AU2012241131B2 - A pipe fitting and a subterranean pipeline installation - Google Patents

Abstract

A subterranean pipeline installation 50 beneath the ground surface 52 is 5 disclosed. The installation 50 includes a first body component 30 configured to form a water seal and a second body component 32 defining an access opening 18 providing access into a flow path 23 having a closure 20 removably mounted thereon. The closure 20 has a flow path defining formation 22 complementing the internal surface of the component 32 and to provide a 10 smooth flow path. The installation 50 includes an access shaft 54 around the access opening 18 and extending up to the ground surface 52 for providing access into the flow path 23. The access shaft 54 comprises a lower wall 24 projecting up from the component 32 and a pipe section 70 extending up to the ground surface 52. A handle 76 is mounted on the shaft and extends up the 15 shaft towards the ground surface 52. A top cap 74 is removably mounted on the pipe section 70. Fig 10 for publication iolTi IIf

Description

A PIPE FITTING AND A SUBTERRANEAN PIPELINE INSTALLATION FIELD OF THE INVENTION 5 This invention relates to a pipe fitting and to a water trap. This invention also extends to a subterranean pipeline installation and a method of providing access to an interior flow path of a subterranean pipeline installation. 10 This invention relates particularly but not exclusively to a pipe fitting for use in draining waste water from one or more plumbing fixtures in a building structure that is a detached house. It also extends to a subterranean pipeline installation including a water trap that is used to drain waste water from the building structure into a sewerage main. It will therefore be convenient to hereinafter 15 describe the invention with reference to this example application. However, at the same time it must be recognized that the invention is capable of broader application. For example the invention extends to pipe fittings used on pipeline installations in general and is not limited to draining waste water from building structures, e.g. that are domestic houses. 20 DEFINITIONS In the specification the term "pipe fitting" shall be understood to have a broad meaning. It shall be interpreted to include pipe devices that include more than 25 one component. While the term pipe fitting includes fittings comprising one component, it shall be specifically understood to include pipe devices having a plurality of components, e.g. 2 to 6 components. 1 In this specification the term 'plumbing fixture' means a structure or amenity of the type often found in a bathroom, a kitchen or a laundry, the use of which results in the generation of waste water which has to be drained therefrom and disposed in a waste water removal system. A plumbing fixture in the bathroom 5 might typically include a toilet, a shower, a bath and a hand basin. Each of these fixtures has a drain outlet associated therewith through which waste water is drained. The shower floor and the bathroom floor typically also include a floor waste for draining water therefrom. A plumbing fixture found in the kitchen might typically include a kitchen sink, and a dishwasher and each of 10 these plumbing fixtures generate waste water which needs to be drained and disposed of. A plumbing fixture in the laundry might typically include a washing tub or washing basin, and a washing machine and each of these fixtures similarly generates waste water. 15 In the specification the term "comprising" shall be understood to have a broad meaning similar to the term "including" and will be understood to imply the inclusion of a stated integer or step or group of integers or steps but not the exclusion of any other integer or step or group of integers or steps. This definition also applies to variations on the term "comprising" such as "comprise" 20 and "comprises". BACKGROUND TO THE INVENTION A plumbing system that is operatively associated with the drainage and 25 disposal of waste water from a building is known as a drain, waste and vent system (a DWV system). The DWV system comprises a set of drain pipes which couples a plurality of plumbing fixtures within a building to an upstream end of a waste water drainage pipeline. Very often a downstream end of the 2 waste water drainage pipeline is connected to a sewerage system although that need not be the case. A waste conduit leads from each plumbing fixture to a combination point where 5 a number of waste conduits leading from different plumbing fixtures are combined into a combined waste water pipe. Each plumbing fixture has its own plumbing fixture water trap positioned adjacent to the plumbing fixture and downstream thereof. Often the water trap is in the form of a section of pipe which is configured to form a U, S or J shaped water trap which is filled with 10 water forming a water seal in use. The plumbing fixture water trap is characterised by the fact that it is associated with and receives water from only a single plumbing fixture. The water seal that is formed by the configuration of the pipe acts as a barrier between the downstream waste water pipes including the sewerage pipes into which the waste water is ultimately discharged and the 15 plumbing fixtures. The water seal prevents sewer gases and other pathogens and foreign matter from travelling in a reverse direction back up the pipe and out through a waste water outlet into the building. It also resists odour from travelling up through the pipe and into the building. 20 Further in DWV systems, an overflow gully is generally located outside of the building which is operatively coupled to a main drain pipe leading to a sewerage main. The overflow gully which is illustrated in Fig. 1 has an open pipe or riser that extends from the waste water pipe to just above the ground surface. The open gully riser is in fluid communication with a flow path within the drain pipe 25 leading to the sewer. The riser is generally covered by a grid to prevent leaves and other debris from entering the gully. The purpose of the gully is to release any backflow or overflow arising from a blockage in the drain pipe downstream of the gully through the riser so that the waste water flows onto the ground outside the building rather than overflowing into a room within the building 30 through a waste water outlet within the building. 3 The gully riser is in fluid communication with the sewerage pipe and also opens up to the outside air adjacent to the building. Thus the gully has a further water trap known as a gully trap downstream of the gully riser. The gully trap resists 5 foul odours and gases from the main pipe from escaping through the gully riser into the air surrounding the building. It also resists other pathogens and foreign matter from travelling up through the pipe and into the gully riser. It also acts as a second line of defence, the individual plumbing fixture water traps being the first line of defence, against pathogens and other foreign matter travelling up 10 the individual pipes and out of the waste outlets and drains of the various plumbing fixtures into the building structure. The gully trap comprises a U-shaped pipe section comprising first and second legs which are connected to each other. The gully trap is operatively connected 15 to upstream and downstream sections of pipe, e.g. by means of pipe connectors. The pipe connector connecting the gully trap to the downstream section of pipe comprises an elbow that directs the vertical flow from the second leg of the U-shaped pipe section to a slight downward flow into the downstream section of the drain pipe as shown in Fig. 1. 