Abstract:
A resilient inspection brush used in electrically inspecting pipelines for abnormalities is described which employs highly conductive metals, such as nickel. Since bristles [ 330]  made from these metals cannot be secured firmly by soldering or epoxy, they are folded over a retaining member [ 350] , or wrapped around the retaining member [ 350] . The retaining member [ 350] is secured inside of a base housing [ 320] . The top [ 321]  portion of the base housing [ 320]  may be crimped or swedged to reduce the size of the opening, thereby physically holding the bristles [ 330] . This also insures that the retaining member [ 350]  does not pass through the opening, securing the retaining member [ 350]  inside of the base housing [ 320] . In another embodiment, an inner sleeve [ 810]  is used to further secure the bristles [ 330]  and simplify assembly.

Description:
RELATED APPLICATIONS  
       [0001]     This application claims priority from U.S. Provisional Patent Application 60/607,387 “RESILIENT PIPELINE INSPECTION BRUSH” filed Sep. 3, 2005 in which a portion of the information was originally filed whereas additional information is being filed in this application as a continuation-in-part application. 
     
    
     BACKGROUND OF THE INVENTION  
       [0002]     1. Field of the Invention  
         [0003]     This present invention relates to the field of pipeline inspection and testing, and more specifically to the field of pipeline inspection using electronic testing apparatus.  
         [0004]     2. Discussion of the Prior Art  
         [0005]     It is sometimes necessary to periodically inspect gas, oil, water and other metal pipelines for cracks, weakened spots, wall thinning, and other abnormalities caused by wear, trauma and/or corrosion. These typically are inspected using currently known electronic testing techniques, such as a magnetic flux leakage technique. The magnetic flux leakage technique is more fully explained in “Intelligent Pig Inspection of Uncoated Seamless Pipelines” by Terry R. Shamblin, Columbia Gas Transmission, Charleston, W. Va. in the March 200 issue of  Pipeline and Gas Journal , and in “Research on Intelligent Pipeline Flux Leakage Detector” by Yang-Lijian and Wong-Yumei from the School of Information Science and Engineering, Shenyang Univ. Of Technology, Shenyang, China, hereby incorporated by reference as if set forth in their entirety herein. In this technique, conductive brushes each having a conductive base mounted around the perimeter of a hub, are rotated as they are passed through the inside of a pipeline. A magnetic source passes magnetic flux through the hub, through the base of the brushes and through the bristles. The bristles are brushed against the inner walls of the pipeline, thereby passing magnetic flux into the metal pipeline walls.  
         [0006]     A magnetic flux measuring device having a number of magnetic sensors, follows closely behind the inspection brush on or near the pipeline inner surface and reads the remaining magnetic flux. The difference in the magnetic flux induced by the brushes and the readings from the magnetic sensors results in a measure of magnetic flux leakage for each location inside of the pipe. The magnetic flux leakage is related to pipe thinning, pipe weakening, pipe corrosion and other abnormalities. The magnetic flux leakage test therefore is an efficient test for abnormalities of a metal pipeline.  
         [0007]     The inspection brush is comprised of a plurality of elongated pencil end brushes, having conductive metal bristles extending from a base cup. These prior art pencil end brushes are typically constructed having metal bristles, usually steel, that are soldered into a base cup. The base cup is connected to a magnetic source and is designed to pass magnetic flux from the magnetic source, to the bristles, then from the bristles to the pipeline walls.  
         [0008]     There are known prior art methods of constructing these pencil brushes. These include cutting the bristles to a specified length, inserting them into a cup and attaching to the cup with an attaching medium such as solder or epoxy. The open edge of the cup may or may not be crimped where the bristles enter the cup.  
         [0009]     The prior art attachment methods are subject to failure where the bristles are not fully embedded in the attaching medium. Brush integrity requires that every bristle be fully in contact with the attaching medium. Partial contact with the medium results in reduced strength of the brush. It is difficult, if not impossible to assure that each bristle is in full contact and the only method of being certain of that is by a destructive disassembly of the brush.  
