Patent Publication Number: US-2023151914-A1

Title: Tensioner and method of using same

Description:
TECHNICAL FIELD 
     The present disclosure relates generally to tensioners, and more particularly, to hydraulic stud or bolt tensioners and methods of using the same. 
     BACKGROUND 
     Studs or bolts may be used with nuts to couple two or more structures (e.g., pipe flanges) together. To secure a coupling, the structures may need to be urged together and the studs or bolts tensioned or stretched (i.e., “preloaded”) before securing nuts are tightened to properly secure the structures. Stud or bolt tensioners may be used to urge structures together and stretch the studs or bolts. Once the stud tensioners are activated, securing nuts may be tightened to properly secure the structures, and the tensioners may be removed from the structures. 
     Existing tensioners may be overly complex, require specialized tools, and may be limited to sizes according to studs or bolts, which increases time spent during a tightening process. To tighten multiple studs or bolts, each stud or bolt may require its own tensioner. 
     U.S. Pat. No. 9,009,945, issued on Apr. 21, 2015, describes a hydraulic flange connector having a piston with a first end engaged with a first stud and a second end acting as and/or engaged with a second stud. As the piston is extended due to hydraulic fluid, the first and second studs are urged to connect two flanges. The hydraulic connector is not removed, and thus forms a permanent part of the coupling. One hydraulic connector is required for each circumferential position along the flange. 
     The tensioner of the present disclosure may solve one or more of the problems set forth above and/or other problems in the art. The scope of the current disclosure, however, is defined by the attached claims, and not by the ability to solve any specific problem. 
     SUMMARY 
     In one aspect, a tensioner may assist in coupling two pipe flanges. The tensioner may include a body and a piston. The body may include a central longitudinal axis, a pair of fastener holes extending through the body in a direction parallel to the central longitudinal axis, and a piston housing having an inner bore disposed about the central longitudinal axis. The piston housing may be provided between the pair of fastener holes. An axial end of the piston housing may define a distal end of the body. The piston may be at least partially disposed in the inner bore of the piston housing. The piston may be axially moveable parallel to the central longitudinal axis through an opening of the inner bore at the distal end of the body. 
     In another aspect, a coupling system may couple a pair of pipe flanges using a plurality of fasteners. The coupling system may include a plurality of tensioners. Each tensioner may include a body and a piston. The body may include a proximal end, a distal end, and a central longitudinal axis extending from the proximal end to the distal end. The body may include a pair of fastener holes extending through the body in a direction parallel to the central longitudinal axis. The body may include a piston housing provided between the pair of fastener holes. The piston may be at least partially located in the piston housing and extendable distally from the body to exert a force to couple the pipe flanges. 
     In another aspect, a method of tensioning first and second pipe flanges with a plurality of tensioners may include inserting each tensioner of the plurality of tensioners onto at least two fasteners of a plurality of fasteners. A first nut of each fastener may be disposed between the first pipe flange and a corresponding tensioner. The method may include coupling a second nut onto each fastener. Each tensioner may be disposed between the first and second nuts of each corresponding fastener. The method may include tightening the second nut of each fastener against a proximal end surface of each corresponding tensioner, urging a piston of each tensioner against the first pipe flange to move the first and second pipe flanges from a first axial spacing to a second axial spacing relatively closer together than the first axial spacing, tightening the first nut of each fastener against the first pipe flange to maintain the second axial spacing between the first and second pipe flanges, and removing each tensioner from the corresponding fasteners. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate various exemplary embodiments and together with the description, serve to explain the principles of the disclosed systems and methods. 
         FIG.  1    is a perspective view of a pipe system and a plurality of tensioners applied to the pipe system according to aspects of the disclosure. 
         FIG.  2    is a perspective view of two tensioner studs and a tensioner of  FIG.  1   . 
         FIG.  3    is a perspective view of the tensioner of  FIG.  2    without the tensioner studs. 
         FIG.  4    is a cross-sectional view the tensioner of  FIG.  2    along lines  4 - 4  of  FIGS.  3  and  6    with a piston in a first position. 
         FIG.  5    is a cross-sectional view of the tensioner along lines  5 - 5  of  FIGS.  3  and  6    with a piston in a second position. 
         FIG.  6    is a top view of the tensioner of  FIG.  2   . 
         FIG.  7    is a front view of the tensioner stud shown in  FIG.  2   . 
         FIG.  8    is a view of the tensioner stud and stud shown in  FIG.  2   . 
         FIG.  9    is a front view of the pipe system of  FIG.  1    showing an internal cross-section of a tensioner. 
         FIG.  10    provides a flowchart depicting an exemplary method for operating the system of  FIGS.  1 - 9   . 
     
    
    
     DETAILED DESCRIPTION 
     Both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the features, as claimed. As used herein, the terms “comprises,” “comprising,” “has,” “having,” “includes,” “including,” or other variations thereof, are intended to cover a non-exclusive inclusion such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements, but may include other elements not expressly listed or inherent to such a process, method, article, or apparatus. In this disclosure, unless stated otherwise, relative terms, such as, for example, “about,” “substantially,” and “approximately” are used to indicate a possible variation of ±10% in the stated value. 
       FIG.  1    illustrates a coupling system  10  including a plurality of tensioners  100  applied to a pipe system  200 .  FIG.  2    illustrates a perspective view of a portion of the coupling system  10  with the pipe system removed for clarity. Referring to  FIGS.  1 - 2   , the pipe system  200  may include a first or upper pipe  212  having a first or upper pipe flange  222  and a second or lower pipe  214  having a second or lower pipe flange  224 . The first and second pipe flanges  222  and  224  may include a plurality of fastener holes through which studs or bolts  300  extend to couple the first and second pipe flanges  222  and  224 . Two or more fasteners (e.g., studs or bolts  300 ) may also extend through tensioner  100  and may be secured via a plurality of nuts  410 ,  420 , and  430 . It is contemplated that tensioner  100  may be used to assist the coupling of any two components, such as pipe flanges  222 ,  224 , two or more plates, or any other components that are coupled together by elongated fasteners. Also, while tensioner  100  may be used with any appropriate fastener, such as studs, bolts, etc., the use of stud assemblies  300  will be referenced hereinafter for ease of reference. Details of the stud assemblies  300  will be described in more detail with reference to  FIGS.  6 - 7   . 
