METHODS FOR JOINING LINED PIPES AND ASSOCIATED APPARATUS

Abstract

Methods and apparatus for making lined pipelines utilize lined pipes and fittings attached to the ends of the lined pipes. Castellations are formed on the inner surfaces of the fittings. First and second ends of a fit-up sleeve are inserted into the fittings on the ends of first and second lined pipes and the first and second ends of the fit-up sleeve force portions of the liners within the pipes into engagement with the castellations on the inner surfaces of the fittings. The fittings are then attached to each other to join the first and second lined pipes together.

Claims

1. A pipeline comprising: a first lined pipe having a first liner; a second lined pipe having a second liner; a first fitting joined to the first lined pipe, wherein a plurality of castellations are provided on an internal surface of the first fitting; a second fitting joined to the second lined pipe, wherein a plurality of castellations are provided on an internal surface of the second fitting; and a fit-up sleeve, comprising: a first end that is inserted into the first fitting such that the first end of the fit-up sleeve forces a first portion of the first liner against a corresponding first portion of the castellations of the first fitting; and a second end that is inserted into the second fitting such that the second end of the fit-up sleeve forces a first portion of the second liner against a corresponding first portion of the castellations on the second fitting; and wherein the first fitting is joined to the second fitting.

2. The pipeline of claim 1, wherein the plurality of castellations on the first and second fittings are formed in a corrosive resistant alloy cladding applied to the first and second fittings.

3. The pipeline of claim 1, wherein the plurality of castellations on the first and second fittings are formed in body portions of the first and second fittings.

4. The pipeline of claim 1, wherein the castellations on the first and second fittings project from the internal surfaces of the first and second fittings.

5. The pipeline of claim 1, wherein the castellations on the first and second fittings comprise a series of grooves formed on the internal surfaces of the first and second fittings.

6. The pipeline of claim 1, wherein the first portions of the castellations on the first and second fittings comprise tapered inner diameter portions of the first and second fittings.

7. The pipeline of claim 1, further comprising: a first sealing ring mounted inside the first fitting such that the first sealing ring forces a second portion of the first liner against a second portion of the castellations on the first fitting; and a second sealing ring mounted inside the second fitting such that the second sealing ring forces a second portion of the second liner against a second portion of the castellations on the second fitting.

8. The pipeline of claim 7, wherein the second portions of the castellations on the first and second fittings comprise constant inner diameter portions of the first and second fittings.

9. The pipeline of claim 7, wherein the first and second portions of the castellations on the first and second fittings are axially separated from one another on the first and second fittings.

10. The pipeline of claim 1, wherein the fit-up sleeve comprises a substantially cylindrical central portion, a first tapered liner engaging portion on the first end and a second tapered liner engaging portion on the second end, and wherein an outer diameter of the cylindrical central portion is greater than outer diameters of the first and second tapered liner engaging portions such that a first shoulder is formed between the cylindrical central portion and the first tapered liner engaging portion and such that a second shoulder is formed between the cylindrical central portion and the second tapered liner engaging portion.

11. The pipeline of claim 10, wherein a first insertion rim is provided on an inner surface of the first fitting, wherein a second insertion rim is provided on an inner surface of the second fitting, wherein the first shoulder on the fit-up sleeve abuts the first insertion rim and wherein the second shoulder on the fit-up sleeve abuts the second insertion rim.

12. The pipeline of claim 11, further comprising a first o-ring or gasket located between the first shoulder of the fit-up sleeve and the first insertion rim on the first fitting and a second o-ring or gasket located between the second shoulder of the fit-up sleeve and the second insertion rim on the second fitting.

13. The pipeline of claim 11, further comprising a first spacer ring located between the first shoulder on the fit-up sleeve and the first insertion rim on the first fitting and a second spacer ring located between the second shoulder on the fit-up sleeve and the second insertion rim on the second fitting.

14. The pipeline of claim 1, wherein the first fitting is welded to the second fitting.

15. The pipeline of claim 1, wherein the first and second lined pipes and the first and second fittings all have substantially the same outer diameter.

16. The pipeline of claim 1, wherein the first and second fittings each comprise a flange and wherein the first and second fittings are joined by the flanges.

17. The pipeline of claim 1, wherein the first and second liners each comprise an inner polymer pipe, a barrier layer surrounding the inner polymer pipe and an outer polymer pipe surrounding the barrier layer, wherein the inner polymer pipe is porous.

18. The pipeline of claim 17, further comprising: a first sealing ring mounted inside the first fitting such that the first sealing ring forces a second portion of the first liner against a second portion of the castellations on the first fitting and such that the inner polymer pipe along the second portion of the first liner is rendered non-porous; and a second sealing ring mounted inside the second fitting such that the second sealing ring forces a second portion of the second liner against a second portion of the castellations on the second fitting and such that the inner polymer pipe along the second portion of the second liner is rendered non-porous.

19. The pipeline of claim 17, further comprising: a first sealing ring mounted inside the first fitting such that the first sealing ring forces a second portion of the first liner against a second portion of the castellations on the first fitting and wherein the inner polymer pipe of the first liner terminates at the second portion of the first liner such that the first end of the fit-up sleeve bears against the barrier layer of the first liner; and a second sealing ring mounted inside the second fitting such that the second sealing ring forces a second portion of the second liner against a second portion of the castellations on the second fitting and wherein the inner polymer pipe of the second liner terminates at the second portion of the second liner such that the second end of the fit-up sleeve bears against the barrier layer of the second liner.

