Abstract:
The present invention relates to a pipe joint for connecting tubular conduits, in particular for connecting lengths of pipe to form a fluid transport system. The pipe joint ( 2 ) comprises: a conduit ( 14 ) formed with at least one connection end ( 18 ). The or each connection end ( 18 ) comprises: a wall defining a receiving recess ( 8 ) for receiving an end of a pipe length ( 4 ); a groove ( 12 ) formed to a depth in an internal surface of the wall of the receiving recess ( 8 ); and a channel ( 34 ) communicating between the groove ( 12 ) and an external surface of the connection end ( 18 ). The pipe joint further comprises a connector ( 30 ) formed from a length of material which is seatable within the groove ( 12 ) via the channel ( 34 ) and which is wider than the depth of the groove ( 12 ) so that when seated within the groove ( 12 ) the connector ( 30 ) extends into the receiving recess ( 8 ).

Description:
FIELD OF THE INVENTION 
       [0001]    The present invention relates to a joint for connecting tubular conduits, in particular for connecting lengths of pipe to form a fluid transport system. 
       BACKGROUND OF THE INVENTION 
       [0002]    Fluid transport systems are known for conveying materials, such as liquids and gasses, with common examples including water and fuels such as gas and oil. The systems may include oil and gas pipelines for conveying fuel over thousands of miles. The tubular conduits used in fluid transport of fuel may be made of different metals, including steel, iron, copper, aluminium and plastic. 
         [0003]    For small bore plastic pipes a press or screw fit joint can be used, and in copper pipe, the use of soft solder is the usual means of joint connection. 
         [0004]    For larger diameter pipes, typically 1 to 1.5 metres (around 40 to 60 inches) in diameter, used in the transport of fuel, welded joints are commonly used. However, welded joints have the disadvantage of requiring skilled workers as well as having negative health and safety and environmental implications. For example, construction of gas or oil conveying pipelines, which are typically made from approximately 12 metre (40 feet) long lengths of steel pipe with a diameter of 1 to 1.5 metres (around 40 to 60 inches) and conventionally use welded joints. Each joint can take a skilled team a whole day to make, when taking into consideration, the deployment of equipment at the joint location and inspection of the joint by X-ray equipment. Also, around 1 in 10 of such welded joints will have to be repaired after an inspection. This makes oil and gas pipelines expensive and time consuming to construct and maintain. 
         [0005]    A further problem with press fit and welded joints is that they are difficult to disconnect, for example, for repair or maintenance, and once disconnected are not generally re-useable. Furthermore, disconnection of press fit or welded joints often results in damage to the pipe lengths. 
       SUMMARY OF THE INVENTION 
       [0006]    In accordance with one aspect of the present invention, there is provided a pipe joint comprising: 
         [0007]    a conduit formed with at least one connection end wherein the or each connection end comprises:
       a wall defining a receiving recess for receiving an end of a pipe length;   a groove formed to a depth in an internal surface of the wall of the receiving recess;   a channel communicating between the groove and an external surface of the connection end, and       
 
         [0011]    a connector formed from a length of material which is seatable within the groove via the channel and which is wider than the depth of the groove so that when seated within the groove the connector extends into the receiving recess. 
         [0012]    A length of pipe to be connected to the pipe joint is formed with a groove on its external surface corresponding to the or each groove in the internal surface of the wall of the or one of the connecting ends. The connector, when seated in the groove in the wall of the end connection, extends into the corresponding groove in the pipe length. In order to provide a stable fixing, which also contributes to the sealing of the pipe length within the pipe joint, the connector may fit snugly between the grooves. 
         [0013]    A pipe length may be fitted into the pipe joint by following the steps of: inserting an end of the pipe into the receiving recess; aligning the or each groove in the pipe with the corresponding groove or grooves in the internal wall of the receiving recess; and inserting the or each connector, via the channel, into a spaced formed by the aligned grooves. The or each groove in the pipe may match a corresponding groove in the wall of the receiving recess and a connector may be provided for each set of corresponding grooves. 