     The pipe system  200  may include American Petroleum Institute (API) and/or American Society of Mechanical Engineers (ASME) compliant materials, but systems and methods disclosed herein are not limited. The first and second pipes  212  and  214  and the first and second pipe flanges  222  and  224  may be made of a metal material, such as a carbon steel material (e.g., 1018 and/or 1020) or a stainless steel material (e.g., SS315 up to SS410). The first and second pipe flanges  222  and  224  may be designed for 8 studs, 12 studs, 16 studs, etc. As an example, the first and second pipe flanges  222  and  224  may be API 6A 5⅛″, 15000 pounds per square inch (psi) flanges and/or 7 1/16″, 15000 psi flanges, but aspects disclosed herein are not limited to a particular size or pressure capability of flanges. 
     The tensioner  100  may be connected to a hydraulic fluid supply system  500  for supplying and draining hydraulic fluid from tensioners  100 . The hydraulic fluid supply system  500  may include a pump  502 , and hydraulic tubing or hoses  504  to supply and drain fluid to and from each of the tensioners  100 . The hydraulic tubing  504  may be made of steel, braided wire, or a flexible or elastomeric material (e.g., rubber, thermoplastic, or polytetrafluoroethylene), but aspects disclosed herein are not so limited. Further, the pump  502  may be a hand pump or a powered pump. 
     Referring to  FIGS.  2 - 3   , the tensioner  100  may include a body  110  and a piston  150  moveable within the body  110 . The body  110  may be made of a rigid material (e.g., metal such as steel). The body  110  may have a flange or collar  111 , a piston housing or cylinder  116  generally disposed on a central axis  600  and extending below the flange  111 , an extension or upper casing  118 , a proximal or upper end  122 , and a distal or lower end  124 . Each of the proximal end  122  and distal end  124  may be parallel to each other, as shown. The distal end  124  may form a distal planar surface. The central axis  600  may extend from the proximal end  122  to the distal end  124  of the body  110 , and may alternatively be referred to as a central longitudinal axis. Line  4 - 4  indicates arrows pointing in a left direction to indicate a direction in which the cross-section of  FIG.  4    is viewed. Line  5 - 5  indicates arrows pointing in a forward direction to indicate a direction in which the cross-section of  FIG.  5    is viewed. 
     The flange  111  may have a pair of sides or wings  112 ,  114  generally extending perpendicular to the central axis  600 , a pair of fastener holes  144  and  146  (e.g., stud or bolt holes), a continuous side surface  126 , and a pair of couplers or fittings  132  and  134 . The pair of sides  112 ,  114  may include a first side  112  and a second side  114 . The first side  112  may extend from a first side (e.g., left side in  FIG.  3   ) of the extension  118 , and the second side  114  may extend from a second side (e.g., right side in  FIG.  3   ) of the extension  118 . The first and second sides  112  and  114  may extend, with respect to a radial direction of the central axis  600 , beyond an outer surface of the piston housing  116 . The first and second sides  112  and  114  may have a symmetrical arrangement (e.g. mirror images) about the central axis  600 . 
     The pair of fastener holes  144  and  146  may include a first fastener hole  144  and a second fastener hole  146 . The first fastener hole  144  may be provided in the first side  112  at a position radially outside of the piston housing  116  with respect to the central axis  600 . The second fastener hole  146  may be provided in the second side  114  at a position radially outside of and non-overlapping with the piston housing  116  with respect to the central axis  600 . The first and second fastener holes  144  and  146  may have a symmetrical arrangement (e.g. mirror images) about the central axis  600 . The first and second fastener holes  144 ,  146  may extend through the respective first and second sides  112 ,  114  in a direction parallel to the central axis  600 . The first and second fastener holes  144 ,  146  may have center axes  145  and  147 , respectively, which are parallel to the central axis  600 . 
     The first and second fastener holes  144  and  146  may be configured to receive fasteners  300  (e.g., stud assemblies) therethrough. For convenience of description, the fasteners  300  will be described as stud assemblies  300 . Each stud assembly  300  may include a tensioner stud  330 , and the first and second fastener holes  144  and  146  may be configured to receive a pair of tensioner studs  330 , respectively. The pair of tensioner studs  330  may be configured to be coupled to a pair of studs  310  and  320 , respectively, such that each stud assembly  300  includes one stud  310  or  320  and one tensioner stud  330 . The stud assembly  300  will be described in more detail with reference to  FIG.  6   . As an alternative to the stud assembly  300  shown in  FIG.  6   , the first and second fastener holes  144  and  146  may be configured to receive the pair of studs  310  and  320 , which may extend through the tensioner  100 , and the tensioner stud  330  may be omitted. 
     The continuous side surface  126  may be perpendicular to each of the proximal end  122  and distal end  124  (e.g., parallel to the central axis  600 ). The continuous side surface  126  may have a shape based on the pipe system  200 . For example, the continuous side surface  126  may have a first or rear portion  128  for positioning adjacent pipe system  200 , and a second or front portion  130  located away from pipe system  200 . The rear portion  128  may have a concave curvature with respect to the central axis  600 , while the front portion  130  may have a convex curvature with respect to the central axis  600 . The continuous side surface  126  will be described in more detail with reference to  FIG.  5   . 
     The pair of fittings  132 ,  134  may be provided at the front portion  130  of the continuous side surface  126 . The pair of fittings  132 ,  134  may include a first coupler or fitting  132  (e.g., inlet coupler) and a second coupler or fitting  134  (e.g., outlet coupler). The first fitting  132  and the second fitting  134  may be configured to receive the hydraulic tubing  504  of the hydraulic fluid supply system  500  ( FIG.  1   ) and may alternatively be referred to as first and second hydraulic fittings. The first and second fittings  132  and  134  may each have internal shut off valves configured to stop or reduce a flow of fluid when the hydraulic tubing  504  is disconnected. 
     The first and second fittings  132  and  134  may be positioned closer to the proximal end  122  of the body  110  than the distal end  124 . The first fitting  132  and the second fitting  134  may be disposed perpendicular to the central axis  600 . The first fitting  132  and second fitting  134  may be aligned at a same axial height along the central axis  600 , in other words being spaced an equal distance from a bottom of the continuous side surface  126 . Positions of the first and second fittings  132  and  134  may be positioned on the front portion  130  of the body  110 , which may face away from the pipe system  200  for convenience. Details of a shape of the body  110  will be described in more detail with reference to  FIG.  5   . The first and second fittings  132  and  134  may protrude from the front side of the extension  118  at circumferential positions, with respect to central axis  600 , that are offset from a front center position that is aligned, in a front-rear direction, with the central axis  600 . 
