Abstract:
System, method and/or apparatus repairs an area of damaged mesh in a sifter screen ( 80 ). Such sifter screens ( 80 ) have woven wire mesh ( 81 ) stretched, tensioned and/or secured over a supporting frame ( 85 ) having cells ( 82 ). Damage occurs to the mesh ( 81 ) over certain cells ( 82 ). A plug ( 10 ) having a mesh layer ( 14 ) inserts and/or locks into place in the damaged cell ( 89 ). The mesh layer ( 14 ) of the plug ( 10 ) is flush with the mesh ( 81 ) on the sifting screen ( 80 ). Ridges ( 62 ) and/or ledges ( 66 ) secure the plug ( 10 ) in place by engaging a lip ( 96 ) in the damaged cell ( 89 ) to snap-fit the plug ( 10 ) in place.

Description:
BACKGROUND 
     The embodiments disclosed herein relate generally to a system, an apparatus, and/or a method for filtering and/or separating particles. More specifically, embodiments disclosed herein relate to a system, an apparatus, and/or a method for repairing damaged sifter screens using plugs with a mesh layer. 
     Sifter screens are used to filter particles in industrial filtration systems. Different sizes and/or types of particles may be separated using filter screens in a vibratory separator. In the oil and gas industry, for example, shale shakers use filter screens to separate drill cuttings from drilling fluid in on-shore and/or off-shore oilfield drilling. The sifter screens have a wire mesh fixed across a frame. The frame has a rectangular grid of support ribs that divide the frame into an orthogonal array of cells. The mesh is secured to the ribs as well as to the surrounding frame. To promote separation, vibrational and/or circular motion is applied to the sifter screen. 
     The wire mesh has different mesh sizes defined by the size of the apertures between the individual wires in the mesh. The size of the apertures of the mesh is selected depending on the size of the particle to be filtered. Particles smaller than the aperture pass through the wire mesh and/or through the cells between the ribs. The remaining particles are discharged at an end of the filter screen. The discharged particles are collected in a bin and/or a pit. The particles and/or fluid that pass through the mesh are collected in a pan and/or a sump below the sifter screen. The particles and/or fluid that pass through the mesh may also pass through a secondary processing system, such as a degasser. 
     Over the life of the filter screen, the particles cause wear on the wire mesh. Because of the cellular structure, the strain and/or damage experienced by the mesh is isolated over each cell. Damage causes a breach in the mesh in one or more of the small unsupported areas between the cells. As a result, that area of the mesh allows larger particles to pass through than desired. Once the damage occurs, the screen must be replaced or repaired. Certain regions of the mesh are more prone to damage than other regions. For example, the mesh stretched across cells below where the particles are introduced experience greater wear than the mesh stretched across cells towards the exit end of the screen. 
     To extend the operational life of the screen, the cell with the damaged mesh may be blocked by epoxy or other plastic or resin based material. Alternatively, solid plugs may be installed into the cell to block particles from going through damaged wire mesh. These solid plugs fit into the cells and have a solid surface oriented towards the damaged mesh. The solid plugs fit into the cell from below and are hammered into place. As such, these solutions are designed to block particles from traveling through the damaged screen and/or the cell. Therefore, the cells with the epoxy or solid plugs no longer filter particles. 
     The solid plugs cannot be reused as they are hammered in place without a way to remove them. As more of the plugs are installed into more of the cells, the filtering ability of the filter screen is reduced. As more solid plugs are installed, the filter screen must eventually be replaced. When the filter screen is discarded, the installed plugs are also discarded. 
    
    
     
       DESCRIPTION OF THE DRAWINGS 
         FIG. 1  illustrates an isometric view of an embodiment of a plug. 
         FIG. 2  illustrates an isometric view of an embodiment of the plug with a mesh layer. 
         FIG. 3  illustrates a top view of an embodiment of the plug. 
         FIG. 4  illustrates an isometric view of the bottom of a sifter screen with an embodiment of the plug inserted into a cell of the sifter screen. 
         FIG. 5  illustrates an isometric view of the top of the sifter screen with an embodiment of the plug inserted into a cell of the sifter screen. 