         [0014]    The fitting of the pipe length into the pipe joint may be carried out by sliding the length of material forming the connector along the space between the corresponding grooves via the channel. The connector straddles the groove in the internal surface of the wall of the receiving recess and the groove in the external surface of the pipe length to fix the pipe length in the pipe joint. 
         [0015]    The pipe joint according to the present invention is relatively cheap to make and install. It is also safe to install as it does not require welding. In addition, the fixing can be undone for repair or maintenance from the outside of the pipe joint by simply removing the connector from the grooves via the channel. An engagement means may, for example, be a graspable hook provided at one end of the connector for this purpose. 
         [0016]    Fitting the pipe length within the pipe joint may comprise the additional steps of forming the groove in the internal surface of the wall of the or each connecting end and forming the groove in the external surface of the pipe length. Cutting tools are available in the art for cutting such grooves in pipes and pipe joints. 
         [0017]    The connector may be formed from a length of resilient material which is able to take up the shape of the groove in the internal surface of the wall of the receiving recess, when the connector is moved via the channel into the groove. For example, the connector may be formed from a length of metal, such as a bar of spring steel or a length of metal wire. In addition, the connector may be covered with a lubricating coating, such as Teflon®, to aid the movement of the connector through the channel and the groove. 
         [0018]    There may be one or more groove in the receiving recess, with a corresponding channel and connector for each groove. In this case a corresponding number of grooves may be formed on the external surface of the pipe end. The or each groove in the receiving recess or the pipe length may have a transverse cross-section which matches a segment of a transverse cross-section of the connector; in particular, the segment may be a substantially circular segment. 
         [0019]    The grooves in the receiving recess may extend in a substantially circumferential direction along the internal surface of the wall of the receiving recess. Similarly, the grooves in the pipe length may extend in a substantially circumferential direction along the external surface of the pipe length. For example, the grooves may be annular grooves and the connector may extend substantially all the way around the groove. This arrangement provides a fixing between the connecting end and the pipe length which extends all the way around the pipe length, thus providing a high-strength connection. The or each groove in the receiving recess may alternatively extend helically around the internal surface of the wall of the receiving recess. In this case the helical groove may extend at least once around the receiving recess. 
         [0020]    The length of material of the connector may have a first end insertable into the channel and a second end, remote from the first end, which second end may be seatable against an external surface of the connection end, for example, when the connector is fully inserted. In order to facilitate insertion of the connector into the groove via the channel, the channel and the groove may merge smoothly. 
         [0021]    The conduit may comprise a valve arrangement, but it may also comprise another length of pipe or any other conduit used to connect to one or more pipe lengths. 
         [0022]    Typically, the internal surface of the wall of the receiving recess may be substantially cylindrical, in order to receive a standard cylindrical pipe. 
         [0023]    The joint may additionally comprise a pipe end face abutment extending inwardly of an internal surface of the conduit. In this case the abutment may be an annular abutment and the abutment may form a seat for an annular seal. 
         [0024]    The annular seal may seal between the annular abutment and an end face of the pipe length. 
