Abstract:
Systems for joining pipes used in the food processing and pharmaceutical industries are disclosed. For example, connections of fluid handling pipes and improved flange-type joints are disclosed. Some disclosed joints comprise a pair of flanges each defining a circumferentially extending channel recessed from an end face A radially extending end wall is positioned radially outward of the end face. Said end faces are retained in axially opposed relationship to each other such that a circumferential groove configured to receive a gasket is defined when the joint is assembled. The groove has a first portion open to the flow passage and a second portion extending radially outward from the first portion. A polymeric gasket can comprise a generally toroidal member axially compressed in the first portion of the groove when the joint is assembled. The radial end walls radially compress the gasket, and the gasket can expand radially outward.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims priority to and the benefit of U.S. provisional patent application No. 61/185,037, filed Jun. 8, 2009, by Jeffrey C. Butte and entitled SELF-ALIGNING SANITARY PIPE JOINT, which is hereby incorporated by reference herein for all purposes as if listed herein in its entirety. 
     
    
     BACKGROUND 
       [0002]    The present disclosure concerns sanitary fittings for pipes of the type employed in the food processing and pharmaceutical industries. More specifically, but not exclusively, the present disclosure concerns connections of fluid handling pipes and improved flange-type joints configured to, for example, retain such pipes in end-to-end relation. 
         [0003]    Pipes can convey fluids or flowable food products and have been joined in end-to-end relation by connecting opposed flanges positioned on respective opposed pipe ends. To meet high force and rapid disassembly objectives, circumferentially extending, multi-section (e.g., hinged) clamps have been used to join such pipe ends to each other. Such clamps can include plural sections pivotally coupled to each other. The clamp sections can define respective recessed channels having internally opposed surfaces oriented at an angle relative to each other (e.g., the respective channels can have internal wedge surfaces) configured to urge against corresponding outer surfaces of opposed flanges. Flanges can define outwardly facing wedge surfaces on the exterior of the joint configured to be engaged by the wedge surfaces of an overlying clamp such that, as the clamp radially contracts, the respective angled surfaces axially compress the opposed surfaces of the flanges forming the joint (together with any gasket positioned therebetween). For example, since the respective surfaces are angled, the clamp urges against the flanges. As the clamp sections are radially drawn together (or the diameter of the clamp is otherwise reduced), the clamp urges the opposed flanges together. Such a clamp ring can be actuated by a thumb screw, configured to draw the plural clamp sections together, thereby reducing a diameter of the clamp ring. 
         [0004]    Such joints are typically used in systems requiring frequent disassembly for cleaning, maintenance, and/or system changeover. In addition, pipes and flanges employed in the food processing and pharmaceutical industries are often suited for forming connecting joints in critical processing systems where fluid entrapment or retention within the system is undesirable, and, in some instances, must be avoided. In such systems, it is often difficult to completely eliminate regions that collect and/or retain process fluids and/or flowable food. Such regions are sometimes referred to herein as “recesses” or “pockets”. For example, process fluid or flowable food retained in such recesses or pockets can contaminate a fluid or food subsequently passing through the pipes and joint (e.g., when processing a second batch of the same fluid or food, or when processing a different fluid or food). 
         [0005]    Problems posed by recesses and fluid trapping pockets are especially prevalent with respect to many pipe joints, which often include one or more resilient, elastomeric seals and packings. For example, a packed joint can be difficult to assemble and frequently forms undesired discontinuities between the connected sections (e.g., a step when moving axially from an interior surface of one pipe to an interior surface of an adjacent pipe, such as when the pipes are not in perfect axial alignment). Such steps and other deficiencies can arise, in part, from the use of a typical clamp mechanism that provides a compressive force, but does not provide axial alignment of the pipes. For example, opposing flanges can be misaligned, yet not so much that a conventional clamp cannot be assembled around them. In such an instance, the clamp can axially compress and retain the flanges in a radially misaligned position. 