         FIG. 6  illustrates a cutting tool useful in embodiments disclosed herein. 
     
    
    
     DETAILED DESCRIPTION 
     The embodiments disclosed herein relate generally to a system, an apparatus, and/or a method for filtering and/or separating particles. More specifically, embodiments disclosed herein relate to a system, an apparatus, and/or a method for repairing damaged sifter screens using plugs with a mesh layer. 
     Sifter screens may be used to filter particles in industrial filtration systems. Different sizes and/or types of particles may be separated using filter screens in a vibratory separator. In the oil and gas industry, for example, shale shakers may use filter screens to separate drill cuttings from drilling fluid in on-shore and/or off-shore oilfield drilling. The sifter screens may have a wire mesh fixed across a frame. The wire mesh may be glued and/or embedded into the frame. The frame may have a rectangular grid of support ribs that may divide the frame into an orthogonal array of cells. The mesh may be secured to the ribs as well as to the surrounding frame. To promote separation, vibrational and/or circular motion may be applied to the sifter screen. 
     Referring to  FIGS. 1-3 , an embodiment of a plug  10  is shown.  FIG. 1  illustrates an embodiment of the plug  10  having a body  12 .  FIG. 2  illustrates an embodiment of the plug  10  wherein the body  12  of the plug  10  has a mesh layer  14 .  FIG. 3  illustrates a top plan view of an embodiment of the plug  10 . 
     In an embodiment, the body  12  may have a top  16 , a bottom  18  and/or a top surface  20 . The body  12  may be manufactured from a resilient plastic material, a thermoplastic material and/or a composite of glass reinforced plastic material. In an embodiment, the body  12  may be molded as one piece. 
     The body  12  may have a first end  22  and/or a second end  24 . The first end  22  may be located in a position opposite to the second end  24 . The first  22  end may have a flat wall  26 , a convex wall  28  and/or a space  30  defined between the flat wall  26  and the convex wall  28 . The convex wall  28  of the first end  22  may extend into an interior portion  31  of the body  12 . The second end  24  may have a flat wall  32 , a convex wall  34  and/or a space  36  defined between the flat wall  32  and the convex wall  34 . The convex wall  34  of the second end  24  may extend into the interior portion  31  of the body  12 . 
     The body  12  may have a first side  38  and/or a second side  40 . The second side  40  may be located in a position opposite to the first side  38 . The first side  38  may extend a length from the first end  22  to the second end  24 . The second side  40  may extend a length from the first end  22  to the second end  24 . The interior portion  31  of the body  12  may be defined by the first side  38  and/or the second side  40 . 
     A support member  46  may extend between the first side  38  and/or the second side  40 . The support member  46  may be located in a position between the first end  22  and/or the second end  24  of the body  12 . In an embodiment, the support member  46  may be equidistant from the first end  22  and the second end  24 . The support member  46  may have an upper portion  48  and/or a lower portion  50 . The upper portion  48  may have a width defined by the first side  38  and/or the second side  40 . The lower portion  50  may be located in a position between the upper portion  48  and the bottom  18  of the body  12 . The lower portion  50  of the support member  46  may have a first side support  52  that may be adjacent to the first side  38 . The first side support  52  may be parallel to the first side  38  and/or perpendicular to the support member  46 . The lower portion  50  of the support member  46  may have a second side support  54  that may be adjacent to the second side  40  as shown in  FIG. 4 . The second side support  54  may be parallel to the second side  40  and/or may be perpendicular to the support member  46 . 
     At the top  16  of the body  12 , the top surface  20  may be formed by the first end  22 , the second end  24 , the first side  38 , the second side  40  and/or the support member  46 . The top surface  20  may be generally planar. A rim  56  may extend from the top surface  20  of the body  12 . The rim  56  may have a thickness less than the thickness of the top surface  20 . The rim  56  may be formed on the top surface  20  on each of the first end  22 , the second end  24 , the first side  38  and/or the second side  40  of the body  12 . Moreover, in an embodiment, the rim  56  may be formed on the top surface  20  on each of the convex wall  28 , the convex wall  34  and/or the support member  46 . 