     The piston housing  116  may be provided under the flange  111  at a central position so as to align with the central axis  600 . The piston housing  116  may be positioned between the first and second fastener holes  144  and  146  with respect to a lateral direction extending perpendicular to the central axis  600  (e.g., in a direction parallel to line  5 - 5  of  FIG.  6   ). The piston housing  116  may have a cylindrical shape, but aspects disclosed herein are not limited. The body  110  may have an inner bore  140  ( FIG.  4   ) configured to receive the piston  150 . The inner bore  140  may extend through the piston housing  116 , the flange  111 , and the extension  118 . An axial end of the piston housing  116  may define the distal end  124  of the body  110 , which may have a flat planar surface, but aspects disclosed herein are not limited. The distal end  124  may include an opening of the inner bore  140 . 
     The extension  118  may extend in a direction parallel to the central axis  600  from the flange  111  at a central position between the first side  112  and the second side  114 . The extension  118  may define the proximal end  122  of the body  110 . An outer surface of the extension  118  may have a cylindrical shape, and the extension  118  may alternatively be referred to as a cylindrical extension or portion. The extension  118  may include a bleeder or valve  136 . 
     The bleeder  136  may be disposed at the proximal end  122  of the body  110 . The bleeder  136  may be configured to exhaust air or gas from inside the body  110 . The bleeder  136  may, for example, be positioned on the proximal end  122  of the body  110  in front of (or alternatively, behind or along) the central axis  600  to be closer to a front side of the extension  118 . Systems and methods disclosed herein, however, are not limited to the illustrated positions of the first fitting  132 , the second fitting  134 , and the bleeder  136 . 
     The piston  150  may be axially moveable through the opening of the inner bore  140  ( FIG.  4   ) in a direction parallel to the central axis  600  and extend beyond the distal planar surface at the distal end  124  of the body  110 . A saddle  152  of the piston  150  may also be configured to rotate. The saddle  152  will be described in more detail with reference to  FIG.  4   . 
     The piston  150  may be coaxially aligned with an inner bore  140  of the body  110  along the central axis  600 . The piston  150  may be at least partially disposed in the piston housing  116 . As shown in  FIG.  3   , the piston  150  may extend to an outside of the piston housing  116  and beyond the distal end  124  defined by the bottom surface of the piston housing  116 . The piston  150  may be made of rigid material such as metal (e.g., stainless steel or carbon steel). The piston  150  may have a cylindrical shape with a flat bottom surface  153  at a bottom of the saddle  152 , but aspects disclosed herein are not so limited. 
     The bottom surface  153  may have an oval shape or otherwise have a length different from a width. The piston saddle  152  may include a side access tool hole  159  to allow rotation. A tool (e.g., screwdriver) may be inserted into the tool hole  159  so that the user may rotate the piston saddle  152  from a side of the piston  150  (e.g. after mounting on pipe system  200 ), and achieve more leverage than rotating the piston  150  with fingers. The piston saddle  152  may be rotated to control an orientation of the bottom surface  153  and to control an area of contact or a bearing load area between the bottom surface  153  and the first pipe flange  222  ( FIG.  1   ). In some applications, the bearing load area defined between the bottom surface  153  and the first pipe flange  222  may be subjected to hundreds, thousands, tens of thousands, or even hundreds of thousands pounds of force. A larger bearing load area may assist in an application of force in a coupling system  10  that may use less stud assemblies  300 . A size of the bottom surface  153  may be configured such that, in some applications, a portion of the bottom surface  153  extends beyond an edge of the first flange  222  ( FIG.  1   ) upon contact. 
       FIG.  4    shows an interior of the tensioner  100  along lines  4 - 4  of  FIG.  3    and  FIG.  6   .  FIG.  5    shows the interior of the tensioner  100  along lines  5 - 5  of  FIG.  3    and  FIG.  6   .  FIG.  4    shows the piston  150  in a first position, while  FIG.  5    shows the piston  150  in a second position. Referring to  FIGS.  4 - 5   , the inner bore  140  may have an inner radial surface  141 . The inner bore  140  may be configured to receive the piston  150  and a spring assembly  180  coupling the piston  150  to the piston housing  116 . The inner bore  140  may have a shape corresponding to an overall shape of at least a portion of the piston  150  (e.g., cylindrical) with inner dimensions (e.g., a diameter) corresponding to the outer dimensions (e.g., a diameter) of the piston  150  to accommodate fluid and movement of the piston  150 . The inner bore  140  may include a sealed annular cavity or hydraulic chamber  142  defined between an upper axial end of the piston  150 , an inner axial surface of the inner bore  140 , and the inner radial surface  141  of the inner bore  140 . The first and second fittings  132  and  134  and the bleeder  136  may be configured to be in fluid communication with the hydraulic chamber  142 . 
     The piston  150  may include the piston saddle  152  and a piston rod  154 . The bottom surface  153  of the piston saddle  152  may define a distal end of the piston  150 . The bottom surface  153  may be provided at an axial end of the piston saddle  152 . The piston saddle  152  may be constructed of a solid piece of material. The piston saddle  152  may be coupled (e.g., threaded, bolted, welded, fused, etc.) to a bottom of the piston rod  154 . For example, a saddle securing bolt  170  may couple the piston saddle  152  to the piston rod  154 . The saddle securing bolt  170  may be inserted through and/or engaged with an upper portion of the piston saddle  152  and a lower portion of the piston rod  154 . The saddle  152  may include an inner bore or hole for the saddle securing bolt  170 , and the saddle securing bolt  170  may be tightened or loosened with a tool (e.g., screwdriver) inserted into the inner bore. Alternatively, the piston rod  154  and the piston saddle  152  may be formed integrally to form a single, one-piece unitary piston  150  formed from a single piece of material. 
     The tool hole  159  may extend through the piston saddle  152 . The tool hole  159  may be provided at a height below a bottom of the saddle securing bolt  170  so as not to interfere with the saddle securing bolt  170 . The tool hole  159  may align with the inner bore or recess of the piston saddle  152  through which the saddle securing bolt  170  is inserted. Alternatively, a bottom of the saddle securing bolt  170  may include a hole that aligns with the tool hole  159 . 
