Abstract:
A loop hanger, such as for supporting fire sprinkler pipe, contains an integral fold-over washer with an annular stiffening rib, the benefits of which are to minimize deflection of the horizontal ears of the hanger under an applied load and offer simplified installation by eliminating the need for additional flat washers.

Description:
[0001]    This application claims priority under 35 USC 119 to U.S. Provisional Patent Application No. 61/088,370, filed Aug. 13, 2008, which is incorporated herein in its entirety. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    1. Technical Field of the Invention 
         [0003]    The invention relates in general to loop hangers. 
         [0004]    2. Description of the Related Art 
         [0005]    In its simplest form, a loop hanger consists of a strip of stamped steel formed with a loop such that the hanger profile resembles the shape of a pear (hence the alternative name of “pear hanger” for this style of hanger). The loop is sized to closely fit the outside diameter of the pipe being supported. Legs extend up and in on either side of the pipe. At the top of each leg are formed horizontal tabs (or ears) with punched holes sized to accept a threaded rod. The hanger is placed around the pipe and the ears are pushed together, one on top of the other, so that the punched holes are aligned. A threaded rod is inserted through the now concentric holes and secured to the loop hanger using hex nuts and flat washers on top and bottom of the overlapping ears. Prior loop hangers used to support fire sprinkler piping often require the installation of flat washers between the hex nuts to provide support for the horizontal tabs and minimize deflection during application of load. The end result is a somewhat rigid composite structure relatively resistant to bending moments. 
         [0006]    Hangers used to support sprinkler piping in the United States must meet the technical requirements of NFPA13, “Installation of Sprinkler Systems”, and be “listed” by a third party agency such as Underwriters Laboratories (UL). UL tests candidate hangers to the requirements of the internal test standard, “UL203 Pipe Hanger Equipment for Fire Protection Service.” Similar standards and approval agencies exist in other regions of the world (e.g., VdS, LPCB). In addition to the UL requirements, other approval agencies such as Factory Mutual Research Corporation (FMRC) may list additional performance requirements, such as a deflection requirement. Deflection is effectively the amount the loop hanger “stretches” when the test load is applied. There are a number of methods employed by manufacturers for strengthening a loop hanger to meet the deflection requirements—the simplest involves making the hanger out of a thicker or stronger strap; a second involves adding the aforementioned flat washers above and below the two hex nuts; and a third involves shortening the horizontal tabs to reduce the amount unsupported length on the overlapping tabs. Each solution presents additional issues such as increased cost or increased difficulty during installation. 
         [0007]    Among the myriad of issues with using traditional loop hangers:
       Loop hangers are generally considered a commodity product purchased based on price and availability (since all hangers used for fire protection must be listed/approved all manufacturers are considered on even footing from the application standpoint). This said, adding thicker, wider or stronger material to stiffen the loop is not desirable due to the extra material cost involved.   Installers need clearance at the top of the loop for fingers and wrenches so they can install and tighten the lower nut. Shortening the horizontal tabs to reduce deflection decreases the amount of space an installer has when tightening the washer and nut.   The clearance mentioned above leads to unsupported portions on the loop hanger that deflect under load (because the hex nuts do not extend out to the legs of the loop hanger), leading to the need to add flat washers that provide additional support to the horizontal tabs. The washers improve the deflection performance because they extend out farther than the nuts, and when compressed between the nuts the washers form a composite surface with the horizontal tabs on the loop hanger.   A manufacturer not desiring to add material or shorten the horizontal tabs will require flat washers be installed under the top and bottom nuts so the deflection requirement can be met.   Most manufacturers will not supply the flat washers or hex nuts, as there is a packaging issue, since the hardware is usually supplied in bags of 50 or 100 pieces, but the hangers themselves are sold by the piece.   The washers also create another issue—dealing with more loose parts during the installation (more loose parts means higher probability of dropping parts during the install).       
 
         [0014]    Even though the washers must be installed to comply with a particular agency approval, many installers will not go through the trouble of finding or using the washers. The result is that loop hangers are installed that are in non-compliance with the specific agency listing/approval. 
       SUMMARY OF THE INVENTION 
       [0015]    A loop-style (hereafter referred to as “loop”) hanger, such as for supporting fire sprinkler pipe, contains an integral fold-over washer with an annular stiffening rib, the benefits of which are to minimize deflection of the horizontal ears of the hanger under an applied load and offer simplified installation by eliminating the need for additional flat washers. 
