GB2527841A

GB2527841A - Methods of testing electrofusion fittings and testing apparatus

Info

Publication number: GB2527841A
Application number: GB1411970.5A
Authority: GB
Inventors: Stephen Barnes
Original assignee: Pioneer Lining Technology Ltd
Current assignee: Pioneer Lining Technology Ltd
Priority date: 2014-07-04
Filing date: 2014-07-04
Publication date: 2016-01-06
Also published as: GB201411970D0; WO2016001622A1

Abstract

Methods and apparatus are provided that enable the integrity of a weld between an electrofusion fitting 301 and a pipe lining 305a, 305b to be tested in the field. Circumferential seals (323, fig 4) are provided at either side of a gap 309 or bevel between sections of lined pipe 303a, 303b to be joined, defining a test region (315, fig 4) between the electrofusion fitting, pipe linings and the seals to allow leak testing, pressure testing and/or vacuum testing to be performed. The methods and apparatus may equally be employed to check the fit up between the electrofusion fitting and the pipe lining prior to welding them together, and may also be used during the welding process to support the electrofusion fitting, maintain fit up and improve weld quality.

Description

1 Methods of Testing Electrofusion Fittings and Testing Apparatus 3 The present invention relates to the field of electrofusion fittings such as employed to join 4 sections of lined pipe. More specifically, the present invention concerns methods that enable the integrity of an interface or weld between an electrofusion fitting and a pipe 6 lining to be tested in the field, and corresponding testing apparatus for performing the 7 tests.

9 Background to the invention

11 It is known that the life and performance of new and existing pipelines can be extended 12 and optimised by lining lengths of metal pipe with polymer liners. For example, the 13 Applicant's Swagelining® pipe lining service allows existing pipelines to be remediated and 14 new pipelines to be provided with corrosion resistance by installing a polymer liner that remains in tight contact with the inside of a host pipe.

2 To join adjacent lined pipe lengths, it is known to provide an electrofusion fitting to connect 3 the inner pipe linings prior to welding the metal pipe lengths together. The Applicant's 4 earlier International Application Publication NumberWO 2010/041016, Figure 1 of which is S reproduced in part in Figure 1 of the present application, discloses an electrofusion fitting 6 101 and a method of forming a pipe joint between two lined metal pipe lengths 103a,103b 7 incorporating such a fitting 101. The electrofusion fitting 101 is a sleeve largely comprised 8 of a thermoplastic material and includes heating coils 107a,107b disposed at either end of 9 the fitting 101. In use, the lining 105a is stripped back and the electrofusion fitting 101 inserted into the end of metal pipe length 103a. The heating coils 107a are then provided 11 with electrical power which causes the fitting 101 and the lining 105a in the vicinity of the 12 coils to melt and fuse together. The process is repeated to fuse the fitting 101 to the lining 13 1 05b of the other metal pipe length 1 03b, after which the metal pipe lengths themselves 14 103a,103b are welded together at 109.

16 The effect is such that a very effective weld is formed between the fitting 101 and the pipe 17 linings 107a,107b. However, if the weld is incomplete it is possible that fluid from within 18 the pipe lining could leak through the weld and come into contact with the metal pipe 19 causing corrosion and potentially ultimate failure, which defeats the purpose of having the metal pipe lined in the first place. To date, the applicant is aware of only two ways to test 21 the integrity of such an electrofusion weld in the field, the first of which is ultrasonic testing 22 which despite the advantage of being a non-destructive and arguably non-disruptive 23 methodology is complex and difficult to perform reliably and repeatedly in the field.

24 Furthermore, the results can be difficult to interpret.

26 The second is disclosed in the Applicant's earlier British Patent Number GB2500285, 27 Figure 2 of which is reproduced in Figure 2 of the present application. The electrofusion 28 fitting 201 in this case is provided with a channel 211 that extends from an aperture 213 29 towards the middle of the fitting 201 to a point between the heating coils 207a, thus providing a means of fluid communication between a point proximal the end of the pipe 31 203a and a test zone (or test region) 215a. After the heating coils 207a have been 32 activated to weld the fitting 201 to the lining 205a, the integrity of the weld can be 33 subjected to a hydrostatic test to determine if there is any pressure loss which would 34 correspond to a leak in one or both of the welds.