     The saddle securing bolt  170  may be coupled to allow rotation of the piston saddle  152  with respect to the piston rod  154  such that, during rotation, the piston saddle  152  rotates independently from the piston rod  154 . A portion of the saddle securing bolt  170  engaged with the piston rod  154  may have threading, and another portion of the saddle securing bolt  170  engaged with the piston saddle  152  may not have threading to facilitate rotation of the piston saddle  152  with respect to the piston rod  154 . As shown more clearly in  FIG.  4   , the saddle securing bolt  170  may be coupled at a position which is laterally offset from a center of saddle  152 , so as to allow different bearing load areas. The saddle securing bolt  170  may serve as an eccentric shaft of rotation, and a rotation of the piston saddle  152  may be similar to that of an eccentric cam. A transverse cross-sectional area of the piston saddle  152  may have an oval shape as shown in dashed lines in  FIG.  6   , which indicates a shape of the bottom surface  153 . 
     The piston rod  154  may be at least partially disposed inside the inner bore  140 . The piston rod  154  may be axially moveable in relation to the inner bore  140 . In a first position of the piston  150  ( FIG.  4   ), a majority of the piston rod  154  may be disposed within the inner bore  140 . Alternatively, the piston rod  154  may be configured to be disposed entirely within the inner bore  140  when the piston is in the first position. In a second position of the piston  150 , the piston rod  154  may extend further outside the inner bore  140  to be exposed to an outside of the body  110 . The first position of the piston  150  may be referred to as a retracted position. The second position of the piston  150  may be referred to as an extended position or a protracted position. 
     The piston rod  154  may include an upper portion  151 , which may be wider than a remaining portion of the piston rod  154 . Inner dimensions of the inner bore  140  may be configured to correspond to outer dimensions of the upper portion  151  of the piston rod  154 . A transverse cross-sectional area of the upper portion  151  may have a circular shape and the inner bore  140  may be cylindrical, but aspects disclosed herein are not limited. A vertical length of the upper portion  151  of the piston rod  154  may define a piston stroke of the piston  150 . 
     An outer surface of the upper portion  151  of the piston rod  154  may include a piston seal or gasket  156  and a piston wear ring  158 . The piston seal  156  may be provided in a recess of the upper portion  151  of the piston rod  154  and assist in maintaining a sealed state of the hydraulic chamber  142 . The piston wear ring  158  may be provided in a recess of the upper portion  151  of the piston rod  154  at a position below the piston seal  156 . The piston wear ring  158  may help maintain a position of the piston rod  154  and distribute even pressure on the piston rod  154  to reduce wear on the piston rod  154 . 
     A top of the piston rod  154  may be positioned lower than a height of the bleeder  136 . However, aspects disclosed herein are not limited to positions of the first fitting  132 , the second fitting  134 , the bleeder  136 , and the hydraulic chamber  142  and/or the piston seal  156 . 
     A stop ring or retainer  160  may surround a portion of the piston rod  154  under the upper portion  151 , and a wiper seal  196  may be provided in a recess of the stop ring  160  to surround the piston rod  154 . The stop ring  160  may be coupled (e.g., threaded) to an inner surface of the piston housing  116 . The stop ring  160  may be provided in a lower recess of the piston housing  116  outside of the inner bore  140 . The stop ring  160  may help to limit a movement of the piston  150 . 
     The piston rod  154  may further include an inner bore that receives at least a portion of the spring assembly  180 . A shape or inner contour of the inner bore of the piston rod  154  may correspond to an outer shape or outer contour of the spring assembly  180 . The spring assembly  180  may elastically couple the piston rod  154  to the flange  111  and/or extension  118  of the body  110  at a side opposite to a side coupled to the piston saddle  152 . The spring assembly  180  may include a spring  182 , a first or upper spring retainer  184 , and a second or lower spring retainer  186 . 
     The spring  182  may be a coil spring or extension spring. The spring  182  may be coupled (e.g., engaged, pressed-fit, adhered, etc.) to the first and second spring retainers  184  and  186 . 
     The first spring retainer  184  may at least partially extend through and securely couple to a first or upper end of the spring  182 . The first spring retainer  184  may be coupled to the flange  111  and/or extension  118  via a first or upper socket head screw  188 . An upper end of the first spring retainer  184  may be formed with a recess or through hole having inner threads, and the first socket head screw  188  may have outer threads to engage with the inner threads of the first spring retainer  184 . An upper end of the extension  118  may include a through hole aligning with the through hole of the first spring retainer  184  and may also be formed with inner threads configured to engage with outer threads of the first socket head screw  188 . The through hole of the extension  118  may be shaped to correspond to an outer contour of the first socket head screw  188  and include a stepped portion configured to support a head of the first socket head screw  188 . A first or upper washer gasket  192  may be provided at the stepped portion. A top end of the first socket head screw  188  may be flush with an upper surface of the extension  118  at the proximal end  122  of the body  110 . 
     The second spring retainer  186  may at least partially extend through and securely couple a second or lower end of the spring  182 . The second spring retainer  186  may be coupled to the piston housing  116  via a second or lower socket head screw  190 . A lower end of the second spring retainer  186  may be formed with a recess or through hole having inner threads, and the second socket head screw  190  may have outer threads to engage with the inner threads of the second spring retainer  186 . A lower end of the second socket head screw  190  may protrude into a secondary inner bore of the piston rod  154  formed in a distal end of the piston rod  154 . At least a portion of the lower end of the second socket head screw  190  may be disposed in the secondary inner bore between the piston rod  154  and the piston saddle  152 . The saddle securing bolt  170  may also extend into the secondary inner bore below the second socket head screw  190 . 
     The piston rod  154  may include a through hole aligning with the through hole of the second spring retainer  186  and may be formed with inner threads configured to engage with outer threads of the second socket head screw  190 . The through hole of the piston rod  154  may be shaped to correspond to an outer contour of the second socket head screw  190  and include a stepped portion configured to support a head of the second socket head screw  190 . A second or lower washer gasket  194  may be provided at the stepped portion. The first and second washer gaskets  192  and  194  may be made of a metal (e.g., copper), but aspects disclosed herein are not limited. 
       FIG.  6    illustrates a top view of the tensioner  100  of  FIG.  2   . As previously described, the continuous side surface  126  of the body  110  may include the rear portion  128  and the front portion  130  opposite the first portion  128 . 
     The rear portion  128  may have a concave section having a concave curvature with respect to central axis  600 . The concave curvature of the concave section of the rear portion  128  may correspond to structures or pipes which are intended to be coupled, such as a curvature along the first and second pipe flanges  222  and  224  and/or around the first and second pipes  212  and  214  ( FIG.  1   ). The rear portion  128  may alternatively be referred to as an inner surface portion. An entirety of the rear portion  128  may not be concave. For example, the rear portion  128  may include straight or angled edges (or convex sections) near the first and second fastener holes  144  and  146 . 