         [0016]    According to an aspect of the invention, a loop hanger has an integral fold-over washer that functions as a strengthening element. 
         [0017]    According to another aspect of the invention, a loop hanger has an integral fold-over washer constructed from the base material of the hanger, and attached via a carry tab to the parent product. 
         [0018]    According to yet another aspect of the invention, a loop hanger has an integral fold-over washer with a tail that extends past the horizontal portion of the washer. The tail may proceeds downward at an angle that matches that of an opposing leg. The tail serves to provide additional support during deflection. 
         [0019]    According to still another aspect of the invention, a loop hanger has a stiffening rib that consists of a raised annular surface within a fold-over washer that enhances its structural stiffness. 
         [0020]    According to another aspect of the invention, an integral washer of a loop hanger has one or more ribs that provide added stiffness. 
         [0021]    According to a further aspect of the invention, a loop hanger includes a metal strip that in turn includes: a rounded pipe-receiving bottom portion; first and second legs rising from opposite respective ends of the rounded pipe-receiving portion; and first and second tabs at ends of the first and second legs, respectively, wherein the tabs overlap at a top of the hanger, wherein the tabs have respective holes that are aligned for receiving a rod therethrough; wherein the first tab has a washer of the loop hanger attached thereto. 
         [0022]    According to a still further aspect of the invention, a method of securing a pipe includes the steps of: placing the pipe in a rounded bottom portion of a loop hanger; and securing the loop hanger to a rod, wherein the rod passes through a pair of tabs of the loop hanger, and through a folded-over washer of the loop that is integrally formed with at least one of the tabs as part of a continuous monolithic metal strip. 
         [0023]    According to another aspect of the invention, a loop hanger includes:a rounded pipe-receiving bottom portion; a pair of legs rising from opposite respective ends of the rounded pipe-receiving portion; and at least three layers of material overlapping at a top of the hanger, and having respective holes that are aligned for receiving a rod therethrough; wherein the bottom portion, the legs, and the at least three layers of material are all parts of a continuous monolithic metal strip. 
         [0024]    To the accomplishment of the foregoing and related ends, the invention comprises the features hereinafter fully described and particularly pointed out in the claims. The following description and the annexed drawings set forth in detail certain illustrative embodiments of the invention. These embodiments are indicative, however, of but a few of the various ways in which the principles of the invention may be employed. Other objects, advantages and novel features of the invention will become apparent from the following detailed description of the invention when considered in conjunction with the drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0025]    The annexed drawings, which are not necessarily according to scale, show various aspects of the invention. 
           [0026]      FIG. 1  is a side view of a loop hanger in accordance with an embodiment of the present invention. 
           [0027]      FIG. 2  is a detail view of a part of the loop hanger of  FIG. 1 , showing stiffening elements in a bend of the hanger. 
           [0028]      FIG. 3  is a detail view of another part of the loop hanger of  FIG. 1 , showing stiffening elements and an annular stiffener. 
           [0029]      FIG. 4  is a cross-sectional view of the lower part of the loop hanger of  FIG. 1 . 
           [0030]      FIG. 5  is an oblique view of an application assembly that includes the loop hanger of  FIG. 1 . 
           [0031]      FIG. 6  is a side view of an alternate embodiment loop hanger in accordance with the invention. 
           [0032]      FIG. 7  is a top view of a top part of the loop hanger of  FIG. 6 . 
       
    
    
     DETAILED DESCRIPTION 
       [0033]    Referring to  FIGS. 1-4 , a loop hanger  100  is a formed steel strip, and is used to support steel or plastic piping. The loop hanger  100  consists primarily of a large rounded bottom portion or loop  1 , a pair of angled upward-extending legs  2  and  3 , top and bottom horizontal tabs  4  and  5 , and an integral fold-over washer  6  with a tail  7 . The rounded bottom portion  1 , the legs  2  and  3 , the tabs  4  and  5 , and the washer  6  all may be integral parts of a single monolithic continuous metal strip, such as a strip of steel, for example stainless steel. The loop  1  contacts the pipe being supported, and may be sized to closely match the diameter of the pipe. 
         [0034]    Bends  8  and  9  are used to form the top and bottom horizontal tabs  4  and  5 , respectively. A bend  10  used to form the fold-over washer tail  7 , bending the tail  7  downward from a horizontal portion  7   a  of the washer  6 . The tail  7  may be bent at an angle corresponding to the slope of the leg  2 . This allows an outside surface of the tail  7  to press against an inside surface of the leg  2 , providing better structural stability for the loop hanger  100  when the hanger  100  is fully assembled and installed. The bends  8 ,  9 , and  10  all have appropriate suitable radiuses, as dictated by good metal forming practice. A 180-degree hem bend  12  is utilized at the interface between the bottom horizontal tab  5  and the fold-over washer  6 . 