20 Plumbing installations are prone to blockage from time to time caused by solid matter which is discharged from the plumbing fixtures into the individual fixture drain pipes and then into the main drain pipe. For example this can be caused by waste from a kitchen fixture such as a kitchen sink or a dishwasher. Often 25 the blockage occurs in the region of the gully trap and in particular blockages are particularly prone to occurring downstream of the gully trap, e.g. a short distance downstream of the gully trap. Without being bound thereby Applicant believes that this is caused by the U-shaped pipe section which results in solid matter accumulating just beyond the gully trap. 4 An elongate rod member that is capable of bending, such as a drain cleaning rod or plumber's rod, can be inserted into the main pipe to try and unblock the pipeline. The gully riser can provide access into the flow path within the waste 5 pipe. However the gully riser is upstream of the gully trap and it is difficult to access blockages downstream of the gully trap through the gully riser. Often a blockage occurs downstream of the gully trap in a position that is reasonably close to the gully trap. While the gully riser provides direct access 10 to the upstream end of the gully trap, it is difficult to insert a rod through the gully trap and then into the downstream pipe, through the gully riser, to remove a blockage. The path which the rod has to follow is tortuous. Further the gully riser has a narrow diameter similar to that of the water pipe through which the waste water flows. Accordingly unless a blockage occurs within the gully trap, 15 or close to the gully trap, it can be extremely difficult to remove the blockage using a plumber's rod through the gully riser. It can also be difficult to reach a blockage from an access opening that is located downstream of the blockage. Very often the access opening is simply 20 too far away from the blockage for a plumber to reach the blockage using a plumber's rod. Fig. 2 illustrates a situation where a plumber has removed an access cap on the sewerage line and inserted a rod to remove the blockage. In cases like this where the blockage cannot be removed by passing a rod 25 through the gully access, it is necessary to excavate from the surface down to the gully trap and then cut into the pipe to clear the blockage. Thereafter the pipeline has to be repaired and the excavation needs to be filled in. It will be appreciated that it is very costly and time consuming and inconvenient to have to repair a pipe blockage in this way. 5 Fig 3 shows an arrangement where waste water conduits extending from individual plumbing fixtures, are combined into a single underground or subterranean waste water pipe, adjacent to the building which leads to a council sewer main at the edge of a property. This arrangement has a 5 secondary water trap that is separate from and additional to the water trap adjacent to each plumbing fixture, located in line on the single subterranean waste water pipe, but it does not have a gully riser. It will be appreciated that if a blockage occurs in this water trap and adjacent pipeline there will be no access from the ground surface into the flow path within the pipe to remove the 10 blockage. Accordingly it will often be necessary to excavate ground and break into the pipe to remove the blockage. It would be advantageous if a contrivance could be devised that enabled blockages in subterranean pipes to this type of blockages to be removed or 15 cleared more efficiently. SUMMARY OF THE INVENTION According to one aspect of this invention there is provided a pipe fitting for a 20 subterranean pipeline installation, including: a fitting body defining an inlet and an outlet and having an internal surface defining a flow path extending from the inlet to the outlet, the fitting body further defining an access opening providing access into the flow path; a closure for removable mounting over the access opening to close off the 25 access opening, wherein the closure includes a flow path defining formation extending, in use, across the access opening and defining part of the flow path through the fitting body; and an access shaft wall surrounding the access opening and projecting away from the access opening to define a free end of the access shaft wall remote from 6 the access opening, the free end suitable for receiving a top cap remote from the flow path defining formation and the flow path. The flow path defining formation may have a rounded concave surface that is 5 configured to complement the internal surface of the fitting body. The closure may include a closure wall that projects away from the flow path defining formation around the periphery of the closure. The closure wall may be configured to complement the access shaft wall surrounding the access 10 opening to resist the passage of water between the access shaft wall and the closure wall. The fitting body may include a curved pipe section for forming the water trap that is configured to turn through at least 160 degrees to form a water trap 15 having a water seal in use, the curved pipe section being positioned upstream of the access opening along the flow path. The fitting body may comprise first and second body components that can be releasably coupled to each other. The first body component may include the 20 curved pipe section and the second body component may be configured to form the access shaft wall surrounding the access opening. The second body component may have an inlet and an outlet that extends orthogonally to the inlet, and the access shaft wall may extend away from the 25 flow path such that it forms a linear extension of a part of the fitting body that is adjacent to the inlet. The access shaft wall may be substantially vertically aligned with a part of the water seal. 7 The access shaft wall surrounding the access opening may have a substantially cylindrical configuration and the closure wall has a complementary substantially cylindrical configuration such that it is receivable within the access shaft wall with a working clearance. 5 The closure wall must be able to be moved relative to the access shaft wall, e.g. by sliding over the access shaft wall, so that the closure can be removed from the fitting body and returned to the fitting body. However the closure wall may also be sized to resist the passage of water between the access shaft wall 10 and the closure wall. The access opening may be substantially circular when it is viewed in a plan view and may be sized to complement the closure wall. The access shaft wall may have a greater diameter than the diameter of the flow path. This assists a user to obtain access to the flow path at points spaced 15 from the access opening during maintenance operations. The access shaft wall may define a closure support on which the closure is located in position and supported extending across the access opening and the closure may include a mounting formation for resting on the closure support. 