Abstract:
The present invention provides a connecting structure for piping members that are easy to connect and ensure prevention of liquid leakage even if sealing performance deteriorates due to weakened crimping force of the connected portion as a result from creep caused by changes in fluid pressure and temperature over prolonged periods and connected parts are susceptible to separation owing to looseness occurring in securing members. The structure is characterized in that a first piping member having a channel therein, the first piping member having at least one of a first joint surface on the periphery of which at least one of a first opening in communication with the channel and with a first annular groove is provided and a second piping member having a channel therein, the second piping member having at least one of a second joint surface on the periphery of which at least one of a second opening in communication with the channel and with a second annular groove is provided are connected with a thinner-walled sleeve with flanges on both ends on the periphery of which elastic bodies are fitted and press-inserted into the first and second annular grooves.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    The present invention relates to a connecting structure for piping members used for fluid transportation in various industries such as chemical, semiconductor, food, biochemistry, in particularly to a connecting structure for piping members being easy to connect and capable of maintaining good sealing performance over prolonged period. 
         [0003]    2. Description of the Related Art 
         [0004]    In conventional connecting structures integrating valve portions therein for use in various chemical lines and pure-water lines, connection has been made by using fittings integrated into a piping member such as valves and tubes between piping members. However, there have been problems in that the piping work for such a configuration is time-consuming and requires wider piping space. 
         [0005]    As a means of solving the problems a manifold valve  101  integrating the valve portions shown in  FIG. 9  has been used. The manifold valve  101  includes a main channel  102  provided inside the valve body  103 , multiple communicating ports  104  vertical to the main channel  102 , multiple valve chests opening upward in communication with the communicating ports  104 , valve seats  106  located in place where the lower side of the valve chest  105  intersects the communicating port  104 , and sub-channels (not shown) provided in the sides of the valve chests  105  in orthogonal direction with respect to the main channel  102  and the communicating port  104 . Multiple driving sections  108  provided with the valve bodies  107  serve to open and close the valves utilizing the pressure of the working fluid and are fixed on the top of the valve body  103  with bolts and nuts (not shown) in relation to the respective valve chests  105 . This forms a structure with multiple integrated valves. However, the manifold valve  101  is inferior in versatility, because its design and manufacture has to be adjusted to each particular requirements, i.e., increasing or decreasing the number of valve chests  105  and sub-channels. If the valve seat  106  is damaged even partly by accidental inclusions or similar events, requiring replacement of parts, the entire valve body  103  as well as the not affected parts have to be replaced, because of the integrated structure of the valve body  103 . This poses problems because of the required extensive labor and high costs. 
         [0006]    As means of solving the aforementioned problems, connecting structures of connecting openings of blocks, as shown in  FIG. 10  has been proposed (refer to Japanese Unexamined Patent Application Publication No. 2001-116155). According to this connecting structure, a first connecting surface  109  is closely connected to a second connecting surface  110 . An annular recess groove  111  is formed in the first connecting surface  109  and an annular projection  112  projects from the second connecting surface  110 . On the periphery of the annular projection  112  an annular projection  115  with a head  113  and a tapered surface  114  are formed (refer to  FIG. 10(   a )). When the connecting surfaces are secured with securing members (not shown) such as bolts, the annular projection  112  is brought into close contact with the periphery of the opening and the annular projection  115  is fitted into the annular recess groove  111 , while the tapered surface  114  of the annular projection  115  is brought into close contact with the inner periphery of the annular recess groove  111  (refer to  FIG. 10  ( b )). 
         [0007]    In this connecting method, however, the connected portions consisting of the annular projection  112 , the annular projection  115 , and the annular recess groove  111  are kept tight at first because they are secured sufficiently with a securing member (not shown) such as a bolt and others. Yet, this does not address the problem that sealing performance deteriorates due to weakened crimping forces of the connected portion resulting from creep action caused by changes in fluid pressure and temperature over prolonged periods, thus rendering connected parts susceptible to separation due to looseness developing in securing members, resulting in leakage of fluid. The tendency becomes more pronounced with polytetrafluoroethylene (hereinafter referred to as PTFE) and tetrafluoroethylene perfluoroalkyl vinylether copolymer (hereinafter referred to as PFA) preferably used as sealing materials. 