     The front portion  130  may be curved or angled to connect to the rear portion  128 . For example, the front portion  130  may have a semicircular curvature. From a front side of the body  110 , a curvature of the front portion  130  may appear convex with respect to central axis  600 , and the front portion  130  may alternatively be referred to as an outer surface portion. The front and rear portions  128  and  130  are not limited to the shown shapes and curvatures, and the front and rear portions  128  and  130  may have shapes and/or curvatures configured for different applications or coupling elements. 
     The center axes  145 ,  147  ( FIG.  3   ) of the first and second fastener holes  144  and  146  may be closer to the rear portion  128  than the front portion  130 . The centers  145 ,  147  of the first and second fastener holes  144  and  146  may be between the central axis  600  of the piston housing  116  and the rear portion  128 . The centers  145 ,  147  ( FIG.  3   ) of the first and second fastener holes  144  and  146  may be intersected by  601  and  603 , respectively, from the central axis  600  of the piston housing  116 , and the first and second fastener holes  144  and  146  may be symmetrical with respect to line  4 - 4 . 
     Positions of the first and second fastener holes  144  and  146  may be configured based on positions of the fastener holes of the first and second pipe flanges  222  and  224  ( FIG.  1   ). A distance between the first and second fastener holes  144  and  146  may correspond to a distance between the fastener holes of the first and second pipe flanges  222  and  224 . With respect to a radial direction of the piston housing  116 , the centers  145 ,  147  ( FIG.  3   ) of the first and second fastener holes  144  and  146  may have radial positions which are spaced apart by an angle θ, which may be in a range of 80 to 100 degrees or 85 to 95 degrees (e.g., 90 degrees or 92 degrees), but aspects disclosed herein are not limited to a spacing of the fastener holes  144  and  146 . Line  4 - 4  may be perpendicular to line  5 - 5 , and lines  601  and  603  may intersect an angle between lines  4 - 4  and  5 - 5 . When the fastener holes  144  and  146  are spaced apart by 90 degrees, lines  601  and  603  may bisect the angle between lines  4 - 4  and  5 - 5  so as to extend at an angle of 45 degrees extend with respect to line  4 - 4  and with respect to line  5 - 5 . 
     Inner diameters of the first and second fastener holes  144  and  146  may correspond to an outer diameter of the stud assemblies  300  ( FIG.  1   ) (e.g., outer diameters of the tensioner stud  330 ) and/or inner diameters of the fastener holes of the first and second pipe flanges  222  and  224 . A diameter and transverse cross-sectional area of the piston  150  (i.e., diameters of both the piston rod  154  and the piston saddle  152 ) may be larger than diameters and transverse cross-sectional areas, respectively, of each of the first and second fastener holes  144  and  146 . In addition, as explained later, the diameter and transverse cross-sectional area of the piston  150  may be larger than diameters and transverse cross-sectional areas of the fastener holes of the first and second pipe flanges  222  and  224 . 
     An interior of the body  110  may include a pair of fluid channel or passages  198  and  199  in fluid communication with the hydraulic chamber  142  ( FIG.  5   ) and the pair of hydraulic fittings  132  and  134 , respectively. The pair of fluid channels  198  and  199  may extend through the flange  111 . The pair of fluid channels  198  and  199  may be symmetrical across line  4 - 4 . The pair of fluid channels  198  and  199  may not align, in a radial direction, with the central axis  600 . The pair of fluid channels  198  may be oriented at an angle in a range of 20 to 60 degrees (e.g., 30 degrees or 45 degrees) with respect to line  4 - 4 . The first and second fittings  132  and  134  may be in fluid communication with the pair of fluid channels  198  and  199 , respectively. The first and second fittings  132  and  134  may have radial positions, with respect to lien  4 - 4 , that correspond to radial positions of outer ends of the pair of fluid channels  198  and  199 . An angle and arc length between the first and second fittings  132  and  134  may be less than the angle θ and the arc length between the first and second fastener holes  144  and  146 . 
     The tensioner  100  may be sized based on a size of the first and second pipe flanges  222  and  224 . For example, the tensioner  100  may be configured to be installed on a 12-bolt flange connection or 16-bolt flange connection, but aspects disclosed herein are not limited. 
       FIG.  7    shows a tensioner stud  330  of the stud assembly  300 , and  FIG.  8    shows an uncoupled stud assembly  300 . Referring to  FIGS.  1  and  7 - 8   , as previously described, the stud assembly  300  may include the stud  310  and the tensioner stud  330 . The stud  310  may include external threading  312  configured to couple to the middle and lower nuts  420  and  430 . A length of the stud  310  may be sufficient for passage through the first and second pipe flanges  222  and  224 , but may be insufficient for passage through the tensioner  100 . 
     The tensioner stud  330  may include a body  331  and a base  332 . The body  331  may include external threading  338  configured to couple to the upper nuts  410 . The external threading  338  may cover a portion of the body  331 , but aspects disclosed herein are not limiting to a threading arrangement. The base  332  may include an inner space or recess  334  including internal threading  336  configured to engage with external threading  312  of the stud  310 . The base  332  may have a larger diameter than the body  331 , but aspects disclosed herein are not limited. The body  331  may be configured to be inserted into the first and second fastener holes  144 ,  146  of the tensioner  100 . The first and second fastener holes  144 ,  146  may be configured to allow a variety of sizes and types of tensioner studs  330 , or may alternatively be configured based on a specific type of tensioner stud  330 . The body  331  may have a same or similar diameter to the stud  310 . The stud  310  may be coupled to the tensioner stud  330  so that the stud assembly  300  has a length sufficient to pass through the first and second pipe flanges  222  and  224  and also the tensioner  100 . A diameter of the inner space  334  may be configured based on a diameter of a type of stud  310  used. 
       FIG.  9    shows three tensioners  100  of the coupling system  10  positioned around pipe system  200 . As noted above, the tensioners  100  may be installed via a plurality of stud assemblies  300  and a plurality of nuts  410 ,  420 , and  430 . The pipe system  200  may include a gasket or seal  226  (e.g., O-ring gasket) provided between the first and second pipe flanges  222  and  224 . The gasket or seal  226  may be made of, for example, a metal, a resilient material such as rubber or plastic, etc. 