20 The closure support may comprise a shoulder that extends in a radial direction in from the access shaft wall and the closure may define a peripheral rim that is configured to rest on said shoulder and support the closure in position. 25 The closure may include a handle formation projecting away from the flow path defining formation for assisting a user to handle the closure. The handle formation may define a socket for receiving a handle extension therein. The handle extension may be in the form of a section of pipe that is sized to be received within the socket with a tight fit. 8 The pipe fitting may include a top cap for use in combination with the access shaft wall. 5 The access shaft wall may have a free end remote from the access opening, and the pipe fitting may include a top cap that can be mounted over the free end. The access shaft wall and the top cap may have complementary engagement 10 formations for releasably engaging them with each other to close off the space defined by the access shaft wall. This enables the top cap to be mounted on the access shaft wall when the fitting is supplied to plumbers. According to another aspect of this invention there is provided a water trap 15 arrangement for a subterranean pipeline installation comprising: a trap body configured to form a water seal when water is passed there through, the trap body defining an inlet for coupling to an upstream conduit, an outlet for coupling to a downstream conduit and a flow path extending from the inlet to the outlet, the trap body further defining an access opening providing 20 access from outside the trap body into the flow path; an access shaft wall surrounding the access opening and projecting away from the trap body for forming part of an access shaft which has a free end, remote from the access opening and the flow path, suitable for receiving a top cap; and a closure removably mountable over the access opening for closing off the flow 25 path, the closure including a flow path defining formation extending across the access opening. 9 The closure may further include a circumferential closure wall that projects away from the flow path defining formation, and the closure wall may be configured to complement the access shaft wall surrounding the access opening to resist the passage of water between the access shaft wall and the 5 closure wall. The flow path defining formation may have a flow path surface having a rounded concave surface that is configured to complement the internal surface of the trap body. The flow path defining member may include a handle formation projecting away 10 from the flow path defining formation for assisting a user to handle the closure. The trap body may include a curved pipe section that is configured to form a water seal. The curved pipe section may be substantially U-shaped. 15 The trap body may comprise first and second body components that can be releasably coupled to each other, and the first body component may include the curved pipe section configured to form the water seal and the second body component may be configured to define the access opening and the access wall surrounding the access opening. The first and second body components 20 can be rotated relative to each other before they are permanently fixed to each other, so that the angle at which the first and second components are coupled to each other can be adjusted during installation to suit installation requirements. 25 According to yet another aspect of this invention there is provided a subterranean pipeline installation received within the ground spaced beneath the surface of the ground comprising: 10 a pipe defining an inlet and an outlet and a flow path extending from the inlet to the outlet, the pipe further defining an access opening providing access into the flow path, and the pipe further defining a trap body for forming a water trap; a closure that is mounted in removable fashion across the access opening; and 5 an access shaft mounted on the pipe extending circumferentially around the access opening and extending away from the access opening up to the ground surface at a position remote from the flow path, whereby to provide access into the flow path within the trap body from the ground surface. 10 The trap body may be provided upstream of the access opening. The trap body may be formed by a section of the pipe being configured to form a water seal having a suitable height. 15 The water trap may be a gully trap. A part of the pipe defining the trap body may be substantially U-shaped and define two legs. The pipe may include a first component forming at least part of the trap body and a second component forming the access opening. 20 The subterranean pipeline installation may include a gully riser upstream of the trap body, the gully riser comprising a vertically extending riser pipe section opening into the flow path and extending from the pipe to the ground surface where it opens to the air. The riser pipe section may have an open upper end 25 and a grate mounted over the upper end. The access shaft may comprise an access shaft wall surrounding the access opening and projecting away from the trap body and an access shaft pipe 11 section extending from the access shaft wall to the ground surface. The access shaft may further include a top cap removably mounted on an upper end of the access shaft pipe section adjacent to the ground surface. 5 The top cap may have a circumferential skirt and may be removably mounted on the upper end of the access shaft pipe section by means of complementary engagement formations. The complementary engagement formations may comprise an external screw thread on the access shaft pipe section and an internal screw thread formed on the skirt of the top cap. 10 The closure may include a flow path defining formation having a concave flow path surface extending across the access opening that is configured to complement the internal surface of the fitting body, and a handle projecting away from the flow path within the pipe. The handle may include a handle 15 formation on the flow path defining formation defining a socket and a handle extension in the form of a section of pipe that is sized to be received within the socket with a tight fit. The handle may extend up to a height that is adjacent to the top cap. 20 According to another aspect of the invention there is provided a subterranean pipeline installation received within the ground spaced beneath the surface of the ground comprising: a pipe defining a flow path therethrough, the pipe defining an access opening 25 providing access into the flow path; a closure that is mounted in removable fashion over the