Abstract:
A preformed hanger rod stiffening clip that improves the strength and stability of hanger rods to withstand compression forces. Precisely positioned screw holes enable the clamping legs of the clip to close completely when the fastening assembly is tightened. Washers on each side of the respective clamping legs deform the legs tightly around the stiffening member and the hanger rod which is disposed between the stiffening member and fastening assembly. It has been found that hole placement for a screw that is used to tighten the apparatus onto the hanger rod and stiffening member is critical. Misalignment of position of the screw openings greater than or equal to 0.005 inches results in a clip that will fail standard AISC compression tests. Edges of the clip are rounded and rolled to increase strength and prevent an installers hand from being cut on sharp edges.

Description:
[0001]    This application is a continuation-in-part application of U.S. patent application Ser. No. 11/999,715 filed on Dec. 6, 2007 which is a continuation-in-part of U.S. patent application Ser. No. 11/057,572 filed on Feb. 14, 2005, now abandoned. 
     
    
     FIELD OF THE INVENTION 
       [0002]    This invention relates to construction hardware, in particular, an apparatus to stabilize and strengthen hanger rods against buckling when the rods are used for supporting pipes, conduits or similar structures found in building construction in the face of unexpected movement as would be experienced in an earthquake. 
       BACKGROUND OF THE INVENTION 
       [0003]    A hanger rod is part of a typical hanger assembly wherein one end of a threaded rod is vertically attached to the building structure and the other end has an attachment mechanism such as a yoke which is used to connect to the part that is to be supported such as water pipes. While these rods can be provided in any diameter, the typical size is either ⅜, ½, ⅝, ¾, ⅞, 1 or 1 ¼ depending on the structure that is to be supported. The lengths can be selected as needed for the particular construction project with less than 120 inches being typical. 
         [0004]    Various structures and methods have been proposed to strengthen the hanger rod against deformation due to unusual stresses. Most of such devices make use of a stiffening channel strut, angle iron or pipe that is positioned substantially parallel to the hanger rod. Connection of the stiffening member can be provided by actually welding the member to the rod, however, this is extremely time-consuming and not practical due to the expense involved. 
         [0005]    U.S. Pat. No. 6,783,104, issued to Roth on Aug. 31, 2004, discloses and claims a deformable clip that connects the stiffening pipe to the hanger rod. This device has the advantage of being low cost and relatively easy to install. However, testing by the inventor has found that this arrangement will buckle quite easily unless the location of the holes are held to very close tolerances contrary to the teachings found in the &#39;104 patent. The &#39;104 patent teaches the use of a carriage bolt to tighten the clip in place. Further, the use of a carriage bolt prevents the legs of the clip from being tightened against one another. This device requires that the stiffening pipe to placed between the hanger rod and the attachment mechanism. The design flaws in this device result in clip failure unless a substantially greater number of them are utilized. 
         [0006]    U.S. Pat. No. 7,188,809, issued to Roth on Mar. 13, 2007, discloses a deformable clip, essentially the same clip as in the above-referenced patent. However, in this case, the hanger rod is between the point of fastening the clip and stiffening pipe while in the above-referenced patent, the stiffening pipe is between the hanger rod and the attachment point of the clip. Both of these designs recite and claim that at least one outer edge of the clip must bite into the stiffening pipe and the hanger rod. In order to have at least one outer edge of the clip be capable of biting into the stiffening pipe and the hanger rod, it clearly must be sufficiently sharp to present a cut hazard to workmen either while either installing the clip or working around an installed clip. 
         [0007]    U.S. Pat. No. 4,141,107 issued to Sheiman et al. on Feb. 27, 1979 discloses a clip attaching a single round member using a clip that is bent in place around the single round member attaching it to the surface. 
         [0008]    U.S. Pat. No. 1,362,244 issued to Farley on Aug. 8, 1919 discloses a “U” shaped hanger assembly that does not have a hanger rod. 
         [0009]    U.S. Pat. No. 2,872,141 issued to Hefner on Feb. 3, 1959 discloses a preformed round “O” shaped cable hanger that is designed to hold a single cable. 
         [0010]    U.S. Pat. No. 6,991,198 issued to Roth on Jan. 31, 2006, discloses a hanger rod stiffening device that is merely a U-shaped Bolt that a threaded rod hanger and a rectangular shaped channel that serves as the stiffening member. 
         [0011]    A hanger rod stiffening clip that can be easily attached, is inexpensive to produce and can be spaced at 24 inch clip spacing for a ⅜ inch hanger rod from one clip to the next along the stiffening pipe, which is equal to the governing with at a least radius of gyration ratio for ⅜ inch hanger rod to resist buckling, and can withstand compression force of at least 325 pounds on a test apparatus using a 120 inch long hanger rod in a typical installation, is not found in the prior art. A ⅜ inch hanger rod that is 24 inches long and is tested without stiffening clips will buckle at 125 pounds of compression pressure on the test apparatus. 