         [0006]      FIG. 1  illustrates a flange connection configuration of the prior art which suffers many deficiencies. In this prior art configuration, longitudinally extending ferrules  1 ,  2  configured to join respective pipe (or tube) ends  3 ,  4  are provided with respective radially outwardly extending flanges  5 ,  6 . The respective ferrules  1 ,  2  can be butt welded to the respective pipe ends  3 ,  4  at a weld location  7 . An adjustable clamp  8  overlies and engages the opposed flanges  5 ,  6 . The clamp  8  can be adjusted by tightening a screw (not shown) which effectively reduces a radial dimension of the clamp  8  and, in combination with the angled surfaces  9 ,  9   a  of the clamp and flanges  10 ,  10   a , thereby compresses an elastomeric gasket  11  positioned between the flanges. 
         [0007]    In the configuration shown in  FIG. 1 , an outer angle of the flanges  5 ,  6  is 20 degrees from a plane oriented perpendicularly to a longitudinal axis of the pipe (e.g., an axial flow direction). The corresponding inner angle of the clamp  8  is 18.5 degrees. As the clamp  8  is drawn against the flanges, the inner surfaces  9 ,  9   a  of the clamp  8  contact and urge against the respective angled surfaces  10 ,  10   a  of the flanges  5 ,  6  thereby axially compressing the gasket  11  between the flanges  5 ,  6 . The annular bead  12  aligns the flanges  5 ,  6  during assembly. When this pipe joint is compressed, a portion  13  of the gasket  11  can extend into the product zone  14  by as much as approximately 0.0625 inches, or more, which in turn can form an internal flow obstruction  13  and/or a region  15  that can collect, retain, etc., a process fluid or flowable food (e.g., a region  6  with an internal angle of about 90 degrees or less) which can lead to an unsanitary operating condition for subsequent uses. For example, piping systems in food processing plants are typically inclined by approximately 2 degrees to facilitate draining. Such an obstruction can trap liquid in a region  15  adjacent (e.g., behind) the gasket  11  (such a region  15  is sometimes referred to herein as a “pocket”), and the trapped liquid can contaminate a subsequent flow of fluid and/or flowable food. The obstruction also reduces a hydraulic diameter (e.g., an open flow cross-sectional area) and forms an orifice within the pipe that increases pressure head losses through the joint. 
         [0008]    The extent of permissible intrusion of the gasket  11  into the product zone  14  is specified by the 3A Sanitary Standards, Inc. Pipeline Process Standard (605.04) which specifies a maximum 0.03125 inch deviation from internal flushness (e.g., gasket intrusion into the product zone, or recessed channel depth). Existing designs generally are incapable of meeting this specification. 
         [0009]    For example, the pipe joint  50  depicted in  FIG. 1  and just described permits the gasket  11  to be compressed by the clamp  8  to various degrees. Consequently, the gasket  11  can migrate into the product zone  14 , which migration increases with increasing compression. Also, the gasket  11  expands during heating (e.g., during use with hot liquid or during steam sterilization) to a much greater extent than typical stainless steel alloys used to form the flanges  5 ,  6 . 
         [0010]    Such deformation of the gasket  11  under excessive compression and/or thermal expansion is depicted in  FIG. 1A . Compression between the flanges  5 ,  6  causes an inner edge of the annular gasket  11  to expand inwardly and form a mushroom shaped bead  16 , creating a pocket  15  between a passage wall  17  and the bead  16 . An internal angle α between a line  18  tangent to the mushroom shaped bead  16  and the passage wall  17  can be less than 90 degrees. 