1 While this electrofusion fitting provides an integrated or self-contained way of testing the 2 integrity of the electrofusion welds it may not be suitable for use in all applications or 3 environments. Accordingly, it is an object of at least one aspect of the present invention to 4 provide an alternative way of testing the integrity of such an electrofusion weld in the field.

S Embodiments of aspects of the present invention are intended to realise this object and to 6 obviate or mitigate one or more further disadvantages of existing methods of testing and 7 provide apparatus for performing the tests.

9 Further aims and objects of the invention will become apparent from reading the following

description.

1 Summary of the invention

3 According to a first aspect of the invention, there is provided a method of testing the 4 integrity of an interface between an electrofusion fitting and a pipe lining of a section of S lined pipe, the method comprising creating a circumferential seal around the section of 6 lined pipe so as to define a test region between the interface and the seal, and performing 7 a leak test on the test region.

9 There may be two lined pipe sections having respective pipe linings to be joined by the electrofusion fitting; the circumferential seal may be applied around one of the two lined 11 pipe sections and another circumferential seal may be applied around the other of the two 12 lined pipe sections; wherein the test region is defined between the circumferential seals 13 and the interfaces between the electrofusion fitting and the pipe linings.

An interface may comprise an electrofusion weld between the electrofusion fitting and a 16 respective pipe lining. Alternatively, it may comprise at least a portion of a surface of the 17 electrofusion fitting in contact with at least a portion of an opposing surface of a respective 18 pipe lining prior to electrofusion welding. Accordingly, the test may be carried out before 19 performing the electrofusion weld and/or after performing the electrofusion weld.

21 Furthermore, performing the leak test may comprise providing fluid to the test region and 22 monitoring pressure within the test region. This may comprise a pressure test.

23 Alternatively, performing the leak test may comprise at least partially evacuating the test 24 region and monitoring pressure within the test region. This may comprise a vacuum test.

26 Advantageously, the method comprises at least partially evacuating the test region while 27 performing the electrofusion weld. This can be achieved by continually pumping fluid 28 and/or other material out of the test region. This may remove air and/or by-products 29 resulting from the electrofusion weld.

31 Optionally, the method further comprises inserting at least one locking ring into a bore of 32 the pipe lining to urge an outer surface of the pipe lining against an inner surface of the 33 lined pipe section. Insertion of the at least one locking ring may further define the test 34 region as being bounded by at least one inner circumferential seal between the pipe lining and the lined pipe section effected by the locking ring.

2 Preferably, the method comprises testing the integrity of the interface before performing an 3 electrofusion weld, performing the electrofusion weld, and testing the integrity of the 4 interface after performing the electrofusion weld.

S

6 Preferably, the method comprises repositioning the electrofusion fitting relative to the pipe 7 lining responsive to a determination that there is a leak in the interface, before performing 8 the electrofusion weld. Preferably, the integrity of the interface is tested again before 9 performing the electrofusion weld.

11 Optionally, the method comprises heating at least a portion of the electrofusion fitting to a 12 firsttemperature lowerthan a melting pointof the material of the electrofusion fitting before 13 performing the electrofusion weld. This initial heating step or pre-heat can expand the 14 electrofusion fitting to improve or ensure contact between the surface of the electrofusion fitting and the pipe lining, i.e. the fit-up.

17 Preferably, the method comprises testing the integrity of the interface after pre-heating the 18 electrofusion fitting and before performing the electrofusion weld. Again, the method may 19 comprise repositioning the electrofusion fitting relative to the pipe lining responsive to a determination that there is a leak in the interface, before performing the pre-heat again.

21 The integrity of the interface may be tested again before performing the electrofusion weld.

23 Optionally, creating a circumferential seal may comprise applying an elastomeric sealing 24 member around the section of lined pipe. Alternatively, creating a circumferential seal may comprise applying an inflatable member around the section of lined pipe. The inflatable 26 member may be a bladder.