       SUMMARY OF THE INVENTION 
       [0008]    The present invention has the purpose of solving the problems encountered the prior art mentioned above. Its purpose is to provide a connecting structure for piping members that are easily connected and capable of surely preventing liquid from leaking even if sealing performance deteriorates due to weakening crimping forces of the connected portion due to creep action caused by changes in fluid pressure and temperature over a prolonged period and thus renders connected parts susceptible to separation due to looseness developing in the securing members. 
         [0009]    The composition of piping members for solving the above problems in the present invention is described below with reference to  FIGS. 1 to 3 . In a first embodiment of the present invention, the structure is characterized in that a first piping member  1  having a channel therein, the first piping member  1  having at least one of a first joint surface  8  on the periphery of which at least one of a first opening  7  in communication with the channel and with a first annular groove  6  is provided and a second piping member  2  having a channel therein, the second piping member  2  having at least one of a second joint surface  11  on the periphery of which at least one of a second opening  10  in communication with the channel and with a second annular groove  9  is provided are connected together in a sealed state through a roughly cylindrical sleeve  3 , wherein a thinner-walled sleeve  3  with flanges  23 , on both ends thereof on the periphery of which elastic O-rings  26  and  27  are fitted, is press inserted into the first and second annular grooves  6  and  9 . 
         [0010]    In a second embodiment of the present invention, the structure is characterized in that the first and second piping members  1  and  2  are connected together by connecting members  30 ,  31 ,  69 , and  70  for connecting the first and second joint surfaces together or a connecting member  85  for connecting the top or undersides of the first and second piping members together. 
         [0011]    In a third embodiment of the present invention, the structure is characterized in that joint fitting portions  14  and  15  are formed in the first and second joint surfaces  8  and  11  of the first and second piping members  1  and  2  respectively and the members are connected through joints  30  and  31  fixed into the fitting portions  14  and  15  with pins  34 ,  35 ,  36 , and  37 . 
         [0012]    In a fourth embodiment of the present invention, the structure is characterized in that the first piping member  1  and/or the second piping member  2  are any of a valve, fitting, mixer, pump, flowmeter, and various types of sensors. 
     
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0013]      FIG. 1  is an exploded perspective view showing a connecting structure for piping members according to a first embodiment of the present invention; 
           [0014]      FIG. 2  is a vertical section showing a first embodiment of the present invention; 
           [0015]      FIGS. 3  ( a ) and  3  ( b ) are enlarged vertical sections of principal parts according to a first embodiment of the present invention; the former being the section before they are connected, and the latter after they are connected; 
           [0016]      FIGS. 4  ( a ) and  4  ( b ) are enlarged vertical sections of principal parts according to a second embodiment of the present invention; the former being the section before they are connected, and the latter after they are connected; 
           [0017]      FIG. 5  is a perspective view showing connecting members according to a third embodiment of the present invention; 
           [0018]      FIG. 6  is a perspective view showing connecting members according to a fourth embodiment of the present invention; 
           [0019]      FIG. 7  is a perspective view showing connecting members according to a fifth embodiment of the present invention; 
           [0020]      FIG. 8  is a plan view showing connecting members according to other embodiments of the present invention; 
           [0021]      FIG. 9  is a vertical section showing a manifold valve as described in the prior art; 
           [0022]      FIG. 10  a vertical section of principal parts showing how to connect the openings of blocks as described in the prior art. 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0023]    The preferred embodiment of the present invention is described in detail below with reference to the drawings. It is to be understood that the present invention is not limited to these embodiments. 
         [0024]    A connecting structure for piping members in the first embodiment of the present invention is described below with reference to the  FIGS. 1 to 3 . 
