Abstract:
The following operations are carried out:
   a) digging an exploration hole ( 8 ),   b) using a branch connection ( 10 ) which includes a main plate ( 12 ) and a fixing plate ( 22 ) which are held together,   c) using a device ( 1 ) which has:
       a support ( 36 )   retaining elements, ( 38 ) which are connected to the support ( 36 ),   a foot ( 40 ) which is articulated so as to rotate relative to the support ( 36 ),   actuation elements ( 44 ) for displacing the foot ( 40 ) between an introduction position and a pressing position,   
       d) placing the foot ( 40 ) in an introduction position,   e) retaining the main plate ( 12 ) on the device ( 1 ),   f) positioning the support surface ( 14 ) of the main plate ( 12 ) against the pipeline ( 2 ),   g) bringing the foot ( 40 ) into a pressing position,   h) fixing the main plate ( 12 ) and the fixing plate ( 22 ) together around the pipeline ( 2 ).

Description:
The invention relates to a method for positioning, from ground level, a branch connection on a pipeline and a device intended for this purpose. 
     BACKGROUND OF THE INVENTION 
     More precisely, the device is used to position, from the upper portion of an exploration hole which affords access to the pipeline, branch connections on main pipelines in which a fluid, such as in particular gas or water, circulates in order to supply in particular a new residence. 
     DESCRIPTION OF THE RELATED ART 
     A positioning device is already known as described in FR-A-2 714 710, in which the following operations are carried out:
     digging an exploration hole from the ground in order to open up a portion of the pipeline,   using a branch connection which comprises a plate which has a substantially semi-cylindrical support surface having a circular cross-section defined by an extension axis,   using a device which comprises:
       a support   retaining means which are connected to the support in order to retain the plate,   a foot which is articulated so as to rotate relative to the support about an axis of rotation,   actuation means for displacing the foot in rotation relative to the support between an introduction position and a pressing position,   
       placing the foot in an introduction position,   retaining the main plate on the device using means for retaining in a position in which the extension axis of the support surface is substantially parallel with the first axis of rotation,   positioning the support surface of the plate against the pipeline,   bringing the foot into a pressing position by operating the actuation means in order to press the plate against the pipeline,   welding the plate to the pipeline,   removing the positioning device, placing the branch connection and the pipeline in communication, removing the positioning device and refilling the exploration hole.   

     Of course, this method allows a high standard of positioning to be achieved for the branch connections. However, it does require the use of a positioning tool which is heavy, large and costly. 
     SUMMARY OF THE INVENTION 
     The invention is intended to facilitate and reduce the cost of positioning a branch connection. 
     According to the invention, the following operations are carried out:
     a) digging an exploration hole from the ground in order to open up a portion of the pipeline,   b) using a branch connection which comprises a main plate and a fixing plate, the main plate and the fixing plate each having a substantially semi-cylindrical support surface which has a circular cross-section defined by an extension axis, a retaining edge and a free edge which extends parallel with the extension axis thereof at one side and the other of the support surface, the extension axes being substantially parallel with each other, the main plate and the fixing plate being held together by the retaining edge thereof, whilst the free edges thereof can be moved relative to each other by means of rotation about an axis which is substantially parallel with the extension axes,   c) using a device which comprises:
       a support,   retaining means which are connected to the support in order to retain the main plate,   a foot which is articulated so as to rotate relative to the support about a first axis of rotation,   actuation means for displacing the foot in rotation relative to the support between an introduction position and a pressing position,   
       d) placing the foot in an introduction position,   e) retaining the main plate on the device using means for retaining in a position in which the extension axes of the support surfaces are substantially parallel with the first axis of rotation and the fixing plate substantially comes into contact with the foot,   f) positioning the support surface of the main plate against the pipeline,   g) bringing the foot into a pressing position by operating the actuation means in order to press the pipeline between the main plate and the fixing plate,   h) fixing the main plate and the fixing plate together around the pipeline,   i) welding the main plate to the pipeline, removing the positioning device, placing the branch connection and the pipeline in communication and refilling the exploration hole.   

     The pressure to be applied between the main plate and the pipeline in order to weld the main plate is thus no longer produced by the pressure applied by the positioning tool, but instead by the main plate being fixed to the fixing plate. The positioning device consequently has to apply less force and it can be less robust whilst allowing an excellent standard of positioning to be maintained. The positioning device is thus lighter and smaller. The handling thereof is therefore more simple, which causes the user to become less tired and allows the branch connections to be positioned more quickly and smaller exploration holes to be made. The time saving which is thus brought about compensates to a large extent for the time required to fix the main plate and the fixing plate together. 
