Abstract:
The invention relates to a pipe ( 2 ) including:—a tubular element ( 3 ) defining an inner longitudinal passage ( 5 );—a protective element ( 6 ) attached onto the outer surface of the tubular element ( 3 ) and extending longitudinally in relation to the tubular element ( 3 ), the protective element ( 6 ) and the tubular element ( 3 ) defining a longitudinal receiving passage ( 9 ); and—a detection element ( 12 ) that is detectable with a detection device. The detection element ( 12 ) is linear and includes an electrically conductive core ( 13 ) and an electrically insulating sheath ( 14 ) that covers the electrically conductive core ( 13 ). The detection element ( 12 ) extends longitudinally into the receiving passage ( 9 ) and is movably mounted longitudinally in relation to the tubular element ( 3 ) and the protective element ( 6 ).

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is a National Stage of PCT Application No. PCT/FR2016/050334 filed on Feb. 12, 2016, which claims priority to French Patent Application No. 15/51466 filed on Feb. 20, 2015, the contents each of which are incorporated herein by reference thereto. 
     
    
     TECHNICAL FIELD 
       [0002]    The present invention concerns a piping equipped with a sensing member, a method for manufacturing such a piping and a method for sensing such a piping. 
       BACKGROUND 
       [0003]    It is important, for saving time and costs but also for safety, to be able to sense the presence of a piping, and in particular a fluid flow piping, and to locate it accurately, without digging into the ground, nor destroying structures, during subsequent works. 
         [0004]    Several methods can be used to carry out the sensing of buried piping. 
         [0005]    The electromagnetic sensing is the most used method. This electromagnetic sensing may be performed using an electromagnetic sensor comprising in a known manner a transmitter, such as a current generator, and a receiver. In this case, the electromagnetic sensing is carried out on the one hand by injecting, using the transmitter of the electromagnetic sensor, an electrical signal, which produces an electromagnetic field, into an electrically conductive sensing member associated to the piping to be identified and disposed along the path of said piping, through connection housings installed along the piping in order to serve as injection points of the electrical signal, and on the other hand, by capturing using the receiver of the electromagnetic sensor, the electromagnetic field created by the alternating current circulating in the sensing member. 
         [0006]    In a manner known per se, the sensing member is covered by a cylindrical sheath made of an electrically insulating material and is fastened on the piping to be identified using fastening means, such as for example, circlips, self-gripping strips, or adhesive strips. 
         [0007]    Such fastening means enable, mostly, a displacement of the sensing member on the outer surface of the piping to be identified, and this in particular when the piping is of circular section. These movements of the sensing member may lead to an inaccurate positioning of the sensing member, and therefore to an inaccurate and difficult sensing of the associated piping. 
         [0008]    However, taking into account the drastic evolution of the accuracy standards in terms of sensing of buried piping, it is necessary to ensure an optimum positioning of the sensing member, including after burial of the associated piping. 
       BRIEF SUMMARY 
       [0009]    The present invention aims to overcome these drawbacks. 
         [0010]    The technical problem underlying the invention therefore consists in providing a piping which is of simple and economical structure, while ensuring an easy and optimal positioning of the sensing member and therefore an easy sensing of the piping. 
         [0011]    To this end, the present invention concerns a piping intended to be buried, comprising:
       a tubular member delimiting a longitudinal inner passage,   a protective strip extending longitudinally relative to the tubular member, the protective strip comprising two longitudinal lateral portions fastened on the outer surface of the tubular member, the protective strip and the tubular member delimiting a longitudinal receiving passage, and   a sensing member intended to be sensed with a sensing device, the sensing member being linear and comprising an electrically conductive core and an electrically insulating sheath covering the electrically conductive core, the sensing member extending longitudinally in the receiving passage and being movably mounted longitudinally relative to the tubular member and the protective strip, the two longitudinal lateral portions of the protective strip extending on either side of the sensing member.       
 