         [0025]    In the figures the reference numeral  1  refers to a valve body as a first piping member made of PTFE, inside which a first channel  4  is provided through the first valve body  1 , and has an annular groove  6  on the periphery of the side to which a second valve body described later is connected, equipped with a first joint surface  8  on which a first opening  7  in communication with the provided first channel  4 , and is equipped with a similar joint surface  12  on the opposite side. A notch-shaped fitting section  14  is formed on both ends (left and right) of the first joint surface  8 . Through holes  16  penetrating the fitting portions  14  respectively are provided vertically at the four corners of the body. At the center inside the body a communicating port  18  is provided vertically with respect to the first channel  4  and a valve chest  19  with its top opening is provided in communication with the communicating port  18 . A valve seat  20  lies on the periphery of the communicating port  18  at the bottom of the valve chest  19 . On the side of the valve chest  19  a sub-channel  18  is provided in an orthogonal direction with respect to the first channel  4  and the communicating port  18 . The first channel  4  is provided in a straight line with the first valve body  1  penetrating the present embodiment. Alternatively, it may be bent at a right angle at a point intersecting with the communicating port  18 , or it may be provided on one side of the first valve body  1  by opening it without penetration, that is to say, this structure imposes no special limitations on the configuration of the channel. Furthermore, although the sub-channel  21  is provided in orthogonal direction with respect to the first channel  4 , an opening in communication with the sub-channel  21  can be provided on the first joint surface  8  in the same direction with the first opening  7 . In that case, however, the second valve body to be connected needs to have a similar opening. The fitting section  14  has in the present embodiment a notch shape, but it can also be shaped as a recess on the joint surface. 
         [0026]    The reference numeral  2  refers to a valve body as a second piping member made of PTFE, inside which a second channel  5  is provided through the second valve body  2 , having an annular groove  9  on the periphery of the side to which the first valve body is connected and is equipped with a second joint surface  11  on which a second opening  10  in communication with the second channel  5  is provided, and is further equipped with a similar joint surface  13  on the opposite side. The second valve body is similar to the first valve body in inner structure. 
         [0027]    The reference numeral  3  refers to a roughly cylindrical sleeve made of PTFE, at the center of which a through hole  22  having approximately the same bore as the first and second channels  4  and  5  of the first and second valve bodies  1  and  2  is provided in coaxial direction of the first and second channels  4  and  5 . Inserting sections  24  with flanges  23  and a partition  25  are provided at both ends and at the center of the sleeve respectively. The inserting sections  24  are formed to be thinner-walled as compared to the partition  25  (refer to  FIG. 3 ). The inserting sections  24  are press inserted into the first and second annular grooves  6  and  9  with elastic O-rings  26  and  27  fitted between the flange  23  and partition  25  compressed flat in radial direction. The sleeve  3  is sealed and fixed with, and held between the first and second openings  7  and  10 . The outer diameters of flange  23  and partition  25  are almost the same as the outside  28  of the first and second annular grooves  6  and  9 . The inner diameters of the inserting sections  24  are the same as the insides  29  of the first and second annular grooves  6  and  9 . The length between the end surfaces of the sleeve  3  is designed to be equal to the total dimensions of depth at the bottom of the first annular groove  6  in the tube axis from the first joint surface  8  and depth at the bottom of the second annular groove  9  in the tube axis from the second joint surface  11 . That is to say, sleeve  3  is adapted to be inserted and fitted into the first and second annular grooves  6  and  9 , and brought into close contact with the insides  29  of the grooves by the elastic action of the O-rings  26  and  27 . 
         [0028]    The reference numeral  30  is a joint of polypropylene (hereinafter referred to as PP) and has two through holes  32  and  33 . The through holes  32  and  33  of the joint  30  are formed to have almost the same diameter as the through holes  16  and  17  of the first and second valve bodies  1  and  2  and designed to be coaxial with the through holes  16  and  17  when the joint  30  is fitted into the fitting portions  14  and  15 . Both valve bodies  1  and  2  are connected and fixed together in such a manner that both sides of the joints  30  are fitted into respective fitting portions  14  and  15  of the first and second joint surfaces  8  and  11  and the then the cylindrical metallic pins  34 ,  35 ,  36 , and  37  formed to be approximately the same as the through holes  16 ,  17 ,  32 , and  33  in diameter are inserted into the through holes  16  and  17  of both valve bodies  1  and  2  and through holes  32  and  33  of the joint  3 . The size and shape of the fitting portions  14  and  15  are not limited unless they affect the actions of both valves  1  and  2 , and at the same time the shape of the joint  30  is not limited as long as it can be inserted into the fitting portions  14  and  15  even if it protrudes from both valve bodies  1  and  2 . Flanges can be provided on the upper sections of the pins  34 ,  35 ,  36 , and  37  to facilitate disassembly of the connection portion. The pins  34 ,  35 ,  36 , and  37  can be screwed to be fitted into the joint. The material of the pins  34 ,  35 ,  36 , and  37  may be any of metals such as aluminum, iron, copper and alloy and may be resin as of engineering plastic unless strength poses a problem. The joint  31  is made of PP and is the same as the joint  30  in structure. 
