This invention relates to a pipe connector assembly and to a method of connecting a pipe using the connector. This invention particularly, but not exclusively, relates to a connector suitable for connecting two sections of pipe together, and is particularly useful for connecting sections of pipe with an outer pipe and a polymeric or elastomeric liner pipe located

concentrically within the outer pipe. Embodiments of the invention also allow liners to be connected to line the pipe. Such lengths of pipe are typically found in pipes such as oil or gas pipelines and flow lines. Certain embodiments are not restricted to connecting two sections of pipe, and can be used for connection a single section of pipe to another structure.

Oil and gas pipelines and flow lines are typically made up of lengths of metal pipe that are welded together at their ends. The metal pipe usually has a liner pipe located concentrically within it, which contains the fluids passing along the pipeline or flow line. The liner pipe is typically inserted into the bore of the outer pipe, and it is typically cut to length to match the outer pipe during the insertion process. The combined lengths of outer pipe and liner pipe are then connected to the next section of outer pipe by means of a pipe connector. Existing designs of pipe connector are complex and require several sequential steps of machining and welding, etc. during their manufacture and installation, which can impact adversely on the construction of the pipeline or flow line.

According to the present invention there is provided a pipe connector assembly, the assembly comprising a connector and a pipe comprising an outer pipe with a liner pipe disposed within the outer pipe, the connector comprising a body having at least one free end with a seal assembly provided on the free end, the seal assembly and the free end being configured to be received axially within the bore of the liner pipe, and being configured to seal against the inner surface of the liner pipe, wherein the connector has a flange extending radially from the body and having sealing formations to seal against the inner surface of the outer pipe.

Typically the connector is configured to be received within the bore of the outer pipe.

The seal assembly typically has circumferentially extending ribs on the radially outermost surface of the flange, which are typically configured to engage the inner wall of the outer pipe. The ribs are typically parallel to one another and are typically perpendicular to the axis of the body of the connector. The flange and the ribs can optionally be provided on the seal assembly.

The sealing assembly can optionally comprise liner pipe sealing ribs. The liner pipe sealing ribs can optionally extend axially so as to be parallel to the axis of the body of the connector, and parallel to the axis of the liner pipe. The ribs can be provided at the free end that is inserted into the liner pipe, and their axial arrangement typically facilitates the push-fit

connection between the connector and the liner pipe.

The body of the connector typically has an axis that is disposed co-axially with the axis of the outer pipe and liner pipe.

Typically the body has two free ends, each with a respective seal assembly. Accordingly, the connector of the invention can optionally be used to connect two lengths of pipe section, end to end. In some embodiments, however, the connector can be used as a terminal connector, to connect a single pipe section to another structure or installation.

The sealing assembly can optionally comprise a stiff portion relative to the liner pipe to deform the inner surface of the liner. Alternatively, in some embodiments of the invention, if being used with stiff liner pipe, the sealing assembly can be resilient relative to the liner pipe so that on contact it deforms against the liner pipe. Typically the liner pipe and the sealing assembly each have a different stiffness, so that upon contact between the two, one of them is forced to deform the other to enhance the seal between them, and fill the spaces between the ribs with the deformed liner pipe (or with the deformed ribs, in the case of the sealing assembly being softer than the liner pipe). Pressure differentials across the connector body therefore tend to compress the sealing assembly and the liner pipe more tightly together to enhance the sealing effect between them.

The sealing assembly and free end of the body typically compresses the liner pipe radially outwards against the inner surface of the outer pipe. The body can optionally comprise an inner sleeve, which can optionally be a rigid supporting sleeve of metal, polymer or composite material. The sleeve can be corrosion resistant, and can be formed of a corrosion resistant alloy e.g. stainless steel or a noble metal or polymer or composite material. The inner sleeve is typically resistant to deformation during the connection process, and holds the sealing assembly in a fixed radial position so that the liner pipe and the portion of the sealing assembly that is inside the liner pipe in the made up connector are both compressed between the outer surface of the inner sleeve and the inner surface of the outer pipe. The outer surface of the sleeve is typically provided with gripping formations to hold the sealing assembly in place on the free end of the sleeve. The gripping formations can comprise circumferential ribs or corrugations extending at least partly around the circumference of the sleeve, and located such that the sealing assembly covers them in the made up connector. The gripping formations typically enhance the grip between the sealing assembly and the sleeve.