28 The circumferential seal or seals may be applied by providing a pipe repair clamp around a 29 gap between adjacent lined pipe sections whose respective pipe linings are to be joined by the electrofusion fitting. The pipe repair clamp may be provided with one or more 31 interfaces to permit fluid communication between leak testing apparatus and the test 32 region.

34 According to a second aspect of the invention, there is provided a method of testing the integrity of interfaces between an electrofusion fitting and pipe linings of two sections of 1 lined pipe to be joined together, the method comprising creating circumferential seals 2 around the sections of lined pipe on either side of a gap between the lined pipe sections so 3 as to define a test region between the interfaces and the seals, and performing a leak test 4 on the test region.

S

6 The method may comprise testing the integrity of the interface between the electrofusion 7 fifting and one of the pipe linings by performing the leak test after performing an 8 electrofusion weld on the other interface. The electrofusion weld on the other interface 9 may have been performed prior to inserting the electrofusion fitting into the pipe lining.

11 Embodiments of the second aspect of the invention may comprise features corresponding 12 to the preferred or optional features of the first aspect of the invention or vice versa.

14 According to a third aspect of the invention, there is provided an apparatus for testing the integrity of an interface between an electrofusion fitting and a pipe lining of a section of 16 lined pipe, the apparatus comprising a sealing member adapted to apply a circumferential 17 seal around the section of lined pipe to define a test region between the interface and the 18 seal, and leak testing means operable to perform a leak test on the test region.

The apparatus may comprise a pipe repair clamp comprising one or more interfaces to 21 permit fluid communication between the leak testing means and the test region.

23 Preferably, the leak testing means comprises pressure monitoring means. Optionally, the 24 leak testing means further comprises fluid delivery means, which may comprise a pump configured to supply fluid to the test region. Alternatively, the leak testing means further 26 comprises fluid extraction means, which may comprise a pump configured to remove fluid 27 from the test region.

29 Optionally, the apparatus comprises two spaced sealing members positioned on the apparatus to apply corresponding circumferential seals around, and on either side of a gap 31 between, two lined pipe sections to be joined together.

33 Optionally, the sealing members may comprise elastomer seals. Alternatively, the sealing 34 members may comprise inflatable bladders.

1 Embodiments of the third aspect of the invention may comprise features corresponding to 2 the preferred or optional features of the first or second aspects of the invention or vice 3 versa.

S According to a fourth aspect of the invention there is provided a method of constructing a 6 pipeline comprising two or more sections of lined pipe, the method comprising testing the 7 integrity of interfaces between an electrofusion fitting and pipe linings of two sections of 8 lined pipe to be joined together in accordance with the first or the second aspect.

The method may comprise pre-heating the electrofusion fitting to improve fit-up between 11 the electrofusion fitting and the pipe linings. The integrity of the interfaces may be tested 12 before, during and/or after performance of electrofusion welds between the electrofusion 13 fitting and the pipe linings.

The method may comprise welding the lined pipe sections together, responsive to a 16 determination that there is no leak in either of the interfaces after the electrofusion welds 17 have been performed.

19 The method may be repeated to join subsequent sections of lined pipe to the pipeline until a desired length of pipeline is constructed.

22 Embodiments of the fourth aspect of the invention may comprise features corresponding to 23 the preferred or optional features of the first, second or third aspects of the invention or 24 vice versa.

26 According to a fifth aspect of the invention there is provided a method of laying a pipeline, 27 the method comprising testing the integrity of interfaces between an electrofusion fitting 28 and pipe linings of two sections of lined pipe to be joined together and welding the lined 29 pipe sections together, in accordance with the fourth aspect.

31 Optionally, the method comprises feeding the pipeline out from a pipe-laying vessel as it 32 travels forward. The pipeline may preferable be fed out from the stern of the vessel, or 33 from any other location on the vessel. Optionally, the method comprises constructing the 34 pipeline length-by-length. Adjacent sections of lined pipe may be welded on board.

1 Embodiments of the fifth aspect of the invention may comprise features corresponding to 2 the preferred or optional features of the first to fourth aspects of the invention or vice 3 versa.