access opening; an access shaft mounted on the trap body extending circumferentially around the access opening and extending up to the ground surface for maintenance to be carried out on the pipe; 12 a water trap in line with the pipe upstream of the access opening; and a gully riser upstream of the water trap and comprising a vertically extending riser pipe section opening into the flow path and extending from the pipe to the ground surface where it opens to the air. 5 According to yet another aspect of this invention there is provided a method of providing access to a subterranean pipeline received in the ground spaced beneath the ground surface, the pipeline defining an inlet and an outlet and a flow path extending from the inlet to the outlet, the 10 pipeline having a water trap downstream of the inlet, including: providing an access opening in the pipeline, distinct from the inlet and the outlet, to facilitate access to the flow path therethrough and a closure that is removably mounted across the access opening; and forming an access shaft from the access opening to the ground surface, the 15 access shaft being distinct from the inlet and the outlet, whereby to enable a person to gain access to the flow path from the ground surface without having to carry out any excavation. The method may include mounting a removable top cap on an upper end of the 20 access shaft whereby to close off the access shaft. The method may include closing off the access opening to resist the passage of water through the access opening when water is flowing through the pipeline. In particular the method may include sealing the closure to the pipeline around 25 the access opening whereby to resist the passage of water through the access opening. 13 The closure may form a flow path defining formation having a rounded concave surface that is configured to complement an internal surface of the pipeline, and the method may include directing water smoothly across the flow path 5 defining formation past the access opening such that the flow pattern of the water is substantially the same as in the rest of the flow path. According to another aspect of this invention there is provided a method of removing a blockage in a pipe received in the ground below the ground surface 10 having a flow path therethrough, the pipe defining an access opening providing access into the flow path and a closure that is mounted in removable fashion over the access opening, and an access shaft mounted on the trap body extending circumferentially around the access opening and extending up to the ground surface, the method including: 15 lifting the closure off the pipe fitting body and up through the access shaft; inserting a rod through the shaft and into the pipe to remove the blockage; and returning the closure to its position mounted on the pipe fitting extending across the access opening. 20 The access shaft may include a top cap on an upper end of the access shaft and the method may include removing the top cap to gain access to the access shaft and to the closure to enable the closure to be lifted off the access opening. 25 DETAILED DESCRIPTION OF THE INVENTION A pipe fitting, a water trap, and a pipeline installation in accordance with this invention may manifest itself in a variety of forms. It will be convenient to 14 hereinafter describe one embodiment of the invention in detail with reference to the accompanying drawings. The purpose of providing this detailed description is to instruct persons having an interest in the subject matter of the invention how to carry the invention into practical effect. However it is to be clearly 5 understood that the specific nature of this detailed description does not supersede the generality of the preceding broad description. In the drawings: Figure 1 is a schematic sectional view of one example of a waste water pipeline installation having a gully riser in accordance with the prior art showing some 10 detail of components that are received under the ground below the ground surface; Figure 2 is a perspective view of the drain waste water pipeline installation of Figure 1 showing a plumber trying to unblock a blockage in the pipeline near 15 the gully trap by removing an access closure on a waste water pipe leading to the sewerage main; Figure 3 is a schematic sectional view of another example of a waste water pipeline installation leading from a building in accordance with the prior art 20 showing some detail of components that are located under the ground; Figure 4 is a perspective view of a pipe fitting in accordance with one embodiment of the invention which has been cutaway to show some internal structure within the pipe fitting; 25 Figure 5 is an exploded three dimensional view of the pipe fitting shown in Figure 4; 15 Figure 6 is a perspective view of a pipeline installation in accordance with one embodiment of the invention including the pipe fitting shown in Figure 4; Figure 7 is an exploded view of the pipeline installation shown in Figure 6; 5 Figure 8 is a longitudinal cross sectional view of the pipeline installation shown in Figure 6; Figure 9 is a close up cross sectional view of a part of the pipeline installation of Figure 8 including a flow path insert; and 10 Figure 10 is a schematic perspective view of the pipeline installation of Figure 6 showing how a plumber can access a blockage within the pipe fitting through an access shaft and use this to help clear the blockage. 15 Figures 1 to 3 illustrate pipeline installations in accordance with the prior art and these prior art installations have been described above in the Background to the Invention. As these drawings have already been described they will not be described in the following detailed description of some example embodiments of the invention. 20 Figures 4 and 5 illustrate a pipe fitting in accordance with one embodiment of the invention. In the drawings the pipe fitting is indicated generally by the reference numeral 10. 25 The pipe fitting 10 comprises broadly a fitting body 12 having an internal surface defining a flow path 13 therethrough between an inlet 14 and an outlet 16. The fitting body 12 also defines an access opening 18 providing access into 16 the flow path 13. The fitting 10 also includes a closure 20 for removable mounting over the access opening 18 which includes a flow path defining formation 22 extending across the access opening 18. The flow path defining formation 22 has a concave curved or rounded surface for complementing the 5 surface of the surrounding pipe fitting body 12. The pipe fitting 10 also includes an access shaft wall 24 surrounding the access opening 18 and projecting away therefrom. The closure 20 includes a circumferential closure wall 26 that projects away 10 from the flow path defining formation 22. The closure wall 26 is configured to complement the access shaft wall 24 surrounding the access opening 18 to resist the passage of water between the access shaft wall 24 and the closure wall 26. 