The sealing assembly can be moulded in place on the sleeve.

Alternatively the sealing assembly can be shrunk or pushed onto the sleeve in some embodiments.

The flange is typically provided on the sealing assembly, and typically has a radial dimension that is similar to the thickness of the liner pipe, so that the end of the liner pipe abuts against the flange, and the outer surface of the liner pipe is generally flush with the outer surface of the flange, so that the rigid inner sleeve compresses the liner pipe and the sealing assembly flush against the inner surface of the outer pipe. The invention also provides a method of attaching a connector to a pipe section, the pipe section comprising an outer pipe with a liner pipe disposed within the outer pipe, the method comprising the steps of inserting a free end of a connector body with a seal assembly provided on the free end into the bore of the liner pipe, whereby the seal assembly seals against the inner surface of the liner pipe, and inserting the connector body into the bore of the outer pipe, whereby the connector seals against the bore of the inner pipe by means of a flange extending radially from the body of the connector. Typically the body has an outer jacket located between the sealing assemblies (in the case of double ended connectors) and typically the jacket comprises a heat resistant material, such as a ceramic material or silicon beads or glass wool. The jacket can optionally have an outer diameter that is similar to the outer diameter of the liner pipe and the sealing assembly, so that the whole of the outer surface of the connector is a close fit within the bore of the outer pipe. The jacket can bridge the gap between adjacent pipe sections, and can optionally comprise a channel extending radially inwardly into the jacket for a short distance, and configured to be located at the interface between the adjacent pipe sections, where it can retain molten metal formed during welding of the two adjacent pipe sections. Typically the weld channel is spaced apart from the axial ends of the jacket, which abut against the sealing assembly, so that heat transferred to the jacket during welding of the pipe sections is not transferred to the sealing assemblies during connection.

An embodiment of the present invention will now be described, by way of example, and with reference to the accompanying drawings, in which, Fig.1 is a side view of a pipe being lined;

Fig.2 is a close up of Fig 1 , showing the insertion of a polymeric liner pipe into the bore of an outer pipe;

Fig.3 is a side sectional view of a connector of the invention;

Fig.4 is an sectional view though the line A-A of the Fig. 3 connector;

Fig.5 is an exploded view of the Fig. 3 connector;

Fig.6 is a side view of the Fig. 3 connector in use connecting two adjacent sections of lined pipe;

Fig.7a is a sectional view of the Fig. 6 arrangement through line A- A in Fig 6; Fig.7b is a sectional view similar to Fig 7a of a second embodiment of a connector;

Fig.8 is a side view of the Fig. 3 connector in use connecting a section of lined pipe to an end terminus.

Referring now to the drawings, Fig 1 shows an outer pipe P of carbon steel for use in constructing a pipeline. The outer pipe P is being lined internally using a liner pipe L formed from a polymer such as polyamide, typically with low permeability. The liner pipe L is a close fit within the bore of the outer pipe P and is being inserted into the bore of the outer pipe P by means of a rubber tyred or caterpillar tracked feeder F and a tapered guide funnel G. The feeder F can be a tracked pipe tensioner or a linear cable engine. The manufactured outside diameter of the polymer liner is specified to be equal to or greater than the bore of the host pipe into which it is being installed. The concentric tapered guide funnel G is temporarily clamped to the end of the outer pipe P where the polymer liner pipe L will be inserted. The minimum bore of the funnel G is typically a specified amount less (e.g. 2%) than that of the outer pipe P to which it is attached. The bore at the outer end of the funnel G is typically greater than the manufactured outside diameter of the polymer liner pipe L.

