Patent Publication Number: US-8985160-B2

Title: Corrugated metal pipe

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     The present application is a continuation of U.S. patent application Ser. No. 12/849,641 entitled CORRUGATED METAL PIPE filed Aug. 3, 2010, which is a continuation of U.S. patent application Ser. No. 12/604/005 filed Oct. 22, 2009, the entirety of the disclosures of which are expressly incorporated herein by reference. 
    
    
     STATEMENT RE: FEDERALLY SPONSORED RESEARCH/DEVELOPMENT 
     Not Applicable 
     BACKGROUND 
     The present invention relates in general to pipes, and more particularly, to corrugated metal pipes. 
     Corrugated metal pipe is used extensively in flood control, drainage and sewer systems because of its economic value strength and durability. The pipe is usually fabricated in 20 foot and 24 foot sections; however sections in other lengths are available. Widely used pipe diameters may range from 6 to 216 inches and typical wall thicknesses are 0.052 inches (18 gauge), 0.064 inches (16 gauge), 0.079 inches (14 gauge), 0.109 inches (12 gauge), 0.138 inches (10 gauge) and 0.168 inches (8 gauge). 
     Corrugated metal pipe derives most of its inherent strength from the corrugations formed into the metal sheets at the time of fabrication. Helical corrugated pipe is corrugated pipe with helical corrugations, fabricated from corrugated metal sheet, with a continuous helical seam. Corrugated metal sheet is a mill product in sheet or coil form for fabricating helical corrugated pipe products. Corrugations commonly used for metal pipes are circular arcs connected by tangents, and are described by pitch and depth. Pitch is measured at right angles to the corrugations from crest to crest on a same side of a pipe sheet. Depth of a corrugation is measured from a crest of a corrugation to the lowest portion of an adjoining valley, both measured on a same side of a pipe sheet. A corrugation is named using its pitch and depth as “pitch by depth.” 
     A standard “3×1” corrugation profile features a 3 inch pitch and a 1 inch depth. Seven (7) corrugations are included on each side of the metal sheet. The corrugated metal sheet is formed from a flattened sheet width is about 27 inches (specifically 27¼ inches). The finished (corrugated) sheet width is 21′ (+−½ inch) with a lock seam. A standard “5×1” corrugation profile features a 5 inch pitch and a 1 inch depth. Six (6) corrugations are included on each side of the metal sheet. The corrugated metal sheet is formed from a flattened sheet width is about 34 inches (specifically 33 5/16 inches). The finished (corrugated) sheet width is 30″ (+−½ inch) with a lock seam. 
     For large pipe diameters (over 48 inches), a 3×1 corrugation profile is the established industry profile. The traditional 5×1 corrugation profile utilizes approximately 13% less material that the 3×1 corrugation profile. However, for engineering purposes, pipes with 3×1 and 5×1 corrugation profiles are considered to have the similar enough structural properties to be equal products. Nonetheless, pipe fabricators must stock both metal sheets with 27 and 34 inch flat sheet widths to accommodate desired the 3×1 and 5×1 corrugation profiles. 
     Accordingly, there exists a need in the art for an improved corrugated pipe arrangement in comparison to the prior art. 
     BRIEF SUMMARY 
     According to an aspect of the present invention, there is provided a metal pipe of single piece includes a wall formed of a single corrugated metal sheet. The sheet has opposing first and second edges extending longitudinally along the sheet. The wall includes a seam formed by abutting portions of the first and second edges. The seam extends helically about and along a length of the wall. The wall has an interior wall side and an opposing exterior wall side. The metal sheet has an interior wall side and an opposing exterior wall side. The interior wall side defines an inner wall surface of the wall, and the exterior wall side defines an outer wall surface of the wall. The sheet has a sinusoidal cross-sectional profile defining 5 corrugation peaks at the inner wall surface and 5 corrugation peaks at the outer wall surface. The sheet has a flattened sheet width of approximately 27¼ inches and a finished sheet width of approximately 23 inches. 