15 The fitting body 12 comprises first and second body components 30, 32 that can be releasably coupled to each other. The first body component 30 includes a curved pipe section that is configured to form a water seal that is positioned upstream of the access opening 18 along the flow path 13. The curved pipe section is conveniently configured in the form of a U-shape so that the flow path 20 within the section turns through about 180 degrees. The first body component 30 includes a reinforcing web or gusset 34 extending between adjacent legs of the U-shape to stiffen and strengthen the first body component 30. The second body component 32 is configured to define the access opening 18 25 and the access shaft wall 24 surrounding the access opening 18. The second body component 32 has a component outlet forming the outlet 16 of the fitting as a whole that extends orthogonally to a component inlet 36, and the access shaft wall 24 extends away from the flow path 13 in such a manner that it forms a linear extension of the flow path 13 adjacent to the inlet 14. This way the 17 access shaft wall 24 is vertically aligned with a leg of the water seal and this enhances the access that can be provided to the flow path of a pipeline through the access shaft wall 24. 5 The access shaft wall 24 surrounding the access opening 18 is substantially cylindrical and the closure wall 26 is also substantially cylindrical and sized to be received within the access shaft wall 24 with a working clearance. The closure wall 26 must be able to be displaced relative to the access shaft wall 24 so that the closure 20 can be removed from the fitting body 12 and returned to 10 the fitting body 12. However the closure wall 26 is also sized to resist the passage of water between the access shaft wall 24 and the closure wall 26. Correspondingly the access opening 18 is substantially circular when it is viewed in a plan view being substantially defined by an inner surface of the access shaft wall 24. 15 It should be noted that the access shaft wall 24 has a greater diameter than the diameter of the flow path 13. Typically it might have a diameter of about 150 to 180mm whereas the diameter of the pipe might typically be about 75 to 100mm. This is done to enhance the usefulness of the access that is provided 20 through the shaft wall 24 to the flow path 13 to clear a blockage in the flow path 13. That is it assists a user to obtain access to the flow path at points spaced from the access opening 18 during maintenance operations. The access shaft wall 24 defines a closure support in the form of a shoulder 40 25 on which the closure 20 can be located and supported extending across the access opening 18. In the illustrated embodiment the shoulder 40 extends in a radial direction inward from the access shaft wall 24 and extends fully circumferentially around the access shaft wall 24. In the illustrated embodiment 18 the closure 20 defines a peripheral rim 42 that is configured to rest on said shoulder 40 and support the closure 20 in position. The closure 20 includes a handle formation 44 projecting orthogonally away 5 from the flow path defining formation 22 for assisting a user to handle the closure 20. In the illustrated embodiment the handle formation 44 defines a socket 46 within which a handle extension can be received. The handle extension will typically be in the form of a section of pipe that is sized to be received within the socket 46 with a tight fit as will be described in more detail 10 below with reference to Figures 7 and 8. The access shaft wall 24 has a free end that is remote from the flow path defining formation 22 and the pipe fitting 10 includes a top cap 48 for mounting over the free end. Conveniently the access shaft wall 24 and the top cap 48 15 have complementary engagement formations for releasably engaging them to each other to close off the space defined by the access shaft wall 24. The pipe fitting 10 also includes a rubber sealing O-ring 49 for mounting on the inside of the top cap 48 for sealing off the top cap 48. 20 In use the pipe fitting 10 is mounted on a subterranean pipeline or pipeline installation having a gully trap and a gully riser, one example of which is illustrated in Figures 6 to 8. In the drawings the subterranean pipeline is referred to generally by the reference numeral 50 and the same reference numerals will be used to refer to the same components that are shown in 25 Figures 4 and 5 unless otherwise indicated. The pipeline installation 50 includes a pipe fitting 10 and is mounted adjacent an edge of a building such as a house received within the ground 51 spaced beneath the ground surface 52. The pipe fitting 10 includes a pipe section that 19 is a fitting body 12 defining an access opening 18 for facilitating access into the flow path 13 and a closure 20 that is removably mounted over the access opening 18 to close off the access opening 18. 5 The pipeline installation 50 also includes an access shaft 54 mounted on the pipe section 12 extending circumferentially around the access opening 18 and extending up to the ground surface 52. The access shaft 54 provides access into the flow path 13 within the pipe section 12 from the ground surface 52. The pipeline installation 50 also includes a water trap 56 that is a gully trap 10 adjacent to and upstream of the access opening 18. The water trap 56 comprises a curved pipe section that is configured to form a water seal that is positioned upstream of the access opening 18 along the flow path 13. The curved pipe section is conveniently configured in the form of a U-shape to turn through about 180 degrees 15 The pipeline installation 50 also includes a gully riser indicated generally by numeral 60 upstream of the water trap 56. The gully riser 60 comprises a vertically extending riser pipe section 62 opening into the flow path 13 within the pipeline 50 and extending from the pipeline to the ground surface 52 where it 20 opens up to the surrounding air. The gully riser 60 has a grate 64 mounted on an upper end thereof which opens to the atmosphere above the ground surface 52. Thus the gully riser 60 is permanently open to the surrounding air and this is why it has to be positioned upstream of the water trap 56. 25 The pipeline installation 50 includes an upstream section 66 that is upstream of the water trap 56 and the access opening 18, and a downstream section 68 that is downstream of the trap 56 and the access opening 18. Each of the components of the pipeline will now be described in more detail below. 