     Referring to  FIGS. 1 and 2 , the flat wall  26  at the first end  22  of the body  12  and/or the flat wall  32  at the second end  24  of the body  12  may have a reduced width portion  54 . Thus, a portion of the flat wall  26  at the first end  22  and/or a portion of the flat wall  32  at the second end  24  may extend beyond the first side  38  of the body  12  and/or the second side  40  of the body  12 . The first side  38  of the body  12  and/or the second side  40  of the body  12  may be recessed within the overall width of the flat wall  26  and/or the flat wall  32 . 
     The first side  38  of the body  12  and/or the second side  40  of the body  12  may each have ridges  62  which may protrude outwardly from the body  12 . In an embodiment, the first side  38  and/or the second side  40  may each have a central ridge  62   a , a first end ridge  62   b  and/or a second end ridge  62   c . The central ridge  62   a  may be longer than the first end ridge  62   b  and/or the second end ridge  62   c . In an embodiment, the central ridge  62   a  on the first side  38  may be located in a position at which the support member  46  may intersect the first side  38 . Additionally, the central ridge  62   a  on the second side  38  may be located in a position at which the support member  46  may intersect the second side  40 . The first end ridge  62   b  may be located in a position that may be adjacent to the reduced width portion  54  of the flat wall  26  at the first end  22  of the body  12 . The second end ridge  62   c  may be located in a position that may be adjacent to the reduced width portion  54  of the flat wall  32  at the first end  24  of the body  12 . 
     In another embodiment, the central ridge  62   a  on the first side  38  and/or the second side  40  may be equidistant from the first end and the second end  24 . The first end ridge  62   b  may abut the first end  22 . Additionally, the second end ridge  62   c  may abut the second end  24 . The ridges  62  may have a triangular cross-section. The ridges  62  may have a flat side  64  that may extend perpendicular to the first side  38  of the body  12  and/or the second side  40  of the body  12 . 
     The first side  38  and/or the second side  40  may each have ledges  66  that may be located on the body  12 . The ledges  66  may be located in positions between the ridges  62 . The ledges  66  may have a tapered portion  68  and/or a body portion  70 . The body portion  70  may protrude outwardly away from the first side  38  of the body  12  and/or from the second side  40  of the body  12 . The body portion  70  of the ledges  66  may extend outwardly a first distance from each of the first side  38  and/or the second side  40  of the body  12 . The ridges  62  may extend outwardly a second distance from each of the first side  38  and/or the second side  40  of the body  12 . In an embodiment, the first distance and the second distance may be equal. 
     The tapered portion  68  of each of the ledges  66  may protrude outwardly from each of the first side  38  of the body  12  and/or the second side  40  of the body  12 . The tapered portion  68  may be angled downwardly to the body portion  70  of the ledge  66 . 
     As shown in  FIG. 2 , the mesh layer  14  may be affixed onto the top  16  of the body  12 . The mesh layer  14  may have a top side  74  and/or a bottom side  76 . The bottom side  76  of the mesh layer  14  may be located in a position opposite to the top side  74  of the mesh layer  14 . In an embodiment, the bottom side  76  of the mesh layer  14  may be supported by the rim  56  extending from the top surface  20  of the body  12 . The mesh layer  14  may be glued to the rim  56 . 
     In another embodiment, the mesh layer  14  may be embedded into the rim  56 . In such an embodiment, the body  12  may be made from a thermoplastic material. The mesh layer  14  may be placed on the rim  56 . Heat and/or pressure may be applied to the mesh layer  14  and/or the rim  56 . The thermoplastic material of the rim  56  may melt around the mesh layer  14 . The rim  56  may subsequently cool, harden and/or encompass the portion of the mesh layer  14  in contact with the rim  56  to hold the mesh layer  14  in place. 
     The mesh layer  14  may be a single layer of woven mesh wire or may be multiple layers of woven mesh wire. The mesh layer  14  may be a mesh cloth. The mesh layer  14  may have a mesh size to filter particles. For example, the mesh layer  14  may have the mesh size to separate drill cuttings from circulated drill fluid. The mesh size as used herein refers to the size of the apertures in the mesh layer  14 . 