     According to various embodiments, the finished sheet width may be between 21½ inches and 23½ inches. The seam may be a lock seam. The sheet may have a corrugation pitch of approximately 4½ inches. The sheet may have a corrugation height between adjacent corrugations of approximately 1 inch. In this regard, in this embodiment, the corrugation profile would be “4½×1”. This is roughly a “5×1” corrugation profile. This is significant in that a corrugated pipe fabricator can stock just sheets with sheet widths of 27¼ inch and still be able to produce sheets either “3×1” or a roughly “5×1” corrugation profile. In addition, the wall may define a pipe diameter between 36 inches and 216 inches. The wall may be cylindrical shaped. The metal sheet may have a thickness between 18 gauge and 8 gauge. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       These and other features and advantages of the various embodiments disclosed herein will be better understood with respect to the following description and drawings, in which like numbers refer to like parts throughout, and in which: 
         FIG. 1  is a cross sectional view of a prior art “3×1” corrugated metal sheet; 
         FIG. 2  is a cross sectional view of a prior art “5×1” corrugated metal sheet; 
         FIG. 3  is a cross sectional view of a corrugated metal sheet utilized in the fabrication of corrugated metal pipe according to an aspect of the invention; 
         FIG. 4  is a side view of a corrugated metal pipe in accordance with an aspect of the invention; 
         FIG. 5  is a cross sectional view as viewed from the axis  5 - 5  of  FIG. 4 ; 
         FIG. 6  is an enlarged cross sectional view of a portion of a length of corrugated metal pipe constructed in accordance with an aspect of the present invention; and 
         FIG. 7  illustrates a section of corrugated metal pipe during fabrication from the corrugated metal sheet. 
     
    
    
     DETAILED DESCRIPTION 
     The detailed description set forth below in connection with the appended drawings is intended as a description of the presently preferred embodiment of the invention, and is not intended to represent the only form in which the present invention may be constructed or utilized. Reference throughout the detailed description to “one embodiment” or “an embodiment” means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the present invention. Thus, appearances of the phrases “in one embodiment” or “in an embodiment” in various places throughout this detailed description are not necessarily all referring to the same embodiment. The following description is given by way of example, and not limitation. Given the above disclosure, one skilled in the art could devise variations that are within the scope and spirit of the invention disclosed herein. Further, the various features of the embodiments disclosed herein can be used alone, or in varying combinations with each other and are not intended to be limited to the specific combination described herein. Thus, the scope of the claims is not to be limited by the illustrated embodiments. In the following description, numerous specific details are shown to provide a thorough understanding of embodiments of the invention. One skilled in the relevant art will recognize, however, that the invention may be practiced without one or more of the specific details, or with other methods, components, materials, etc. In other instances, well-known structures, materials, or operations are not shown or described to avoid obscuring aspects of the invention. It is further understood that the use of relational terms such as first and second, and the like are used solely to distinguish one from another entity without necessarily requiring or implying any actual such relationship or order between such entities. 
     Referring now to  FIG. 1 , there is depicted a cross sectional view of a prior art “3×1” corrugated metal sheet  10 . A standard “3×1” corrugation profile features a 3 inch pitch (P1) and a 1 inch depth (D1). The metal sheet  10  includes seven (7) corrugations  12   a - g  on one side and seven (7) corrugations  18   a - g  on an opposing side. Each of the corrugations  12   a - g  respectively includes corrugation peaks  14   a - g . Adjacent to each of the corrugations  12   a - g  respectively are corrugation valleys  16   a - g . Each of the corrugations  18   a - g  respectively includes corrugation peaks  20   a - g . Adjacent to each of the corrugations  18   a - g  respectively are corrugation valleys  22   a - g . The metal sheet  10  has first and second edges  24 ,  26 . In the embodiment depicted, each of the first and second edges  24 ,  26  are bent back upon themselves in a lock seam configuration. The corrugated metal sheet  10  is formed from a flattened sheet width is about 27 inches (specifically 27¼ inches). The finished (corrugated) sheet width (W1) is 21″ (+−½ inch) with a lock seam. 