         [0011]    Sanitary pipe joints, designed for pipe sizes of 1.0 inch or less, are commonly referred to as “mini” fittings. Mini fittings are typically found in high purity applications in pharmaceutical and biotechnology applications. In some instances, pipe joints across a variety of internal flow dimensions share a common flange size, allowing use of a same-size clamp  8  for each of the variety of internal flow dimensions, especially in pipes having an interior flow dimension of less than about 1 inch. In such pipe joints, an annular bead  12  is often positioned in the same radial position in the flange  5 ,  6 , regardless of the corresponding interior flow dimension of the joint. For example, each of the variety of flanges defines a same-size, circumeferentially-extending, recessed channel, or groove, configured to receive a bead for a gasket. Gaskets for such flanges can physically be interchanged, since the grooves and beads share common dimensions, albeit without assurance that an open interior diameter of the gasket corresponds to an unobstructed interior diameter of the pipe. An annular gasket  11  having an open interior sized for a small interior flow dimension might not be suitable for use in a joint between pipes having a larger interior flow dimension, since at least a portion of the gasket could extend inwardly of the interior of the pipes. Conversely, an annular gasket having an open interior sized for a relatively larger interior flow dimension might not be suitable for use in a joint between pipes having a small interior flow dimension, since at least a portion of the joint between the pipes could define a recessed channel that otherwise would be occupied by a properly sized gasket. 
         [0012]    Consequently, improperly sized gaskets can be used in a variety of pipe joints, including mini-fittings. Installing an improperly sized gasket  11  in a pipe joint can create an unsanitary pocket  15  (e.g., an internal bead  16 , as shown in  FIG. 1A ) when a gasket with a relatively smaller interior diameter is installed in a larger pipe joint ( FIG. 1A ), or a recessed, circumferentially extending channel  19  can be formed within the joint ( FIG. 1B ), such as when a gasket  11   a  with an oversized opening (relative to an open interior dimension of the pipe) is used. 
         [0013]    Improperly sized gaskets can suffer other deficiencies, as well. For example, an inwardly extending gasket can obstruct an internal pipe flow, increasing loss of pressure head through the joint and increasing pressure losses that must be overcome, as by a pump. Such inefficiencies can increase operating costs compared to more efficient assemblies. 
         [0014]      FIG. 1C  illustrates unsanitary pockets  15 ,  19   a  that can form when the flanges  5 ,  6  are improperly aligned. In  FIG. 1C , misalignment is shown where the flanges  5 ,  6  are offset, resulting in unsanitary pockets  15 ,  19   a  both in a region adjacent the annular bead  12  and the corresponding recessed channel in the flange, and in the product zone  14 . The gasket  11  is also shown deformed, which can exacerbate formation of such pockets  15 ,  19   a.    
         [0015]    One common sanitary pipe connection, described in U.S. Pat. No. 2,789,844, the entire disclosure of which is incorporated by reference herein, utilizes annular beads molded into an otherwise flat gasket in an attempt to align opposed flanges. Excessive compression applied to the joint will cause the gasket to extrude (or otherwise deform and enter) into an interior of the pipe (sometimes also referred to as a product zone), as shown for example in  FIG. 1A . Because the portion  13  of the gasket extending into the product zone  14  is under less longitudinal compression than the portion between the flanges  5 ,  6 , the portion extending into the product zone  14  can expand. Such expansion can form a region  15  on the interior of the joint bounded in part by the expanded gasket portion  16  and the interior of the passage wall  17 . For example, the wall  17  and a generally axially extending line  18  tangent to the expanded gasket portion  16  can form an acute angle α. This results in an unsanitary condition because process fluids and/or flowable food can be trapped in regions  15  having internal angles of less than 90 degrees with no radius (e.g., due to surface tension). 
         [0016]    Pipeline process standard No. 605-04, published by 3A Sanitary Standards; Inc., specifies a maximum 1/32 inch minimum deviation of an elastomeric gasket into the product zone  14  of a process pipe. A surface discontinuity of 1/32 inch or less is considered “substantially flush” according to 3A Sanitary Standards, Inc., which is a requirement under the Sanitary Fittings standard 63-03. 
         [0017]    One approach of ameliorating such deficiencies is disclosed in U.S. Pat. No. 6,039,319, the entire disclosure of which is incorporated by reference herein. The &#39;319 patent discloses a reduced gasket size relative to an open volume of the gasket-receiving channel, which provides a region into which an axially compressed gasket can expand. The flanges disclosed in the &#39;319 patent are brought together in physical contact radially outward of the gasket. Such metal-to-metal contact limits compression of the gasket. The &#39;319 patent discloses a flat sealing surface defined by the flange and configured to interact with the gasket, which can allow a portion of the gasket to migrate into the product zone under various temperature or vacuum conditions. Also, verifying that a gasket is present in the joint disclosed in the &#39;319 patent is not possible by visual inspection because contact between the opposed flanges is positioned radially outward of the gasket. 