         [0025]    Further features and advantages of the invention will become apparent from the following description of preferred embodiments of the invention, given by way of example only, which is made with reference to the accompanying drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0026]      FIG. 1  shows a partial longitudinal cross-section of a pipe joint incorporating a valve and a length of pipe in accordance with a first embodiment of the present invention; 
           [0027]      FIG. 2  shows a partial transverse cross-section through line A-A of  FIG. 1 ; 
           [0028]      FIG. 3  shows a partial longitudinal cross-section of a pipe joint in accordance with a second embodiment of the present invention; 
           [0029]      FIG. 4 , shows a partial transverse cross-section through line B-B of  FIG. 3 ; 
           [0030]      FIG. 4   a  shows an alternative configuration of part of the pipe joint of  FIG. 3 ; 
           [0031]      FIG. 5  shows a partial longitudinal cross-section of a pipe joint in accordance with a third embodiment of the present invention; 
           [0032]      FIG. 6  shows a side view of the pipe joint of  FIG. 5 ; 
           [0033]      FIG. 7  shows a partial transverse cross-section of the pipe joint of  FIG. 5 ; 
           [0034]      FIG. 8  shows a partial longitudinal cross-section of a pipe joint in accordance with a fourth embodiment of the present invention; 
           [0035]      FIG. 9  shows a side view of the pipe joint of  FIG. 8 ; 
           [0036]      FIG. 10  shows a partial longitudinal cross-section of a pipe joint in accordance with a fifth embodiment of the present invention; 
           [0037]      FIG. 11  shows a partial transverse cross-section of the pipe joint of  FIG. 10 ; 
           [0038]      FIG. 12  shows a partial longitudinal cross-section of a pipe joint in accordance with a sixth embodiment of the present invention; 
           [0039]      FIG. 13  shows a partial transverse cross-section of the pipe joint of  FIG. 12 ; 
           [0040]      FIG. 14  shows a partial longitudinal cross-section of a pipe joint in accordance with a seventh embodiment of the present invention; 
           [0041]      FIG. 15  shows a partial longitudinal cross-section of a pipe joint in accordance with an eighth embodiment of the present invention; and 
           [0042]      FIG. 16  shows a partial transverse cross-section of the pipe joint of  FIG. 15 . 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0043]    Like parts are represented by like numerals in each of the Figures. 
         [0044]      FIG. 1  shows a partial longitudinal cross-section through a pipe joint  2  connected to a length of pipe  4 . Only the end of the pipe length  4  connected to the pipe joint  2  is shown in  FIG. 1 . The pipe joint  2  comprises a conduit  14  with two open connection ends  18 . The conduit  14  incorporates a valve arrangement  6 , as is known in the art; however, the conduit  14  need not incorporate a valve arrangement, but may comprise any length or shape of conduit with one or more such open connection ends  18 . 
         [0045]    Each connection end  18  is formed with a receiving recess  8  shaped to receive an end of a pipe length  4 ; the receiving recess  8  generally has a substantially circular transverse cross-section. The receiving recess  8  is formed with an end face  24 . A substantially circumferential annular groove  12  is formed in the internal surface of the wall of the receiving recess  8 , which annular groove  12  has a substantially semi-circular transverse cross-section. The groove  12  may be formed when the pipe joint  2  is formed; alternatively, the groove  12  can be cut into the internal surface of the receiving recess  8  using a cutting tool of the type known in the art for cutting such grooves. The groove  12  communicates with an external surface of the wall of the receiving recess  8  via a channel  34 , as shown in  FIG. 2 . The channel  34  merges smoothly into the groove  12 , extending substantially tangentially from the bed of the groove  12 . Each receiving recess  8  is terminated at its end remote from the end face  24  by a collar  22 , which collar  22  extends radially inwardly from the internal surface of the conduit  14 . In  FIG. 1 , each collar  22  also forms part of the chambers of the valve arrangement  6 . The collar  22  is formed with an annular abutment  16  extending from the collar  22  in a direction towards the end face  24 , so as to form an annular seal recess  26  in a face of the collar facing towards the end face. The annular seal recess  26  is formed in the face of the collar  22  between the annular abutment  16  and the internal surface of the wall of the receiving recess  8 . A resilient annular seal  28  is seated within the seal recess  26 . 
         [0046]    The pipe length  4  has formed at its end, and is connected to the pipe joint  2  by, a substantially circumferential annular groove  10  on its external surface, which annular groove  10  has a substantially semi-circular cross-section. The groove  10  may be formed when the pipe is formed; alternatively, the groove can be cut into the end of the pipe length  4  using a cutting tool of the type known in the art for cutting such grooves. 