S According to another aspect of the invention, there is provided a method of testing a weld 6 between an electrofusion fitting and a pipe lining, a method of testing fit-up between an 7 electrofusion fitting an a pipe lining prior to performing a weld, or a method of joining 8 sections of lined pipe substantially as herein described with reference to Figures 3 and 4 of 9 the appended drawings.

11 According to a further aspect of the invention, there is provided an apparatus for testing a 12 weld between an electrofusion fitting and a pipe lining, an apparatus for testing fit-up 13 between an electrofusion fitting an a pipe lining prior to performing a weld, or an apparatus 14 for joining sections of lined pipe substantially as herein described with reference to Figures 3 and 4 of the appended drawings.

1 Brief description of the drawings

3 Aspects and advantages of the present invention will become apparent upon reading the 4 following detailed description and upon reference to the following drawings (like reference S numerals referring to like features) in which: 7 Figure 1 is a partial reproduction of Figure 1 of the Applicant's earlier International 8 Application Publication Number WO 2010/041016, showing a schematic sectional view of 9 an electrofusion fitting according to the prior art; 11 Figure 2 is a reproduction of Figure 2 of the Applicant's earlier British Patent Number 12 GB2500285, showing a schematic sectional view of an electrofusion fitting having a 13 channel extending to a test region according to the prior ad; Figure 3 is a cross-sectional view of an electrofusion fitting located between two sections 16 of lined pipe and a testing apparatus for testing the integrity of the interfaces between the 17 electrofusion fitting and the linings according to aspects of the present invention; and 19 Figure 4 is an enlarged view of the region marked "A" in Figure 3, specifically showing a test region created by the testing apparatus.

1 Detailed description of preferred embodiments

3 As discussed in the background to the invention above, it is desirable to provide an 4 alternative way to test the integrity of a weld formed between an electrofusion fitting and S pipe linings in the field to those known from the prior art. An embodiment of the present 6 invention will now be described with reference to Figures 3 and 4 which provides such an 7 alternative and may obviate or mitigate one or more problems with prior art methods.

9 An electrofusion fitting 301 is formed by a cylindrical sleeve of a thermoplastic material having pairs of heating coils 307a,307b disposed toward either end of the fitting 301. The 11 electrofusion fitting 301 is shaped and sized to be inserted into the end of a lined pipe 12 section 303a/303b and received in a recess 306a/306b in the end of the pipe lining 13 305a/305b. The heating coils 307a/307b are embedded in the outer surface of the fitting 14 301, so as to be adjacent to and facing an inner surface of the pipe lining 305a/305b, such that when provided with electrical power the thermoplastic material of the fitting 301 and of 16 the lining 305a/305b in the vicinity of the coils melts and fuses together, thus creating 17 circumferential or annular welds between the fitting 301 and the pipe lining 305a/305b.

19 As previously acknowledged, it is important to validate that the welds created between the fitting 301 and the pipe lining 305a/305b are leak free, to ensure that the corrosion 21 resistance provided by the polymer lining of the pipe is intact across the joint between 22 subsequent lined pipe sections. This prevents ingress of fluids from the bore of the lined 23 pipe to the annular space between the lining and the pipe itself when the pipe is filled and 24 working under pressure.

26 To this end, a testing apparatus 321 is disposed on and around the pipe sections 27 303a,303b so as to encapsulate the gap 309 between the ends of the pipe sections 28 303a,303b. Sealing members 323 provide circumferential seals around respective pipe 29 sections. The sealing members 323 may for example comprise inflatable bladders to selectively or controllably apply the circumferential seals, however in this embodiment they 31 comprise an elastomeric material which is compliant with the outer diameter of the pipe 32 sections 303a,303b.

34 Structurally the testing apparatus 321 may resemble (physically and/or functionally) a pipeline repair clamp although the testing apparatus 321 is provided with an interface 324 1 for the connection of vacuum pumping equipment, fluid delivery equipment, pressure 2 gauges and/or the like.