         [0018]    Another improvement upon the disclosure of the U.S. Pat. No. 2,789,844 is shown in U.S. Pat. No. 6,857,638, the entire disclosure of which is incorporated by reference herein. The &#39;638 patent discloses a gasket having an elastomeric O-ring portion and an incompressible ring member. The gasket is configured for establishing a seal between flanges of sanitary pipe fittings. The O-ring portion has a substantially flat cross-section to limit compression of the O-ring. The &#39;638 patent design limits compression of a gasket, but does not correct or ameliorate other deficiencies noted above with regard to sanitary pipe joints. 
         [0019]    Therefore, there remains a need in the art of pipe fittings for use in the food and/or pharmaceutical industries for a joint construction which is easy to assemble. There also remains the need with the field for a joint construction that does not form pockets, recesses, or other undesirable discontinuities which can trap, collector or retain process fluids, flowable food, or both. The present disclosure addresses these and other needs. 
       SUMMARY 
       [0020]    Innovations disclosed herein can be used in a wide variety of applications, including sanitary fittings for pipes of the type employed in the food processing and pharmaceutical industries. 
         [0021]    For example, some presently disclosed innovations concern methods of forming lengths of pipe for assembly together to form fluid flow conduits. Such methods can include the acts of providing a pipe having a first inner diameter and a central longitudinal axis, providing a ferrule which has an annular first end, having an inner diameter equal to the pipe inner diameter and having a second end formed into a flange adapted to form a flange coupling when abutted against and connected to another similar or identical flange. The first end of each ferrule is welded to an end of a pipe, wherein the end face of the flange assumes an orientation wherein the end face is substantially normal to the central longitudinal axis. 
         [0022]    A clamped flange pipe or tube fitting assembly can a resilient seal ring compressed by a clamp, whereby the shape of the inner surfaces of clamp provides for correct alignment of the flanges and fixed compression of the gasket. In some embodiments, correct alignment and improved ease of assembly is provided by increasing the internal angled surfaces of the clamp from 18.5 to approximately 37 degrees. Fixed compression of the gasket can be provided by seating the flange ends into mating grooves in the clamp at the completion of assembly. 
         [0023]    Sealing gaskets for insertion into a circumferentially continuous groove of a flange joint for joining axially aligned tube ends are disclosed. The flange joint has axially opposed flanges at the tube ends forming a groove therebetween when the joint is assembled. The groove is formed by axially opposed seal faces and radial end faces of the flanges. The groove can include a circular O-ring groove first portion that is open to an interior flow passage of the tubes and a second groove second portion that extends radially outward from the groove first portion. The gasket has a gasket first portion that seals the circular groove first portion and a flat gasket second portion that extends from the circular gasket section. A space formed between the terminus of the gasket second section and the terminus of the center ridge on the clamp forms an expansion space in the joint when the joint is assembled. The expansion space is vented to atmosphere. Some disclosed clamps include sections that are hinged and/or bolted together. 
         [0024]    Some disclosed innovations include a tube joint assembly that is configured to eliminate or greatly reduce gasket extrusion, reduce flow restriction, reduce contamination, reduce fluid retention, and/or provide improved alignment during assembly. For example, some tube joint assemblies include a pair of cylindrical tube ends in axially aligned end-to-end relationship. Each tube end can have a cylindrical interior surface of substantially the same diameter in aligned relationship with the cylindrical interior surface of the opposed tube end. Connecting flanges can extend radially outward of each tube end with axially opposed faces defining a circumferentially continuous packing groove including a first arced-shaped surface, and an axially wide portion defined by a semi-circular groove. A second axially narrow portion of the groove is positioned radially outward of the first portion and has a radial outer face radially overlying and aligned with the first semi-circular portion. A soft material gasket is positioned in the packing groove. One disclosed gasket configuration has a toroidal portion of the type commonly known in the art as an O-ring that is sized and dimensioned to completely fill the first semi-circular portion of the packing groove and engage the axially opposed sealing faces with substantial sealing pressure. A second portion of the gasket can have a unitary construction with the first portion, and can be sized and dimensioned to extend into the second, axially narrow portion of the packing groove. The second portion can have an inner radial dimension that forms an interference fit with the tube ends for ease of assembly and/or sufficient mass to hold the tube ends in a desired aligned relation during assembly of the joint. Such structural features can contribute to improved alignment of the components in the assembled fluid system, thereby improving the ease of assembly. 