       SUMMARY OF THE INVENTION 
       [0012]    It is an aspect of the invention to provide a hanger rod stiffening clip that can be manufactured from malleable galvanized straps to a precise tolerance using stamping techniques well known in the art. 
         [0013]    It is another aspect of the invention to provide a hanger rod stiffening clip that can fit a plurality of hanger rod sizes. 
         [0014]    It is still another aspect of the invention to provide a hanger rod stiffening clip that has a preformed tapered shape that will keep the clip in position on the hanger rod and associated stiffening pipe until the clip can be firmly tightened. 
         [0015]    Another aspect of the invention is to provide a hanger rod stiffening clip that can be spaced in accordance with AISC formulas which are well known in the art and that provides a substantial increased resistance to buckling than is experienced with unstiffened rods. 
         [0016]    Another aspect of the invention is to provide a hanger rod stiffening clip such that as the screw that pulls the legs of the clip are tightened, the clip urges the hanger rod which is disposed against the stiffening pipe at the edge of a flat washer under the head of the nut or the edge of a flange nut, which thereby deforms the clip. When the screw is completely tightened via the nuts, sufficient resistance is created by applying the clamping force at the center of the width of the strap to prevent buckling of the hanger rod within the predetermined distance between clips and the loading force placed thereon. 
         [0017]    Still another aspect of the invention is to provide a hanger rod stiffening clip such that the clip has rolled and rounded edges to strengthen the clip. 
         [0018]    Another aspect of the invention is to provide a hanger rod stiffening clip that has the clip edges rolled and rounded to prevent injury to a workman when the apparatus is installed. 
         [0019]    Finally, it is an aspect of the invention to provide a hanger rod stiffening clip that has tapered legs so that the clip will stay in position until the clip can be tightened. 
         [0020]    These and other aspects of the invention will become apparent in light of the detailed description of the invention that follows. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS  
         [0021]      FIG. 1  is a plan view of the clip in accordance with the invention. 
           [0022]      FIG. 2  is front view of the clip showing the preformed preferred embodiment shape. 
           [0023]      FIG. 3  is an end view of the clip shown in  FIG. 2 . 
           [0024]      FIG. 4  is a cross-sectional view of the clip showing the rounded and rolled edges. 
           [0025]      FIG. 5  is an isometric view of the clip attached around a stiffening pipe and a hanger rod showing how the clip edges are prevented from biting into the hanger rod or stiffening pipe. 
           [0026]      FIG. 6  is a cross-sectional view of the invention in place around a stiffening member and a hanger rod illustrating how the clip can be fully tightened so that the two clamping members can be pinched together. 
           [0027]      FIG. 7  is a plan view of clip showing a single pair of opposing screw openings. 
           [0028]      FIG. 8  is a front view of the clip shown in  FIG. 7 . 
           [0029]      FIG. 9  is an end view of the clip shown in  FIG. 7   
           [0030]      FIG. 10  is an end view of the clip showing an alternative embodiment of the legs of clip. 
           [0031]      FIG. 11  is a detailed view of the rod  30  and stiffening member  32  using clips  10  in accordance with the invention. 
           [0032]      FIG. 12  is a detailed top view of the flange bolt used to tightening the legs of the clip together during installation. 
           [0033]      FIG. 13  is a detailed side view of the flange bolt in  FIG. 12 . 
           [0034]      FIG. 14  is a detailed top view of the flange nut used to fasten the flange bolt shown in  FIG. 12 . 
           [0035]      FIG. 15  is a side view of the flange nut of  FIG. 14 . 
           [0036]      FIG. 16  is a bottom view of the flange nut of  FIG. 14 . 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0037]    The invention is a clip used for clamping around two round members, a hanger rod  30  and a stiffening member  32 . Referring now to  FIG. 1 , clip  10  is preferably stamped from 1/16 inch thickness of galvanized sheet material. This thickness will provide sufficient strength (increased by rounding and rolling edge  13  of clip  10 ) to stabilize hanger rod  30  (shown in  FIG. 5 ) by way of stiffening member  32  (also shown in  FIG. 5 ) yet be sufficiently malleable to permit easy installation of clip  10  as is discussed below. 
         [0038]    In the preferred embodiment, two sets of opposing screw holes  12 ,  14  are provided. When positioned as noted below, clip  10  is able to accommodate three different sizes of hanger rod  30  . . . ⅜ inch, ½ inch and ⅝ inch. Other sizes of hanger rod  30  could also be used by merely adjusting the positioning of the screw holes as described herein. Clip  10  is preferably 7 ¼ inches long by ¾ inches wide. Hole set  14  is preferably 0.698 inches from edge  15 . Note that all tolerances are ±0.005 inches and well within the manufacturing limitations of most stamping equipment. Hole set  12  is preferably 1.062 inches from edge  15 . Holes  12  and  14  are preferably 0.261 inches in diameter. 