     Referring to  FIGS. 4 and 5 , a sifter screen  80  which may be used in an industrial filtration system (not shown) is illustrated. The sifter screen  80  may have a bottom  78  and/or a top  79 . The top of the sifter screen  80  may have a mesh  81  that may filter liquids and/or particles. As shown in  FIGS. 4 and 5 , the sifter screen  80  may be divided into rectangular cells  82  by an orthogonal array of ribs  84  and/or a perimeter frame  86 . In an embodiment, the sifter screen  80  may have twelve cells  82  as shown. However, in other embodiments, depending upon the size and/or configuration of the sifter screen  80 , the number of cells  82  may be more than 100 cells, for example. 
     In an embodiment of the sifter screen  80 , the mesh  81  may be glued to the orthogonal array of ribs  84  and/or the perimeter frame  86 . In an embodiment, the mesh  81  may be embedded into the orthogonal array of ribs  84  and/or the perimeter frame  86 . In such an embodiment, the sifter screen  80  may be made from a thermoplastic material. The mesh  81  may be placed on the top  79  of the sifter screen  80 . Heat and/or pressure may be applied to the mesh  81  and/or to the sifter screen  80 . The thermoplastic material of the sifter screen  80  may melt around the mesh  81 . The sifter screen  80  may subsequently cool, harden and/or encompass the portion of the mesh  81  in contact with the sifter screen  80  to hold the mesh  81  in place. The mesh  81  may cover the top  79  of the sifter screen  80  and/or may extend over the perimeter frame  86 . 
     In another embodiment, the mesh  81  may be attached to the orthogonal array of ribs  84  and/or the perimeter frame  86 . Moreover, the mesh  81  above each of the cells  82  may be isolated from one cell  82  to another adjacent cell  82 . 
     During use, the sifter screen  80  may become damaged. For example, shale shakers that may be used in the oil and gas industry may separate drill cuttings from drilling fluid in on-shore and/or off-shore oilfield drilling. Such a harsh environment may be destructive to the sifter screen  80  over a period of extended use. For example, the mesh  81  above one or more of the cells  82  may become damaged from repeated exposure to the drill cuttings. Periodic inspections of the sifter screen  80  may indicate that damage may have occurred to the mesh  81 . For example,  FIG. 5  illustrates a damaged cell  89 . The mesh  81  may be torn and/or otherwise damaged above the damaged cell  89 . The mesh  81  may be removed without removing the non-damaged portion of the mesh  81  over the other cells  82 . 
     To begin a repair of the damaged cell  89 , the sifter screen  80  may be removed from the industrial filtration system (not shown). The damaged portion of the mesh  81  of the sifter screen  80  may be identified. In particular, the damaged cell  89  corresponding to the damaged portion of the mesh  81  may be identified. If a large portion of the mesh  81  becomes damaged, more than one cell  82  may be damaged. Thus, more than one cell  82  may be identified and/or repaired. The mesh  81  of the sifter screen  80  above the damaged cell  89  may be removed. 
       FIG. 6  illustrates a cutting tool  90  that may be useful in embodiments of a repair system for the sifter screens  80  as disclosed herein. The cutting tool  90  may be sized and/or configured to fit over the damaged cell  89 . The cutting tool  90  may have a rectangular shape to replicate the rectangular shape of the damaged cell  89 . The cutting tool  90  may have cutting edges  92  on the rectangular periphery of the cutting tool  90 . The cutting tool  90  may be dimensioned to fit on the orthogonal array of ribs  84  over the mesh  81  of the damaged cell  89 . 