Prior to inserting the polymer liner pipe L, lubrication can optionally be applied to the bore of the receiving outer pipe P and the funnel G to reduce the installation friction between the liner pipe L and outer pipe P.

With the outer pipe P, guide funnel G and feeder F axially aligned and secured relative to each other, the polymer liner pipe L is placed into the feeder F and the wheel or track positions adjusted to grip the liner surface. The feeder is then used to drive the polymer liner pipe L through the tapered funnel G and along the length of the outer pipe P. If necessary, temporary stiffening devices (e.g. smaller diameter support pipes) can be fitted inside the polymer liner pipe to react against the external pressure applied by the feeder wheels or tracks. After the polymer liner pipe L has been installed in a first joint of outer pipe P, the end of the liner pipe L is optionally trimmed a specified distance from the end of the outer pipe P to allow for fitting of an connector 10, typically in the form of an internal connection sleeve. The connector is shown in Figs 2 and 3, and has a body 10 having a long axis X typically comprising a profiled cylindrical inner sleeve 12 of corrosion resistant metal such as stainless steel. The inner sleeve 12 has free ends 12e which have, on their outer surfaces, seal assemblies 20. Pre-formed corrugations 13 on the free ends of the inner sleeve improve the axial bond strength between the inner sleeve 12 and the moulded sealing assemblies 20.

The sealing assemblies are typically identical to one another and each is typically formed as an annular sleeve that extends around the inner sleeve 12 and is co-axial therewith. Each sealing assembly typically comprises an axial liner sealing profile 21 having axial ribs 22 extending parallel to one another and to the axis of the body 10. The axial liner sealing profile is configured to be received within the bore of the liner pipe L and to be a close fit within that bore. The outer diameter of the axial ribs 22 are selected in conjunction with the diameter of the liner pipe L to have a slightly larger outer diameter than the inner diameter of the liner pipe L, so that when the axial liner sealing profile is offered to the bore of the liner, some deformation of the sealing assembly or the liner is necessary for connection to take place. The axial ribs 22 are typically formed from a material that has a different resilience to the material that forms the liner pipe L. For example, the liner pipe L can typically be formed of polyamide and the axial ribs 22 (typically the whole of the sealing assembly 20) can be formed of a stiffer less resilient material such as polyurethane. In such cases, the liner pipe L material is softer than the axial ribs 22, and when the two engage one another and force is applied to them, then the ribs 22 deform the liner pipe material, filling the spaces between the ribs. The ribs 22 can typically be parallel to one another and can be spaced

circumferentially around the outer surface of the axial liner sealing profile 21 . The circumferential spacing between the ribs 22 can be selected in accordance with their dimensions and tendency of the liner pipe L material to deform when engaged with the ribs 22, so that the displaced liner pipe material tends to fill up the circumferential spaces between the ribs 22, thereby restricting leak paths between the liner pipe L and the sealing assembly 20.

In circumstances where the liner pipe material is stiffer than the ribs 22, the ribs will tend to deform on contact with the inner surface of the liner pipe P and the deformed rib material will tend to fill the circumferential spaces between the ribs 22.

Typically, the ribs 22 can be asymmetric, and the circumferential spaces between the axial ribs 22 are the same in each case, and optionally, the circumferential space between two particular axial ribs diverges as the ribs extend radially from the axis of the body, so that the circumferential spacing between adjacent ribs at their roots, i.e., near to the axis of the sealing assembly 20 is less than the circumferential spacing between the ribs at their tips, i.e., spaced radially further away from the axis of the sealing assembly 20. This closer spacing at the roots of the ribs 22 helps to close off any axial leak paths between the ribs 22. As shown in Fig. 4, the appropriate circumferential spacing between the axial ribs 22 and the dimensions of the ribs 22 can be selected by forming the ribs 22 with an end profile in a general sine wave pattern, with regular spaces between each of the ribs. The axial ribs 22 can optionally be formed in different patterns that deform to seal the annulus between the liner pipe L and the sealing assembly 20 in other ways, for example, by forming the ribs with an end profile that is a square wave with regular spaces between the roots and the tips of the ribs 22. The leading edges of the axial ribs 22 are typically chamfered or otherwise reduced in height radially as they reach the ends of the sealing assembly, so that the outer diameter of the sealing assembly 20 at the very end of the sleeve 12 is less than the maximum outer diameter of the axial ribs 22. This chamfer or other shaping of the ribs 22 eases the initial make up between the liner pipe L and the sealing assembly 20, so that the liner pipe L slides more easily onto the chamfered end of the sealing assembly 20, without deflecting the liner pipe L and causing a misconnection. The chamfer at the outer end tips of the ribs 22 has a relatively short axial length (e.g. less than 5% of the length of the axial ribs 22) , and is shallow enough to facilitate initial make up of the liner pipe L with the connector 10, but not too shallow to reduce the sealing effectiveness of the connector 10 with the liner pipe L.