         [0025]    The second portion of the gasket can have a radial dimension sufficient to extend radially across the second portion of the packing groove and into compressive engagement with the radial outer face thereof when the joint is completed. The axial extent of the packing groove can be sufficiently large to define an expansion space into which the gasket can expand, such as when the gasket is subjected to an increase in temperature. The expansion space can reduce and/or eliminate radially inward extrusion of the gasket beyond the cylindrical interior surfaces of the tube ends. 
         [0026]    In some instances, rigid members are defined by surface portions of the opposed faces of the connecting flanges. The clamp can align the flanges axially and prevent movement of the flanges toward one another beyond a predetermined minimum point. 
         [0027]    Methods for forming lengths of pipe for assembly together to form fluid flow conduits are also disclosed. Such methods can include (a) providing (i) a pipe having a first inner diameter and a central longitudinal axis, (ii) a plurality of ferrules having an annular first end, an inner diameter substantially equal to the first inner diameter and (iii) a second end formed into a flange substantially adapted to form a flange coupling when abutted against and connected to another ferrule having a flange. 
         [0028]    For example, such fluid flow conduits can have the first end of each ferrule welded to an end of a pipe, whereby the end face of the flange assumes an orientation wherein the end face is substantially normal to the central longitudinal axis. Further still, a clamped flange pipe or tube fitting assembly can further include a resilient seal ring compressed by a clamp, whereby the angle of the inner surfaces of clamp, being substantially greater than the respective angle of the flanges, during compression, can correct initial flange misalignment and provide for correct axial alignment of the flanges as well as fixed gasket compression by guiding the ferrule ends during compression and seating the flange ends into respective mating grooves in said clamp at the completion of compression. There is further disclosed a sealing gasket for insertion into a circumferentially continuous groove of a flange joint for joining axially aligned tube ends, the flange joint being of the type having axially opposed flanges at the tube ends to form a groove there between when the joint is assembled, the groove being formed by axially opposed seal faces and radial end faces of the flanges, wherein the groove comprises a circular O-ring groove first portion that is open to an interior flow passage of the tubes and a second groove second portion that extends radially outward from the groove first portion, wherein the gasket comprises a gasket first portion that seals the circular groove first portion and a flat gasket second portion that extends from the circular gasket section. A space formed between the terminus of the gasket second section and the terminus of the center ridge on the clamp forms an expansion space in the when the joint is assembled that is vented to atmosphere at the hinged and bolt portions of the clamp. 
         [0029]    A flange joint and gasket for joining and sealing tube or pipe ends that define an axial flow passage therethrough are disclosed. The joint includes a first annular flange and a second annular flange, each of said flanges being at a respective one of the tube ends. Each of said flanges define a respective end face, a circumferentially extending channel recessed from the end face, and a radially extending end wall positioned radially outward of the end face. Said end faces are in axially opposed relationship to each other such that a circumferential groove configured to receive a gasket is defined when the joint is assembled. Said groove has a first portion open to the flow passage of the tubes and has a second portion that extends radially outward from said groove first portion. Said groove second portion is radially bounded by said radially extending end walls. The joint also includes a polymeric gasket configured to sealingly engage the groove when the joint is assembled for preventing a loss of fluid from the flow passage of the tubes. Said gasket has a gasket first portion configured to sealingly engage said groove first portion and has a gasket second portion that extends from said gasket first portion and into said groove second portion. Said gasket first portion includes a generally toroidal member that is axially compressed when the joint is assembled and said gasket second portion is axially compressed when the joint is assembled and engages with said radial end walls to produce a radial compression of said gasket. Said gasket second portion has a volume that is less than a volume of said groove first portion to enable radially outward expansion of the gasket when the joint is assembled. 