20. The pipeline of claim 17, further comprising: a first sealing ring mounted inside the first fitting such that the first sealing ring forces a second portion of the first liner against a second portion of the castellations on the first fitting and wherein the inner polymer pipe of the first liner terminates before reaching the second portion of the first liner; and a second sealing ring mounted inside the second fitting such that the second sealing ring forces a second portion of the second liner against a second portion of the castellations on the second fitting and wherein the inner polymer pipe of the second liner terminates before reaching the second portion of the second liner.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0174] There will now be described, by way of example only, embodiments of aspects of the invention with reference to the drawings (like reference numerals being used to denote like features, whether expressly mentioned in the detailed description below or not), of which:

[0175] FIGS. 1 to 12 illustrate various steps of a method of joining two lined pipes together in accordance with the invention, and in particular;

[0176] FIG. 1 shows a partial cross-section through a lined carbon steel pipe;

[0177] FIG. 2 shows a partial cross-section through the lined carbon steel pipe shown in FIG. 1, identifying target lengths and intended locations of welds;

[0178] FIG. 3 shows a partial cross-section through the lined carbon steel pipe after a first cut;

[0179] FIG. 4 shows a partial cross-section through the lined carbon steel pipe after connection of a mechanical towing head to the liner;

[0180] FIG. 5 shows a partial cross-section through the lined carbon steel pipe after tensioning the mechanical towing head and pulling the liner away from the pipe;

[0181] FIG. 6 shows a partial cross-section through the lined carbon steel pipe following a second cut and subsequent insertion of an insulation sleeve;

[0182] FIG. 7 shows a partial cross-section through the lined carbon steel pipe following attachment of a corrosion resistant alloy clad fitting to the end of the host pipe;

[0183] FIG. 8 shows a partial cross-section through the lined carbon steel pipe following release of pulling tension, removal of the mechanical towing head, and insertion of a sealing ring;

[0184] FIG. 9 shows a partial cross-section through the lined carbon steel pipe following removal of excess liner;

[0185] FIG. 10 shows a partial cross-section through the lined carbon steel pipe following insertion of a fit-up sleeve;

[0186] FIG. 11 shows a partial cross-section through the lined carbon steel pipe and another lined carbon steel pipe to which it is being joined;

[0187] FIG. 12 shows a partial cross-section through the joined lined carbon steel pipes;

[0188] FIG. 13 shows a partial cross-section through lined carbon steel pipes joined using fittings comprised only of carbon steel;

[0189] FIG. 14 is an exploded view of the components of an alternative embodiment to that shown in FIG. 13;

[0190] FIG. 15 shows a partial cross-section through a lined carbon steel pipe following removal of excess liner, in an alternative embodiment to that shown in FIG. 9;

[0191] FIG. 16 shows a partial cross-section through the lined carbon steel pipe following removal of a portion of the porous layer;

[0192] FIG. 17 shows a partial cross-section through the lined carbon steel pipe following insertion of a fit-up sleeve;

[0193] FIG. 18 shows a partial cross-section through the lined carbon steel pipe and another lined carbon steel pipe to which it is being joined;

[0194] FIG. 19A shows a partial cross-section through two lined carbon steel pipes prior to an initial weld;

[0195] FIG. 19B shows a partial cross-section through two lined carbon steel pipes prior to a first repair weld;

[0196] FIG. 19C shows a partial cross-section through two lined carbon steel pipes prior to a second repair weld;

[0197] FIG. 20 shows a cross-section of the fitting of the embodiment of FIGS. 19A-19C;

[0198] FIG. 21 shows a sealing ring of the embodiment of FIGS. 19A-19C;

[0199] FIG. 22 shows a cross-section of the fit-up sleeve of the embodiment of FIGS. 19A-19C;

[0200] FIGS. 23A-23C show cross sections of spacer rings corresponding to FIGS. 19A-19C; and

[0201] FIG. 24 shows a shows a partial cross-section through two lined carbon steel pipes prior to joining together, in accordance with another embodiment of the invention.

[0202] Unless stated otherwise, features in the drawings are not to scale. Scales are exaggerated in order to better illustrate the features of the invention and the problems which the invention are intended to address.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

[0203] In the examples which follow, embodiments of the invention are described in the context of the Applicant's above-mentioned improved (multilayer polymetal) pipe liner, for which it finds particular utility, but it will be understood that the methods and/or apparatus described are equally applicable to conventionally lined pipes, such as polyethylene lined water injection flowlines and the like.

[0204] Furthermore, although the preferred technique for installation of pipe liners is the reduction (via a swaging die), insertion and reversion technique developed by British Gas and subsequently refined for the oil and gas industry by Swagelining Limited, it will be appreciated that the invention is not limited to nor by any particular method by which the pipe has been lined. For example, it is known that instead of pulling a liner through a reduction die it may be pulled through one or more reduction rollers (sometimes termed roll-down). Such a technique is employed in the Tite Liner system developed by United Pipeline Systems.

[0205] Alternatively, the liner may be folded or otherwise deformed into an H-, U- or C-shaped cross-section, inserted into the host pipe, and then allowed or caused to return to its original shape by application of heat and/or pressure for example. This is sometimes referred to as close-fit lining or fold and form lining.

Improved Pipe Liner

[0206] FIG. 1 shows a cross-section through a lined pipe 101 which comprises a carbon steel host pipe 103 and a liner 105. As explained in the background to the invention above, a carbon steel host pipe may be provided with corrosion resistance by installation of a polymer liner (using a reduction and reversion process) which remains in tight contact with the interior surface of the carbon steel host pipe. For the avoidance of doubt, the internal bore of the lined pipe through which fluid is transported is indicated by reference numeral 102.

[0207] The liner 105 differs from conventional liners in at least one key detail. The liner 105 is a multilayer liner and comprises an outer polymer layer, polymer pipe 105B, which is bonded to barrier layer 111 using an adhesive (not shown). It is the outer polymer pipe 105B which contacts the host pipe 103 after the liner 105 has reverted. It will be understood that the outer polymer pipe is substantially cylindrical, hence describing same as a pipe. It might equivalently be termed an outermost polymer layer of the liner.