         [0047]    The annular groove  12  formed in the receiving recess  8  and the annular groove  10  formed in the pipe length  4 , match each other, having substantially identical cross-sections. Also, the annular groove  10  formed in the pipe length  4  may be formed at a predetermined distance from an end face  32  of the pipe length  4 , so that when the end face  32  abuts the annular abutment  16  of the receiving recess  8 , the annular grooves  10 ,  12  are aligned. When the grooves  10 ,  12  are aligned, they form an annular space of substantially circular cross-section. Referring now to  FIGS. 1 and 2 , a connector, referred to herein as a connection ring  30  is fitted in the annular space formed by the aligned grooves  10 ,  12  so as to fix the pipe length  4  within the connection end  18  of the pipe joint  2 . The connection ring  30  is formed from a length of material, for example a length of metal wire (which may be multi-stranded) or a bar of sprung steel, which material has a substantially circular cross-section. One end of the length of material may be formed into a graspable handle, for example, in the form of a hook  36 . With the handle  36  abutting the external surface of the wall of the receiving recess  8 , adjacent the channel  34 , the length of material is long enough to fill the annular space formed by the annular grooves  10 ,  12 , ie. long enough to extend completely around the groove  10  in the pipe end  4 . The cross-section of the connection ring  30  is matched to the cross-section of the space formed by the aligned grooves  10 ,  12 , so that the connection ring  30  fits snugly between the aligned grooves. The connection ring  30  performs the function of locking the pipe end  4  within the receiving recess  8  of the pipe joint  2 . This is achieved by providing an interference fit which inhibits separation of the pipe joint  2  when the connection ring  30  is located within the annular space formed by the aligned annular grooves  10 ,  12 . 
         [0048]    The connection between the pipe joint  2  and the end of the pipe length  4  is formed as follows. The end of the pipe length  4  is slideably located within the receiving recess  8  of the pipe joint  2  until the end face  32  of the pipe length  4  abuts the abutment  16 . This traps the annular seal  28  between the end face  32  of the pipe length  4  and the collar  22  of the conduit  14 . The annular seal  28  forms a fluid-tight seal between the pipe length  4  and the conduit  14  of the pipe joint  2 . With the end face  32  of the pipe length  4  abutting the abutment  16 , the grooves  10 ,  12  are aligned. 
         [0049]    An end  38  of the length of material forming the connection ring  30 , which end  38  is remote from the graspable handle  36 , is inserted via the channel  34  into the space formed by the grooves  10 ,  12 . The length of material forming the connection ring  30  is pushed around the annular space formed by the grooves  10 ,  12  until the graspable handle  36  abuts the external surface of the wall of the receiving recess  8  and the connection ring  30  surrounds the pipe end  4 . The connection ring  30  can be pushed into the annular space manually or by means of machinery, for example a hydraulic system. The length of material forming the connection ring  30  is flexible and resilient so that it is capable of taking the shape of the annular space formed between the grooves  10 ,  12  as it is inserted into the channel  34  and pushed around the annular space. The length of material forming the connection ring  30  may also be covered by a lubricating coating, such as a coating made from Teflon®. Alternatively or in addition, the connection ring  30  may be lubricated with oil or any other suitable lubricant before it is inserted into the annular space formed between the grooves  10 ,  12 . 
         [0050]    It will be appreciated that the lubricant will also serve a sealing purpose. In certain applications the conduit or pipe may not be used as part of a fluid transport system; for example, the conduit could be used an electrical conduit for housing electrical wires. Alternatively, the conduit may be used in the construction industry and may be installed as a structure such as a barrier, handrail, mast or the like. The conduit may be used as a support, for example, as scaffolding, a support beam, rafter or the like. In these applications the joint may not require a seal  28 . 
         [0051]    Referring now to  FIG. 3  there is shown an alternative embodiment of the present invention. The pipe joint  31  is in the form of a flange connector that can be used to join a pipe length  33  to another device (not shown) such as a valve, a T-joint or another flange connector. The end face  35  of the pipe length  33  is provided with a chamfer which can be inserted into a receiving recess  37  of the pipe joint  31  and urged against an annular seal  28 . As shown in  FIG. 3 , the annular seal  28  is not located in a recess and deforms against the chamfered end face  35  to take up a triangular cross-section, and form a fluid-tight seal between the end face  35  of the pipe length  33  and the pipe joint  31 . Owing to the three sealing surfaces provided by the deformed annular seal  28 , the annular seal  28  is able to withstand higher pressures than that of a standard ‘O’ ring seal. 