         [0015]    Such a configuration of the piping, and more particularly the disposition of the sensing member in the longitudinal receiving passage partially delimited by the tubular member, ensures an optimal and stable final positioning of the sensing member along the upper generatrix of the associated piping, including after burial of the associated piping. 
         [0016]    Thus, the configuration of the piping according to the present invention ensures an easy and accurate electromagnetic sensing of the piping. 
         [0017]    Furthermore, the fact that the sensing member is movably mounted longitudinally in the receiving passage allows avoiding a rupture, and in particular a tearing, of the protective strip when the piping is wound on a crown or a reel. Thereby, the configuration of the piping according to the present invention allows holding the sensing member in place during the unwinding and the laying of the piping in a trench intended to receive said piping. 
         [0018]    Furthermore, such mounting of the sensing member allows an easy access to one end portion of the sensing member by tearing one end portion of the protective strip using, for example, a simple tool such as a screwdriver or the like, for the purpose of connecting the sensing member to a sensing member of an adjacent piping, or to a connection member of a sensing terminal. 
         [0019]    The configuration of the piping according to the present invention, and in particular the fact that it is pre-equipped with the sensing member, allows on the one hand reducing the costs and the time of laying, and on the other hand facilitating the laying thereof in particular in a narrow trench, and also using a trencher. These dispositions further allow ensuring an easy laying of the piping in sinking and in directional drilling. 
         [0020]    In the present patent application, the term &lt;&lt;piping&gt;&gt; means any pipe, tube and sheath intended for the long-distance transport or the distribution of a liquid, gas, electricity, or light, or an empty sheath placed ready for further use. 
         [0021]    According to an embodiment of the invention, the longitudinal inner passage is intended for the flow of a fluid, or for the passage of at least one optical fiber and/or at least one electrical cable. 
         [0022]    According to an embodiment of the invention, the tubular member is flexible. 
         [0023]    The piping may further have one or more of the following feature(s), taken alone or in combination. 
         [0024]    According to an embodiment of the invention, the sensing member extends along the upper generatrix of the tubular member. 
         [0025]    According to an embodiment of the invention, the longitudinal receiving passage extends substantially over the entire length of the tubular member. 
         [0026]    According to an embodiment of the invention, the longitudinal receiving passage includes a first and a second passage openings disposed respectively substantially at the first and second ends of the tubular member. 
         [0027]    According to an embodiment of the invention, the sensing member has a cross-section smaller than the cross-section of the receiving passage. 
         [0028]    According to an embodiment of the invention, the two longitudinal lateral portions of the protective strip are each fastened on the outer surface of the tubular member by ultrasonic welding. 
         [0029]    According to an embodiment of the invention, the protective strip is made of a synthetic material, and for example of a polymeric material. The protective strip might be made of a non-woven synthetic material comprising polyethylene fibers, such as high-density polyethylene fibers, and for example of Tyvek (registered trademark). The protective strip might be also made of polypropylene. 
         [0030]    According to an embodiment of the invention, the sensing member is an electrically conductive wire. 
         [0031]    According to an embodiment of the invention, the tubular member includes a tubular wall delimiting the longitudinal inner passage, the two lateral portions of the protective strip being fastened on the outer surface of the tubular wall. For example, the tubular wall of the tubular member may be ringed or have a smooth outer surface. 
         [0032]    According to an embodiment of the invention, the electrically insulating sheath is made of polyethylene or polypropylene. 
         [0033]    According to an embodiment of the invention, the sensing member has a rectangular, oval or circular section. 
         [0034]    According to an embodiment of the invention, the tubular member is made of polyethylene. 
         [0035]    The present invention further concerns an installation comprising:
       at least one piping according to the invention, and   at least one connection housing including at least one connection member electrically connected to the sensing member of the at least one piping.       
 
         [0038]    According to an embodiment of the invention, the installation includes at least one sensing terminal including the at least one connection housing. The sensing terminal may be, for example, in accordance with those described in the documents FR2982889, FR3006061 and FR2997195. The sensing terminal may be, for example, a curb box. 
         [0039]    According to an embodiment of the invention, the sensing terminal includes an electrically conductive portion electrically connected to the connection member and accessible from the outside of a structure on which the sensing terminal is fastened. The term &lt;&lt;structure&gt;&gt; in particular means a sidewalk, a pavement, a brick wall, an access hatch to a technical gallery, a manhole cover or a manhole. 
         [0040]    According to an embodiment of the invention, the piping is a fluid flow piping or a protective piping for optical fiber and/or electrical cable, or else for a fluid flow conduit. 
         [0041]    The present invention also concerns a method for manufacturing a piping according to the invention, comprising the steps consisting in:
       extruding the tubular member,   laying the sensing member longitudinally on the outer surface of the tubular member,   laying the protective strip longitudinally on the outer surface of the tubular member so as to cover the sensing member, and   fastening the longitudinal lateral portions of the protective strip on the outer surface of the tubular member so as to form the longitudinal receiving passage.       
 