4 A test region 315 is thereby provided between the testing apparatus 321 and the S electrofusion fitting 301. The test region 315 is bounded by the sealing members 6 323a,323b and the interface or seal between the electrofusion fitting 301 and the pipe 7 linings 305a,305b. This region can then be pressurised or evacuated to test the integrity 8 of the interface or seal between the electrofusion fitting 301 and the pipe linings 305a,305b 9 by monitoring the pressure within the test region 315..

11 Note that the term interface" relates to the surface areas of the electrofusion fitting and 12 the pipe linings which are or should be in contact, and includes inter a/ia the situation 13 where these surfaces are welded together (such as post-energising of the heating coils) 14 and where these surfaces are merely in contact prior to energising the heating coils (so-called fit-up). Integrity therefore includes the effectiveness of the seal provided by the 16 electrofusion welds and the continuity of the contact between the surfaces prior to being 17 welded together.

19 The test region 315 can be subjected to a low level of air pressure using a pump (not shown) in fluid communication with the test region 315-for example by connection to the 21 interface 324. The pressure can be monitored and any loss of pressure can be attributed 22 to the existence of an escape path through one or both of the interfaces or seals between 23 the electrofusion fitting 301 and the pipe linings 305a,305b, that is, a leak.

Alternatively, a vacuum pump (not shown) connected to the interface 324 or otherwise in 26 fluid communication with the test region 315 can be used to draw air out of the test region 27 315. Similarly, if the vacuum is unstable, or if it is not possible to reach an expected 28 vacuum pressure, this may be attributed to the existence of an escape path or leak in one 29 or both of the interfaces or seals between the electrofusion fitting 301 and the pipe linings 305a,305b.

32 While the test may be carried out after the electrofusion welds have been made between 33 the fitting 301 and the pipe linings 305a,305b, it is also envisaged and it is in fact 34 advantageous to carry out the test before and/or during creation of the welds between the electrofusion fitting 301 and the pipe linings 305a,305b. Accordingly, performance of the 1 test at any or all stages of the process of joining sections of lined pipe (or indeed any 2 combination in between) are within the scope of the present invention.

4 By way of example, the Applicant has developed a method of creating a weld between a S section of lined pipe and an electrofusion fitting in which the heating coils are supplied 6 electrical current at a sufficiently low level such that the electrofusion fitting is heated to a 7 first temperature lower than a melting point of the material of the electrofusion fitting prior 8 to performing the actual electrofusion welding step. This is termed "pre-heat' by the 9 Applicant. By virtue of the initial pre-heat step, the electrofusion fitting can expand to improve the fit-up between the surface of the fitting and the pipe lining. Accordingly, when 11 the welding step is performed, reliability is much improved.

13 The test region 315 can therefore be leak tested, pressurised or evacuated in accordance 14 with the procedures described above to test the integrity of the fit-up between the electrofusion fitting 301 and the pipe linings 305a,305b before the heating coils 307a,307b 16 are energised. If a leak is detected, the fit-up can be remade and re-tested before 17 energising the heating coils to create the welds between the electrofusion fitting 301 and 18 the pipe linings 305a,305b. Of course depending on machining tolerances etc. it may not 19 be necessary to perform the pre-heat step if the fit-up between the electrofusion fitting and the pipe linings is adequate or leak-free; accordingly the pre-heat step might only be 21 performed responsive to a pressure or vacuum test indicating that there is a leak in the fit-22 up.

24 It is particularly advantageous if, when using evacuation/vacuum techniques to test the integrity of the fit-up, the evacuation/vacuum is maintained while the heating coils 26 307a,307b are energised to create the welds between the electrofusion fitting 301 and the 27 pipe linings 305a,305b. Any air or by-products created or released from the components 28 during the electrofusion process may thereby be drawn away from the fusion zones and as 29 a result reduce the risk of voiding -thus resulting in an improved weld.

31 The vacuum will also act to keep the electrofusion fitting 301 compressed to the pipe 32 linings 305a,305b during the electrofusion process. This might remove the need for 33 additional physical support.