[0208] The multilayer liner further comprises an inner polymer pipe 105A which is porous, and is bonded to the barrier layer 111, on the opposite side of the barrier layer 111 from the outer polymer pipe 105B, using a (preferably porous) adhesive (again, not shown). It will again be understood that the porous pipe 105A is also substantially cylindrical, hence describing same as a pipe. Likewise, it might equivalently be termed an innermost polymer layer of the liner.

[0209] For the avoidance of doubt, the purpose of the porous pipe 105A is expressly to permit the passage of gas (or liquid) through the inner layer (or layers) of the liner 105, between the internal bore 102 of the lined pipe 101 and the barrier layer 111 and vice versa. The porous pipe 105A comprises a polymer material and purposely has a plurality of pores or interstices which permit the passage of gas (or liquid), in contrast with conventional polymer liners which are substantially solid (i.e. do not permit the passage of gas or liquid). While gas or liquid, particularly under pressure, might gradually and eventually permeate through a conventional liner, the skilled person will realise that this is not at all desirable and is potentially catastrophic.

[0210] The liner 105 prevents permeation and furthermore does so without moving the risk from an annulus between a liner and a host pipe to an interface between a barrier layer and an inner polymer pipe (for example, of a barrier pipe). By preventing permeation in a way that does not compromise the integrity of the pipeline, corrosive attack on a carbon steel host pipe can be reliably prevented. It follows that the necessity for CRA materials will be significantly reduced because the carbon steel host pipe is no longer being exposed to corrosive products in service. This will result in a significant reduction in the total cost as well as in the environmental impact of such pipelines. Even if the barrier layer comprises a CRA material, this would still represent a significant reduction in CRA material overall because a CRA barrier layer would contain only a small fraction of the amount of CRA that would be used to line or clad the same length of pipe.

[0211] It will now be described how such lined pipes can be joined.

Joining Lined Pipes

[0212] As discussed above, it is preferred that the pipes to be joined have been (or will be, as discussed below) lined using a reduction and reversion process, such as Swagelining or roll-down. It will however be understood that other methods of lining a pipe with such a liner are possible (as intimated above with examples). The following description of a process of joining sections of lined pipe in a cut to length operation allows certain preferred and optional features of the methods and apparatus to be understood in context. Note that these methods are applicable whether the liner is a single layer liner or multilayer liner, and/or whether or not the multilayer liner comprises a porous inner pipe or a barrier layer. It is also discussed below how certain steps may be omitted in different operations; a cut to length operation being one specific operation which comprises steps not necessary in other operations (as will become clear).

[0213] FIG. 2 indicates at A the extent of the fabricated and lined length of the pipe 101, at B the measured length for tie in weld termination, and at C the intended location of the connection between the pipe 101 and associated fitting (not shown but indicated by reference numeral 151 in subsequent Figures). FIG. 3 shows the pipe 101 following a first cut through the host pipe 103 to the liner 105, and a rough cut of the liner 105 leaving a relatively short (for example 500 mm) length of liner 105 protruding from the host pipe 103.

[0214] Following removal of the host pipe section and exposing the liner 105, a mechanical towing head 121 is attached to the end of the liner 105 as shown in FIG. 4. The towing head 121 is then tensioned which extends the liner 105 axially and consequently results in a reduction in the outer diameter of the liner 105, thus producing an annular space 123 between the liner 105 and the host pipe 103 as shown in FIG. 5. The host pipe 103 is then cut to the target length C as shown in FIG. 6 and an insulation sleeve 125 is inserted into the annular space 123.

[0215] It is anticipated that instead of carrying out two separate cuts of the host pipe 103 (as shown in FIG. 3 and FIG. 6, respectively) a single cut, for example to location C, could be made without first making a cut to location B, particularly if the liner 105 is not expected to move when the host pipe is cut 103 (if there is a high level of residual strain the liner might expand). Alternatively, the pipe 101 could instead be provided with a portion of the liner 105 already protruding beyond the end of the host pipe 103, for example by lining the pipe 101 with an oversized liner 105 or by cutting the host pipe 103 in an earlier preparatory step, ready for attachment of the mechanical towing head 121 and subsequent joining steps as follow.

[0216] Tubular fitting 151, which comprises a carbon steel body 153 with an internal corrosion resistant alloy cladding 155, is positioned over the liner 105 and welded to the host pipe 103 using an annular girth weld as shown in FIG. 7. The insulation sleeve 125 previously inserted between the liner 105 and the host pipe 103 protects the liner 105 during this step. Of course, the insulation sleeve 125 might be omitted if sufficient space can be provided between the liner 105 and the host pipe 103 or if the welding process can otherwise avoid heat damage to the liner 105. The insulation sleeve 125 could be removed after the welding step is carried out, but in this example it remains in place post-welding. It is also anticipated that instead of (or in addition to) inserting the insulation sleeve, active cooling might be employed. For example, cooling jackets 126, as shown in FIG. 6, may be wrapped around the host pipe in the vicinity of the weld to actively draw heat away and prevent damage to the liner.

[0217] Note that the fitting 151 might alternatively be referred to as an extension or a pipe extension as it effectively extends the host pipe 103 as well as providing it with castellations (as described below). Also note that the fitting might be comprised entirely of corrosion resistant alloy or carbon steel.

[0218] The inner surface of the fitting 151 is provided with a series of projections or castellations 157, further details of which will be discussed below. After the welding step is carried out, the mechanical towing head 121 is removed and the liner 105 begins to revert to its original (pre-tensioned) size and length, whereupon it comes into contact with the inner surface of the fitting 151 and hence the castellations 157, which the liner 105 overlaps.

[0219] Note that the castellations 157 define a series of corresponding grooves and as such the inner surface of the fitting 151 might, alternatively, be described as being provided with a series of grooves. In fact, instead of directly providing castellations (which project out from the inner surface of the fitting) the inner surface of the fitting might be provided with a series of grooves in the inner surface of the fitting which inevitably results in a castellated surface. It is preferred however that the castellations project from the internal diameter of the fitting.