         [0052]    As shown in  FIG. 3  and  FIG. 4 , the connection ring  30  does not have a handle  36  at its end. Instead, the connection ring  30  has a retainer  39  attached to the connection ring  30  for enabling insertion of the connection ring  30  into the annular space provided by the grooves  10 , 12  and for allowing extraction of the connection ring  30  from the annular space, when required. The retainer  39  can be screwed to a corresponding threaded portion on the pipe joint  31 . When the connection ring  30  is required to be removed from the annular space between the grooves  10 ,  12  the retainer  39  can be rotated to unscrew it from the pipe joint  31 ; this rotation acts to initially free or ‘waken-up’ the connection ring  30 , which can be particularly advantageous if the connection ring  30  has been located in the annular space for a long period of time. The retainer  39  is provided with a groove  41  on its periphery; this groove  41  allows a tool (not shown) to engage the retainer  39  to facilitate extraction of the connection ring  30  from the annular space between the grooves  10 ,  12 . 
         [0053]    The connection ring  30  is also provided with a ferrule  45  attached to an end  43  thereof to prevent movement of the connection ring further into the annular space between the grooves  10 ,  12  once it has been inserted therein. The ferrule  45  may be attached to the connection ring  30  by swaging, for example. The ferrule  45  is seated in a recess  49  in the retainer  39  and held therein by a nipple  47 ; the size of the recess  49  and the arrangement of the nipple  47  are such that the ferrule  45  can freely rotate within the retainer  39 . The difference in size between the recess  49  and the ferrule  45  provides a channel therebetween through which a lubricant or sealant, which can be inserted through the nipple  47 , can pass to reach the annular space in which the connection ring  30  is located. 
         [0054]    The ferrule  45  can be shaped to have a number of flat sides around which a tool (not shown) can be placed to indirectly engage the connection ring  30  and thereby assist with insertion and/or removal of the connection ring  30  into/from the annular space formed by the grooves  10 ,  12 . If the ferrule  45  is provided with six flat sides, so that it has a hexagonal cross-section, for example as shown in  FIG. 3 , the recess in the retainer  39  should be arranged to be large enough to allow the hexagonal ferrule  45  to rotate in the recess. The recess need not be the same shape as the ferrule  45 ; for example the ferrule  45  may be a hexagon and the recess  49  circular. 
         [0055]    Referring now to  FIG. 5 , there is shown an alternative embodiment of the present invention.  FIG. 5  shows a pipe joint in the form of a simple coupler  50  which can be used for joining two lengths of pipe together. The coupler  50  is provided with an annular seal in the form of an O-ring  52  located in an annular groove  54  formed in the internal surface of the walls of the receiving recess  8 . Referring also to  FIGS. 6 and 7 , the connection ring  30  in this embodiment does not include a graspable handle  36 . Instead the channel  34  is provided with a bore having a threaded portion for receiving a plug  56  which may be used to prevent ingress of any unwanted matter, for example, rain water, soil, dew or the like, from entering the channel  34 . The connection ring  30  may be integral with the plug  56 . 
         [0056]    Referring now to  FIGS. 8 and 9 , in an alternative embodiment the coupler  50  may be arranged to include a flange  58  at at least one of its ends. The flange  58  may be drilled and tapped to provide a threaded bore. A securing collar  62  which can be slipped over the pipe end  4  may be fastened to the flange  58  by bolts  60  that can be received in the threaded bore of the flange  58 . The flange  58  may also be provided with a recess  64  in which a sealing ring  52  can be located to form a seal between the flange  58  and the collar  62 . 