         [0039]    As shown in  FIGS. 2 and 3 , the preferred preformed shape of clip  10  is illustrated. The clip  10  is bent in the center  19  of the length to provide a substantially U-shape of equal clamping members  16 . The radius  17  is 0.650 inches. In the preferred embodiment, the legs are bent inwardly at angle  20  so that the open end of the clip is less than the diameter of the circular arc portion of the clip. 
         [0040]    As shown in  FIGS. 3 and 9 , the clamping members (legs) of the clip bend slightly towards one another. However, it is possible that the legs could be parallel to one another so that the distance between them always remains the same. In  FIG. 10 , another embodiment shows each of clamping members  16  tapered at point  18  by forming clamping members inward by angle  20  and outward from point  18  by angle  22 . Angle  20  preferably ranges from 3 to 5 degrees and angle  22  ranges from 4 to 6 degrees. In this manner, when clip  10  is placed around hanger rod  30  and stiffening member  32  prior to tightening as shown in  FIG. 5 , clip  10  will be held in place while it is securely fastened. 
         [0041]    Referring now to  FIGS. 5 and 6 , it can be seen why the present invention provides much greater strength and stability than prior art devices such as disclosed and claimed in the prior art. Hanger rod  30  is disposed between stiffening member  32  and locking mechanism  28 . Critical dimension  26  is to the edge of the round flange on the flange nut or washer and is achieved by maintaining a distance of 5.162 inches ±0.005 inches between 0.261 inch diameter holes on the flat pattern, prior to forming the U-shaped clip, and increasing the distance between the holes by 0.364 inches for each ⅛ inch increase in hanger rod diameter. This is achieved by precise hole placement of hole sets  12 ,  14  with respect to the length of clamping members  16 , which provides the proper pinching on hanger rod  30 . In fact, the inventor has found that a deviation of more than ±0.005 inches in hole placement could result in degradation of the clamping effect and could result in a clip that fails the compression test. The deformation of the clip, precise location of the holes and the use of flange nuts/bolts or flat washers are required for the clip to develop sufficient clamping force to prevent slippage of the hanger rod relative to the stiffening pipe. 
         [0042]    The edges  13  and the ends  15  of the clip  10  are rounded and slightly rolled in the direction away from the surface of the stiffening pipe  32  and hanger rod  30 . The rolling of the clip edges strengthens the clip. The rounding of the edges and the ends of the legs of the clip, along with rolling the edges, removes any sharp edges, which would present a cut hazard to construction personnel when handling them during installation. In addition, after the clips are installed the ends of the clip protrude perpendicularly from the hanger rod/stiffening pipe assembly, which would present an ongoing cut hazard to other personnel after installation. 
         [0043]    Since the edges and the ends of the Rod Stiffening Clip are rounded and slightly rolled in the direction away from the surface of the stiffening pipe and hanger rod, it is impossible for the edges of the clip, even inadvertently, to dig into either the stiffening pipe or the hanger rod. Thus, the clip can easily slide over the surface of the stiffening pipe or hanger rod without binding or causing a workman to cut his hand during installation. The strength of the clip is achieved solely from providing the proper dimensions when tightened and does not rely on imprecisely achievable biting by the clip edge into the stiffening pipe or hanging rod by the clip edge during the tightening process. The strength of reinforcement relies entirely on the flange nut/flange bolt (or alternatively hex nut with washer/hex nut with washer if that method is selected to fasten the clip) to provide the clamping force required for the clip to work. 
         [0044]    As noted above, in order for the flange nut/flange bolt (or alternatively hex nut with washer/hex bolt with washer) to provide the clamping force required for the clip to work, the distance from the centerline of the stiffening pipe to the near edge of the round flanges on the flange nut and flange bolt must be precisely controlled and they must be tightened to the minimum specified installation torque. This distance is controlled by precisely locating the holes in the clip and relying on the round flange on the flange nut (or washer if hex nut/bolt is used) to maintain this distance without regard to how much they are turned in tightening. If the round flange or washer was not used, this distance would vary depending on whether the point or the flat of the hex head was nearest the centerline of the stiffening pipe and insufficient clamping force could result. While the stiffening pipe diameter may remain constant, hanger rod diameters vary according to the requirements for hanging the equipment. Since the distance from the centerline of the stiffening pipe to the near edge of the flange on the flange nut varies with the hanger rod diameter and since that distance is critical to the function of the clip, different bolt hole locations are required to correspond the specific hanger rod sizes. 