[0220] In this embodiment, the castellations 157 comprise a first castellation section 157A and a second castellation section 157B. The first castellation section 157A has a substantially constant inner diameter whereas the second castellation section 157B tapers outwardly towards the distal end of the fitting 151 (with respect to the host pipe 103) from an inner diameter similar or corresponding to that of the first castellation section 157A to a larger inner diameter closer to the inner diameter of the body 153 of the fitting 151.

[0221] As shown in FIG. 8, a sealing ring 159 is inserted into the fitting 151, within the liner 105, which forces the liner 105 into contact with the first castellation section 157A. This serves to prevent subsequent movement of the liner 105 (should it be required) and provides a first seal. Note that the sealing ring 159 compresses all layers of the liner 105, including the porous layer which is compressed sufficiently to render it non-porous. The sealing ring 159 is formed from a corrosion resistant alloy but might be formed from a different material such as carbon steel with a corrosion-resistant coating

[0222] It is envisaged that the castellations might comprise a single section which is tapered in its entirety. That is, there is no section of constant inner diameter. To provide a similar effect to the substantially constant inner diameter section 157A, the gradient of the single taper may increase towards the distal end of the fitting. This may not be necessary, for example if the sealing ring is tapered in the opposite sense.

[0223] Excess liner is then trimmed back as shown in FIG. 9 such that the liner 105 terminates short of the ends of the fitting 151, in alignment with an insertion rim 161 (or extending slightly beyond), in this case provided by the internal corrosion resistant alloy cladding 155. A fit-up sleeve 163 is then inserted into the end of the liner 105. The fit-up sleeve 163 comprises a first liner engaging portion 165 which is tapered in the opposite sense to the taper of the second castellation section 157B. In this region the fit-up sleeve 163, and in particular the first liner engaging portion 165, forces the liner 105 into the castellations in the second castellation section 157B and provides a second seal.

[0224] The fit-up sleeve 163 comprises a central portion 167 which is substantially cylindrical and has an outer diameter larger than that of the first liner engaging portion 165 so as to define a shoulder 168 which abuts the insertion rim 161 of the fitting 151 and creates an airtight seal. Accordingly, the depth to which the fit-up sleeve 163 is inserted can be controlled or pre-determined. The fit-up sleeve 163 is symmetrical and comprises a second liner engaging portion 169, corresponding to the first liner engaging portion 165, at the opposite end of the fit-up sleeve 163.

[0225] It is foreseen that o-rings or gaskets can be employed at the interfaces between, for example, the shoulders and the insertion rims, to improve the seals at these locations. O-ring or gasket sizes can be selected from a look up table based on the final dimensions and other parameters of the joint, for example gap sizes and/or the actual depth of the insertion rim following any necessary preparation of the fitting for welding. For example, j preparation for automatic welding or v preparation for manual welding will result in variability which can be compensated for using appropriately sized o-rings or gaskets.

[0226] Like the sealing ring 159, the fit-up sleeve 163 is formed from a corrosion resistant alloy but might likewise be formed from a different material such as carbon steel suitable corrosion protection.

[0227] It is envisaged that in some embodiments the sealing ring 159 could be dispensed with and the fit-up sleeve used alone. In such an arrangement, the first and second liner engaging portions of the fit-up sleeve might have the same axial extent as the corresponding castellations. Likewise, the distal ends of the first and second liner engaging portions may comprise a first section of substantially constant outer diameter (at distal ends thereof) and a second section which tapers outwardly from the first section towards the central portion. The first section of substantially constant outer diameter would cooperate with the castellations of substantially constant inner diameter, and the tapered second section would cooperate with the tapered second castellation section.

[0228] To join the pipe 101, which we will now refer to as the first pipe, to a second pipe 201, the second pipe 201 is prepared in a similar manner to the first 101 up to but before the point at which the fit-up sleeve 163 is inserted. As such, the liner 205 of the second pipe 201 is forced against a first castellation section 257A of a second fitting 251 by a sealing ring 259, and the liner 205 terminates at a corresponding depth stop or insertion rim 261.

[0229] As shown in FIG. 11, the second pipe is stationary and the first pipe 101, terminated by the fitting 151 and fit-up sleeve 163, is pushed or otherwise moved towards the second pipe 201. The fit-up sleeve 163 is received in the second pipe 201 and further movement causes the second liner engaging portion 169 to force the liner 205 into the castellations in the second castellation section 257B. Note that the depth stop or insertion rim 161 of the first fitting 151 acts against the shoulder 168 of the fit-up sleeve 163 as a ram to push the fit-up sleeve 163 into the liner 203. Similarly, opposing shoulder 170 abuts corresponding insertion rim 261 of the second fitting 251, forming another airtight seal.

[0230] In addition to providing seals (the implications of which are discussed below) these abutments also prevent the fit-up sleeve from being inserted beyond a target depth (or target depths). A further benefit of the fit-up sleeve 163 is that by having an internal diameter commensurate with the diameter of the bore 102 it can effectively act as a pigging sleeve which facilitates the transit of pigs over the resulting pipe joint.

[0231] It will of course be understood that in this scenario the first pipe 101 (terminated by the fitting 151 and fit-up sleeve 163) could be stationary and the second pipe 201 instead pushed or otherwise moved towards the first pipe 101.

[0232] An annular girth weld can then be performed to join the fittings 151,251 together as shown in FIG. 12. Note that the airtight seals provided at the abutments between insertion rims 161,261 and shoulders 168,170 (respectively) prevent backdraughts and provide a boundary for a welding back purge, thus enabling CRA welding (necessitated by the use of a CRA cladding in the fittings 151,251) without the requirement for purging facilities within the closed pipeline. The relatively small volume of the annular space in the region of the weld (between the abutments) will be filled much more quickly than in normal back purged welding operations.