         [0029]    The reference numeral  38  is a driving section of PP formed with an internal cylinder. The reference numeral  40  is a piston of PP, and is inserted and fitted so that it can slide up- and downward into the cylinder of the driving section  38 . The reference numeral  41  is a valve body presser of PP having a through hole therein, into which the bottom of the piston  40  is inserted and fitted so that it can slide up- and downward. Moreover the upper part of the valve body presser  41  is inserted and fitted into the lower part of the cylinder of the driving section  38  and its lower part is inserted and fitted into the valve chest  19  of the first valve body  1 , thereby holding the valve body presser  41  between the driver  38  and the first valve body  1 . The reference numeral  42  is a valve body of PTFE with a membrane section, its periphery being held between the valve body presser  41  and the first valve body  1 . The piston  40  is screwed into the central upper part of the valve body  42  . The valve body  42  can be moved up- and downward by the vertical motion of the piston  40 . The reference numeral  43  is a metallic spring held between the ceiling surface of the cylinder inside the driving section  38  and the upper part of the piston  40  and fixed there between the piston  40  energized normally downward. That is to say, the valve body  42  joined to the piston  40  is also energized in downward direction and brought into contact with the valve seat  20  of the first valve body  1  by pressurizing. The reference numeral  39  is a driving section of PP and is similar to the driving section  38  in structure. 
         [0030]    The reference numerals  44  and  45  are pipe fittings made of PTFE. One end of the pipe fitting has a connecting section on which a pipe connecting section  46  and a male screw section  47  are integrally provided, the other end is structurally the same as the first joint surface  8 . The pipe fittings  44  and  45  are coupled with the first and second valve bodies  1  and  2  respectively. The connection method for them is the same as that for the first and second valve bodies  1  and  2 . 
         [0031]    Below the function of the first embodiment with above structure is described. 
         [0032]    In the figures, the flow of fluid into the first and second channels  4  and  5  fills the channels  4  and  5  and at the same time attempts to outflow through the interstice between the first and second valve bodies  1  and  2 , and the sleeve  3 . The sleeve  3 , however, is press inserted into the first and second annular grooves  6  and  9  and thus sealed and held there, preventing the fluid from leaking from the connected portion between the sleeve  3  and the first and second valve bodies  1  and  2 . 
         [0033]    The use of fluororesin such as PTFE as material for the connecting portion between sleeve  3  and the first and second valve bodies  1  and  2  as shown in the present embodiment may generate creep and strain in sleeve  3  and both valve bodies  1  and  2  by the creep action of the material itself caused by variation in fluid pressure and temperature after prolonged use and thus lead to the formation of interstices between the valve bodies. Even if such interstices form between the first and second valve bodies  1  and  2  by creep and strain, fluid will be securely blocked with the sealing section of the insides  29  of the first and second annular grooves  6  and  9  and the inside  48  of the inserting section  24  of the sleeve  3 , preventing the fluid from leaking, because the inside  48  of the inserting section  24  of the sleeve  3  is pressed against the former and ensures a close contact between the insides  29  of the first and second annular grooves  6  and  9  through the function of the elastic O-rings  26  and  27 . Furthermore, sealing performance can be maintained, because the first and second valve bodies  1  and  2  are connected together with the pins  34 ,  35 ,  36 , and  37 , and joints  30  and  31  so that the piping members do not separate from each other. 
