Abstract:
A field replaceable wing nut having an arcuate body and an arcuate insert is disclosed. The wing nut is designed to replace an existing wing nut which has deformed or non-useable lugs on a hammer union connection. The wing nut has accurate alignment of the mounting threads using an alignment attachment device. Replacing the wing nut in the field does not require any special equipment or training. Each wing nut is designed for a particular pipe diameter.

Description:
BACKGROUND 
       [0001]    Hammer unions are commonly employed to join pipe segments together. Typically, the wing nut component of the hammer union, which has a wing nut pipe segment with a threaded wing nut having integrated lugs, is tightened onto a male threaded pipe component by hammering upon the lugs. When the wing nut becomes unusable, it is usually necessary to remove the entire wing nut pipe segment from service. 
         [0002]    It is standard practice to capture the wing nut on the wing nut pipe segment which prevents users from removing or replacing the wing nut. Once captured, the wing nut and the wing nut pipe segment are generally inseparable. 
         [0003]    Often, before the full, useful life of the wing nut pipe segment is reached, one or more lugs on the wing nut will become deformed. A wing nut with one or more deformed lugs cannot reliably be mated to a male threaded piece of piping equipment. The piping equipment, however, would generally still be usable if the wing nut is replaced. At this time, there is no safe, field-installable wing nut that can be used to replace deformed, damaged or worn-out wing nuts which are captured on the wing nut pipe segment. 
         [0004]    Currently, when a wing nut becomes deformed due to damaged or deformed lug(s), the end of the wing nut pipe segment on which the wing nut is installed is cut off, the deformed wing nut is replaced with a new wing nut, and the pipe is machined and welded together. Unfortunately, this repair approach often has quality problems. These quality problems lead to safety issues. 
         [0005]    Safety of a joined hammer union is a major concern because hammer unions are often used to connect piping carrying large volumes of fluid under high pressures. Due to the internal forces on the pipe joint, hammer union joints commonly fail in an explosive manner. A misaligned wing nut on a hammer union joint may hold pressure for a period of time, but may ultimately fail as the pressure pushes against the joint. 
         [0006]    An attempted field repair of a wing nut using common cutting and welding techniques creates a significant risk for misaligned or poorly welded joints. In normal field situations, there are few or no field personnel qualified to perform the highly skilled welding and machining operations required for a safe repair. Additionally, there is usually an absence of qualified welding and machining standards for field personnel to follow. 
         [0007]    Since field repairs may result in significant down time, there is also an economic impact when removing a pipe section to replace a deformed wing nut. In manufacturing and drilling operations, down time directly impacts a company&#39;s cost of operations. 
         [0008]    As identified herein, there is a need for a field replaceable hammer union wing nut that does not require welding or machining. Additionally, there is a need for a field replaceable hammer union wing nut that may be easily and efficiently installed by field personnel. 
       SUMMARY OF THE INVENTION 
       [0009]    One embodiment discloses a field replaceable wing nut comprising an arcuate body, an arcuate insert, and an attachment device. The arcuate body defines a first portion of a mounting thread, and the arcuate insert defines a second portion of a mounting thread. The attachment device is for connecting the arcuate body and arcuate insert. When the arcuate body and arcuate insert are connected, the first and second portions of the mounting thread define a complete mounting thread for receiving a threaded male pipe end. 
         [0010]    Another embodiment discloses a multiple piece wing nut comprising a first arcuate body, a second arcuate body, and an attachment device. The first arcuate body has a first threaded portion, and the second arcuate body has a second threaded portion. The attachment device connects the second arcuate body to the first arcuate body. The connected first and second arcuate bodies form an annular body having a collar extending therefrom. 