20 In the illustrated embodiment the pipe fitting 10 described above with reference to Figures 2 to 4 defines the access opening 18, and forms the water trap and a lower region of the access shaft 54. In particular the pipe fitting 10 includes an access shaft wall 24 surrounding the access opening 18 and projecting away 5 from the flow path 13. Further the closure 20 includes a flow defining formation 22 and a closure wall 26 extending away from the flow path defining formation 22. The fitting body 12 comprises a first pipe component 30 defining the access opening 18 and a second pipe component 32 defining at least part of the water trap 56 which is positioned upstream of the access opening 18 on the 10 pipe fitting 10. The access shaft 54 comprises an access shaft pipe section 70 mounted on the access shaft wall 24 and extending from the access shaft wall 24 up to the ground surface 52. The access shaft pipe section may comprise two actual 15 pieces of pipe that are operatively coupled together, e.g. by means of a spigot socket connection or the like. In the illustrated embodiment the upper piece of pipe defines a socket which snugly receives the lower piece of pipe therein. The access shaft 54 further includes a top cap 74 mounted on an operatively upper end of the access shaft pipe section 70 that is adjacent to the ground surface 20 52. The top cap 74 has a circumferential skirt 76 and is removably mounted on the upper end of the access shaft pipe section 70 by means of complementary screw thread formations on the pipe section 70 and the skirt 76 of the top cap 74. The upper piece of pipe of pipe section 70 has the screw thread formation formed thereon and the lower piece of pipe is cut to size according to the 25 particular application. The closure 20 includes a flow path defining formation 22 having a curved or rounded concave flow path surface that is configured to complement the internal surface of the fitting body 12. The access shaft wall 24 defines a 30 shoulder 40 on which the closure 20 can be located and supported. The 21 closure 20 defines a peripheral rim 42 that is configured to rest on said shoulder 40 and support the closure 20 in position. The closure 20 also includes a handle formation projecting away from the flow path defining formation up into the access shaft 54 for assisting a user to handle the closure 5 20. The handle formation defines a socket 46 and a handle extension 80 is mounted in the socket 46 and extends up the shaft 54. This handle extension and the handle formation together form a handle 82 within the access shaft 54 that enables a person to lift and remove the closure 20 off the fitting body 12 from a position where their hands are close to the ground surface 52. 10 Conveniently the handle extension 80 can be formed by a section of pipe that is cut to the correct length. One end of the pipe is inserted into the socket 46 and thereby mounted to the handle formation 44. Fig 9 shows some detail of the closure 20 mounted on the pipe fitting body 12 15 and the section of pipe forming the handle extension 80 received within the socket 46 defined in the handle formation 44. In particular it shows how the closure 20 is mounted on the access shaft wall 24. It also shows how the flow path defining formation 22 maintains a smooth flow path along the pipeline generally in the region of the access opening 18 to maintain smooth flow 20 without excessive turbulence or pockets of stationary water. In use, if there is a blockage downstream of the water trap 56, a plumber can remove the top cap 74 of the access shaft 54 to provide access to an interior of the access shaft 54. The plumber can then use the handle 82 to lift the closure 25 20 off the access opening 18 on the pipe section. This opens up the flow path 13 within the pipeline 50 to the outside environment. A plumber can then insert a bendable rod 84 through the shaft 54 and into the flow path 13 in the manner shown in Fig 10. In particular the plumber can manipulate the rod 84 to direct it into the downstream pipe section 68 that is downstream of the access opening 30 18. This can be used to remove a blockage in this pipe section 68. The 22 closure 20 can then be replaced and the top cap 74 mounted once again on top of the access shaft 54. This maintenance operation can be carried out swiftly and effectively and no ground excavation is required. 5 An advantage of the pipe fitting described above with reference to the drawings is that it enables a plumber to access a blockage in a subterranean pipeline installation that is downstream of a gully trap. It would be difficult to reach such a blockage through the gully riser and without the access shaft it might be necessary to excavate down to the pipe. 10 Another advantage of the pipe fitting described above is that it preserves the overall shape of the flow path consistent with upstream and downstream sections of the pipe when it passes through the pipe fitting. This is due to the closure having a flow path defining formation that maintains smooth continuity 15 with upstream and downstream sections of the pipe without any abrupt changes. This way the pipe fitting isolates the access shaft from the flow path of the pipe so that the access shaft is not filled with water from the flow path in use. This helps to manage odour and also facilitates clean access through the access shaft to the flow path inside the pipe when maintenance activities are 20 carried out on the pipe, bearing in mind that waste water is passed through the pipeline. Yet another advantage of the pipeline installation is that the access shaft wall has a shoulder on which the closure can be located and supported in its correct 25 position on the pipe fitting. The closure 20 is not positively engaged with the access shaft wall 24 in such a way that it could get jammed and stuck in position mounted on the access shaft wall 24. 23 Yet another advantage of the pipe fitting is that it provides a suitably sized socket 46 in which a handle extension 80 can be inserted to provide a handle 82 extending from the pipe up to the ground surface. The handle extension can simply be cut from a section of pipe that is commonly available when plumbing 5 work is being carried out and which is commonly carried about by plumbers. Yet another advantage of the access shaft described above with reference to the drawings is that it has a greater diameter than that of the surrounding pipes. By the shaft entry formation having a diameter that is greater than 100mm, e.g. 10 120 to 180mm, it is easier for a plumber to manipulate an elongate member that is passed through the shaft and into the flow path to unblock a blockage within the pipeline. This enables a greater angle to be obtained when manipulating a bendable rod and this increases the ability to unblock blockages in the pipe through the access shaft. 15 Yet another advantage of the pipe fitting described above is that it includes a first pipe fitting component that is configured to form a water trap having a water seal. Thus the component is manufactured in this form by an injection moulding operation and does not need to be formed on site by using two ninety 20 degree elbows. This reduces the chances of leakage occurring in the bend of the water trap. Further the second pipe fitting component is designed so that the access shaft wall is vertically aligned with a downstream leg of the water trap and this increases the range of access provided to the flow path through the access shaft. 25 It will of course be realized that the above has been given only by way of illustrative example of the invention and that all such modifications and variations thereto, as would be apparent to persons skilled in the art, are 24 deemed to fall within the broad scope and ambit of the invention as is herein set forth. 25