1 While the Applicant's Swagelining® pipe lining service installs a polymer liner that remains 2 in tight contact with the inside of a host pipe, it is possible that such a liner, or a liner 3 installed using alternative or competing methodologies, may be slightly spaced from the 4 host pipe or there may exist discrete channels or gaps. In these situations, fluid may leak S out of the test region through these channels or gaps when pressurised or leak tested, or 6 fluid may leak into the test region through these channels or gaps if a vacuum is applied.

8 Accordingly, it is advantageous to insert locking rings 325a1325b to tightly compress the 9 pipe linings 305a/305b against the inside wall of the pipe sections 303a/303b. The locking rings 325a/325b thereby provide a seal which prevents fluid from crossing over the area of 11 the compression and may also serve to anchor the pipe linings to prevent any movement 12 due to residual strain which may be released when machining the recesses to receive the 13 electrofusion fitting.

When the locking rings 325a,325b are in place, the test region 315 can be further defined 16 as being bounded by corresponding compression areas -that is, the surfaces of the pipe 17 linings 305a,305b which are urged against the inside wall of the pipe sections 303a/303b.

19 It is known that fluids can reside behind the liner in the annular space; when a large number of short pipe sections are joined there is a risk that these fluids accumulate along 21 an extended annulus resulting from the joined sections which raises the risk of liner 22 collapse -a particular concern in hydrocarbon applications. The locking rings 325a1325b 23 prevent such accumulation occurring by effectively partitioning the annular space along a 24 continuous lined pipe length.

26 The locking rings 325a/325b may be inserted prior to machining recesses to receive the 27 electrofusion fitting, or simply prior to receiving the electrofusion fitting in the recesses.

28 Alternatively, the locking rings 325a/325b may be inserted when the pipe sections are 29 lined, which might even be prior to transporting the lined pipe sections to a location where they are to be joined together.

32 Once it has been determined that the electrofusion welds have been performed 33 satisfactorily, the testing apparatus 321 can be removed and the pipe lengths 303a,303b 34 themselves can be welded together at gap 309. If the optional locking rings 325a/325b have been employed these are generally left in position to avoid transferring any residual 1 strain in the pipe linings 305a,305b to the welds and/or the electrofusion fitting which might 2 cause damage to the former or cause the latter to move. Of course these can be removed 3 if desired, but it is envisaged that in most applications the locking rings 325a/325b will 4 remain in place. The locking rings 325a/325b may therefore be comprised of a corrosion S resistant material, or for example carbon steel with a corrosion protective coating.

7 It is particularly advantageous if the integrity test can be carried out as a leak test rather 8 than as a pressure test, because this reduces complexity and means that the test can be 9 performed in situations where pressure tests might be unsuitable (e.g. where there are explosion oi ignition risks).

12 Furthermore, rather than inserting the electrofusion fitting 301 into the pipe linings 13 303a,303b and performing the welds at either end of the electrofusion fitting 301 14 simultaneously, the welds may be performed one at a time and the integrity of each weld can therefore be tested individually. Alternatively, the electrofusion fitting 301 may already 16 be welded at one end to the lining 305b of pipe 303b (and the integrity of the weld tested 17 using the methods of the invention or otherwise) for example, prior to bringing the pipe 18 sections 303a,303b together in which case the methods of the invention can be employed 19 to test the integrity of the weld and/or fit-up between the electrofusion fitting 301 and pipe lining 305a. This allows at least one of the welds to be performed off the critical path, 21 reducing operational complexity.

23 It will of course be understood that while the present invention has been illustrated with 24 reference to electrofusion fittings for joining lined pipe sections, the methods (and apparatus) may be applied to an electrofusion fitting employed to join standalone plastic 26 pipes.

28 Common techniques for laying pipe on the sea floor include s-lay pipeline installation and 29 j-lay pipeline installation. In these methods, pipe is fed out from the stern of a pipe-laying vessel as it travels forward; s-lay refers to the "s' shape of the pipeline between the vessel 31 and the seabed resulting from the substantially horizontal deployment direction, and j-lay 32 refers to the j" shape of the pipeline between the vessel and the seabed resulting from the 33 substantially vertical deployment direction. In s-lay and j-lay operations, a pipeline can be 34 constructed length-by-length in which case adjacent sections of pipe are welded on board 1 (as contrasted with a reel-lay method in which case a continuous length of pipe is 2 deployed from a reel).