         [0034]    The focused pressure of the inside  48  of the sleeve  3  against the insides  29  of the first and second annular grooves  6  and  9  results in a close contact with the O-rings  26  and  27  fitted into the sleeve  3 , and the focused pressure of flange  23  of the sleeve  3  results in a close contact with the bottom of the first and second annular grooves  6  and  9 , thereby providing excellent sealing performance and permits to maintain the elastic function of the sleeve  3  over longer periods. 
         [0035]    The sleeve  3  is press inserted into the first and second annular grooves  6  and  9  with the O-rings  26  and  27  compressed flat in radial direction relative to the axis of the first and second channels  4  and  5 . Thus the flow of fluid into the first and second channels  4  and  5  exerts a separating force on both joint surfaces  8  and  11  of both valve bodies  1  and  2  through hydrostatic pressure, thereby tending to reduce the elastic function in axial direction of the O-rings  26  and  27 . In radial direction, however, a constant elastic function can be maintained even if hydrostatic pressure increases, so that a good long-term sealing properties can be maintained against the creep of both valve bodies  1  and  2 . Furthermore, this structure ensures that excellent sealing properties can be maintained even if the first and second channels  4  and  5  are subjected to higher hydrostatic pressure. 
         [0036]    Even if a crack develops in sleeve  3  has due to accidental inclusions and poor contact, resulting in liquid leak from the sleeve  3 , the outsides  28  of the first and second annular grooves  6  and  9  also assist the sealing because the O-rings  26  and  27  are compressed flat in radial direction in relation to the axis of the channels, thus a liquid leak can be eventually blocked between the O-rings  26  and  27  and the outsides  28  of the first and second annular grooves  6  and  9 , so that fluid will never leak outside. Fluororubber of excellent heat and chemical resistances is the preferable material for the O-rings  26  and  27 , but any material may be used, as long as its properties suite the conditions of the application. An elastic body such as a short tubular packing or rubber plastic can be used instead of the O-rings  26  and  27 . 
         [0037]    The function of the driving section  38  is described below with reference to  FIG. 2 . In a normal state the piston  40  in the driving section  38  is pushed downward by the repulsive force of the spring  43  and the valve body  42  joined to the piston  40  is brought into contact with the valve seat  20  of the first valve body  1  by pressurizing, so that fluid flowing through the first channel  4  will not flow into the valve chest  19  and the sub-channel  21  through the communicating port  18 . The flow of working fluid, for example compressed air, into the interstices formed between the piston  40  and valve body presser  41  causes the piston  40  to rise by the pressure of the working fluid and at the same time the valve body  42  joined to the piston  40  leaves the valve seat  20 . Thus the fluid flowing through the first channel  4  is supplied to the valve chest  19  and the sub-channel  21  through the communication port  18 . The exhaust of the working fluid causes the piston  40  to be pushed downward again by the spring  43 , bringing the valve body  42  into contact with the valve seat  20 , stopping the supply of the fluid to the sub-channel  21 . The function of the driving section  39  is also the same as that of the driving section  38 , so that its description is omitted here. 
         [0038]    The connection method in the present embodiment is described below with reference to  FIGS. 1 to 3 . 
         [0039]    Firstly, the O-rings  26  and  27  are fitted on the periphery of the sleeve  3 . One inserting section  24  of the sleeve  3  is press inserted into the first annular groove  6  of the first valve body  1 , and then the other inserting section  24  is press inserted into the second annular groove  9  of the second valve body  2 , thereby joining the first and second joint surfaces  8  and  11  to each other. In this junction the use of the sleeve  3  can provide the effect of centering of the first and second channels  4  and  5  of both valve bodies  1  and  2 . Secondly, the joints  30  and  31  are inserted into the inserting sections  14  and  15 , the pins  34  and  36  are inserted and fitted into the through hole  16  of the first valve body  1  and the through hole  32  of the joints  30  and  31 , and then pins  35  and  37  are inserted and fitted into the through hole  17  of the second valve body  2  and the through hole  33  of the joints  30  and  31 , thereby coupling the first and second valve bodies  1  and  2  together. As described above, it is extremely easy to connect the piping members using the present embodiment without requiring any tools for the connection. 