         [0030]    Some disclosed joints also include a clamp defining longitudinally spaced and circumferentially extending recessed regions separated by a flange-engaging ridge. The clamp can overlie the pair of flanges such that at least a portion of the flange-engaging ridge is positioned radially outward of the gasket. A radially outermost portion of the gasket can be radially spaced from the flange-engaging ridge of the clamp to define an expansion space configured to permit radially outward expansion of the gasket. 
         [0031]    Said radial compression can opposes radial pressure from fluid in the flow passage to prevent radial displacement of said gasket into the product zone of the pipe. The radial compression can be limited by seating the flanges in corresponding mating portions of the recessed regions of the clamp such that the flange-engaging ridge is positioned between the flanges. 
         [0032]    The clamp can have angled surfaces that are oriented at respective angles greater than an angle of the corresponding flanges and align with angled surfaces of the respective flanges to urge the flange ends together as said clamp radially compresses the flanges. Said gasket second portion can engage said radial end walls and allow for radial expansion of the gasket. A region adjacent the gasket second portion and the gasket first portion can form a secondary seal against a radially oriented surface. 
         [0033]    Said gasket second portion can have an outer edge face in radial alignment with said gasket first portion. Said gasket second portion can be axially symmetric about a radial line that is common to said gasket first and second portions. 
         [0034]    Said engagement between said gasket second portion and said radial end walls can provide a barrier to prevent ingress of matter into said groove from outside the assembly. 
         [0035]    Said flanges can define radially extending clamp-engaging portions positioned radially outward of said radial end walls. A radial distal portion of said gasket second portion can include a flat gasket that engages said radial end walls when the joint is assembled. The flat gasket can terminate adjacent the clamp-engaging portions of said flanges. 
         [0036]    Said gasket second portion can have a unitary construction with said gasket first portion. Said gasket second portion can be axially wider than said gasket first portion with a shoulder formed at an interface of said gasket first and second portions. Said interface can permit said gasket to be centered and retained on one of said flanges during assembly of the joint. Said gasket second portion when uncompressed can have an axial dimension that is less than said axial dimension of said groove second portion. Said gasket second portion can comprise any suitably stiff material (e.g., a plastic, a metal alloy, such as, for example, an alloy of steel) and serve to stiffen the gasket and maintain a desired alignment of the gasket relative to the flanges during assembly of the joint. Said gasket can have a skeleton key-shaped cross-section. 
         [0037]    Said gasket first portion can include an O-ring with an inner annular surface. Said O-ring annular surface can have a first diameter before the gasket is positioned on one of said flanges and a second diameter that is greater than said first diameter after the gasket is positioned on one of said flanges and before the gasket is compressed. 
         [0038]    Said radial end walls can be formed by rigid radial outer extensions of said flanges that engage independently into mating grooves in the clamp when the joint is assembled to prohibit axial movement of the flanges. Said engagement of flange ends into mating grooves in the clamp when the joint is assembled can provide a limited, or a fixed, compression of the gasket. 
         [0039]    Said gasket first portion can be axially compressed in the range of about 10% to about 20% strain when the joint is assembled. Said gasket second portion can be axially compressed in the range of about 5% to about 15% strain. 
         [0040]    Disclosed gaskets can be formed of any suitable materials. Some gaskets are formed entirely of an elastomeric material. Some gaskets comprise a combination of a stiff material and an elastomer. 
         [0041]    Sealing gaskets for insertion into a circumferentially continuous groove of a flange joint for joining axially aligned tube ends are disclosed. Some disclosed gaskets define a gasket first portion for sealing a groove first portion and a gasket second portion that extends from said gasket first portion and into a groove second portion. Said gasket first portion can include an O-ring that is axially compressed when the joint is assembled. The O-ring when under compression in the assembled joint can be radially displaced to form a substantially flush seal that is contiguous with interior surfaces of the tubes. The O-ring and the interior surfaces of the tubes can define an internal angle of greater than 90 degrees within the product-contact zone. Radial compression can oppose radial pressure from fluid in the flow passage to prevent radial displacement of said gasket. Said radial compression can increase an effective hoop strength of said gasket. 