     As noted above, the plurality of stud assemblies  300  may include a pair of stud assemblies  300 , each pair of stud assemblies  300  corresponding to one tensioner  100 . The pair of stud assemblies  300  may be extended through the pair of fastener holes  144  and  146 , respectively, of the tensioner  100 . The stud assemblies  300  may be provided at positions that that do not interfere with a movement of the piston  150 , and the piston  150  may be provided between stud assemblies  300  in a pair of stud assemblies  300 . The stud assemblies  300  may also be extended through fastener holes of the first and second pipe flanges  222  and  224 . At least a portion of the studs  310  and tensioner studs  330  may have threads (see  FIGS.  2  and  6 - 7   ) configured to engage with the plurality of nuts  410 ,  420 , and  430 . 
     The plurality of nuts  410 ,  420 , and  430  may secure the plurality of stud assemblies  300  and the tensioner  100  to the first and second pipe flanges  222  and  224 . The plurality of nuts  410 ,  420 , and  430  may include a first or upper nut  410 , a second or middle nut  420 , and a third or lower nut  430 . The middle nut  420  may alternatively be referred to as the first nut, and the upper nut  410  may alternatively be referred to as the second nut. The upper, middle, and lower nuts  410 ,  420 , and  430  may be standard hexagonal nuts (hex nuts) and may have internal threading configured to grip the studs  300 . The upper, middle, and lower nuts  410 ,  420 , and  430  and the studs  300  may be made of a metal (e.g., stainless steel), but aspects disclosed herein are not limited. 
     A lower nut  430  may be inserted onto a first stud  310  of a first stud assembly  300 , and the first stud  310  may be inserted through the first and second pipe flanges  222  and  224 . A lower nut  430  may be inserted onto a second stud  320  ( FIG.  2   ) of a second stud assembly  300 , and the second stud  310  may be inserted through the first and second pipe flanges  222  and  224 . The lower nuts  430  may remain below the first and second pipe flanges  222  and  224  to be positioned at a lower side of the second pipe flange  224  ( FIG.  1   ). As an alternative to inserting lower nuts  430 , distal ends of the first and second studs  310  and  320  may include a fastener (e.g., a bolt head). A pair of middle nuts  420  may be inserted onto the first and second studs  310  and  320 , respectively, to be above the first and second pipe flanges  222  and  224 . The tensioner  100  may be placed on the first and second studs  310  and  320  above the middle nuts  420 . The middle nuts  420  may be positioned at a second or lower side of the body  110  to be under the tensioner stud  330  and the flange  111 . The middle nuts  420  may be positioned above the first and second pipe flanges  222  and  224  to be provided at an upper side of the first pipe flange  222  ( FIG.  1   ). A pair of upper nuts  410  may be placed on the first and second studs  310  and  320 , respectively, to be provided above the tensioner  100 . The upper nuts  410  may be provided at a first or upper side (or a proximal end surface) of the body  110  toward first or upper ends of the first and second studs  310  and  320 . 
       FIG.  9    shows forces during a tightening operation of the tensioner  100 . Prior to actuation of the tensioner  100 , at least the upper and lower nuts  410  and  430  may be tightened to be flush with the surfaces they are contacting. The fastener holes of the first pipe flange  222  and the fastener holes of the second pipe flange  224  may be respectively aligned in a vertical or axial direction of the first and second pipes  212  and  224 , while the first and second fastener holes  144  and  146  ( FIG.  5   ) of the tensioner  100  may be aligned with at least some of the fastener holes of the first and second pipe flanges  222  and  224 . The stud assemblies  300  may extend through aligned fastener holes of the first and second pipe flanges  222  and  224 , along with the first and second fastener holes  144  and  146  of the tensioner  100 . Before tensioning, the first and second pipe flanges  222  and  224  may be spaced apart by a first axial spacing, and the gasket  226  may be provided in the first axial spacing. 
     When the pump  502  ( FIG.  1   ) is actuated, hydraulic fluid (e.g., oil)  506  may be supplied through the first fitting  132  to the hydraulic chamber  142  of the flange  111  via the hydraulic tubing  504  and a fluid channel or passage  198 . The hydraulic tubing  504  may be in fluid communication and aligned with the fluid channel  198 , which may be in fluid communication with the hydraulic chamber  142 . As hydraulic fluid  506  fills the hydraulic chamber  142 , air and/or gas may be exhausted through the bleeder  136 . 
     The plurality of hydraulic stud tensioners  100  may be connected in series via the hydraulic tubing  504 , and the hydraulic fluid  506  may be supplied to all of the hydraulic chambers  142  of the plurality of hydraulic stud tensioners  100 . Although hydraulic pressure will initially be uneven among all of the plurality of hydraulic stud tensioners  100 , eventually, the hydraulic pressure may even out as hydraulic fluid  506  is supplied to all of the hydraulic chambers  142  of the piston housings  116  of each tensioner  100  via the first and second fittings  132  and  134  and the hydraulic tubing  504 . Hydraulic fluid  506  may, for example, enter through first fitting  132  and exit through the second fitting  134  via fluid channel  199 . 
     As more hydraulic fluid  506  is supplied to the hydraulic chamber  142 , the hydraulic fluid  506  may create a hydraulic pressure which acts on a proximal or top side of the piston rod  154 , pushing the entire piston  150  (i.e., the piston rod  154  and the piston saddle  152 ) downward to extend out of the piston housing  116  and toward the first pipe flange  222 . This hydraulic force is exemplified by the downward direction of arrow  602 . As the piston  150  is extended downward, the spring  182  may be in tension and expanded. 
     Eventually, the hydraulic force will cause the piston  150  to apply a downward force, on the first pipe flange  222 , as indicated by arrow  602 . The piston  150  may be aligned axially with a fastener hole of the first pipe flange  222 . The piston saddle  152  may have a diameter which is greater than a diameter of the fastener holes in the first and second pipe flanges  222  and  224  such that the piston saddle  152  may contact the first pipe flange  222  at an area which is radially outside of the fastener hole of the first pipe flange  222 . The pistons  150  of each tensioner  100  may press down together on the first pipe flange  222  to apply an even downward force on the first pipe flange  222  (arrow  604 ). 
     As a downward force is exerted on the piston  150 , an upward force is exerted on the body  110  against the upper nuts  410 , which may urge the flange  111  upward against the upper nuts  410  at the first and second sides  112  and  114 , indicated by arrow  604 . The bodies  110  of each tensioner  100  together may press upward against the upper nuts  410 . The upper nuts  410  may serve as a leverage point for hydraulic pressure to exert the downward force on the piston  150  and for the piston  150  to exert a downward force on the first pipe flange  222  (arrow  602 ). 