         [0045]    A compression test is conducted by placing an unstiffened hanger rod of a length equal to that prescribed by the American Institute of Steel Construction (AISC) Allowable Stress Design (ASD) buckling formula (Kl/r) between two steel plates. An ever increasing compression load is applied until buckling occurs to establish a base line resistance to buckling under compression force. Loss of pressure on the gauge of the test apparatus indicates that buckling has occurred. In the case of ⅜ inch hanger rod, the unstiffened length per the Kl/r formula is 24 inches. Then a 3/8 inch hanger rod 120 inch long with rod stiffening clips spaced at a distance that is equal to the maximum length of the unstiffened rod permitted by the Kl/r formula, which is 24 inch for ⅜ inch rods, is tested. 
         [0046]    The 120 inch long hanger rod/stiffening assembly is placed in the test apparatus and subjected to the same test of ever increasing compression pressure until buckling failure is indicated by the sudden loss of pressure on the gauge of the test apparatus. The stiffening clips are successful, if buckling failure pressure on the gauge of the test apparatus is greater than or equal to the compression failure level for the 24 inch rod. 
         [0047]    As noted above, this embodiment is useful for three different diameters of hanger rod  30 . For use with a ⅜-inch hanger rod  30 , hole set  12  is used, flange nuts and flange bolts wherein a fully threaded screw (diameter size and thread size ¼-20×1¼) is inserted in the holes. Alternatively, the clip could be held via standard flat washers and lock nuts yet the flange bolts and nuts are easier to install, as less parts are required. In fact, any bolt type is suitable as long as the legs of the clip can be drawn tightly together as shown in  FIGS. 5 and 6  and is sufficiently strong to withstand the design forces that may be encountered. 
         [0048]      FIG. 11  is a detailed view of hanger rod  30  and stiffening member  32  using clips  10  in accordance with the invention.  FIG. 11  depicts the installation of a typical pipe/rod stiffening member  32  on hanger rod  30  using three stiffening clips  10 . The use of hanger rod  30  is to hold a braced pipe  64  that is substantially parallel to the surface of the structure. Stiffening member  32  attempts to maintain the compression value of hanger rod  30  to resist buckling. The clips  10  stiffen further hanger rod  30  to increase the prevention of buckling under various load conditions so that the stiffening rod will not go into compression as quickly as it would without the use of this device. In order for clips  10  to work, they must be tightened to sufficiently deform clip  10  to the contours of the contacted surfaces of hanger rod  30  and hanger rod stiffening member  32  assembly. The hanger rod and stiffening pipe assembly are held together with sufficient force to prevent them from slipping parallel to each other. 
         [0049]    The clip&#39;s manufacture requires critical locations of the holes to a ±0.005 tolerance. Additionally, washers (not shown) must be installed under the nut and bolt, when the flange nut/flange bolt is not used, in order to tighten the connection until both legs of clip  10  are flush. Without the use of a flange nut/flange bolt or a washer under nuts and bolts, there will not be sufficient room to use a socket wrench to tighten a connection until both legs of clips  10  are flush. The preferable location and spacing is as follows. The maximum dimension between structure  68  to the first clip  10  is preferably 3 inches. The preferable distance between the first clip and the second clip and the second and third, which is the bottom most clip, varies in accordance with maximum allowable horizontal loads as determined by loads well known in the art such as found in allowable stress design manuals. Left and right sway braces  66  complete this section. 
         [0050]    In the ⅜ inch hanger rod test, the unstiffened hanger rod failed at 125 psi on the apparatus test gauge and the 120-inch rod stiffened with the invention failed at 325 psi. 
         [0051]    The typical installation is for use with a ⅝-inch hanger rod  30 , hole set  14  as described above. For use with a 12 inch hanger rod  30 , one hole of hole set  12  and one hole of the opposing hole set  14  is used. Stiffening member  32  is preferably 1 inch nominal schedule  40  or schedule  10  pipes as both these sizes have the same outside diameter. In this manner, the critical dimension is achieved. To adjust clip  10  for use with other sizes of hanger rods and/or stiffening members, the dimensions would be scaled according to the specifications provided herein. 
         [0052]      FIGS. 12 to 16  show the preferred method of fastening the clip  10  around the stiffening pipe  32  and hanger rod  30  as noted above. Serrated flange bolts and serrated flange nuts (well known in the art) are preferably used to ensure that the bolt does not move within the opening of the clip since even slight variations of the critical distance discussed above can significantly alter the strength of the results. Moreover, since the washers are integral with the bolt and nuts, there are a smaller number of parts to install or drop during the installation process. 
         [0053]    While certain representative embodiments of the invention have been described herein for the purposes of illustration, it will be apparent to those skilled in the art that modification therein may be made without departure from the spirit and scope of the invention.