         [0042]    The groove first portion can be axially narrower than the groove second portion to form a shoulder at the radial interface thereof. Said gasket can be sized to have an interference fit with said shoulder to retain the gasket in position when the joint is assembled. Said gasket second portion when uncompressed can have an axial dimension that is less than an axial dimension of said groove second portion and has sufficient mass to stiffen the gasket and maintain a desired alignment of the gasket relative to the flanges during assembly of the joint. 
         [0043]    Methods for sealing flange joints between an opposed pair of flanges configured to join axially aligned tube ends and forming a groove therebetween with the groove being defined by axially opposed seal faces and a radial end face are disclosed. For example, a polymeric gasket can be positioned in a first and second portion of the groove between axially opposed seal faces of the flanges with said groove second portion being radially bounded by said radial end walls. The gasket can be compressed axially when the joint is assembled to displace a portion of the gasket that radially engages the radial end face. An O-ring of said gasket can be axially compressed in the groove first portion so that said O-ring is radially displaced to form a seal that is substantially flush with interior surfaces of the tubes. The gasket can be axially compressed when the joint is assembled. 
         [0044]    An interference fit between the gasket and the flanges can be used to retain the gasket in a desired centered position during assembly of the joint. A sufficient mass can be provided to the gasket to maintain a desired alignment of the gasket with respect to the flanges during assembly of the joint. 
         [0045]    The inventor of the presently disclosed innovations discovered that materials used for such gaskets undergo an extrusion-like expansion due to an initial configuration of a joint, due to increased temperature, or a combination thereof. By providing expansion space at a location disposed radially outward of the inner O-ring sealing portion of the gasket, a significant reduction of gasket expansion into the flow path can be achieved. Moreover, the compressive engagement forms a secondary seal radially outward of the primary O-ring seal. 
         [0046]    The inventor also discovered that improper alignment of pipe joints can arise, in part, because there is no metal to metal contact between opposed ferrules and because a clamp  8  ( FIG. 1 ) allows such misalignment. Such misalignment can also arise from the pipes being out of position due to poor workmanship or temperature variations, or due to damage to the flanges  5 ,  6  ( FIG. 1 ), from improper handling or excessive heat applied during welding procedures that can warp the flanges. 
         [0047]    A further problem occurs in that when a ferrule is welded to the pipe, there is a tendency for the pipe to shrink slightly in the vicinity of the weld. This causes a small amount of tilting of the faces of the flange away from the central axis so that they will not be able to come into flush abutment with each other. Excessive heat during welding operations can also cause the ferrules to warp, which can result in improper gasket seating, ferrule misalignment and/or the creation of unsanitary pockets within the pipe joint, as shown for example in  FIG. 1C . 
         [0000]    As indicated above, pipe fitting and gasket assemblies that reduce the extent of extrusion of the gasket into a fluid flow path, among other innovations, are disclosed. A smooth, substantially continuous inner wall surface is thereby maintained, reducing fluid retention, flow restriction and/or system contamination during subsequent uses. Also, improved alignment of the components of the joint assembly is provided using substantially identical pairs of opposing flanges. Such joints are easy to assemble, in part because, at least in some embodiments, there is no metal contact between the opposing flanges. An increased inner angle of the clamp of approximately 37 degrees (as compared to about 18.5 degrees in the prior art) provides surprisingly improved alignment during assembly and use. In addition, hard seating of the outermost portions of the flanges (also referred to sometimes as “flange ends into mating grooves in the clamp improves alignment compared to heretofore known joints. 
         [0048]    The foregoing and other features and advantages will become more apparent from the following detailed description, which proceeds with reference to the accompanying drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0049]      FIG. 1  shows a fragmentary cross-sectional view of a flange type pipe connection in the prior art. 