     As the body  110  is moved upward against the upper nuts  410 , the stud assemblies  300  may be tensioned. As the stud assemblies  300  are tensioned and as the piston  150  exerts a downward force on the first pipe flange  222 , a distance between the first pipe flange  222  and the middle nuts  420  may increase. In this way, the hydraulic force of the tensioner  100  may move the piston  150  in a direction opposite to a direction in which the upper nuts  410  are urged, in which the stud assemblies  300  are tensioned, and in which the second pipe flange  224  may be moved. 
     The first pipe flange  222  may exert a downward force on the gasket  226  provided between the first and second pipe flanges  222  and  224 , as indicated by arrow  608 . In addition, as the stud assemblies  300  are tensioned, the lower nuts  430  may exert an upward force on the second pipe flange  224 , as indicated by arrow  610 , which may cause the second pipe flange  222  to exert an upward force on the gasket  226 , as indicated by arrow  612 . The gasket  226  may be compressed or crushed between the first and second pipe flanges  222  and  224  as an axial spacing between the first and second pipe flanges  222  and  224  is decreased from the first axial spacing to a second axial spacing which is closer or shorter than the first axial spacing. 
     Once the gasket  226  is compressed, the middle nuts  420  may be tightened downward against the first pipe flange  222  to maintain a compressed state of the gasket  226  and to maintain the second axial spacing. Because the middle nuts  420  are exposed and not within the body  110 , the middle nuts  420  may be tightened with an open-faced hand wrench. 
     Once the middle nuts  420  are sufficiently tightened or positioned (based on the clamping of the flanges  222 ,  224  provided by tensioners  100 ), the hydraulic pressure may be released via a release valve of the pump  502 . Releasing the hydraulic pressure in tensioners  100  will allow the springs  182  to urge the pistons  150  back inside the inner bore  140  in the distal direction via an elastic restoring force. Then, the upper nuts  410  may be removed, along with the tensioner  100 . 
       FIG.  10    illustrates the above described method for tensioning studs to couple two flanges. For convenience of description, an example where the stud assemblies  300  include tensioner studs  330  and studs  310 ,  320  will be described, but aspects disclosed herein are not limited to a configuration of the stud assemblies  300 . Referring to  FIGS.  1 - 10   , in step S 1001 , to prepare the first and second pipe flanges  222  and  224  for tightening, a plurality of pairs of studs  310 ,  320  may be inserted through a plurality of fastener holes of the first and second pipe flanges  222  and  224 . Each pair of studs  310 ,  320  may include a first stud  310  and a second stud  320 . Before insertion of the first and second studs  310 ,  320 , the gasket  226  may be inserted between the first and second pipe flanges  222  and  224 . 
     Not every fastener hole of the first and second pipe flanges  222  and  224  may have a stud  310 ,  320  inserted therethrough. For example, where the first and second pipe flanges  222  and  224  are 12-bolt flanges, four pairs of studs  310  and  320  (for a total of eight) may be used. The first and second studs  310 ,  320  may be arranged in the first and second pipe flanges  222  and  224  to have an empty fastener hole between the first and second studs  310  and  320 . The empty fastener holes of the first and second pipe flanges  222  and  224  may be aligned with each other in an axial direction and may be configured to ultimately align with the piston  150  of the tensioner  100 . The second stud  320  of one pair of studs  300  may be inserted into a fastener hole which is adjacent to a fastener hole in which a first stud  310  of an adjacent pair of studs  300  is inserted. 
     Once the pairs of studs  310 ,  320  have been inserted through the first and second pipe flanges  222  and  224 , in step S 1002 , middle and lower nuts  420  and  430  may be threaded onto the studs  300 . The lower nuts  430  may be tightened against the first second pipe flange  224  and fixed to distal ends of the studs  300 , while the middle nuts  420  may be left to rotate freely and/or the middle nuts  420  may be hand-tightened or loosely tightened. The first and second pipe flanges  222  and  224  may be positioned between the middle and lower nuts  420  and  430 . The lower nut  420  may be tightened using an open-faced hand wrench, but embodiments disclosed herein are not limited. The tensioner studs  330  may be coupled to the first and second studs  310  and  320  after placing the middle nuts  420 . 
     In step S 1003 , to install the tensioner  100 , at least one tensioner  100  may be placed on two or more tensioner studs  330  above the middle nuts  420 . When tensioner studs  330  are omitted, the at least one tensioner  100  may be placed on two or more studs  310 ,  320  above the middle nuts  420 . At this step, a plurality of hydraulic stud tensioners  100  may be provided on the plurality of stud assemblies  300 . For example, when using 12-bolt flanges, four hydraulic stud tensioners  100  may be applied to eight stud assemblies  300  arranged on the first and second pipe flanges  222  and  224 . Each tensioner  100  may be applied to a pair of stud assemblies  300 , where each pair has the first and second studs  310  and  320 . 
     The first and second fastener holes  144  and  146  of each tensioner  100  may be inserted onto the pair of stud assemblies  300 , respectively, to be aligned with the fastener holes of the first and second pipe flanges  222  and  224 . The tensioners  100  may be configured based on a size of the first and second pipe flanges  222  and  224 . In addition, at least some aspects of the stud tensioners  100  (e.g., the first and second fastener holes  144  and  146 ) may be configured based on sizes of the stud assemblies  300 . Step S 1003  may also be performed on a previously tightened pair of first and second pipe flanges  222  and  224 . For example, tensioner studs  330  may be coupled to previously tensioned studs  310 ,  320  above middle nuts  420 , and the tensioner  100  may be placed on the tensioner studs  330 . Steps S 1004  through S 1008  may be performed to further tighten and compress the gasket  226  between the first and second pipe flanges  222  and  224 . 
     In step S 1004 , upper nuts  410  may be placed on the studs  300  above the first and second sides  112  and  114  of the tensioner  100 . The upper nuts  410  may be tightened against the proximal end surface of the body  110  at the first and second sides  112  and  114  and fixed to proximal ends of the studs  300 . The upper nuts  410  may be tightened using an open-faced hand wrench, but embodiments disclosed herein are not limited. 
     In step S 1003 , step S 1004 , or before step S 1005 , hydraulic tubing  504  may be connected to the first fitting  132 . When a plurality of tensioners  100  are used, the plurality of tensioners  100  may be connected in series by connecting hydraulic tubing  504  between a second fitting  134  of a first tensioner  100  and a first fitting  134  of an adjacent second tensioner  100 . As an alternative, each tensioner  100  may be connected to its own pump  502  and/or hydraulic fluid supply system  500 , and the pumps  502  and/or hydraulic fluid supply systems  500  may be connected in series via hydraulic tubing  504 . 