         [0010]     During use of the inspection brush inside of the pipeline, bristles may be pulled out of or otherwise fall out of the brush or the entire brush may fall apart. The pieces will be dispersed throughout the system. This would cause great damage to the pipeline pumps, valves, seals and related equipment. It would also be a very costly and time consuming process to ‘fish’ all of the pieces.  
         [0011]     Since nickel is a good electrical conductor and conducts magnetic flux very well, nickel plated bristles are preferred. The use of nickel plating would allow the testing process to be performed much more quickly and efficiently indirectly saving large amounts of money in ‘down time’ since the pipeline may not be used during the testing process. However, the attachment of nickel plated parts is not easily attached using solder or epoxy. This again results in reduced strength of the brush.  
         [0012]     Another goal of the brush is to maximize electrical conductivity from the base housing to the bristles to the pipeline wall. Firm contact must be maintained between the base housing and the bristles to maintain high magnetic flux. Bristles that are held partially by solder or epoxy will have reduced contact and therefore reducing conductivity.  
         [0013]     An alternate means of securing nickel plated bristles would be to position the bristles inside the base housing, then compress the upper edge of the base housing to crimp the bristles in place. This crimping alone results in a weakened brush with low electrical conductivity.  
         [0014]     Therefore, there currently is a need for a high magnetic testing brush which is very resilient and would not release bristles into the pipeline. 
     
    
     BRIEF DESCRIPTION OF DRAWINGS  
       [0015]      FIG. 1  is a plan view of an inspection brush used for nondestructive testing of metal pipelines having a plurality of pencil end testing brushes mounted on a rotating hub.  
         [0016]      FIG. 2  is a side elevational view of the inspection brush of  FIG. 1 .  
         [0017]      FIG. 3  is a sectional elevational view from the side of a pencil end brush according to one embodiment of the present invention.  
         [0018]      FIG. 4  is a sectional elevational view from the front of the pencil end brush of  FIG. 3 .  
         [0019]      FIG. 5  is a cross-sectional, plan view of the embodiment of  FIGS. 3 and 4 , as viewed from the line  5 - 5  of  FIG. 4 .  
         [0020]      FIG. 6  is an illustration of the bristles of another alternate embodiment of the present invention  FIGS. 7   a ,  7   b ,  7   c  and  7   d  illustrate a process for making a brush compatible with the present invention.  
         [0021]      FIG. 8  is a partially cut-away side elevational view of another embodiment of the present invention in a disassembled view.  
         [0022]      FIG. 9  is a partially cut-away side elevational view of another embodiment of the present invention shown in  FIG. 8  in an assembled view. 
     
    
     SUMMARY OF THE INVENTION  
       [0023]     The present invention includes a resilient inspection brush for electronic inspection of pipelines, and method of constructing the same.  
         [0024]     The invention employs a plurality of resilient pencil end inspection brushes each having increased magnetic flux capacity. These are constructed of a high flux material, and are constructed without the need for solder or epoxy. They are very resilient and will resist breakage and dismemberment when in use.  
         [0025]     The resilient inspection brush includes an electrically conductive base housing having a generally cylindrical shape with a bottom portion and a top portion. A recess passes generally through the base housing lengthwise from top to bottom. The bottom may be enclosed to make a cup shape.  
         [0026]     A retaining member is secured in, or near the bottom of the base housing and extends in a direction generally perpendicular to the length of the recess, passing at least partially across the recess.  
         [0027]     A number of electrically conductive bristles are tightly packed into the base housing. Each bristle has at least a first end, a second end and a securing portion between the first and second ends. The securing portion of each bristle at least partially encircles the retaining member, with the end portions extending out of the top of the base housing.  
         [0028]     The present invention also includes a method for constructing the resilient inspection brush.  
         [0029]     First, an electrically conductive base housing is provided having a generally cylindrical shape, a bottom portion, a top portion and a recess passing generally lengthwise from the top to bottom portions.  
         [0030]     Next a number of bristles are formed.  
         [0031]     The number of bristles are positioning in a generally parallel configuration across the top of the base housing such that they are generally perpendicular to the length of the recess.  
         [0032]     The elongated retaining member is positioned across the bristles.  