         [0057]    Referring now to  FIGS. 10 and 11 , in yet a further alternative embodiment of the present invention, there is provided a pipe joint  2  comprising a sealing assembly  66 . The sealing assembly  66  includes a boss  68  on the pipe joint  2  in which a seal  70  is located. The seal  70  extends around the outer circumference of the pipe length  4 , when the end of the pipe length  4  is positioned within the recess  8 . The seal  70  may be tightened and secured onto the pipe length  4  by means of any suitable clamping means  72 , such as a band clamp, hose clip or Jubilee clip. The seal  70  may be made of rubber or any other suitable material. The pipe joint  2  is not shown to have a connection ring in the embodiment of  FIG. 10 . The connection ring  30  can be omitted in applications where the strength of the joint does not have to be particularly high, such as domestic applications. However, it could be re-introduced for high-strength applications. 
         [0058]    In  FIGS. 12 and 13 , an alternative form of the sealing assembly  66  is shown. The sealing assembly  66  includes a snap ring  69  and a separate clamp  71 . The force exerted by the sealing assembly  66  may be such that, for certain applications, the connection ring  30  is not required. Therefore, the connection ring  30  is not shown in  FIGS. 12 and 13 . It can be seen that neither the end of the pipe length  4  nor the connection end  18  of the pipe joint  2  are formed with respective grooves  10 ,  12  in this case should the pipe joint  2  be required for a high-strength application, the connection ring  30  could be re-introduced. 
         [0059]    Referring now to  FIG. 14 , the pipe joint  2  may comprise a securing collar  74 . The securing collar  74  is provided with a threaded inner surface  76  that is adapted to mate with a threaded outer surface  78  of the connection end  18  of the pipe joint  2 . The connection ring  30  is replaced by a resilient split-ring  80  having an internal diameter slightly smaller than an outer diameter of the pipe length  4 . This arrangement allows the split-ring  80  to be slipped over the end of the pipe length  4  and locked into position in the groove  10  formed in the end of the pipe length  4 . The end of the pipe length  4  is joined to the connection end  18  by “running-up” the securing collar  74  onto the threads  78  on the connection end  18 . Once the securing collar  74  has been run-up far enough, the securing collar  74  will abut the split-ring  80  and will drive the end of the pipe length  4  into the recess until the end face  32  is seated against the annular seal  28 . The securing collar  74  may be run-up using a C spanner or by any other suitable method known in the art. 
         [0060]    It will be appreciated that a connection ring  30  could also be used with the securing collar  74  described in the embodiment of  FIG. 14 . 
         [0061]    Referring now to  FIGS. 15 and 16 , a further embodiment of the pipe joint  2  is shown. The pipe joint of  FIGS. 15 and 16  includes a split ring  80 , a screw collar  82 , and a tapered split ring  84 . The screw collar  82  is provided with an outer threaded surface  86  that is adapted to mate with a threaded inner surface  88  of the connection end  18  of the pipe joint  2 . In this embodiment of the pipe joint  2 , the connection ring  30  has been replaced by the split tapered ring  84 , which may comprise a body  90  formed of a resilient material, such as nylon. The split ring  80  may be integral with the tapered split ring  84 ; alternatively the split ring  80  and the tapered split ring  84  could be two discrete components. 
         [0062]    In use, the arrangement of the pipe joint  2  shown in  FIG. 15 , would be assembled by first slipping the screw collar  82  over the end of the pipe  4 . The split ring  80  would then be positioned so as to be located in a groove  10  of the pipe  4 . The tapered split ring  84  would be slipped over the end of the pipe  4  so that a groove  92  located on an inner surface of the tapered split ring  84  is located over the split ring  80 . The end of the pipe  4  would then be positioned within the recess  8  of the pipe joint  2  until the outer surface of the tapered split ring  84  abutted the inner surface of the recess  8 . The end of the pipe length  4  would be joined to the connection end  18  by “running-up” the screw collar  82  onto the threads  88  of the connection end  18  using a C spanner which would engage notches  94  of the screw collar  82 . 