Claims (28)

1. A pipe fitting for a subterranean pipeline installation, including: a fitting body defining an inlet and an outlet and having an internal surface 5 defining a flow path extending from the inlet to the outlet, the fitting body further defining an access opening providing access into the flow path; a closure for removable mounting over the access opening to close off the access opening, wherein the closure includes a flow path defining formation extending, in use, across the access opening and defining part of the flow path 10 through the fitting body; and an access shaft wall surrounding the access opening and projecting away from the access opening to define a free end of the access shaft wall remote from the access opening, the free end suitable for receiving a top cap remote from the flow path defining formation and the flow path. 15

2. A pipe fitting according to claim 1, wherein the flow path defining formation has a rounded concave surface that is configured to complement the internal surface of the fitting body. 20

3. A pipe fitting according to claim 1 or claim 2, wherein the closure includes a circumferential closure wall that projects away from the flow path defining formation, and the closure wall is configured to complement the access shaft wall surrounding the access opening to resist the passage of water between the access shaft wall and the closure wall. 25

4. A pipe fitting according to claim 3, wherein the access shaft wall surrounding the access opening has a substantially cylindrical configuration and the closure wall has a complementary substantially cylindrical configuration such that it is receivable within the access shaft wall with a working clearance. 26

5. A pipe fitting according to any one of claims 1 to 4, wherein the fitting body includes a curved pipe section that is configured to turn through at least 160 degrees to form a water seal that is positioned upstream of the access 5 opening along the flow path.

6. A pipe fitting according to claim 5, wherein the fitting body comprises first and second body components that can be releasably coupled to each other, and the first body component includes the curved pipe section and the second 10 body component is configured to form the access shaft wall surrounding the access opening.

7. A pipe fitting according to any one of claims 1 to 6, wherein the access shaft wall defines a closure support on which the closure can be located in 15 position extending across the access opening and on which the closure can be supported, and the closure includes a mounting formation for resting on the closure support.

8. A pipe fitting according to claim 7, wherein the closure support 20 comprises a shoulder that extends radially in from the access shaft wall and wherein the closure defines a peripheral rim that is configured to rest on said shoulder and support the closure in position.