[0233] In an alternative embodiment, discussed briefly below with reference to FIG. 13, the fittings may be wholly formed from carbon steel rather than having CRA cladding. In such an embodiment this necessity for CRA welding and the associated complications (such as back purging) are not a concern. It is envisaged that the fittings might be so formed regardless of whether the pipeline is intended for transporting corrosive species because there may be no risk of said corrosive species reaching the fittings because of a barrier in the liner, the seals formed by the sealing rings and the fit-up sleeve, and/or the seals between the shoulders of the fit-up sleeve and corresponding insertion rims. As mentioned below, there may also be provided o-rings or gaskets to supplement these seals.

[0234] FIG. 13 shows a joint between two lined pipes 1101 and 1201 created in a similar manner to that described above but with some key differences as shall now be described. In this case, the fittings 1151,1251 are machined from solid oversized carbon steel pipe; that is, there is no internal CRA cladding. Instead, the castellations 1157,1257 and the insertion rims 1161,1261 are formed directly in the carbon steel pipe. Of course, the fittings may be formed from any suitable material.

[0235] As intimated above, in this embodiment there are provided o-rings 1173 and 1273 between insertion rims 1161,1261 and shoulders 1168,1170 (respectively). Of course, the o-rings could be replaced or supplemented with gaskets or the like. O-rings or gaskets may also (or alternatively) be provided between the sealing ring and the fit-up sleeve (as indicated by reference numerals 1175 and 1275) thus providing a further seal.

[0236] Also, in this embodiment, the liners 1105,1205 comprise conventional polyethylene pipe; that is to say there is no barrier layer or porous inner layer. As such, the pipeline illustrated might be deemed unsuitable for, say, sour hydrocarbon service (for which the previous embodiment would be particularly suited) but might be particularly well suited for water injection flowlines.

[0237] FIG. 14 shows an exploded view of a joint between two lined pipes 2101 and 2201, similar to the joint shown in FIG. 13 but again with some key differences as shall now be described. Again, the fittings 2151,2251 are machined from solid oversized carbon steel pipe. However, the castellations 2157,2257 are formed directly in the carbon steel pipe by creating a number of recesses.

[0238] In this embodiment there are provided o-rings 2173 and 2273 between insertion rims 2161,2261 and shoulders 2168,2170 (respectively). However, rather than provide o-rings (or gaskets) between the sealing rings and the fit-up sleeve 2163, the fit-up sleeve 2163 is sized and shaped such that the leading ends of the fit-up sleeve 2163 touch the respective sealing rings 2159,2259.

[0239] There is also provided a copper backing strip 2181 to accommodate automatic welding of the fittings 2151,2251. To this end, in this embodiment the ends of the fittings are also provided with j-shaped bevels 2183 to accommodate narrow gap welding.

[0240] In further contrast with the embodiment shown in FIG. 13, the liners 2105,2205 comprise a barrier layer and porous inner layer, similar to the liner shown in FIGS. 1 to 12. It is envisaged that the use of such liners will negate the need to use CRA cladding (the fittings in this embodiment comprised solely of carbon steel) even in the presence of very aggressive corrosive species, such as in sour hydrocarbon service. It will however be appreciated from the foregoing that the nature of the liner is irrelevant to the invention.

[0241] In other alternative embodiments, not shown, one or more of the welds can be replaced with alternative means of joining tubular components. For example, it is foreseen that instead of carrying out an annular girth weld between fittings, the fittings could be provided with flanges which are instead bolted or otherwise fastened together (see FIG. 24 and brief discussion below). In such an arrangement, the action of bringing the flanges together by the tightening of bolts, application of a clamp (or clamps), or the like might remove the necessity to push the pipes (that is, the fittings on the ends of the pipes) together completely. In other words, the final stages of compressing the liner material between the fit-up sleeve and the castellations is achieved as the flanges are brought together. Also, instead of welding the fittings to the ends of the respective pipes, it is foreseen that the fittings could be attached to the ends of the respective pipes by flanged connections similar to that described briefly above. The fittings could still be welded together (when joining the pipes together) if required or desired.

[0242] As an alternative to flanged connections, and hence a further alternative to welding, other mechanical connections may be employed. For example, the inventive arrangements described herein permit connections between lined pipe sections using mechanical connectors not previously deemed suitable for joining lined pipe (certainly not for hydrocarbon service, and especially not sour service).

[0243] Mechanical connectors such as GMC Limited's proprietary mechanical connector which forms part of their Intelligently Connected Pipe (ICP) product for offshore riser and flowline applications, and Oil States Industries' proprietary Merlin connection, may be employed to join the fittings together. In such an arrangement, according to a further alternative embodiment of the invention, one of the fittings comprises a pin section and the other fitting comprises a box section to receive the pin section of the other. The box section comprises a plurality of internal grooves and/or projections and the pin section a plurality of corresponding external grooves and/or projections.

[0244] When fitting together, the annular space between the pin section and the box section is pressurised (for example by injecting hydraulic fluid) so as to expand the box section. A clamp or a ram pushes (or pulls) the pin section fully into the box section, the pressure is reduced and the box shrinks onto the pin and the grooves and/or projections cooperate to provide a series of metal-to-metal seals. As with the flanged connection described above, the clamping action may provide the final stage of compression between the fit-up sleeve and the respective liner.

[0245] As discussed above, it is preferred that the pipes to be joined have been lined using a reduction and reversion process, such as Swagelining or roll-down, that results in a tight-fitting liner. It will also be understood that other methods of lining a pipe with a liner are possible, and this would include close-fit lining or fold and form lining as described briefly above.