     The presence of the fixing plate does not increase the time required for positioning the branch connection in so far as it is connected to the main plate and is automatically positioned opposite the main plate when the foot is displaced. 
     Furthermore, it is not necessary to retain the positioning device in position in order to press the main plate onto the pipeline for the entire duration of the electro-welding operation and cooling of the main plate after welding. The positioning device can therefore be removed more quickly in order to position another branch connection. The number of positioning devices required for positioning a given number of branch connections is thus reduced, which results in an additional saving. 
     Advantageously, during step g), the free edges of the main plate and the fixing plate are brought close to each other and, during step h), the free edges of the main plate and the fixing plate are screwed together. Fixing the main plate and the fixing plate is thus simplified. Furthermore, it allows high levels of pressure to be applied between the main plate and the pipeline. 
     The invention further relates to a device. According to the invention, the device comprises:
     a support,   retaining means which are connected to the support in order to retain the main plate,   a foot which is articulated so as to rotate relative to the support about a first axis of rotation,   actuation means for displacing the foot in rotation relative to the support between an introduction position and a pressing position,   a support element,   means for articulating in rotation about a second axis of rotation which is substantially parallel with the first axis of articulation, said articulation means being arranged between the support element and the foot, said support element being intended to come into contact with the fixing plate in order to bring it into contact with the pipeline.   

     The fixing plate is thus precisely guided relative to the main plate and is positioned precisely opposite the main plate when the foot is displaced. 
     In order to allow the support element to be automatically positioned by means of rotation about the second axis of rotation in order to provide the most effective guiding for the fixing plate, according to the invention, the support element comprises a base, a first skid-like member which has a first support surface and a second skid-like member which has a second support surface, the support surfaces defining a divergent shape, the skid-like members being connected to the base, the base pivoting relative to the foot about the second axis of rotation, by means of the articulation means. 
     It is thus not necessary to provide means for controlling the rotation of the support element relative to the foot by means of rotation about the second axis of rotation in accordance with the rotation of the foot relative to the support about the first axis of rotation, since this is carried out automatically in an optimal manner. 
     The two skid-like members allow two contact surfaces to be provided on the fixing plate spaced from each other, which promotes the guiding action. 
     According to another feature in accordance with the invention, the first skid-like member is mounted so as to pivot relative to the base about a third axis of rotation which is substantially parallel with the first axis of rotation. The contact surface and the relative sliding between the first skid-like member and the fixing plate are increased, which further improves the bringing about of satisfactory positioning of the fixing plate relative to the main plate. 
     So that these advantages are even more evident, according to the invention, the second skid-like member is mounted so as to pivot on the base about a fourth axis of rotation which is substantially parallel with the first axis of rotation. 
     In order to be able to adapt to a wide range of branch connections, which correspond in particular to various pipeline diameters, the support element comprises adjustment means for translating the first skid-like member radially relative to the second axis of articulation. 
     According to a feature in accordance with the invention, the device further comprises means for limiting the extent of the rotation movements of the support element relative to the foot. 
     The extent of useful rotation of the support element relative to the foot whilst the foot pivots relative to the support is not very great (a few tens of degrees at the very most). Consequently, by limiting the rotation of the support element relative to the foot to movements of relatively small extent, it is made more efficient in terms of guiding the fixing plate and easier to handle. 
     In order to be able to position various models of branch connection and in particular to be able to position branch connections on pipelines of different diameters, according to the invention, the first axis of rotation comprises a plurality of adjustment positions on the foot. 
     And in particular, according to the invention, an assembly which comprises, in addition to the device, a branch connection comprising a main plate and a fixing plate is as in the pressing position:
     the main plate and the fixing plate each have a semi-cylindrical support surface having a circular cross-section defined by an extension axis, and the extension axis of the fixing plate is substantially aligned with the extension axis of the main plate,   the extension axis of the main plate and the extension axis of the fixing plate extend substantially in a plane defined by the first axis of rotation and the second axis of rotation.   