         [0046]    According to an embodiment of the manufacturing method, said manufacturing method comprises a step of cooling the tubular member carried out between the step of extruding the tubular member and the step of laying the sensing member. 
         [0047]    According to an embodiment of the manufacturing method, the step of laying the protective strip is carried out continuously. 
         [0048]    According to an embodiment of the manufacturing method, the step of fastening the protective strip is carried out continuously. 
         [0049]    According to an embodiment of the manufacturing method, the step of fastening the protective strip is carried out at the end of the manufacturing cycle of the tubular member. Advantageously, the laying steps are also carried out at the end of the manufacturing cycle of the tubular member. 
         [0050]    According to an embodiment of the manufacturing method, the step of laying the sensing member comprises a step consisting in unwinding the sensing member from a sensing member coil. 
         [0051]    According to an embodiment of the manufacturing method, the step of laying the protective strip comprises a step consisting in unwinding the protective strip from a protective strip coil. 
         [0052]    According to an embodiment of the manufacturing method, the step of laying the protective strip consists in laying the longitudinal lateral portions of the protective strip on either side of the sensing member. 
         [0053]    According to an embodiment of the manufacturing method, said manufacturing method comprises a step consisting in displacing the tubular member longitudinally, that is to say parallel to the direction of extension thereof, and for example along the extrusion direction thereof, during the steps of laying the sensing member and the protective strip and during the step of fastening the protective strip. 
         [0054]    According to an embodiment of the manufacturing method, the fastening step consists in fastening the longitudinal lateral portions of the protective strip on the outer surface of the tubular member by ultrasonic welding. 
         [0055]    According to an embodiment of the manufacturing method, the fastening step is carried out using a sonotrode. 
         [0056]    According to an embodiment of the manufacturing method, the sonotrode has a resonance frequency comprised between 20 kHz and 70 kHz, and for example of 20, 30, 35, 40 or 70 kHz. 
         [0057]    According to an embodiment of the manufacturing method, the sonotrode has a vibration amplitude comprised between 10 and 120 micrometers. 
         [0058]    Furthermore, the present invention concerns a method for sensing a buried piping according to the invention, comprising the steps consisting in:
       injecting an electrical signal into the sensing member,   sensing the electromagnetic field generated by the sensing member.       
 
         [0061]    The injection step is advantageously carried out using an electrical signal generator, such as a current generator. According to an embodiment of the sensing method, the injection step comprises a step consisting in electrically connecting the electrical signal generator to the sensing member, and for example, electrically connecting the electrical signal generator to an electrically conductive portion of a sensing terminal, said electrically conductive portion being electrically connected to the sensing member and being accessible from outside a structure on which the sensing terminal is fastened. 
         [0062]    The sensing step is advantageously carried out using an electromagnetic sensor. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0063]    In any case, the invention will be well understood using the following description with reference to the appended schematic drawing representing, by way of non-limiting example, an embodiment of this piping. 
           [0064]      FIG. 1  is a partial perspective view of a piping according to the invention. 
           [0065]      FIG. 2  is a cross-sectional view of the piping of  FIG. 1 . 
           [0066]      FIG. 3  is a schematic view of the piping of  FIG. 1  during manufacture. 
           [0067]      FIG. 4  is a schematic view of an installation comprising a piping according to  FIG. 1  and a sensing terminal. 
       
    
    
     DETAILED DESCRIPTION 
       [0068]      FIGS. 1 and 2  show a piping  2  intended to be buried. The piping  2  may be for example a fluid flow piping or else a protective piping for an optical fiber and/or an electrical cable. 
         [0069]    The piping  2  comprises a tubular member  3  including a tubular wall  4  delimiting a longitudinal inner passage  5  intended for example for the flow of a fluid, such as a gas or water, and for example rain water, waste water, potable water, or intended for the passage of at least one optical fiber and/or at least one electrical cable. For example, the tubular wall  4  may be ringed or have a smooth outer surface. Furthermore, the tubular member  3  may be made for example of polyethylene. 
         [0070]    The piping  2  further comprises a protective member  6 , made in the shape of a protective strip, fastened on the outer surface of the tubular member  3 . The protective member  6  extends longitudinally along the upper generatrix of the tubular member  3 . The protective member  6  comprises more particularly two longitudinal lateral portions  7 ,  8  fastened on the outer surface of the tubular member  3  by ultrasonic welding. The protective member  6  is advantageously made of a synthetic material, and more particularly of a polymeric material. The protective member  6  may be made of a non-woven synthetic material comprising polyethylene fibers, such as high-density polyethylene fibers, and for example of Tyvek (registered trademark). However, the protective member  6  might be also made of another polymeric material, such as of polypropylene. The protective member  6  may have for example a width comprised between 3 and 4 cm. 
         [0071]    The protective member  6  and the tubular member  3  delimit a longitudinal receiving passage  9  extending over the entire length of the tubular member  3 . The longitudinal receiving passage  9  includes a first and a second passage openings  11  disposed respectively at the first and second ends of the tubular member  3 . 
         [0072]    The piping  2  also comprises a sensing member  12 , made in the shape of an electrically conductive wire, adapted to be sensed with a sensing device, such as an electromagnetic sensor. The sensing member  12  extends longitudinally in the receiving passage  9  and is movably mounted longitudinally relative to the tubular member  3  and to the protective member  6 . The two longitudinal lateral portions  7 ,  8  of the protective member  6  advantageously extend on either side of the sensing member  12 . According to an embodiment of the invention, the sensing member  12  has a cross-section smaller than the cross-section of the receiving passage  9 . 
         [0073]    The sensing member  12  may have a rectangular, oval or even circular cross-section. The sensing member  12  advantageously comprises an electrically conductive core  13  and an electrically insulating sheath  14  covering the electrically conductive core  13 . The electrically conductive core  13  may be for example made of copper, stainless steel or another metal, and the electrically insulating sheath  14  may be for example made of polyethylene or polypropylene. 
         [0074]    A method for manufacturing a piping  2  according to the invention will now be described. Such a method comprises the following steps consisting in:
       extruding the tubular member  3 ,   cooling the tubular member  3 ,   displacing the tubular member  3  longitudinally,   laying the sensing member  12  longitudinally on the outer surface of the tubular member  3 ,   laying the protective strip  6  longitudinally on the outer surface of the tubular member  3  so as to cover the sensing member  12  and such that the longitudinal lateral portions  7 ,  8  of the protective member  6  extend on either side of the sensing member  12 , and   fastening the longitudinal lateral portions  7 , 8  of the protective member  6  on the outer surface of the tubular member  3  by ultrasonic welding so as to form the longitudinal receiving passage  9 .       
 