         [0040]    Below a connecting structure for piping members according to the second embodiment of the present invention is presented with reference to  FIG. 4 . 
         [0041]    The reference numeral  49  is a basically cylindrical sleeve made of PTFE, at the center of which a through hole  66  having roughly the same bore as the first and second channels  52  and  53  of the first valve body  50  of PTFE as a first piping member and the second valve body  51  of PTFE and  51  as a second piping member is provided in coaxial direction of the first and second channels  52  and  53 . An inserting section  55  with a flange  54  is provided at both ends of the sleeve. The inserting sections  55  are formed to be thinner-walled (refer to  FIG. 4 ). The inserting section  55  is press inserted into the first and second annular grooves  57  and  58  with a short tubular elastic packing  55  fitted onto the periphery of the sleeve and compressed flat in radial direction. The sleeve  49  is sealed and held between the first and second openings  59  and  60 . The outer diameter of flange  54  is almost the same as the outside  61  of the first and second annular grooves  57  and  58 . The inserting section  55  has the same inner diameter as the inside  62  of the first and second annular grooves  57  and  58 . The length between the end surfaces of the sleeve  49  is designed to be equal to the total dimensions of depth at the bottom of the first annular groove  57  in tubular axial direction from the first joint surface  63  and depth at the bottom of the second annular groove  58  in tubular axial direction from the second joint surface  64 . That is, the sleeve  49  is inserted and fitted into the first and second annular grooves  57  and  58  and brought into close contact with the insides  62  of the first and second grooves  57  and  58  by the elastic action of the packing  56 . Other structures of this embodiment are the same as those in the first embodiment, so that their description is omitted here. 
         [0042]    The function of the second embodiment with above structure is described below. 
         [0043]    Since the inside  65  of the sleeve  49  is pressed in concentrically against and thus brought into close contact with the insides  62  of the first and second annular grooves  57  and  58  with the packing  56  as an elastic body fitted to the sleeve  49 , and at the same time the flange  54  of the sleeve  49  is pressed in concentrically against and thus brought into close contact with the bottom of the first and second annular grooves  57  and  58 , resulting in extremely good sealing properties and in effect can maintain the elastic function of the sleeve  49  over prolonged periods. 
         [0044]    Furthermore, the sleeve  49  is press inserted into the first and second annular grooves  57  and  58  with the packing  56  compressed flat in radial direction in relation to the axis of the first and second channels  52  and  53 . Thus, the flow of fluid into the first and second channels  52  and  53  exerts a separating force on both joint surfaces  63  and  64  of both valve bodies  50  and  51  by the action of hydrostatic pressure, tending to decrease the elastic effect in axial direction of the packing  56 . In radial direction, however, a constant elastic action can be maintained even if hydrostatic pressure increases, so that a good sealing performance can be maintained against the creep of both valve bodies  50  and  51  over prolonged periods. Furthermore, this structure permits good sealing properties to be maintained even if the first and second channels  52  and  53  are subjected to high hydrostatic pressure. 
         [0045]    Even if the sleeve  49  is cracked due to accidental inclusions and poor contact, resulting in liquid leak from the sleeve  49 , fluid can eventually be blocked between the packing  56  and the outsides  61  of the first and second annular grooves  57  and  58  in the same way as in the first embodiment, so that fluid will never leak. 
         [0046]    Below a connecting structure for piping members according to the third embodiment of the present invention is described with reference to  FIG. 5 . 
         [0047]    The reference numerals  67  and  68  are U-shaped metallic pins with a circular cross-section. Joints  69  and  70  of PP are fitted into and held by fitting portions  73  and  74  formed in the joint surfaces  72  of the valve body  71  made of PTFE as a first piping member and of the valve body  72  of PTFE as a second piping member. Both valve bodies are coupled and fixed to each other through insertion into the through holes  75  and  76  of both valve bodies  71  and  72  and two through holes  77  of the joints  69  and  70  the pins  67  and  68  with the same diameter as the through holes. Other structures and functions of the present embodiment are the same as those of the first embodiment, so that their description is omitted here. 
         [0048]    Below the structure of the connecting members in the fourth embodiment according to the present invention is described with reference to  FIG. 6 . 