         [0011]    Still another embodiment discloses a wing nut comprising a first arcuate body, a second arcuate body, and a retaining ring. The first arcuate body has a first portion of a mounting thread thereon. The first arcuate body has a first and second clearance end defining a circumferential gap therebetween. The second arcuate body has a second portion of a mounting thread thereon. The second arcuate body has first and second mating ends for engaging the first and second clearance ends. The retaining ring is disposed about the first and second arcuate bodies. The first and second threaded portions define a complete connecting thread for receiving a threaded male pipe when the first and second arcuate bodies are connected. 
         [0012]    A method is disclosed for replacing a wing nut assembly in the field comprising the following steps:
       (a) providing a first arcuate body;   (b) radially receiving a pipe on which the wing nut is to be installed through a circumferential gap defined by the first arcuate body;   (c) providing a second arcuate body;   (d) inserting the second arcuate body in the gap; and   (e) securing the first arcuate body to the second arcuate body.       
 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0018]      FIG. 1  is an exploded bottom perspective view of the wing nut. 
           [0019]      FIG. 2  depicts a top plan view of an arcuate body. 
           [0020]      FIG. 3  is a top plan view of the wing nut. 
           [0021]      FIG. 4  is a cross-sectional view taken from  FIG. 3  along line  4 - 4 . 
           [0022]      FIG. 5  is an exploded plan view of the wing nut with a pipe section. 
           [0023]      FIG. 6  is a top perspective view depicting the assembled wing nut. 
           [0024]      FIG. 7  is a cross-sectional view of the wing nut installed on a male threaded pipe segment. 
       
    
    
     DETAILED DESCRIPTION 
       [0025]    This disclosure is directed to a field-installable wing nut that requires no welding or machining operations. The wing nut installation does not require any special qualifications or procedures, and can easily be accomplished by field maintenance personnel in normal field situations. 
         [0026]    Generally, wing nut  10  is selected to correspond to a defined nominal pipe diameter. It is anticipated that a series of wing nuts  10  will be available for different sizes of pipes being employed. 
         [0027]    Referring to  FIGS. 1-7 , wing nut  10  is generally comprised of arcuate body  12 , arcuate insert  14 , retaining ring  16 , and attachment devices  18 . Attachment devices  18  are used to connect, or join, arcuate insert  14  with arcuate body  12 . Arcuate body  12  may also be referred to as the first arcuate body  12 , and arcuate insert  14  may also be referred to as the second arcuate body  14 . 
         [0028]    Wing nut  10  is preferably an alloy or carbon steel piece capable of withstanding high pressure when fully assembled and installed. Arcuate body  12  and arcuate insert  14  are preferably manufactured out of the same material. A non-limiting example of the material to form arcuate body  12  and arcuate insert  14  is to use a circular metal slug of hot, rolled grade 4340 steel. Retaining ring  16  is preferably manufactured out of a material different than that of arcuate body  12  and arcuate insert  14 . A non-limiting example is to use grade 4140 steel tubing for retaining ring  16 . Furthermore, retaining ring  16  preferably has material properties with specific capabilities as described herein. Wing nut  10  may be fabricated from other types of materials. These materials are preferably matched to a pipe size, and with a desired pressure containment capability. 
         [0029]    As depicted in the drawings, assembled wing nut  10  defines an annular body  20  with a plurality of lugs  22  thereon. Annular body  20 , which may be referred to as upper ring  20 , has inner diameter  21  and first outer diameter  24 , and in the embodiment shown has three lugs  22  defined thereon. Assembled wing nut  10  has a collar  26  extending longitudinally from annular body  20 . Collar  26  may be referred to as lower ring  26 . Collar  26  has second outer diameter  28 , which is preferably smaller than first outer diameter  24 , so that shoulder  30  is defined by, and extends between, first and second outer diameters  24  and  28 . Wing nut  10  has a length  32 . Collar  26  has a collar length  34  that is shorter than length  32 . Collar  26  has a threaded inner surface  38  extending along collar length  34  to define mounting or connecting threads  40 , and has a collar thickness  42 . Wing nut  10  is thus compatible with a male thread  36 , and will receive a threaded male pipe segment as will be described in more detail herein. 