     Referring now to  FIG. 2  there is depicted a cross sectional view of a prior art “5×1” corrugated metal sheet  28 . A standard “5×1” corrugation profile features a 5 inch pitch (P2) and a 1 inch depth (D2). The metal sheet  28  includes six (6) corrugations  30   a - f  on one side and six (6) corrugations  36   a - g  on an opposing side. Each of the corrugations  30   a - f  respectively includes corrugation peaks  32   a - f . Adjacent to each of the corrugations  30   a - f  respectively are corrugation valleys  34   a - f . Each of the corrugations  36   a - f  respectively includes corrugation peaks  38   a - f . Adjacent to each of the corrugations  36   a - f  respectively are corrugation valleys  40   a - f . The metal sheet  10  has first and second edges  42 ,  44 . In the embodiment depicted, each of the first and second edges  42 ,  44  are bent back upon themselves in a lock seam configuration. The corrugated metal sheet  28  is formed from a flattened sheet width is about 34 inches (specifically 33 5/16 inches). The finished (corrugated) sheet width (W2) is 30″ (+−½ inch) with a lock seam. 
     Referring now to  FIG. 3  there is depicted a cross sectional view of a corrugated metal sheet  46  utilized in the fabrication of corrugated metal pipe according to an aspect of the invention. The metal sheet  46  includes five (5) corrugations  48   a - e  on one side and five (5) corrugations  54   a - e  on an opposing side. Each of the corrugations  48   a - e  respectively includes corrugation peaks  50   a - e . Adjacent to each of the corrugations  48   a - e  respectively are corrugation valleys  52   a - 2 . Each of the corrugations  54   a - e  respectively includes corrugation peaks  56   a - e . Adjacent to each of the corrugations  54   a - e  respectively are corrugation valleys  58   a - e . The metal sheet  46  has first and second edges  60 ,  62 . In the embodiment depicted, each of the first and second edges  60 ,  62  are bent back upon themselves in a lock seam configuration. The corrugation profile of the metal sheet  46  is characterized by a pitch (P3) and a depth (D3). The corrugated metal sheet  46  has a finished (corrugated) sheet width (W3) of approximately 23 inches with a lock seam. As used herein approximately 23 inches refers to 23 inches +−manufacturing tolerances or specifications. In this regard, a 1½ lower tolerance and a ½ inch upper tolerance would result in approximately 23 inches being used herein to mean between 21½ inches and 23½ inches. The corrugated metal sheet has a flattened sheet width of approximately 27¼ inches. As used herein approximately 27¼ inches refers to 27¼ inches +−manufacturing tolerances or specifications. In this regard, a ½ inch tolerance would result in approximately 27¼ inches being used herein to mean be between 26¾ inches and 27¾ inches. 
     Referring now to  FIG. 4  there is depicted a side view of a corrugated metal pipe  64  in accordance with an aspect of the invention.  FIG. 5  is a cross sectional view as viewed from the axis  5 - 5  of  FIG. 4 .  FIG. 6  is an enlarged cross sectional view of a portion of a length of the corrugated metal pipe  64  constructed in accordance with an aspect of the present invention.  FIG. 7  illustrates a section of the corrugated metal pipe  64  during fabrication from the corrugated metal sheet  46 . As is illustrated, the metal sheet  46  may be “feed” towards the forming metal pipe  64 . 
     According to an aspect of the invention, the metal pipe  64  includes a wall  70 . The wall  70  is formed from of a single corrugated metal sheet, such as the metal sheet  46 . The metal sheet has the opposing first and second edges  60 ,  62  extending longitudinally along the sheet  46 . The wall  70  includes a seam, such as lock seam  66 , formed by abutting portions of the first and second edges  60 ,  62 . The seam  66  extends helically about and along a length of the wall  70 . The sheet  46  has an interior wall side  78  and an opposing exterior wall side  76 . The interior wall side  78  defines an inner wall surface  72  of the wall  70 , and the exterior wall side  76  defines an outer wall surface  74  of the wall  70 . The sheet  46  has a sinusoidal cross-sectional profile defining 5 corrugation peaks at the inner wall surface  72  and 5 corrugation peaks at the outer wall surface  74 . The sheet  46  has a flattened sheet width of approximately 27¼ inches and a finished sheet width of approximately 23 inches. 