         [0081]    According to an embodiment of the manufacturing method, the steps of displacing the tubular member  3  and laying the sensing member  12  and the protective member  6  are carried out continuously. 
         [0082]    According to an embodiment of the manufacturing method, the fastening step and the laying steps are carried out at the end of the manufacturing cycle of the tubular member  3 . 
         [0083]    According to an embodiment of the manufacturing method, the step of laying the sensing member  12  comprises a step consisting in unwinding the sensing member  12  from a sensing member coil  15 , and the step of laying the protective member  6  comprises a step consisting in unwinding the protective member from a protective member coil  16 . 
         [0084]    According to an embodiment of the manufacturing method, the step of fastening the protective member  6  is carried out continuously. 
         [0085]    According to an embodiment of the manufacturing method, the fastening step is carried out using a sonotrode  17 . The sonotrode  17  may have a resonance frequency comprised between 20 kHz and 70 kHz, and for example of 20, 30, 35, 40 or 70 kHz, and a vibration amplitude comprised between 10 and 120 micrometers. 
         [0086]    According to an embodiment of the manufacturing method, the sensing member coil  15  and the protective member coil  16  have winding axes perpendicular to the displacement direction of the tubular member  3 . 
         [0087]    A method for sensing a piping  2  according to the invention will now be described. Such a method comprises the following steps consisting in:
       providing a sensing terminal  18  comprising a connection housing  19  equipped with at least one connection member,   baring one of the ends of the sensing member  12  belonging to the piping  2 ,   electrically connecting the bared end of the sensing member  12  to the connection member of the sensing terminal  18 , for example using an electrical cable portion  20 ,   fastening the sensing terminal  18  on a structure, such as a sidewalk  24  or a wall  21 ,   electrically connecting an electrical signal generator, such as a current generator, to the connection member of the sensing terminal  18 ,   injecting an electrical signal into the sensing member  12 , in particular via the connection member, using the electrical signal generator, and   sensing the electromagnetic field generated by the sensing member  12  using an electromagnetic sensor so as to sense and follow the piping  2 .       
 
         [0095]    According to an embodiment of the sensing method, the sensing terminal  12  comprises an electrically conductive portion  22  electrically connected to the sensing member, and the step of fastening the sensing terminal  18  is carried out such that the electrically conductive portion  22  is accessible from the outside of the structure. 
         [0096]    According to an embodiment of the sensing method, the injection step comprises a step consisting in electrically connecting the electrical signal generator to the electrically conductive portion  22  of the sensing terminal. 
         [0097]    According to another embodiment of the sensing method, the fastening step consists in fastening the sensing terminal  18  in the vicinity of a cabinet of gas meter  23 , of water meters or any other flush. 
         [0098]    According to a variant of the sensing method, the bared end of the sensing member  12  might be electrically connected to a cabinet placed in an inspection manhole, and the electrical signal might be then injected into the sensing member  12  via the cabinet. 
         [0099]    According to yet another variant of the sensing method, the bared end of the sensing member  12  might be left pending and the electrical signal might be then directly injected into the sensing member  12  from the bared end thereof. 
         [0100]    Of course, the invention is not limited to the only embodiment of this piping  2 , described above by way of example, on the contrary it embraces all the variants thereof.