         [0030]    As depicted in  FIG. 2 , arcuate body  12  has an arc that is preferably equal to or greater than arcuate insert  14 , and that is at least circumferentially 180 degrees. The embodiment shown has an arc of approximately 220 degrees. Arcuate insert  14  will complement arcuate body  12  so that when assembled, arcuate body  12  and arcuate insert  14  comprise wing nut  10 . 
         [0031]    Arcuate body  12  has a first clearance end  44  and a second clearance end  46  defining a gap or space  48  therebetween. Gap  48  will receive a pipe segment  50  therethrough. When pipe segment  50  is received through gap  48 , and arcuate body  12  and arcuate insert  14  are connected, the assembled wing nut  10  will provide fluid communication between pipe segments  50  and  52  when connecting threads  40  are properly mated with male threads  36  on pipe segment  52 . 
         [0032]    Arcuate insert  14  has first and second mating ends  54  and  56 . First clearance end  44  of arcuate body  12  will mate with first mating end  54  of arcuate insert  14 . Second clearance end  46  of arcuate body  12  will mate with the second mating end  56  of arcuate insert  14 . First and second seams, or joints  58  and  60 , are formed when arcuate insert  14  is inserted or positioned in gap  48  with first clearance end  44  adjacent to and engaging first mating end  54 , and second clearance end  46  adjacent to and engaging second mating end  56 . 
         [0033]    Joints  58  and  60  are designed to ensure a tight seal between arcuate body  12  and arcuate insert  14 . Thus, it is preferred that joints  58  and  60  have a radially straight seam as depicted in  FIGS. 2 ,  3  and  6 . Joint  58  preferably has an exemplary angle  62  of about 13 degrees. However, it is understood that angle  62  may be any angle that allows arcuate body  12  and arcuate insert  14  to be joined. Similarly, joint  60  preferably has an exemplary angle  66  of about negative 13 degrees. It is also understood that angle  66  may be any angle that allows arcuate body  12  and arcuate insert  14  to be joined. In  FIG. 2 , angles  62  and  66  are measured relative to horizontal centerline  64 . 
         [0034]    Referring to  FIG. 5 , attachment openings  68  and  70  are preferably threaded, countersunk attachment openings centered on joints  58  and  60 , and, referring to  FIG. 3 , having a radial center point  72  positioned on upper surface  74  of assembled wing nut  10 . Preferably, radial center point  72  is positioned between first outer diameter  24  and inner diameter  21 . Attachment devices  18  are threaded connectors that will hold arcuate body  12  and arcuate insert  14  in place so that connecting threads  40  may receive male thread segment  36 , such as that on pipe segment  52 , to connect pipe segments  50  and  52 . 
         [0035]    Arcuate body  12  and arcuate insert  14  each define a portion of connecting threads  40  as depicted in  FIGS. 1 ,  6  and  7 . Arcuate body  12  has first thread portion  76  of mounting thread  40  thereon, while arcuate insert  14  has second thread portion  78  of mounting thread  40  thereon. When arcuate body  12  and arcuate insert  14  are connected and aligned, first and second threaded portions  76  and  78  form connecting or mounting thread  40 . The alignment of first and second mounting thread  76  and  78  to form connecting thread  40  is facilitated by the insertion of attachment devices  18  into attachment openings  68  and  70 . In the preferred embodiment, connecting threads  40  are preferably machined into arcuate body  12  and arcuate insert  14  while they are joined. As will be understood, arcuate body  12  and arcuate insert  14  may be threaded prior to being machined from a single piece into the separate arcuate body  12  and arcuate insert  14 . Connecting threads  40  may also be part of a cast or forged wing nut  10 . As described above, connecting threads  40  are located on threaded inner surface  38  of collar  26 . 