     According to various embodiments, the sheet  46  may have a corrugation pitch (P3) of approximately 4½ inches. The sheet  46  may have a corrugation depth (D3) between adjacent corrugations of approximately 1 inch. In this regard, in this embodiment, the corrugation profile would be “4½×1”. This is roughly a “5×1” corrugation profile. This is significant in that a corrugated pipe fabricator can stock just sheets with sheet widths of 27¼ inch and still be able to produce corrugated metal sheets with either “3×1” or a roughly “5×1” corrugation profiles. As a result inventory costs may be significantly reduced by avoiding such double inventory requirements because the metal sheets with flattened sheet width of 34 inches (for the traditional “5×1” profile would no longer be needed). 
     The wall  70  is defined by a longitudinal axis  68 . The wall  70  defines a pipe diameter (PD) with reference to the longitudinal axis  68 . The pipe diameter (PD) may be between 36 inches and 216 inches. In the embodiment illustrated, the metal pipe  64  is cylindrical shaped. The sheet  46  may have a thickness between 18 gauge and 8 gauge. The metal utilized to fabricate the metal sheet  46  may be chosen from any of those which are well known to one of ordinary skill in the art, such as steel. Further, the metal sheet  46  may be surface coated as may be desired. 
     The particular manufacturing processes for forming the metal sheet  46  with the corrugation profile may be chose from any of those processes which are well known to one of ordinary skill in the art. Moreover, the particular manufacturing processes for forming the metal pipe  64  from the metal sheet  46  may be chose from any of those processes which are well known to one of ordinary skill in the art. While the seam  66  is depicted as a lock seam, it is contemplated other attachment or bonding arrangements, such as welding may be utilized, may be selected from those which are well known to one of ordinary skill in the art. 
     It is contemplated that a corrugating bed of a standard metal sheet production mill is 29½ inches (+−a margin depending up the particular mill used). A metal sheet with a traditional “5×1” corrugation profile, begins with a flattened sheet width of 34 inches (+−manufacturing tolerances). However, this is wider than the corrugating bed of the standard metal sheet production mill. As such (in the absence of the present invention), a fabricator would either have to width of the corrugating bed of the standard metal sheet production mill or purchase a new mill with a wider. The corrugation profile of the metal sheet  46  of the present invention is configured to fit a corrugating bed with a width of 29½. This allows a fabricator to produce corrugated metal sheets with either “3×1” or a roughly “5×1” corrugation profiles using their standard metal sheet production mill. 
     From an engineering point of view the metal sheet  46  with its corrugation profile utilizes approximately 10% less material than the traditional “3×1” profile (the “3×1” corrugation profile is the established industry profile). However, the structural strength characteristics of the “3×1” and “5×1” corrugation profiles are considered similar enough to be equal products. A metal sheet with a traditional “5×1” corrugation profile utilizes approximately 13% less material than a metal sheet with a “3×1” corrugation profile, and the traditional 5×1 corrugation profile product thus has a competitive advantage over “3×1” corrugation profile products. The metal sheet  46  with its corrugation profile utilizes approximately 10% less material than a metal sheet with a “3×1” corrugation profile (making it more competitive against the traditional “5×1” corrugation products) while utilizing a single inventory of flattened metal sheets with the width of 27 inches. 
     Moreover, given the metal sheet  46  utilizes approximately 3% more material than the traditional “5×1” corrugation profile products, such metal sheet  46  is contemplated to be slightly structurally stronger. Advantageously, the corrugation profile of the metal sheet  46  of the present invention is contemplated to fall within present engineering tolerances of both ASTM and AASHTO associated with the traditional “5×1” corrugation profile products. In this regard, it is contemplated that the metal sheet  46  may be utilized as a direct substitute for traditional “3×1” or “5×1” corrugation profile products.