9. A pipe fitting according to any one of claims 1 to 8, wherein the closure 25 includes a handle formation projecting away from the flow path defining formation for assisting a user to handle the closure, and wherein the handle formation defines a socket for receiving a handle extension. 27

10. A pipe fitting according to any one of claims 1 to 9, wherein the pipe fitting includes a top cap that can be mounted on the free end of the access shaft. 5

11. A water trap arrangement for a subterranean pipeline installation comprising: a trap body configured to form a water seal when water is passed there through, the trap body defining an inlet for coupling to an upstream conduit, an outlet for coupling to a downstream conduit and a flow path extending from the 10 inlet to the outlet, the trap body further defining an access opening providing access from outside the trap body into the flow path; an access shaft wall surrounding the access opening and projecting away from the trap body for forming part of an access shaft which has a free end, remote from the access opening and the flow path, suitable for receiving a top cap; and 15 a closure removably mountable over the access opening for closing off the flow path, the closure including a flow path defining formation extending across the access opening.

12. A water trap arrangement according to claim 11, wherein the closure 20 further includes a circumferential closure wall that projects away from the flow path defining formation, and the closure wall is configured to complement the access shaft wall surrounding the access opening to resist the passage of water between the access shaft wall and the closure wall, and wherein the flow path defining formation has a flow path surface having a rounded concave 25 surface that is configured to complement an internal surface of the trap body.

13. A water trap arrangement according to claim 12, wherein the trap body includes a curved pipe section that is configured to form the water seal. 28

14. A water trap arrangement according to claim 13, wherein the trap body comprises first and second body components that can be releasably coupled to each other, wherein the first body component includes the curved pipe section configured to form the water seal and the second body component is 5 configured to define the access opening and the access wall surrounding the access opening, and wherein the angle at which the first and second components are coupled to each other can be adjusted during installation to suit installation requirements. 10

15. A subterranean pipeline installation received within the ground spaced beneath the surface of the ground comprising: a pipe defining an inlet and an outlet and a flow path extending from the inlet to the outlet, the pipe further defining an access opening providing access into the flow path, and the pipe further defining a trap body for forming a water trap; 15 a closure that is mounted in removable fashion across the access opening; and an access shaft mounted on the pipe extending circumferentially around the access opening and extending away from the access opening up to the ground surface at a position remote from the flow path, whereby to provide access into the flow path within the trap body from the ground surface. 20

16. A subterranean pipeline installation according to claim 15, wherein the trap body is provided upstream of the access opening.

17. A subterranean pipeline installation according to claim 16, wherein the 25 trap body is formed by a section of the pipe that is configured to form a water seal having a suitable height. 29

18. A subterranean pipeline installation according to any one of claims 15 to 17, wherein the pipe includes a first component forming at least part of the trap body and a second component forming the access opening. 5

19. A subterranean pipeline installation according to any one of claims 15 to 18, including a gully riser upstream of the trap body, the gully riser comprising a vertically extending riser pipe section opening into the flow path and extending from the pipe to the ground surface where it opens to the air. 10

20. A subterranean pipeline installation according to any one of claims 15 to 18, wherein the access shaft comprises an access shaft wall surrounding the access opening and projecting away from the trap body and an access shaft pipe section extending from the access shaft wall to the ground surface, and a top cap removably mounted on an upper end of the access shaft pipe section 15 adjacent to the ground surface.

21. A subterranean pipeline installation according to any one of claims 15 to 20, wherein the closure includes a flow path defining formation having a concave flow path surface extending across the access opening that is 20 configured to complement the internal surface of the pipe, and a handle projecting away from the flow path within the access shaft.

22. A method of providing access to a subterranean pipeline received in the ground spaced beneath the ground surface, the pipeline defining an inlet and 25 an outlet and a flow path extending from the inlet to the outlet, the pipeline having a water trap downstream of the inlet, including: providing an access opening in the pipeline, distinct from the inlet and the outlet, to facilitate access to the flow path therethrough and a closure that is removably mounted across the access opening; and 30 forming an access shaft from the access opening to the ground surface, the access shaft being distinct from the inlet and the outlet, whereby to enable a person to gain access to the flow path from the ground surface without having to carry out any excavation. 5

23. A method of providing access to a subterranean pipeline received in the ground according to claim 22, including mounting a removable top cap on an upper end of the access shaft whereby to close off the access shaft. 10

24. A method of providing access to a subterranean pipeline received in the ground according to claim 22 or claim 23, including closing off the access opening to resist the passage of water through the access opening when water is flowing through the pipeline. 15

25. A method of providing access to a subterranean pipeline received in the ground according to claim 24, wherein the closure forms a flow path defining formation having a rounded concave surface that is configured to complement an internal surface of the pipeline, and the method includes directing water smoothly across the flow path defining formation past the access opening such 20 that the flow pattern of the water is substantially the same as in the rest of the flow path.

26. A pipe fitting substantially as herein described in the detailed description of the invention with reference to at least Figures 4 and 5. 25

27. A combination of a gully trap and an access opening and access shaft providing access into a flow path of a pipe substantially as herein described in the detailed description of the invention with reference to Figures 4 to 8. 31

28. A subterranean pipeline installation received within the ground spaced beneath the surface of the ground substantially as herein described in the detailed description of the invention with reference to Figures 4 to 8. 32