     In step S 1005 , hydraulic fluid  506  may be supplied to the tensioner  100  via the hydraulic tubing  504  and the first fitting  132 . As previously described, when a plurality of tensioners  100  are used, hydraulic fluid  506  may enter all of the hydraulic chambers  142  of the hydraulic stud tensioners  100  via the first and second fittings  132  and  134  to apply a generally uniform compressive force on flanges  222 ,  224 . The hydraulic pressure may urge the pistons  150  downward toward and ultimately against the first pipe flange  222 . Where the piston  150  may axially align with empty fastener holes in the first and second pipe flanges  222  and  224 , the piston  150  may be pressed against the first pipe flange  222  at an area radially outside of the empty fastener hole in the first pipe flange  222 . As the pistons  150  are forced downward, the first and second sides  112  and  114  of the flange  111  of the tensioner  100  may be forced upward, pulling the upper nuts  410  and studs  300  upward. The gasket  226  may be compressed between the first pipe flange  222  and the second pipe flange  224 . 
     The hydraulic pressure may be increased by controlling the pump  502 . As an example, the pump  502  may be controlled to apply a pressure to provide a required force to complete a coupling of the first and second pipe flanges  222  and  224 . For example, the pump  502  may be controlled to apply a pressure of 2300 pounds per square inch (psi) when three hydraulic stud tensioners  100  are used on six studs  300 . As another example, the pump  502  may be controlled to apply a pressure of 3500 psi when two hydraulic stud tensioners  100  are used on four studs  300 . A pressure gauge may indicate a pressure of the pump  502 . The pump  502  may be configured to apply a predetermined pressure based on the materials and dimensions of the pipe system  200  and the tensioner  100 . The pump  502  may be set to apply the predetermined pressure, and further monitoring may not be necessary, so other sensors may not be required. The predetermined pressure may be applied for a predetermined time period or until the pistons  150  have extended by a predetermined amount or piston stroke. 
     In step S 1006 , the middle nuts  420  may be tightened using an open-faced hand wrench against the first pipe flange  222  to secure a connection between the first and second pipe flanges  222  and  224  and to maintain a compression of the gasket  226 . 
     In step S 1007 , hydraulic pressure may be released by removing hydraulic fluid  506  from the hydraulic chamber  142  via a pressure release at pump  502 . The hydraulic fluid  506  may be urged by the return movement of pistons  150  via spring  182  to enter the hydraulic tubing  504  and return to the pump  502 . The spring  182  may pull the piston  150  back to an initial position such that the piston rod  154  may be inside the piston housing  116 . The hydraulic tubing  504  may be removed from the first and/or second fittings  132  and/or  134  once the hydraulic pressure is released. 
     In step S 1008 , to remove the tensioner  100 , the upper nuts  410  may be loosened via an open-faced wrench and removed. The tensioner  100  may be lifted off the tensioner studs  330 , and the tensioner studs  330  may be removed from the first and second studs  310  and  320 . The first and second studs  310  and  320  may remain. After the tensioner  100  is removed, the tensioner  100  may be ready for a next operation without any further manipulation. The tensioner  100  may also be further tightened by repeating the method starting at step S 1003 . 
     INDUSTRIAL APPLICABILITY 
     The disclosed aspects of the tensioner of the present disclosure may be used to tension fasteners (e.g., studs or bolts) in coupling two structures together and may also be used to move the two structures toward each other. For example, the tensioner may be used to urge studs running through pipe flanges and also to provide a force that compresses a gasket or seal between the two pipe flanges to seal a connection. The tensioner may be used to pre-tension two fasteners (e.g., bolts or studs) prior to coupling two structures together. 
     Aspects of the present disclosure may provide a tensioner that requires just one piston to pull two fasteners which are spaced apart in a direction perpendicular to a direction in which the fasteners are pulled (e.g., a lateral or circumferential direction). Aspects of the present disclosure may provide a tensioning method that does not require fasteners to be directly coupled to a piston, providing an easier and quicker installation process and a less complicated connection. 
     Aspects of the present disclosure may provide a tensioning method that uses a tensioner having a rotatable piston saddle to customize a bearing load area during tensioning. Aspects of the present disclosure may allow a larger piston to accommodate higher pressures and bearing loads. The tensioner disclosed herein may withstand a pressure of 7,500 psi or 15,000 psi. Aspects of the present disclosure may provide a tensioner stud which allows for use of shorter studs, bolts, or other fasteners in tensioning. Using shorter studs may provide a more compact coupling system once the tensioner and tensioner stud are removed, and there may not be excess stud length exposed in the coupling system. 
     Aspects of the present disclosure may provide a tensioning method that uses a small number of standard tools, such as tools already known to be compliant with American Petroleum Institute (API), American Society of Mechanical Engineers (ASME), American Society for Testing and Materials (ASTM International), and/or American National Standards Institute (ANSI) standards, to streamline a process and reduce manufacturing costs. Aspects of the present disclosure may provide a tensioner that uses readily available or standard size pistons to reduce manufacturing costs and that uses pistons having a solid bottom surface to apply a more even force on a structure to be tightened. 
     Aspects of the present disclosure may use less accessory parts and standard tooling, making repair and installation simpler and quicker, saving, for example, an hour of time connecting parts. Aspects of the present disclosure may provide a tensioning method which is safer by reducing a number of required connections and by providing standard pistons having a flat bottom surface. Aspects of the present disclosure may provide a tensioner which is sized according to a flange size rather than a fastener (e.g., stud or bolt) size, making identification of which tool to use easier. Aspects of the present disclosure may provide a tensioner with multiple seals to seal an inner bore of a piston housing, making a process of applying hydraulic pressure more effective. Aspects of the present disclosure may provide a quicker and less complicated tensioning method by allowing for hand and/or manual wrench tightening only. Aspects of the present disclosure may provide a quicker and more efficient tensioning method by reducing a number of fasteners (e.g., studs). Aspects of the present disclosure may tighten two coupling elements (e.g., plates or pipe flanges) using less studs than a number of stud holes provided in the coupling elements. Aspects of the present disclosure may provide a tensioner which can be reused for multiple tensioning processes. 
     It will be apparent to those skilled in the art that various modifications and variations can be made to the disclosed system without departing from the scope of the disclosure. Other embodiments of the system will be apparent to those skilled in the art from consideration of the specification and practice of the system disclosed herein. It is intended that the specification and examples be considered as exemplary only, with a true scope of the disclosure being indicated by the following claims and their equivalents.