Patent Publication Number: US-10333231-B2

Title: Clamping assembly for attaching a grounding conductor to a structure having a protective coating

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     The present disclosure is a continuation of co-pending U.S. application Ser. No. 15/176,927 filed on Jun. 8, 2016 entitled “Clamping Assembly for Attaching a Grounding Conductor to a Pipe Having a Protective Coating” the contents of which are incorporated herein in their entirety by reference. 
    
    
     TECHNICAL FIELD 
     The present invention relates to clamping devices, and in particular mechanical clamps for attaching a grounding conductor to a coated pipe. 
     BACKGROUND OF THE INVENTION 
     A series of interconnected large diameter pipes (i.e., pipes with at least 12 inches in diameter) are used to carry fluid such as oil from one location to another. To properly discharge the potential electricity buildup from lightening or static electricity buildup from the flowing fluid, the pipes are connected to a grounding conductor which is then connected to an underground grounding system through, for example, a grounding rod. 
     For protection from the elements and corrosion resistance, however, the pipes are typically coated with a protective or insulative coating such as powder coating or paint, which makes it difficult to make a solid electrical connection to the pipes. 
     Conventionally, a grounding connection is accomplished by stripping the protective coating from the pipes and then welding a grounding conductor to the pipes. However, stripping and welding are very time consuming processes and are very expensive as they require a licensed welder and a licensed inspector to inspect the weld. 
     Therefore, it would be desirable to provide a device and method for connecting the pipes to a grounding conductor which is easy to install in a cost efficient and time saving manner. 
     BRIEF SUMMARY OF THE DISCLOSURE 
     In one aspect of the present invention, a clamping assembly for attaching a grounding conductor to a pipe having a protective coating is provided with an elongate conductive strap and a clamp. The conductive strap is sufficiently long to circumferentially surround the pipe and has longitudinally spaced sharp projections that are sufficient to penetrate the protective coating around the pipe to make an electrical coupling between the strap and a conductive part of the pipe beneath the protective coating. The clamp is coupled to a grounding conductor and clamps the conductive strap to the pipe at a tension sufficient to maintain an electrical connection between the conductive part of the pipe and a grounding conductor. 
     Since the sharp projections in contact with the conductive part of the pipe maintains a solid electrical connection between the pipe and the grounding conductor, the present invention advantageously eliminates the need for any welding of the grounding conductor to the pipe and any stripping of the protective coating from the pipe. Consequently, the clamping assembly of the present invention allows attachment of a grounding conductor to a coated pipe in a cost efficient and time saving manner. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  illustrates a grounding clamp assembly according to an aspect of the present invention. 
         FIG. 2  illustrates a side view of a clamp of  FIG. 1 . 
         FIG. 3A  illustrates a front view of the clamp of  FIG. 1 . 
         FIG. 3B  illustrates a cross-sectional side view of  FIG. 3A  taken along lines  3 B- 3 B. 
         FIG. 4  illustrates sharp projections on a large diameter pipe according to an aspect of the present invention. 
         FIG. 5A  is a perspective view of one embodiment of the sharp projections according to an aspect of the present invention. 
         FIG. 5B  is a perspective view of an alternative embodiment of the sharp projections according to an aspect of the present invention. 
         FIG. 6A  is a perspective view of another embodiment of the sharp projections according to an aspect of the present invention. 
         FIG. 6B  is a cross-sectional view of  FIG. 6A  taken along lines  6 B- 6 B. 
         FIG. 7A  is a perspective view of another embodiment of the sharp projections according to an aspect of the present invention. 
         FIG. 7B  is a cross-sectional view of  FIG. 7A  taken along lines  7 B- 7 B. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       FIG. 1  illustrates a grounding clamp assembly  2  according to an aspect of the present invention. The grounding clamp assembly  2  includes a grounding clamp  4  and an elongate conductive clamping strap  6  having sharp projections  8  that are longitudinally spaced along the strap. When installed, the conductive clamping strap  6  surrounds a large diameter pipe  10  and its two ends are clamped by the grounding clamp  4 . As an example construction, the conductive strap  6  is at least 37 inches long to accommodate the circumference of a 12 inch diameter pipe. A grounding conductor  1  has one end which is coupled to a grounding system (not shown) and an opposite end which is electrically coupled to the clamp  4 . 
     As shown in  FIGS. 1 and 4 , the pipe  10  has a corrosion resistant coating  22  on its outside to protect the pipe from the elements. As an example, the coating  22  can be an electrically insulative coating. When the conductive strap  6  is under tension provided by the clamp  4 , the projections  8  are sufficiently sharp to penetrate the protective coating  22  of the pipe  10  to make a solid electrical contact with a conductive part of the pipe underneath the coating. The projections  8  provide an electrical path from the pipe  10  to the grounding conductor  1 . 