The sealing assembly 20 also has a flange 25 with a circumferential sealing profile 26 extending radially outwardly from the inner sleeve 12, creating a radial step in the diameter of the sealing assembly 20, and having a larger outer diameter than the axial ribs 22 on the axial liner sealing profile 21 . The flange 25 with the circumferential sealing profile 26 is spaced axially from the axial liner sealing profile 21 . The outer diameter of the flange 25 is typically similar to the outer diameter of the liner pipe L, and the flange 25 typically acts as an end stop for the liner pipe L to abut at its free end, when it has been pushed over the axial liner sealing profile 21 . The flange 25 typically has circumferential ribs 27 on its outer surface, which are perpendicular to the axial ribs 22 and to the axis of the sealing assembly 20, the body 10 and the liner pipe L. The circumferential ribs 27 extend radially from the flange 25 and run continuously around the circumference of the flange. There are typically at least three

circumferential ribs 27 on each flange 25. The ribs 27 and optionally the entire flange 25 can be resilient, and is adapted to be a close fit within the bore of the outer pipe P, so that the inner surface of the outer pipe P will compress the flange 25 and the ribs 27 to seal axial leak paths across the flange 25. The profile of the circumferential ribs 27 can optionally be asymmetric, similar to the profile of the axial ribs, in that the spacing between adjacent ribs at their roots can be closer than the tips, so that leak paths between the circumferential ribs 27 are closed when the flange 25 is compressed within the bore of the outer pipe P and so that the flange restricts leakage of fluids through the bore of the outer pipe P axially across the sealing assembly 20. The sealing assembly 20 can be moulded onto the ends of the inner sleeve 12, and can be formed of a polymeric or elastomeric material. The profiled sealing assembly is therefore designed to seal against the bore of both the outer pipe P and the polymeric or elastomeric liner pipe L. When the connector 10 is pushed into the prepared end of a lined pipe, or when the next length of pipe is offered to the connector, sealing is achieved by material displacement at the ribbed interfaces.

A separate sealing assembly 20 is typically provided at each axial end of the inner sleeve 12, and between them a heat-resistant material is typically applied externally over the central portion of the inner sleeve 12. The heat resistant material is typically in the form of a ceramic jacket 30, which extends between the two sealing assemblies on the free ends of the body 10. Alternatively the heat resistant material can be in the form of silicon beads or glass wool. A circumferential scollop or groove 31 is typically provided around the ceramic jacket 30, and is typically spaced from the ends at the central point of the jacket. The groove 31 is configured to be located at the interface between adjacent lengths of outer pipe P to be connected, and allows for retention of weld material during girth welding of the adjacent lengths of outer pipe P after insertion of the connector 10.