[0246] The above described embodiments relate to what may be described as a cut to length operation in which an already-lined pipe is joined to another already-lined pipe, and the liner must be manipulated in order to retro-fit the fittings to the host pipes. However, it is foreseen that in many cases instead of attaching the fittings to the ends of pipes that have already been lined, the fittings may be attached to the ends of pipes before the pipes are lined, and the liner then pulled (or inserted) through both the pipe and the fitting and allowed to revert. In such situations, which might in fact represent the most common way in which the invention will be implemented and the benefits realised, FIG. 7 may illustrate the final step of such a process in which the first fitting 151 is welded to the first host pipe 103 before inserting the first liner 105 (i.e. the first pipe 101 is not initially a lined pipe), and the first liner 105 subsequently pulled through the first host pipe 103 and first fitting 151 (for example using a solid pulling head). The second pipe 201, to which the first pipe 101 is to be joined, may also have been lined in this way, that is after the second fitting 251 has been joined to the second host pipe 203 (i.e. the second pipe 201 is not initially a lined pipe either). All the following steps (including but not limited to inserting the sealing ring 159, trimming the liner 105 back to the insertion rim 161, inserting the fit-up sleeve 163 in the first pipe 101, inserting the fit-up sleeve in the second pipe 201 by pushing the first pipe 101 towards the second pipe 201, and joining the first fitting 151 to the second fitting 251) may then be carried out as described above with reference to FIGS. 7 to 12.

[0247] It is likely that a joint between lined pipes formed using the latter method (described in the previous paragraph) may be indistinguishable from a joint between lined pipes forms using the cut to length method described above with reference to FIGS. 1 to 12.

[0248] Alternatively, the ends of the pipes themselves can be machined (or clad in CRA material and machined) to provide the desired internal profile (in which case any features described above in relation to fittings may be provided instead in the pipe; for example castellations, flanges or mechanical connections). Accordingly, it is possible to also omit the steps set out above and discussed with reference to FIG. 7 (at least), and corresponding steps as they may relate to other embodiments described herein.

[0249] Furthermore, the subsequent steps of inserting the sealing ring (FIG. 8) and cutting back the liner to the depth stop or insertion rim (FIG. 9) could constitute the final steps of a lining process which produces a section of lined pipe ready to be joined, as required, to another like section of lined pipe by inserting a first end of a fit-up sleeve into one of the lined pipes, pushing a second end of the fit-up sleeve into the other lined pipe, and then joining the two lined pipes (or their respective fittings) together by welding or by a mechanical connection therebetween as intimated above.

[0250] As described above in relation to FIG. 8, the sealing ring is inserted into the fitting within the liner so as to prevent subsequent movement of the liner (should it be required) and to provide a seal which prevents axial transit or permeation of liquid or gas along the porous layer in the region between the sealing ring and the respective fitting. The seal is formed by compressing all layers of the liner, and in particular the porous layer which is compressed sufficiently to render it non-porous. Another seal is provided by the fit-up sleeve which also compresses a subsequent portion of the liner against the fitting and a further seal may be provided by the optional provision of o-rings or gaskets between the fit-up sleeve and the sealing ring (as illustrated in FIG. 13).

[0251] In the unlikely event that the porous layer is not sufficiently compressed, for example because the sealing ring is incorrectly sized or incorrectly inserted, there is a slight possibility that liquid or gas may be able to transit or permeate through the porous layer in this region and therefore bypass the sealing ring when in service. It is expected that even in this situation, said liquid or gas would follow the path of least resistance and transit through the uncompressed porous layer at the other side of the sealing ring and re-enter the internal bore of the lined pipe. Nonetheless, it is seen as desirable to mitigate risk and to this end the process described above with reference to FIG. 1 to 12 (or 7 to 12 as the case may be) may be modified as follows.

[0252] FIG. 15 corresponds to FIG. 9 and this embodiment may share any or all features and steps leading up to this point with that embodiment (for example as described with reference to FIGS. 1 to 8). FIG. 15 (similarly to FIG. 9) shows that after insertion of the sealing ring 3159, the liner 3105 is trimmed back such that it terminates short of the ends of the fitting 3151, coincident with (or slightly proud of) an insertion rim 3161 formed by the castellated internal corrosion resistant alloy cladding 3155.

[0253] A section of the porous layer 3105A is then removed such that the porous layer 3105A terminates at the edge or end of the sealing ring 3159 as shown in FIG. 16. The exact process by which the porous layer 3105A is removed will be dependent on the materials from which the liner 3105 is made (for example the material of the porous layer and/or the adhesive between the porous layer and the barrier layer 3111). One way in which the porous layer 3105A may be removed is by chemically dissolving the polymer material of the porous layer 3105A without damaging the barrier layer 3111. Alternatively, the porous layer 3105A may be mechanically removed, for example by cutting or by machining to reduce the thickness of the porous layer 3105A and subsequently peeling it away from the barrier layer 3111. The effectiveness of the adhesive between the porous layer 3105A and the barrier layer 3111 can be reduced, aiding removal of the porous layer 3105A, for example by application of heat or chemical means (such as a suitable acid composition). Alternatively, the adhesive (at least in this region) can be selected to enable the porous layer to be peeled away from the barrier layer.

[0254] Subsequent steps may then correspond to the abovementioned embodiment (for example as described with reference to FIGS. 10 to 12). As shown in FIG. 17 (similarly to FIG. 10) a fit-up sleeve 3163 is then inserted into the end of the liner 3105. The fit-up sleeve 163 comprises a first liner engaging portion 3165 which is tapered in the opposite sense to the taper of the second castellation section 3157B and the liner 3105 is compressed therebetween. In contrast with the abovementioned embodiment, the fit-up sleeve 3163, and in particular the first liner engaging portion 3165, is in direct contact with the now-exposed barrier layer 3111. The absence of the porous layer in this region means that any liquid or gas which transits or permeates past the sealing ring 3159 through the compressed porous layer vents directly back to the internal bore.