     The cutting tool  90  may have an alignment rod  94  to aid in positioning the cutting tool  90  over the damaged cell  89 . The alignment rod  94  may be located in the center of the cutting tool  90 . The alignment rod  94  may be placed on the center of the damaged cell  89  to position the cutting tool  90  over the damaged cell  89  for removal of the damaged mesh  81 . The cutting tool  90  may have a striking rod  97 . A hammer and/or a mallet (not shown) may be used to hit the striking rod  97  to impart a force to the cutting edges  92  of the cutting tool  90 . The cutting edges  92  may thereby sever the mesh  81  around the periphery of the damaged cell  89 . All layers of screen cloth, not just the damaged top layer of the mesh  81 , may be cut from the individual damaged cell  89  relative to the other discrete cells  82 . The removal of the mesh  81  may be performed prior to repairing the sifter screen  80  with the plug  10  having the mesh layer  14 .  FIG. 5  illustrates an open cell  91  after removal of the mesh  81 . The open cell  91  may receive the plug  10  having the mesh layer  14 . 
     U.S. Pat. No. 6,872,466, assigned to the assignee of the present application and incorporated herein by reference in its entirety, discloses a method and apparatus for repairing screens. A plug may be inserted into a cell to form a locking connection. To this end, side faces of the ribs in each cell may be provided with lips which may be parallel to and spaced from the underside of the mesh. The plug may be adapted to be fitted in place by forcing at least part of the plug beyond the lips so that the plug snaps into place below the damaged mesh. The lips may be formed on the side faces of the two ribs defining the cell. The lips and ridges conveniently may have inclined surfaces to facilitate insertion of the plug into the cell and substantially perpendicular faces which may engage to inhibit movement in the reverse direction, once the plug is snapped into place. 
     As shown in  FIGS. 4 and 5 , the plug  10  may be dimensioned to fit within the cell  82 . Different sifter screens  80  may have different sizes of the cells  82 . Accordingly, the plug  10  may have different sizes. The plug  10  may be dimensioned to fit into the cell  82  so that no liquids or solids may pass between the cell  82  and/or the plug  10 . The mesh size of the mesh layer  14  of the plug  10  may be equal to the mesh size of the mesh  81  of the sifter screen  80 . 
     Each of the cells  82  may have interior walls  95  with a lip  96  corresponding to the ridges  62  of the first side  38  of the body  12  of the plug  10  and/or the second side  40  of the body  12  of the plug  10 . The lip  96  may interface with the flat side  64  of the ridges  62  to lock the plug  10  into the cell  82 . The lip  96  may interface with the tapered portion  68  of each of the ledges  66  to lock the plug  10  into the cell  82 . 
     To insert the plug  10  into the cell  82 , the sifter screen  80  may be positioned so that the top  79  of the sifter screen  80  may face down on a flat surface. As shown in  FIG. 4 , the bottom  78  of the sifter screen  80  may face up. The plug  10  may be positioned in the cell  82  so that the mesh layer  14  of the plug  10  may face into the cell  82 . 
     The plug  10  may be pushed by hand into the cell  82  until the plug  10  may encounter resistance from a tight fit. The fit between the plug  10  and the cell  82  may be an interference fit. A hammer and/or a mallet (not shown) may be used to hit the bottom  18  of the plug  10 . The hammer and/or the mallet may be used to hit the lower portion  50  of the support member  46  in the center of the plug  10 . The bottom  18  of the plug  10  may be hit substantially evenly across the bottom  18  by the hammer and/or the mallet until the plug  10  may be inserted into the damaged cell  89 . The plug  10  may be deformable. The ridges  62  of the plug  10  may lock into place with the lip  96  of the interior wall  95  of the cell  82 . The ridges  62  and/or the ledges  66  of the plug  10  may engage the lip  96  in the cell  82 . When installed, the plug  10  may be flush with the bottom  79  of the sifting screen  80 . 
     The sifter screen  80  may be inspected to ensure that the mesh layer  14  of the plug  10  is level with the mesh  81  of the sifting screen  80 . As shown in  FIG. 5 , the mesh layer  14  of the plug  10  may be even with the top  79  of the sifting screen  80  and/or the mesh  81 . The sifting screen  80  may be reinstalled into the industrial filtration system such as the shale shaker in an oil drilling operation, for example. 
     While the present disclosure has been described with respect to a limited number of embodiments, those skilled in the art, having benefit of this disclosure, will appreciate that other embodiments may be devised which do not depart from the scope of the disclosure as described herein. Accordingly, the scope of the present disclosure should be limited only by the attached claims.