         [0035]    Stiffening elements (gussets)  11  are centered on inside surfaces of the bends  8  and  10 , to increase stiffness and reduce deflection of the top and bottom horizontal tabs. One pair of the stiffening elements or gussets  11  is located at the inside of the bend  8 , coupled to both the leg  3  and the tab  4 . Another pair of the stiffening elements or gussets  11  is located at the bend  10 , coupled to both parts of the washer  6 , the tail  7  and the horizontal portion  7   a.  The stiffening elements or gussets  11  may be stamped indentations, deformations of the material of the metal strip located at the bends  8  and  10 . Alternatively the gussets (stiffening elements)  11  may be separate triangular pieces of material, with flat edges against each of the two parts linked by any particular of the gussets  11 . Such separate-piece gussets  11  may be welded or otherwise suitably attached to the parts that they link together. 
         [0036]    The fold-over washer  6  and fold-over washer tail  7  nest inside the bottom horizontal tab  5  with minimal gap. Small clearance holes (cutouts)  13  are located on the 180-degree hem bend  12  to prevent interference with the stiffening elements or gussets  11  located on the top horizontal tab bend  8  and ensure proper nesting of the top and bottom horizontal tabs  4  and  5 . The top and bottom horizontal tabs  4  and  5 , and the integral fold-over washer  6 , have respective closed round holes  14 , 15 , and  16 , to allow an appropriate sized threaded rod to pass through. Nuts are used above the top horizontal tab  4  and below the integral fold-over washer  6  to secure the loop hanger  100  to a threaded rod, which may be secured to building structure, such as a ceiling or fixture. 
         [0037]    The tabs  4  and  5 , and the washer  6 , constitute three layers of material overlapping and in contact with one another, providing stiffness at the top of the hanger  100 , around the rod-receiving holes  14 - 16  in the material layers. It will appreciated that alternatively additional layers of material may be folded over and stacked onto the tabs  4  and  5 , and the washer  6 . Such optional additional layers may be folded over from the tab  4  or the washer  6 , for example. 
         [0038]    The loop  1  has noticeably flared edges  17   a  and  17   b  covering more than the bottom 180 degrees of the loop  1 . A substantial radius  18  is provided between a substantially flat central portion  18   a  of the loop  1 , and each of the edges  17   a  and  17   b  that slope away from it. The flared edges  17   a  and  17   b  extend outward and down, such as at an approximately 45 degree angle, from the central portion. The flared edges  17   a  and  17   b  prevent the supported pipe from contacting sharp edges that would otherwise be present in the formed loop  1 . This is advantageous, particularly for applications involving plastic pipe, in which the presentation of sharp edges can result in damage to the pipe. 
         [0039]    An annular rib  19  is formed in the fold-over washer  6  concentric to the closed round hole  16 . The rib  19  extends in a downward direction toward the supported pipe (toward the loop hanger bottom  1 ). The diameter of the rib  19  is sized to provide bearing area for the bottom hex nut used to secure the threaded rod to the loop hanger. Under load the horizontal tabs  4  and  5  will attempt to bend at the edge of the bottom hex nut. The annular rib  19  increases stiffness in this area and hence reduces deflection. The rib  19  may be a stamped feature, with the stamping used to deform some of the material around the hole  16  to produce the annular rib  19 . 
         [0040]      FIG. 5  shows the loop hanger  100  as part of an installation  110  for supporting a pipe  22 . The loop hanger  100  is supported on a threaded rod  20 , with the threaded rods  20  passing through the holes  14 - 16  ( FIG. 3 ) in the tabs  4  and  5  ( FIG. 1 ), and the washer  6  ( FIG. 1 ). The threaded rod  20  may be connected to a ceiling, fixture, or other building structure (not shown). Hex jam nuts  21  are threaded onto the threaded rod  20  above and below the washer  6  and the tabs  4  and  5 . The nuts  21  are tightened against the upper tab  4  and the washer  6  to secure the hanger  100  in place on the threaded rod  20 . The pipe  22  is surrounded by the loop hanger  100 , with the pipe  22  resting in the rounded bottom portion loop  1 , against the inside surface of the flat central portion  18   a  ( FIG. 4 ) of the loop  1 . 