         [0033]     And the retaining member is forced into the recess, thereby folding the bristles into the recess such that they are held in place by the retaining member.  
         [0034]     Optionally, the top of the base housing may be swedged to further hold the bristles in place.  
         [0035]     The bristles may be made of different materials and tempered or untempered, plated, coated or uncoated of virtually any desired diameter.  
       DETAILED DESCRIPTION OF THE INVENTION  
       [0036]      FIGS. 1 and 2  show a plan view and a side elevational view, respectively, of an inspection brush assembly having a plurality of conductive brushes  101  each having a conductive base housing mounted in holes  205  around the perimeter of a hub  103 . Only a few brushes  101  are shown here for clarity, however they are intended to completely encircle hub  103 . The assembly is inserted into a pipeline, preferably as part of a self-contained pipeline inspection device commonly referred to as a “pig”. The brushes  101  are rotated as they pass through the inside of a pipeline. A magnetic source located inside of hub  103  causes magnetic flux to pass through hub  103 , through the base housing of the brushes  101  and through their bristles. The bristles are brushed against the inner walls of the pipeline, thereby passing magnetic flux into the metal pipeline walls.  
         [0037]     Prior art inspection brushes have individual bristles which were soldered, epoxied, or otherwise glued into the base housing. These do not exhibit the electrical conduction properties and strength exhibited by the present invention. These properties are very important since pieces of the inspection brushes which break off can destroy pipeline equipment, make it unusable for a period of time and may be very expensive to repair.  
         [0038]      FIGS. 3 and 4  show side and front elevational sectional views, respectively, of one embodiment of the present invention having a plurality of bristles  330 . The present invention shows a bristle  331  having three parts, a first elongated end  331   a , a second elongated end  331   b , and an intermediate securing portion  331   c . The bristles are made to fold or wrap-around a conductive retaining member  350 . Therefore, the intermediate securing portion  331   c  is made to partially encircle retaining member  350 , allowing first end  331   a  and second end  331   b  to extend away from the retaining member  350 . The ends may be made to extend substantially parallel to each other as shown in  FIG. 3 , or angle outwardly.  
         [0039]     Similarly, other bristles such as bristle  333  also have a first end  333   a , a second end  333   b , and a securing portion  333   c.    
         [0040]     The bristles for the brushes may be wire that is tempered or untempered, plated, coated or uncoated in virtually any desired diameter. These wires should be electrically conductive. A number of bristles are packed into base housing  320 , thereby causing a tight fit, securing them into the base housing.  
         [0041]     The unique configuration of the base housing  320  allows it to retain the substantially straight sides desired by the end users while firmly holding the bristles in the base housing and maintaining tight contact between all of the bristles and the base housing for excellent conductivity.  
         [0042]     To further secure retaining member  350  inside base housing  320  and to further secure bristles  331 ,  333 , etc. the top portion  321  of base housing  320  is “swedged” by crimping or compressing top portion  321  into a smaller diameter, physically pressing against the bristles.  
         [0043]     Retaining member  350  may be implemented by using a rod slightly shorter than the internal diameter of base housing  320 . If the retaining member  350  is implemented in this manner, swedging base housing  320  after retaining member  350  has been inserted into base housing  320 , secures retaining member  350  inside of base housing  320 , since it is now too large to pass through the smaller opening in the top portion  321  of base housing  320 . ( FIG. 7   d  shows a reduce diameter swedged portion  340 .)  
         [0044]     Retaining member  350  may be secured by other known means as long as the electrical conductivity between base portion  320 , retaining member  350  and bristles  331 ,  333  are maintained.  
         [0045]     In an alternative embodiment of the present invention, the securing portion  331   c ,  333   c  of bristles  331 ,  333  may be wound around securing device  350  several times as shown by the dashed lines shown in  FIGS. 3 and 4 . Securing portions  331   c  and  333   c  are shown in phantom as concentric circles around retaining member  350  in  FIG. 3 . These portions are also shown as circles in phantom immediately above and below retaining member  350 . Winding these bristles around retaining member  350  would result in improved securing of the bristles, and a more resilient inspection brush.  