         [0049]    A recess  80  is provided on a joint surface of the valve body  78  of PTFE as a first piping member. A salient  81  fitted into the recess  80  is provided on the joint surface of the valve body  79  made of PTFE as the second piping member to be connected thereto. A through hole  82  penetrating the recess  80  and the salient  81  fitted therein is provided in vertical direction. Cylindrical metallic pins  83  and  84  with the same diameter as the through hole  80  are inserted into through holes  80 , thereby connecting and fixing both valve bodies  78  and  79  together. Other structures and functions of the present embodiment are the same as those of the first embodiment, so that their description is omitted here. 
         [0050]    In the first to fourth embodiments described above, connecting members for connecting the valve bodies together do no connect multiple piping members, that is to say, they are individually and independently provided between the valve bodies. Thus, even if a valve body located between other parts needs replacing due to defects after for example multiple valve bodies are arranged in series and connected to one another, it is possible to replace that valve body in question by remove only connecting members. In that way, it is easy to replace it without requiring replacement of all connected valves (manifold valve) collectively and thereby allows to reduce replacement costs. 
         [0051]    Below the structure of the connecting members in the fifth embodiment of the present invention is described with reference to  FIG. 7 . 
         [0052]    The reference numeral  85  is a plate. The plate  85  is located at the underside of valve body  86  made of PTFE as a first piping member and valve body  87  made of PTFE as a second piping member. Both valve bodies  86  and  87  are connected and fixed to each other by fixing the valves  86  and  87  on the plate  85  with bolt  88 . Other structures and functions of the present embodiment are the same as those of the first embodiment, so that their description is omitted here. In this embodiment the undersides of the valves  86  and  87  are connected together with the plate  85 , but the invention is not limited to this connecting method. For example, it would be equally acceptable to connect the upper sides of the valves. 
         [0053]    In the present embodiment two valve bodies are connected, however, three valves may be connected as shown in  FIG. 8  ( a ). In that case, a joint for connecting three valves needs three or more through holes. Similarly, four valves can be connected as shown in  FIG. 8  ( b ). In that case, however, a joint for connecting four valves needs four or more through holes. The present embodiments of the invention describe the use of valves and fittings as connected piping members, however, valves, fittings, mixers, pumps, flowmeters, and various types of sensors may also be used as piping members. The invention does not impose any particular limitations regarding the quantity of connected piping members, direction of connection, and combination of piping members. 
         [0054]    The invention relates to the structures described above. Application of these structures provides the following-excellent effects: 
         [0055]    (1) Fitting an elastic body on the periphery of the thinner-walled sleeve causes the inside of the sleeve to be pressed in concentrically against and brings it into close contact with the inside of the first and second annular grooves, thereby causing the flange of the sleeve to be pressed in concentrically against and brings it into close contact with the bottoms of the first and second annular grooves. That allows the structure to resist high hydrostatic pressure and provides extremely good sealing performance. 
         [0056]    (2) Even if the sleeve is cracked due to accidental inclusions and poor contact, resulting in liquid leak from the sleeve, the outsides of the first and second annular grooves are sealed because the elastic bodies are compressed flat in radial direction in relation to the axis of the channels, thus liquid leaking from between the elastic bodies and the first and second annular grooves can be eventually blocked. 
         [0057]    (3) Press-inserting the elastic bodies into the grooves while compressed flat in radial direction permits maintaining an elastic action even if creep or strain is generated in the piping members by changes in pressure and fluid temperature over prolonged periods, thereby maintaining excellent sealing performance. 
         [0058]    (4) Connection work is easy. Connecting members for connecting the valve bodies together do no connect multiple piping members, that is to say, they are individually and independently provided between the valve bodies. Thus, even if a valve body located between other parts replacing due to defects after for example multiple valve bodies are arranged in series and connected to one another, it is possible to remove that valve body in question by removing only the connecting members. In that way, it is easy to replace it without requiring to replace all connected valves (manifold valves) collectively and thereby permits to reduce replacement costs. 
         [0059]    (5) Since it is not required to place fittings and tubes between piping members, piping space can be saved and the piping work is simplified and thereby permits to reduce replacement costs.