         [0041]    The combined effect of the integral fold-over washer  6 , annular rib  19 , and gussets (stiffening elements)  11  allow the loop hanger  100  to achieve high performance with less material content, specifically in regard to the ability to resist deflection. Furthermore, this performance can be achieved without the use of additional flat washers, as are commonly required in the industry. It will be appreciated that a loop hanger need not necessarily utilize both features (integral fold-over washer  6  and annular stiffening rib  19 ) to enjoy improved performance. It has been found that the more important feature in terms of stiffening is the integral fold-over washer  6 , although both features are separately advantageous, as well as being advantageous in combination. The addition of the annular stiffening rib enhances the performance even further, but by itself may not allow the hanger to meet the deflection requirements with a minimum material condition. It will be appreciated that the integrated fold-over washer  6  does not necessarily have to extend across the full length of the bottom tab  5  and proceed down the opposite leg  2 . Alternatively, a shorter fold-over washer may deliver the desired support without the extra length. 
         [0042]    The addition of the integrated fold-over washer  6  and/or the annular rib  19  eliminates the need to add flat washers to a loop hanger installation for additional support. This reduces the number of parts and installation time. This solution also allows a loop hanger to meet agency deflection requirements with less material (thinner, narrower, lower strength). 
         [0043]    An alternative configuration would be to provide a series of longitudinal ribs on both the fold-over washer  6  and the lower horizontal tab  5 , such as horizontal ribs, very similar in form to corrugations found in cardboard. However it was found that the annular rib  19  performed better than the horizontal ribs. 
         [0044]    The shape of the annular rib  19  could be modified to deliver similar stiffness without the circular (annular) shape. For example, a series of corrugations, similar to those found in corrugated cardboard, could deliver comparable stiffness to the annular rib  19 . Further, if the bottom tab  5  also possessed corrugations such that the bottom tab  5  and the corrugated fold-over washer  6  nested within each other, they would create a very strong composite structure. 
         [0045]      FIGS. 6 and 7  illustrate an alternate embodiment loop hanger  200 , in which a washer  206  attached to the end of the top horizontal tab  204  via a carry tab (usable to carry the hanger  200  prior to separation of the washer  206 ). At the time of installation, an installer would simply break off the washer  206  and install it on the bottom side of the lower horizontal tab  205 . There may be score lines or other weakening of material to allow separation of the washer  206  from the tab  205 . The break-off washer  206  would function the same as a typical round washer, but an advantage is that an installer would not have to go out and find the washer, but instead would use the attached washer  206 . Other features of the loop hanger  200  may be similar to corresponding features of the loop hanger  100  ( FIG. 1 ). The configuration of the loop hanger  200  does have the advantage of providing the entire loop hanger as a single piece, solving the issue of finding the washer at the time of installation. However, after the washer  206  is detached it is still loose, meaning that it could be dropped. The loop hanger  100  has the advantage of having its washer  6  attached to the end of the lower horizontal tab  5 , and folded under so the installer does not have to go through any additional steps during the installation. 
         [0046]    The integral fold-over washer could be employed as a stiffening member for other hangers, such as loop hangers that utilize swaging to draw out the material to a width larger than the base width such that a threaded rod can be inserted into a hole in the center of the swaged portion. Adding the integral fold-over washer with a swaged section would provide the dual benefit of stiffening the tabs and improving the tear-out performance of the loop hanger. In addition, even a clevis style hanger would benefit from the fold-over washer, as it would provide additional stiffness to the top half of the clevis hanger, which is the weakest (and therefore least robust) portion of a clevis hanger. 
         [0047]    Although the invention has been shown and described with respect to a certain preferred embodiment or embodiments, it is obvious that equivalent alterations and modifications will occur to others skilled in the art upon the reading and understanding of this specification and the annexed drawings. In particular regard to the various functions performed by the above described elements (components, assemblies, devices, compositions, etc.), the terms (including a reference to a “means”) used to describe such elements are intended to correspond, unless otherwise indicated, to any element which performs the specified function of the described element (i.e., that is functionally equivalent), even though not structurally equivalent to the disclosed structure which performs the function in the herein illustrated exemplary embodiment or embodiments of the invention. In addition, while a particular feature of the invention may have been described above with respect to only one or more of several illustrated embodiments, such feature may be combined with one or more other features of the other embodiments, as may be desired and advantageous for any given or particular application.