         [0063]    In  FIG. 15 , it can be seen that the pipe joint  2  abuts the seal  28  to form a fluid-tight seal. However, the pipe joint  2  may also include a seal  96  which is located between the interface of the tapered split ring  74  and the screw collar  82 . The seal  96  may be utilised when a pipe joint is used in hazardous environments in which two seals are required or where corrosive gases may exist outside the pipe; the seal  96  can be used to stop such gases from coming into contact with either or both of the split ring  80  and the tapered split ring  84 . 
         [0064]    It will be appreciated that, for certain applications, the use of a nylon tapered ring  84  may provide the required fluid-tight seal for the pipe joint  2 , thus dispensing with the need for the seal  28  or the seal  96  in the pipe joint  2 . 
         [0065]    In yet a further alternative embodiment of the present invention, the grooves  10 ,  12  may align when there is a small gap between the end face  32  of the pipe length  4  and the annular abutment  16 , so as to allow for thermal expansion of the pipe length  4 . In this embodiment if the pipe joint requires a seal, a sealing arrangement as shown in any of  FIG. 5 ,  7 ,  10  or  12  may be incorporated into the pipe joint. 
         [0066]    The above embodiments are to be understood as illustrative examples of the invention. Further embodiments of the invention are envisaged. For example, the connection ring  30  and sealing ring  52  illustrated in  FIG. 5  may be interchanged, such that the sealing ring  52  is closer to the annular abutment  16 . Such an arrangement would stop the connection ring  30  from being exposed to the fluid passing through the system, which in certain circumstances may be corrosive to the connection ring  30 . 
         [0067]    As described with reference to  FIG. 3  above, the annular seal  28  does not have to be located in a recess. 
         [0068]    The bolt  60  shown in  FIG. 8  may be replaced with studding that extends from the flange  58  and the collar  62  may be secured by the use of nuts and washers. 
         [0069]    A length of pipe may be provided with a connection end  18  and a groove  12  at one of its ends resulting in this end of the length of pipe being flared; at its opposite end the end of the pipe may be arranged to have an annular groove  10  on its external surface as illustrated in the Figures; in this embodiment a coupler would not have to be used to join two lengths of similar pipe together. Instead, the groove  10  at one end of one pipe section would mate with the groove  12  at the end of an adjacent pipe section. 
         [0070]    Although it has been stated above that the connection ring  30  may be coated with Teflon® to aid with insertion and extraction of the connector from the groove  10 ,  12 , it would also be possible to coat or impregnate the connection ring  30  with another plastics material to lubricate the connection ring. 
         [0071]    The channel  34  may be provided with a thread onto which a nipple may be attached to allow a suitable lubricant such as grease, copper slip or the like to be pumped into grooves  10 ,  12 . 
         [0072]    Although a substantially cylindrical pipe joint  2  and pipe length  4  have been described above, the pipe joint  2  and pipe length  4  could be of any configuration. Similarly, the grooves  10 ,  12  and the connection ring  30  can take any form. For example, the grooves  10 ,  12  can be arranged to form a quadrilateral cross-sectional annular space, such as a square, in which a correspondingly shaped connection ring  30  can be located to connect the pipe length to the pipe joint. A square-shaped annular space may mean that, in use, the connection between the pipe joint and the pipe length withstand greater forces than a connection created when the grooves  10 ,  12  and the connection ring  30  have a circular cross-section. However, providing a square-shaped annulus may, in certain applications, cause stress fractures at the corners of the groove  10  in the pipe length. Therefore, it may be better for the shape of the groove  10  in the pipe length to be semi-circular in those applications. 
         [0073]    It is to be understood that any feature described in relation to any one embodiment may be used alone, or in combination with other features described, and may also be used in combination with one or more features of any other of the embodiments, or any combination of any other of the embodiments. Furthermore, equivalents and modifications not described above may also be employed without departing from the scope of the invention, which is defined in the accompanying claims.