     When the device is close to the pressing position, if the displacement of the support element relative to the pipeline is broken down into a radial component and a tangential component, it can thus be seen that the radial component is much larger than the tangential component, the corresponding forces being inversely proportional; this allows the force produced by the actuation means to be reduced for a given pressure applied to the pipeline, further improves the positioning of the fixing plate and reduces the impact when the fixing plate comes into contact with the pipeline. The device can therefore be more robust, less costly and the standard of positioning can be improved. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention will be appreciated even more clearly from the following description, given with reference to the appended drawings, in which: 
         FIG. 1  is a schematic illustration of a first method step for positioning a branch connection on a pipeline according to the invention, 
         FIG. 2  illustrates a second method step, drawn to an enlarged scale, 
         FIG. 3  illustrates a third method step, also drawn to an enlarged scale, 
         FIG. 4  illustrates the second method step according to  FIG. 2 , with a pipeline having a smaller diameter, 
         FIG. 5  illustrates the third method step for positioning a branch connection on the pipeline of  FIG. 4 , 
         FIG. 6  is a superimposed view of the third method step according to  FIGS. 3 and 5 . 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The Figures illustrate a device  1  which substantially comprises a support  36 , a foot  40  which is articulated so as to rotate relative to the support  36  about a first axis of rotation  42  (perpendicular relative to the plane of the Figures), a jack  44  and a support element  50 . 
     The jack  44  extends between the support  36  and the foot  40  in order to displace the foot between an introduction position illustrated in  FIG. 1  and a pressing position illustrated in  FIGS. 3 ,  5  and  6 . 
     The device  1  further comprises an adaptor  38  which is connected to the support  36  in a releasable manner and which is screwed to the end of the shaft  78  of a main plate  12  of a connection of a branch connection  10 . 
     The main plate  12  has a substantially semi-cylindrical support surface  14  which has a circular cross-section having an extension axis  16 , a retaining edge  18  and a free edge  20 . The retaining edge  18  and the free edge  20  are arranged at one side and the other of the support surface  14  and extend along the extension axis  16 . The shaft  78  extends substantially perpendicularly relative to the extension axis  16  and has an inner passage which opens in the support surface  14 , substantially perpendicularly relative to the surface. The inner passage communicates with a branch pipe  4  which is intended to be connected to the new branching point. 
     The branch connection  10  further comprises a fixing plate  22 . The fixing plate  22  has a substantially semi-cylindrical support surface  24  and outer surface  25  which have a circular cross-section having an extension axis  26 , a retaining edge  28  and a free edge  30 . The support surface  24  of the fixing plate substantially complements the support surface  14  of the main plate. The retaining edge  28  and the free edge  30  are arranged at one side and the other of the support surface  24  and the outer surface  25 . They extend substantially along the extension axis  26 . 
     The fixing plate  22  is articulated so as to rotate relative to the main plate  12  about an axis of articulation  32  by means of an articulation  34  of the cap type, which joins together the retaining edge  18  of the main plate and the retaining edge  28  of the fixing plate. The axis of articulation  32  is substantially parallel with the extension directions  16 ,  26 . 
     In order to position a branch connection  10  on a pipeline  2 , the branch connection  10  is connected to the branch pipe  4 , the device  1  is placed in the introduction position, and the branch connection  10  is retained on the device  1 , by means of the adapter  38 , in such a position that the extension axes  16 ,  26  and the axis of articulation  32  are arranged substantially parallel with the first axis of rotation  42 . The outer surface  25  of the lower plate  22  then substantially comes into contact with the support element  50 . 
     As illustrated more precisely in  FIG. 6 , the support element  50  comprises a base  56 , a first skid-like member  58  and a second skid-like member  60 . The base  56  comprises a transverse element  82 , a first intermediate element  84  and a second intermediate element  86 . The transverse element  82  is articulated so as to rotate relative to the foot  40  by means of a rod  52  which is retained in the foot  40  and which extends through an opening made in the transverse element  82 . This rod  52  extends along a second axis of rotation  54  (perpendicular relative to the plane of the Figures) substantially parallel with the first axis of rotation  42 . Stops  76  are provided on the foot  40  in order to limit the extent of rotation of the transverse element  82  relative to the foot  40 . 
     The first skid-like member  58  has a concave support surface  62 . It is mounted so as to pivot about a third axis of rotation  66 , substantially parallel with the first axis of rotation  42 , on the first intermediate element  84 . Wedges  72  are arranged on the first skid-like member  58  at the side opposite the support surface  62 , close to the third axis of rotation  66 , in order to limit the extent of the rotation of the first skid-like member relative to the first intermediate element  84 . 
     The first intermediate element  84  is fixed in a releasable manner to the transverse element  82 . It can be fixed to the transverse element  82  at various adjustment points  70  which are arranged in a radial direction relative to the second axis of rotation  54  in order to be able to modify the distance d between the third axis of rotation  66  and the second axis of rotation  54 . 