[0255] As shown in FIG. 18 (similarly to FIG. 11), to join the first pipe 3101 to a second pipe 3201, the second pipe 3201 is prepared in a similar manner to the first 3101 up to but before the point at which the fit-up sleeve 3163 is inserted, including removing the porous layer 3205A up to the sealing ring 3259. The first pipe 3101, terminated by the fitting 3151 and fit-up sleeve 3163, is pushed or otherwise moved towards the second pipe 3201. The fit-up sleeve 3163 is received in the second pipe 3201 and further movement causes the liner 3205 to be compressed between second liner engaging portion 3169 and the second castellation section 3257B. Again, in contrast with the abovementioned embodiment, the fit-up sleeve 3163, and in particular the second liner engaging portion 3169, is in direct contact with the now-exposed barrier layer 3211. The absence of the porous layer in this region means that any liquid or gas which transits or permeates past the sealing ring 3259 also vents directly back to the internal bore.

[0256] An annular girth weld can then be performed to join the fittings 3151,3251 together, for example as described above with reference to FIG. 12.

[0257] In a variation of the process described above, instead of terminating the porous layer 3105A at the edge of the sealing ring 3159, the porous layer 3105A may be terminated between the ends of the sealing ring such that the interface or termination resides behind the sealing ring 3159 (or between the sealing ring 3159 and the fitting 3151). In this way, the transition between the porous layer 3105A and the barrier layer 3111 may be sealed. This might be achieved by removing a suitable length of the porous layer 3105A prior to insertion of the sealing ring 3159, the sealing ring 3169 effectively extending between a portion of the liner 3105 where there is a porous layer 3105A present and where the barrier layer 3111 is exposed. Alternatively, in another variation of the process described above, the porous layer 3105A may be terminated at a location between the insertion rim 3161 and the sealing ring 3159 such that it resides behind the fit-up sleeve 3163 (or between the first liner engaging portion 3165 of the fit up sleeve 3163 and the fitting 3151).

[0258] An additional benefit of the invention, which overcomes significant disadvantages of prior art methods of joining lined pipe, is also realised when it is necessary to repair, or specifically re-make, the weld between the fittings. Conventionally, non-destructive testing is carried out on a weld to make sure it is acceptable for service. If it is not acceptable, but it can be repaired, then a repair is carried out and non-destructive testing carried out to make sure the repaired weld is acceptable for service. If the original or the repaired weld cannot be repaired, it is necessary to re-make the weld. Remaking welds with all existing weldable connectors is time consuming on the critical path and thereby significantly expensive and contains reasonable operational technical risk. The present invention negates the risk and the time taken to effect the re-weld and thereby significantly reduces the cost.

[0259] To re-make a welded pipe joint the pipe joint may be cut through, the first and second fittings pulled apart and the fit-up sleeve removed. The skilled person will understand that 18 in order to re-make the weld, it would be usual to cut out a section of the joint containing the weld. This might, for example, be a 30 mm section. In this case it would not be possible to use the same fit up sleeve when re-making the joint because the ends of the fittings would not meet; accordingly a shorter fit up sleeve (for example, 30 mm shorter), would be required to ensure proper fit up is maintained when the fittings are brought together and welded.

[0260] If cutting through the pipe joint also cuts through the fit-up sleeve, the resulting portions of the fit-up sleeve can be removed separately from the first and second fittings. But in general, only the fittings will be cut and the fit-up sleeve can be removed whole. It is foreseen that this fit-up sleeve could be re-used in another joint.

[0261] FIGS. 19A to 23C illustrate a further alternative embodiment which incorporates a number of features specifically intended to facilitate repairing or re-making welds between the first and second fittings of the invention. Fit-up sleeves of various embodiments described above comprise a substantially cylindrical central portion of an outer diameter larger than that of the substantially conical liner engaging portions at either end thereof, providing shoulders which abut corresponding insertion rims of the fittings into which they are inserted. As intimated above, in this way the depth to which the fit-up sleeve is inserted can be controlled or pre-determined.

[0262] In the embodiment illustrated in FIGS. 19A to 23C there are provided a number (three in this example) of spacer rings 4501A,4501B,4501C which are configured to be inserted between the shoulders of the fit-up sleeve 4163 and the insertion rims 4161,4261 of the fittings 4151,4251 (or pipes as the case may be), to further control and indeed modify the depth to which the fit-up sleeve 4163 is inserted. FIGS. 19A-19C corresponds to FIGS. 11 and 18 of embodiments described above. FIG. 19A shows a connector assembly ready for welding to create a joint between respective lined pipes. Located between the shoulders of the fit-up sleeve 4163 and the insertion rims 4161,4261 are a pair of spacer rings 4501A of a first length A.

[0263] If the resulting weld fails or otherwise needs to be repaired or re-made, the weld is cut out and the fit-up sleeve 4163 and the spacer rings 4501A are removed. After re-bevelling the ends of the fittings 4151,4251 (or pipes as the case may be), a pair of spacer rings 4501B of a second, shorter, length B are inserted and the fit-up sleeve 4163 re-inserted, as shown in FIG. 19B. The difference in length of spacer rings 4501B with respect to spacer rings 4501A corresponds to the size of the weld cut-out such that the ends of the fit-up sleeve 4163 extend to the same position relative to the castellation regions 4157,4257 (discussed further below). Should the resulting repair or re-made weld also need to be repaired or re-made the same process is followed but in this case a pair of spacer rings 4501C of a third, shorter again, length C are inserted and the fit-up sleeve 4163 re-inserted, as shown in FIG. 19C. Again, the difference in length of spacer rings 4501C with respect to spacer rings 4501B corresponds to the size of the weld cut-out such that the ends of the fit-up sleeve extend to the same position relative to the castellation regions 4157,4257.

