one is used. The location device 16 is subsequently removed by the rotating head. This involves a rotation to the position shown in Figure 1K, followed by making connection to the location device as shown in Figure IL and retraction as shown in Figure IM. Of course, these steps are not needed if no signal emitting location device is used.

Figure 1 N shows the head rotated to align a bush 20 with the ferrule. The apparatus then presses in the sealing bush 20, which is designed having regard to the lining material. In this example, the fit of the bush is a transition fit. Once the bush is fully home, the press-in force is monitored externally, and a peak press in force is provided. Once the peak press-in force is reached, the insertion tool is retracted as shown in Figure 2, and the crawler unit moves onto the next ferrule position. The post-lining steps are then repeated for other ferrules.

Figure 2 thus shows the completed design of the ferrule, and shows the design enlarged to show more clearly the bush design.

As mentioned above, the bush is a push fit. The bush has a sleeve part 22 for sealing to the machined ferrule opening and a cover part 24 for sealing over the cut liner opening. The liner is shown as 26 within the original pipe 28.

For thinner materials, the material is relatively translucent so a light source or laser will effectively shine through the material to highlight the ferrule position/centre for alignment of the apparatus. For denser materials such as sprayed material a low frequency sond (eg 512Hz) or other technology can be used to generate a signal suitable for detection through the lining.

The bush insert can be rubber coated on all contacting interfaces as shown in Figure 2, so it can seal even if it is not fully pressed in.

The invention can be applied to water applications, but gas applications can also be considered.

In the example above, the bush is a push fit. An alternative can be to machine the ferrule to provide an internal thread, and to use a threaded bush.

is Any other locking design can be used which ensures the bush fixes to the re-machined ferrule.

Various other modifications will be apparent to those skilled in the art.