         [0036]    In the embodiment shown in  FIGS. 1-7 , three lugs  22  are employed. A minimum of one (1) lug  22  is required. The maximum number of lugs  22  is limited by the available circumferential space on annular body  20 . However, it is anticipated that the number of lugs  22  will typically be between two (2) and four (4). Lugs  22  extend radially outward from annular body  20 . The spacing between lugs  22  is not critical in that lugs  22  may be uniformly spaced or not uniformly spaced. 
         [0037]      FIG. 5  depicts a plan view of wing nut  10  with three (3) lugs  22  and wing nut pipe segment  50 .  FIG. 5  depicts wing nut pipe segment  50  positioned to be received by arcuate body  12  through gap  48 . In the preferred embodiment, wing nut pipe segment  50  is able to pass through gap  48  without external force applied. In other words, gap  48  has sufficient clearance for pipe segment  50  to pass therethrough. 
         [0038]    Retaining ring  16 , depicted in  FIGS. 1 and 7 , is designed to secure arcuate body  12  and arcuate insert  14  in the assembled state. Retaining ring  16  is preferably of a material having properties sufficient to resist the circumferential stress exerted upon it by arcuate body  12  and arcuate insert  14 , once installed. It is preferred that retaining ring  16  have a coefficient of thermal expansion sufficient to allow it to expand to an inner diameter that is greater than second outer diameter  28  of collar  26  when heated. The same coefficient of thermal expansion of retaining ring  16  allows it, when cooled to an ambient temperature, to return to an inner diameter less than second outer diameter  28  of collar  26 . Thus, when retaining ring  16  is heated and placed over collar  26  and then cooled, it will apply inwardly directed radial force to collar  26 , and hold arcuate body  12  and arcuate insert  14  in place. Retaining ring  16 , when installed, will preferably have a thickness  82  about equal to the width  84  of shoulder  30 , and as such will have an outer diameter about the same as first outer diameter  24  of upper ring  20 . Retaining ring  16  preferably has a length similar to collar length  34  of collar  26 . 
         [0039]    A method of installing wing nut  10  may require initially removing a deformed or damaged wing nut from a wing nut pipe segment  50 . The damaged wing nut may be removed at any time prior to installing retaining ring  16 . To install wing nut  10 , arcuate body  12  radially receives pipe segment  50  through gap  48 . Once pipe segment  50  is in place, arcuate insert  14  is inserted into gap  48  so that first and second clearance ends  44  and  46  of arcuate body  12  engage first and second mating ends  54  and  56  of arcuate insert  14 . Attachment devices  18  are threaded into attachment openings  68  and  70 , and are also used to align first and second mounting threads  76  and  78 . Once first and second thread portions  76  and  78  are aligned to form connecting thread  40 , the combined unit of arcuate body  12  and arcuate insert  14  is longitudinally moved along pipe segment  50  until it is positioned at pipe segment end  80 , thereby making collar  26  accessible. 
         [0040]    Retaining ring  16  is heated to a temperature that allows it to expand to an inner diameter greater than second outer diameter  28  of collar  26 . The heated and expanded retaining ring  16  is slipped over collar  26 , and allowed to cool to an ambient temperature. In one non-limiting example, retaining ring  16  is heated to about 400° F. It is preferred that retaining ring  16  be uniformly heated in a field oven or similar device. However, it is also acceptable to heat retaining ring  16  in any manner that creates near uniform thermal expansion without changing the material properties. After retaining ring  16  has radially retracted, pipe segment  52  may be threaded into collar  26  of wing nut  10 . Wing nut  10  is thus a field replaceable wing nut that requires no welding, or machining, and requires no special training of field personnel. 
         [0041]    Thus, it is shown that the apparatus and methods of the present invention readily achieve the ends and advantages mentioned, as well as those inherent therein. While certain preferred embodiments of the invention have been illustrated and described for purposes of the present disclosure, numerous changes in the arrangement and construction of parts and steps may be made by those skilled in the art. All such changes are encompassed within the scope and spirit of the present invention as defined by the appended claims.