In use the ceramic jacket 30 is fastened to the sleeve 12, optionally by being bonded to the sleeve in one piece, or being attached by bolts or other fixings in two or more segments. The jacket is attached, with the groove 31 in the correct position to underlie the weld (which need not be central to the connector 10, but in this embodiment the groove 31 is shown in a central location equidistant between the two ends of the connector 10). Then the sealing assemblies 20 are moulded onto the ends of the sleeve, typically on each side of the jacket 30, but it is sufficient if a single sealing assembly is connected on one side of the jacket 30 and two sealing assemblies are not required. The sealing assemblies are typically formed and attached in a single moulding step, but this is not necessary, and they could optionally be formed separately, and shrunk fit, or bonded to the end sections of the sleeve 12. The chamfered outer edge of the ribs 22 is typically aligned with the end of the inner sleeve 12. The assembled connector 10 is then offered to a length of outer pipe P which contains a length of liner pipe L that has been cut to a suitable length before insertion into the bore of the outer pipe P. The connector 10 is advanced through the bore of the outer pipe P until the chamfered end of the ribs 22 engages with the inner bore of the liner pipe L that is concentric within the bore of the outer pipe P, so that the smaller diameter chamfered end of the connector is received within the bore of the liner pipe L. The connector 10 is then pushed into the bore of the outer pipe P with sufficient force to force the axial ribs 22 into the inner bore of the liner pipe L, which causes deformation of the liner pipe L as shown in Fig 7a. In embodiments where the liner pipe is stiffer than the ribs then the ribs tend to deform against the liner pipe as shown in Fig 7b. Therefore, the deformation of the ribs and the liner depends on the relative stiffness of each. The connection force therefore initiates and completes the sealing between the connector 10 and the liner pipe L, by the circumferential spreading and deformation of the liner pipe L or the axial ribs 22 during insertion.

The resilient circumferential ribs 27 on the flange 25 are also compressed radially inwards during insertion of the connector, and this compression seals the annulus between the bore of the outer pipe P and the connector 10.

The connector 10 is pushed into the bore of the outer pipe P until the groove 31 has just reached the bore of the outer pipe P, at which point, the next joint of outer pipe is offered up to the exposed end of the connector 10 protruding from the first joint of outer pipe P, so that the exposed end of the connector 10 is received within the bore of the next joint of outer pipe P. The second joint of outer pipe is pushed onto the exposed end of the connector 10, compressing the circumferential ribs 27 on the flange in the process, and therefore sealing the annulus at another location in the bore of the outer pipe P, and restricting leak paths through the bore of the outer pipe P across the connector.

When the two joints of outer pipe P are abutting at the groove 31 , they can be welded by conventional welding equipment. The ceramic jacket 30 (or other heat resistant material) prevents the heat from the welding process from affecting the integrity of the sealing assemblies 20 or the liner pipe L. The groove 31 accommodates the root bead of the weld, and retains the weld material in a mechanically strong weld profile, and also restricts migration of the molten weld material away from the weld site.

The process can then be repeated for the next section of liner pipe L, which is pushed into the bore of the outer pipe P and at its distal end is forced into the annulus between the axial pipe sealing profile 21 of the connector 10 and the outer pipe P, thereby deforming the axial ribs 22 and sealing the leak paths at the distal inserted end of the liner pipe L as previously described.

Lengths of outer pipe P may optionally be lined with liner pipe L prior to connecting. In this case, attachment of a length of lined pipe to the distal end of an installed connector 10 involves an engagement and sealing process similar to the installation of a connector 10 in a lined outer pipe P.

A modified connection sleeve 1 1 with a modified end configuration can be used to attach pipe end fittings such as flanges, hubs etc for mechanically connecting pipes. Fig. 8 shows an arrangement of a polymer liner pipe L being attached at its end terminus to a modified connector 1 1 , and a flange 2 being connected to the exposed end 1 1 e of the modified connector. Similar components of the modified connector 1 1 have the same reference number and will not be described further, but the modified connector 1 1 is typically not symmetrical like the first embodiment, and the exposed end 1 1 e typically has a circumferential sealing profile 27 but no equivalent axial sealing profile 21 .

Modifications and improvements can be incorporated without departing from the scope of the invention. Embodiments of the invention are useful for connecting pipe used in oil and gas pipelines, but other embodiments of the invention are useful in other industries and for use in connecting other types of pipe and flow lines of small or large diameter.