4 To date, no pipeline installed in an s-lay operation has been lined. This is due to the high S cost and fabrication complexity associated with conventional methods of joining sections of 6 lined pipe. The Applicant's electrofusion fittings provide a robust and rugged way of 7 joining sections of lined pipe, and the method of testing the integrity of the electrofusion 8 welds of the present invention permits these electrofusion fittings and the corresponding 9 welded joints to be tested quickly and effectively in the field and provide confidence that will allow the many and varied benefits of lined pipe to be exploited in s-lay, and j-lay, 11 applications.

13 Accordingly, a pipeline consisting of several lined pipe sections can be constructed and 14 the integrity of the welds between fittings and linings tested in situ as part of the pipeline fabrication process. In fact, even using reel-lay or tow-in pipeline installation methods, 16 subsequent lengths of lined pipe (which may be one or several km long rather than, say, 17 12 m long as used in length-by-length on-deck fabrication methods) can be joined and the 18 joint integrity tested -and of course the continuous pipe (deployed from reel or by tow-in) 19 might itself consist of several lined pipe sections so joined and tested onshore.

21 Very fast modern pipeline welding makes use of a closed bevel. However, to date it has 22 not been possible to use a closed bevel approach in conjunction with electrofusion fittings, 23 other than by employing the approach disclosed in the Applicant's earlier International 24 Application Publication Number WO 2013/136062 in which access to leak test or pressure test the welds can be achieved by drilling one or more holes through the closed bevel.

26 The holes drilled through the closed bevel allow access to the channel through the 27 electrofusion fitting which extends to a test region. A probe can be inserted through the 28 closed bevel and received in the channel and thereby supply leak test or pressure test fluid 29 to the test region.

31 However, the testing method of the present invention can be performed, and the testing 32 apparatus employed, in closed bevel applications as readily as in open bevel applications 33 -without the need to drill through the closed bevel. VVliether "narrow gap" or "closed" fit 34 up approaches are adopted, it is still possible to pressurise or evacuate the test region as 1 described above by creating circumferential seals around the pipe sections at either side 2 of the bevel.

4 Note that subsequent to testing the integrity of the welds and removing the testing S apparatus 321, but prior to welding the pipe sections 303a,303b together, an insulating 6 material can be injected into the test region 315 (specifically the annular space 7 surrounding the electrofusion fifting 301 in the region of the gap 309. This will protect the 8 electrofusion fitting 301 from heat damage while the ends of pipe sections 303a, 303b are 9 welded together. Alternatively, the electrofusion fitting 301 may be provided with an insulating material, which may for example be integrally formed or applied as a coating, 11 prior to use.

13 The invention provides methods and apparatus that enable the integrity of a weld between 14 an electrofusion fitting and a pipe lining to be tested in the field. Circumferential seals are provided at either side of a gap or bevel between sections of lined pipe to be joined, 16 defining a test region between the electrofusion fitting, pipe linings and the seals to allow 17 leak testing, pressure testing and/or vacuum testing to be performed. The methods and 18 apparatus may equally be employed to check the fit up between the electrofusion fitting 19 and the pipe lining prior to welding them together, and may also be used during the welding process to support the electrofusion fitting, maintain fit up and improve weld 21 quality.

23 Throughout the specification, unless the context demands otherwise, the terms comprise' 24 or include', or variations such as comprises' or comprising', includes' or including' will be understood to imply the inclusion of a stated integer or group of integers, but not the 26 exclusion of any other integer or group of integers.

28 The foregoing description of the invention has been presented for the purposes of 29 illustration and description and is not intended to be exhaustive or to limit the invention to the precise form disclosed. The described embodiments were chosen and described in 31 order to best explain the principles of the invention and its practical application to thereby 32 enable others skilled in the art to best utilise the invention in various embodiments and 33 with various modifications as are suited to the particular use contemplated. Therefore, 34 further modifications or improvements may be incorporated without departing from the scope of the invention as defined by the appended claims.