[0264] Throughout the process of repairing or re-making welds, however many times this is performed (within reason), the sealing rings 4159,4259 hold the liners 4105,4205 in place. In this example the number of weld attempts is limited to three but there is no limit on the number of attempts which can be accommodated provided a sufficient number of spacer rings are provided (and the fit-up sleeve is suitably dimensioned).

[0265] In this embodiment, the castellation regions 4157,4257 can be seen to comprise two distinct sets of axially separated castellations 4157A,4257A and 4157B,4257B (see FIG. 20 in particular). The first set of castellations 4157A,4257A correspond to the sealing rings 4159,4259 that hold the liners 4105,4205 in place, and the second set of castellations 4157B,4257B correspond to the liner engaging portions 4165,4169. As will be apparent by comparing the relative insertion depths of the fit-up sleeve 4163 in each of FIGS. 19A-19C this separation serves to define distinct sealing regions. Of course, it is foreseen that the castellation regions might comprise a single continuous castellation, which may comprise a continuous taper, rather than distinct sets which may be of different tapers or one tapered and one of a constant inner diameter.

[0266] FIG. 24 illustrates a variant of the above-described embodiment (although the variation is applicable to any embodiment) in which instead of carrying out an annular girth weld (or other kind of weld) between the fittings (or pipes as the case may be), the fittings (or pipes) are provided with flanges 5199,5299 which are instead bolted together. Steps leading up to this point may be the same or similar to those steps leading up to (but not including) the final step of welding fittings (or pipes as the case may be) together, although it is envisaged that the flanges may aid in the physical insertion of the sealing ring and the fit-up sleeve in the first fitting. Other means of fastening the flanges 5199,5299 together may of course be provided. As intimated above, in such an arrangement the action of bringing the flanges 5199,5299 together by the tightening of bolts, application of a clamp (or clamps), or the like may constitute the final stages of compressing the liners 5105,5205 between the fit-up sleeve 5163 and the respective castellations 5157,5257, although it is envisaged that the sealing rings and the fit-up sleeve (or just the fit-up sleeve as the case may be) may deliver the seal alone. This makes the design and the fitting of the flanges much less sensitive in terms of leaks.

[0267] Furthermore, as suggested above, spacer rings 5501A may actually be dispensed with as it is possible to match the fit-up sleeve to the flange, and in the event the flange has to be opened after fitting for any reason, there will be no requirement for a metal cut out (as in a re-weld) as the flanges are mechanically joined. In general however it may be preferred to retain the sealing rings, for example to prevent liner movement, although in some embodiments these may also be dispensed with (for example if by design there is an extremely tight fit between the liner and the pipe and/or fitting such that the liner will not move).

[0268] The invention provides methods and apparatus for making lined pipelines. Pipes are joined together by attaching fittings at their ends and joining the fittings together. Within the joint there is a fit-up sleeve which forces liners against respective fittings and provides corresponding seals. Other seals can be provided by inserting sealing rings which force different portions of the liners against different portions of the fittings. The fit-up sleeve and sealing rings may force the liners against castellations which prevent movement of the liners. The fit-up sleeve may cooperate with insertion rims on the fittings to provide very accurate spacing, or touching edges which can be desirable if automatic welding is employed. The seals provided by the fit-up sleeve also eliminate backdraughts and assist welding operations. Furthermore, the fit-up sleeve permits pigging through the pipe joint and therefore along the length of the resulting lined pipeline. It is foreseen that the need for CRA components and CRA welding can be largely if not wholly dispensed with.

[0269] In hydrotests carried out to evaluate the integrity of pipe joints formed in accordance with the invention, witnessed by Lloyd's Register, a test spool was pressure cycled between zero and 345 bar three times over the course of a week. During this time no fluid passed the fit up sleeve and the carbon steel surface of the host pipe was untouched by the test water. The invention is therefore already proven capable of use in water injection service without requiring the use of corrosion resistant alloys, and the Applicant expects that further testing will similarly confirm capability for use in hydrocarbon service and, in particular, sour hydrocarbon service.

[0270] The above embodiments and any suggested variants are described in context. However, it will be readily understood that each of the embodiments is capable of being combined (in whole or in part) with one or more of the other embodiments (again, in whole or in part). For example, it is foreseen that a joint may be formed in which a first pipe is provided with a fitting comprising a CRA cladding and a second pipe (to which the first will be joined) may be provided with a fitting which does not comprise a CRA cladding. As a further example, the castellations formed directly in the pipe in one or more embodiments might be replaced with grooves as in one or more other embodiments. As a yet further example, where barrier pipe or the Applicant's improved pipe liner is employed, portions of the innermost or porous layer may be removed in variants of those embodiments which do not expressly describe this step.

[0271] As may be used herein, the terms bottom, lower, below and the like are descriptive of a feature that is located towards a first end/side of an apparatus, system or component while the terms top, upper, above and the like are descriptive of a feature that is located towards a second, opposing end/side of the apparatus, system or component. Such an apparatus, system or component may be inverted without altering the scope of protection which, as below, is defined by the appended claims. Likewise, terms which are descriptive of movement or direction, such as towards or apart, shall be understood in the broadest sense as referring to relative movement or direction.

[0272] Throughout the specification, unless the context demands otherwise, the terms comprise 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 exclusion of any other integer or group of integers.

[0273] The foregoing description of the invention has been presented for the purposes of 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 order to best explain the principles of the invention and its practical application to thereby enable others skilled in the art to best utilise the invention in various embodiments and with various modifications as are suited to the particular use contemplated. Therefore, further modifications or improvements may be incorporated without departing from the scope of the invention as defined in the summary of invention and by the appended claims. For example, and for the avoidance of doubt, the methods and apparatus described herein are not limited to use with pipe liners comprising a barrier layer and/or a porous inner pipe but are also applicable to conventionally lined pipe. Furthermore, it is foreseen that fittings and/or pipes may be joined by mechanical connections such as flanges rather than welding.