     The conductive strap  6  can include any electrically conductive material. In one embodiment, the strap  6  can be an electrically conductive braid made of woven copper wire. In another embodiment, the strap  6  can be a metallic sheet. 
     The sharp projections  8  can be formed on the conductive strap  6 . In one embodiment, the sharp projections  8  can be formed on an annular one-piece eyelet  24  as shown in detail in  FIG. 5A . In one embodiment, the eyelets  24  are uniformly spaced longitudinally on the clamping strap  6 . For example, for a 24 inch diameter pipe, the eyelets  24  can be longitudinally and uniformly spaced every two inches along the strap  6 . The eyelets  24  can be made of steel or other durable and strong material that has a good electrical conductivity. Other eyelets that can be used in the present invention are described in U.S. Patent App. Pub. No. 2012/0110803, which is incorporated herein by reference. 
     As shown in  FIG. 4 , each eyelet  24  is mounted to the strap  6  through a corresponding mounting hole  26  on the strap by swaging the stud  30  after the stud has passed through the mounting hole. The sharp projections  8  are circumferentially formed in the flange  32  with a predetermined space between adjacent projections. Each of the projections  8  can be cut and previously raised from the flange  32  or cut in place and subsequently raised from the flange  32 . Alternatively, the eyelet  24  can be formed with the sharp projections  8  in a mold such as a metal injection mold. Each projection  8  generally tapers to a sharp point and extends laterally away from the flange  32  of the eyelet  24 . 
     As shown in  FIG. 4 , when the clamping strap  6  has been clamped around the pipe  10  under tension, the projections  8  are sufficiently sharp to pierce the corrosion resistant coating  22  to make a solid electrical contact with the conductive portion of the pipe below the coating. 
     In the embodiment shown in  FIG. 5A , four sharp projections  8  are positioned on one side of the eyelet  24  and are equally spaced from each other so as to have a 90 degree angle of separation between two adjacent projections relative to a central axis of the eyelet  24 . Sharp projections  9  are positioned on the other side of the eyelet  24  and are also equally spaced from each other so as to have a 90 degree angle of separation between two adjacent projections relative to a central axis of the eyelet  24 . As can be seen in  FIG. 5A , the projections  8  and  9  are interleaved with each other such that there is a 45 degree angle of separation between projection  8  and adjacent projection  9 . The eyelet  24  of  FIG. 5A  is convenient since an installer can use either side of the clamping strap  6  against the surface of the pipe  10  without being concerned with which side of the conductive strap  6  is to face the pipe  10 . 
       FIG. 5B  is a perspective view of an alternative embodiment of the sharp projections  8  of an eyelet  24  as shown in  FIG. 5A . The four sharp projections  8  are positioned on one side of the eyelet  24  and are equally spaced from each other so as to have a 90 degree angle of separation between two adjacent projections relative to a central axis of the eyelet  24 . The eyelet  24  of  FIG. 5B  is similar to that of  FIG. 5A , except that the sharp projections  8  are only on one side. The eyelets  24  of  FIG. 5B  can be advantageous for an area where there may be a higher risk of injury for installers or maintenance workers from the sharp projections  9 . 
       FIG. 6A  is a perspective view of another embodiment of the sharp projections according to an aspect of the present invention.  FIG. 6B  is a cross-sectional view of  FIG. 6A  taken along lines  6 B- 6 B. Four sharp projections  56  are equally spaced from each other so as to have a 90 degree angle of separation between two adjacent projections relative to a central axis of the eyelet  24 . The eyelet  56  of  FIG. 6A  is similar to that of  FIG. 5B , except that the sharp projections  56  are formed with a mold without cutting so as to form a structurally more rigid projections than the projections  8  of  FIG. 5A . This embodiment can be advantageous when the corrosion resistant coating  22  is relatively thick and more tension of the strap  6  is required to pierce the coating. 
       FIG. 7A  is a perspective view of another embodiment of the sharp projections according to an aspect of the present invention while  FIG. 7B  is a cross-sectional view of FIG.  7 A taken along lines  7 B- 7 B. In this embodiment, the projection  58  is similar to the projection  56  of  FIG. 6A  in that it is formed from a mold to increase the structural rigidity. However, the projection  58  of  FIG. 7A  is an annular ring and is arranged circumferentially around the flange  32 . The projection  58  has a circumferentially continuous sharp edge that projects away from the flange  32 . 