     The second skid-like member  60  has a concave support surface  64 . It is mounted so as to pivot about a fourth axis of rotation  68 , substantially parallel with the first axis of rotation  42 , on the second intermediate element  86 . Wedges  74  are arranged on the second skid-like member  60 , at the side opposite the support surface  64 , close to the fourth axis of rotation  68 , in order to limit the extent of the rotation of the second skid-like member  60  relative to the second intermediate element  86 . 
     The second intermediate element  86  is mounted so as to pivot about a fifth axis of rotation  80 , substantially parallel with the first axis of rotation  42 , on the transverse element  82 . Stops  88  are provided on the foot  40  in order to guide the second intermediate element  86  relative to the foot  40  and limit the extent of the rotation thereof about the fifth axis of rotation  80 . 
     The distance d between the third axis of rotation  66  and the second axis of rotation  54  is adjusted in accordance with the diameter of the pipeline  2 . 
     The ability of the support element  50  to move in rotation about the second axis of rotation  54 , the third axis of rotation  66 , the fourth axis of rotation  68  and the fifth axis of rotation  80 , as well as the various means  76 ,  72 ,  74 ,  88  for limiting the extent of rotation about these axes of rotation allow the support surfaces  62 ,  64  to be effectively positioned on the outer surface  25  of the fixing plate  22 . These support surfaces  62 ,  64  define a divergent shape. 
     After having dug an exploration hole  8  from the ground  6  in order to open up a portion of the pipeline  2 , the device  1 , with the main plate  12  retained on the support  36  by means of the adaptor  38 , is lowered into the exploration hole  8 , with the foot  40  in the introduction position. 
     The support surface  14  of the main plate  12  is positioned against the pipeline  2 , the foot  40  is then brought into a pressing position by means of rotation about the first axis of rotation  42 , with the jack  44  being operated. 
     The first skid-like member  58  and the second skid-like member  60  automatically move in order to guide the outer surface  25  of the fixing plate  22  most effectively in terms of rotation thereof about the axis of articulation  32 , until the free edge  30  thereof is moved opposite the free edge  20  of the main plate  12  and they press the pipeline  2  between the main plate  12  and the fixing plate  22 . 
       FIG. 6  illustrates the positioning device with the foot  40  in the pressing position. The pipeline  2  illustrated in  FIGS. 2 and 3  is illustrated with solid lines in this  FIG. 6 , whilst the pipeline  2  which has a smaller diameter and which is illustrated in  FIGS. 4 and 5  is illustrated with dot-dash lines (mixed) in this  FIG. 6 . 
     As illustrated, the first axis of rotation  42  has a plurality of adjustment positions  90  on the foot  40  in order to adapt to the different diameters of pipeline. 
     The position of the support  36  and the jack  44  in the case of the pipeline  2  illustrated in  FIGS. 4 and 5  is illustrated with dot-dash lines (mixed). 
     When the foot  40  is in a pressing position, the extension axes  16 ,  26  of the main plate  12  and the fixing plate  22  are substantially aligned and extend close to the plane P which extends through the first axis of rotation  42  and the second axis of rotation  54 , regardless of the diameter of the pipeline  2 . 
     The free edge  20  of the main plate  12  is then fixed to the free edge of the fixing plate  22  using fixing screws  46 . 
     The foot  40  is then brought into an introduction position and removed from the exploration hole  8 , with the adaptor  38  being uncoupled from the support  36 . 
     The adapter is then removed by being unscrewed from the end of the shaft  78  of the main plate. 
     The main plate  12  is then welded onto the pipeline by means of an electrical resistor (not shown) embedded in the main plate  12  close to the support surface  14  and electrical connectors  48 . The branch pipe  4  is then placed in communication with the pipeline  2  via the shaft  78  by the pipeline  2  being drilled, advantageously by means of a perforator which is integrated in the shaft  78 . Finally, the exploration hole  8  is refilled. 
     Advantageously, the pipeline  2  has a diameter of substantially between 50 millimetres and 250 millimetres, the branch connection  10  and the pipeline being of plastics material, such as polyethylene. 
     Of course, the invention is by no means limited to the construction which has been described above by way of non-limiting example. Provision could thus be made for the fixing plate  22  to be relatively flexible about a flexion direction which is substantially parallel with the extension axis  26  thereof and for the articulation  34  between the main plate and the fixing plate to be dispensed with. The axis of articulation  32  between the main plate  12  and the fixing plate  22  would then be defined by said flexion direction.