         [0046]      FIG. 5  is a cross-sectional, plan view of the embodiment of  FIGS. 3 and 4 , as viewed from the line  5 - 5  of  FIG. 4 . Bristles  330  are shown as circles in phantom emanating from above and below retaining member  350 . It can be seen here that retaining member  350  extends from one side of the inner surface of base housing  320  to the other side. Slightly above this level, base housing  320  is the swedging area  340  having a smaller circumference thereby preventing retaining member  350  from being pulled out of base housing  320 . (This is shown in  FIG. 7   d .)  
         [0047]      FIG. 6  shows a portion of another alternate embodiment of the present invention. A single wire may be folded back on itself to make a plurality of double stranded bristles  611 ,  613 ,  615 . A plurality of securing portions  601   c ,  603   c , and  605   c  are formed between each of the bristles  611 ,  613 ,  615 . The securing portions  601   c ,  603   c ,  605   c  are intended to be folded back onto each other such that  601   c ,  603   c  and  605   c  are coaxial and fit over retaining member ( 350  of  FIGS. 3 and 4 ). Since each securing portion would be connected to the retaining member  350 , and each bristle would be connected to an adjacent bristle, there is less chance that pieces would break off during use falling into the pipeline and creating damage.  
         [0048]     A method of constructing the present invention is described below.  
         [0049]     1. An electrically conductive base housing  320  is provided having a generally cylindrical shape, a bottom portion  325  and a top portion  321  with a recess  327  passing generally lengthwise from the top to bottom portions.  
         [0050]     2. A number of bristles are formed.  
         [0051]     3. The bristles  330  are positioning in a generally parallel configuration across the top of the base housing  320  such that they are generally perpendicular to the length of the recess  327  as shown in  FIG. 7   a.    
         [0052]     4. An Elongated Electrically Conductive Retaining member  350  is then positioned across the bristles  330 , as shown in  FIG. 7   b.    
         [0053]     5. The retaining member  350  is forced into the recess  327 , thereby folding the bristles  330  into the recess  327  such that they are held in place by the retaining member  350 , as shown in  FIG. 7   c.    
         [0054]     Since the bristles are held in place by the retaining pin, brush integrity is maintained.  
         [0055]     In another embodiment, each of the bristles  330  are wound at least a full circle around the retaining member  350 . The wires are wound before the retaining member  350  is inserted into the base housing  320 .  
         [0056]     Optionally, the top of the base housing  320  may be compressed in swedged section  340  to further hold the bristles  330  in place as shown in  FIG. 7   d.    
         [0057]      FIG. 8  is a partially cut-away side elevational view of another embodiment of the present invention in a disassembled view. In this embodiment, there is an inner sleeve  810  which is intended to hold bristles  330  such that the first end  331   a  and the second end  331   b  extend out of inner sleeve  810 .  
         [0058]     Inner sleeve  810  has at least one catch  811 ,  813  on its outer surface which are designed to fasten easily to a corresponding groove(s)  861 ,  863  when inner sleeve  810  is inserted into central recess  880  in base housing  860 . It can be seen that the catches are wedge-shaped moving from bottom to top, and have an abrupt shoulder  812 ,  814  at the uppermost edge thereby resisting release once fastened.  
         [0059]      FIG. 9  is a partially cut-away side elevational view of another embodiment of the present invention shown in  FIG. 8  in an assembled view.  
         [0060]     In  FIG. 9  inner sleeve  810  is shown after it has been pushed into base housing  860 . Once catches  811 ,  813  snap into groove  861 ,  863  there is a close fit between shoulders  812 ,  814  and groove upper edges  862 ,  864  that does not allow release of the parts. This is a one-time fastener and is designed to fasten, but not release.  
         [0061]     During assembly of the embodiments above, a solder or thermoplastic may be placed in the bottom ( 325  of  FIG. 3 ),  825  of base housing ( 320  of  FIG. 3 ),  860 . The base housing ( 320  of  FIG. 3 ),  860  may then be heated to further hold the bristles  330  in place.  
         [0062]     Other epoxies, glues, and adhesives may also be used to further strengthen the assembly.