     While the flanges  32  and/or the holes  60  of the eyelets  24  in the embodiments shown have a round shape, other shapes such as square, rectangle and triangle for either the flanges or holes are also possible. 
       FIG. 2  is a side view illustrating a clamp of  FIG. 1  while  FIG. 3A  is a front view of the clamp.  FIG. 3B  illustrates a cross-sectional side view of  FIG. 3A  taken along lines  3 B- 3 B. Referring to  FIGS. 2 and 3A-3B , the clamp  4  includes a conductive clamping body  34  and a conductive cap  36 . The bottom surface of the clamping body  34  is angled to match the outer surface of the pipe  10 . While the bottom surface is shown to have a pair of downwardly angled planar surfaces, it can be continuously curved to more closely match the shape of the pipe  10 . 
     The clamping body  34  has a recessed channel  38  that receives the opposite ends of the clamping strap  6 . Tabs  54  above the recessed channel  38  prevent the strap  6  from being lifted and dislodged out of the recessed channel during installation to help secure the strap  6 . The conductive cap  36  clamps the clamping strap  6  to the clamping body  34  with a bolt  14  and a locking assembly  12 . 
     The cap  36  has a pair of downwardly extending sides (wings)  40  with each having a conductor groove  42  on its lower surface to receive the grounding conductor  1 . The clamping body  34  has a pair of overhang pads  44  over which the ground conductor  1  lies. When the conductive cap  36  is clamped to the clamping body  34 , the overhang pad  44  and its corresponding conductor groove  42  clamp the grounding conductor  1  to the clamp  4 . 
     At its center, the conductive cap  36  has a boss  48  and through-hole  46  that extends through the boss. The boss  48  applies pressure on the clamping strap  6  and to carry current from the strap to the grounding conductor  1  through the conductive cap. 
     The clamping body  34  also has a corresponding through-hole  50  at its center and a recess  52  for receiving the head of a threaded bolt  14 . The shape of the recess  52  is designed to match that of the head of the bolt  14  to prevent the bolt from rotating on its axis. For example, if the bolt  14  has a hexagonal shape, then the recess  52  also has a hexagonal shape. As can be seen in  FIGS. 2 and 3A-3B , the bolt  14  is designed to be inserted through the through-hole  50 , holes  60  of the corresponding eyelets  24  which are typically located near the opposite ends of the strap  6 , through-hole  46  of the conductive cap  36  and a lock assembly  12  which includes a flat washer  18 , lock washer  16 , and nut  20 . The lock assembly  12  is torqued to a specified value depending on the application. 
     A method of grounding a coated pipe to a grounding conductor will now be described. With the bolt  14  inserted through the through-hole  50 , the clamping body  34  is rested on the pipe  10 . A hole  60  of an eyelet  24  at a first end of the strap  6  is inserted over the bolt  14 . The strap  6  is then wrapped around the pipe  10  and pulled toward the clamping body  34  at a sufficient tension to cause the sharp projections  8  to pierce the corrosion resistant coating  22 , thereby making a solid electrical contact between the projections and the pipe  10 . While tension is maintained, a hole  60  of an eyelet  24  near a second end of the strap  6  is inserted over the bolt  14  over the first end of the strap such that both sides of the straps are stacked on top of each other as shown in  FIGS. 3A-3B . 
     Once both sides of the strap  8  are inserted through the bolt  14 , the conductive cap  36  is inserted through the bolt  14 . The grounding conductor  1  is then placed over the overhang pad  44  and is received in the conductor groove  42 . While the conductive cap  36  is being pushed downwardly, the lock assembly  12  is used to lock the conductive cap to the clamping body  34  to a preselected torque by tightening the nut  20 . When the conductive cap  36  is locked to the clamping body  34 , the boss  48  and the side  40  respectively press down on the strap  6  and the conductor  1  to make a solid electrical contact between the strap  6  and the grounding conductor. 
     Consequently, the grounding clamp assembly  2  of the present invention allows an installer to electrically attach the grounding conductor to the pipe in an efficient and easy manner without resorting to the expensive process of stripping the protective coating or welding the grounding conductor to the pipe. Advantageously, the strap  6  can be used to fit nearly any size of larger diameter pipes so long as the strap  6  is sufficiently long to wrap around the pipe. 
     The foregoing specific embodiments represent just some of the ways of practicing the present invention. Many other embodiments are possible within the spirit of the invention. Accordingly, the scope of the invention is not limited to the foregoing specification, but instead is given by the appended claims along with their full range of equivalents.