           [0050]      FIG. 1A  is a fragmentary cross-sectional view of the connection shown in  FIG. 1  subjected to over-compression. 
           [0051]      FIG. 1B  shows a fragmentary cross-sectional view of the connection depicted in  FIG. 1 , into which an improperly sized sealing gasket has been inserted (e.g., an internal opening in the gasket is smaller than the corresponding flow cross-section of the pipe. 
           [0052]      FIG. 1C  shows a fragmentary cross-sectional view of a connection of the type illustrated in  FIG. 1  in which the flanges axially misaligned, such as can occur from improper handling when disassembled, warping of the flange during welding or exposure to excessive torque during installation in a piping system. 
           [0053]      FIG. 2A  shows a fragmentary cross-sectional view of one embodiment of a self-aligning flange type pipe connection as disclosed herein. 
           [0054]      FIG. 2B  shows a detailed view of a portion of a flange shown in  FIG. 2A . 
           [0055]      FIG. 3  shows a fragmentary cross-sectional view of the sealing gasket used in the connection shown in  FIGS. 2A and 2B . 
           [0056]      FIG. 4  shows a fragmentary cross-sectional view of an alternative embodiment of a self-aligning flange type pipe connection as disclosed herein. 
       
    
    
     DETAILED DESCRIPTION 
       [0057]    The following describes various principles related to sanitary pipe joint systems by way of reference to exemplary embodiments. One or more of the disclosed principles can be incorporated in various system configurations to achieve various sanitary pipe joint characteristics. Systems relating to one particular application are merely examples of disclosed innovative pipe joint systems and are described below to illustrate aspects of the various principles disclosed herein. Embodiments of the innovations disclosed herein may be used in other sanitary applications without deviating from the principles disclosed herein. 
         [0058]      FIG. 2  shows, as but one example of disclosed innovations, a pair of axially aligned, cylindrical pipe or tube ends  30   a ,  30   b  having respective ferrules  31   a ,  31   b  welded thereto. The ferrules  31   a ,  31   b  define radially outwardly extending flanges  32   a ,  32   b . The flanges  32   a ,  32   b  are joined in end-to-end relation with a gasket  33  positioned therebetween, so as to form a sealed flange-type joint assembly  50 . The illustrated flanges  32   a ,  32   b  are detachably affixed to each other by a circumferentially extending, radially compressing clamp  20  which in some instances is a two-piece bolted clamp. In other instances, the clamp  20  is configured to pivot open and to be retained in a closed position with a clasp (not shown) in a known manner. 
         [0059]    Each tube end  30   a ,  30   b  can have a respective substantially uniform open interior  14  having, for example, an interior diameter D 1 , D 2 . In some instances, the diameters D 1 , D 2  have the same dimension. In  FIG. 2 , the tube ends  30   a ,  30   b  are in axial alignment (i.e., a longitudinal axis  34  defined by the tube end  30   a  is coextensive with a longitudinal axis of the tube end  30   b ). 
         [0060]    Each ferrule member  31   a ,  31   b  shown in  FIG. 2  has an annular portion  35   a ,  35   b  portion configured to be welded or otherwise joined (e.g., by brazing, soldering or other metal joining technique) to a respective tube end  30   a ,  30   b , forming a unitary construction having a tube portion and a flanged portion. In another embodiment, the flanges  32   a ,  32   b  are integrally formed on the respective tube ends  30   a ,  30   b.    
         [0061]    A radially outwardly extending flange  32   a ,  32   b  extends from each ferrule portion  31   a ,  31   b  and defines a clamp engagement region  36  and a gasket receiving region  37 . Each of the respective ferrule portions of the flange members  21 ,  26  is attached to a respective end of each of the tubes. The flanges allow the tube ends to be detachably affixed to each other, as by applying an adjustable clamp ring  24  in a circumferentially overlying engagement with the radially outwardly extending flanges. Such a removable engagement between the clamp ring  24  and the flanges is schematically illustrated in  FIG. 2 . 
         [0062]    Each of the flanges  32   a ,  32   b  defines a sealing end face  39  that can lie in a common plane oriented perpendicularly relative to the center (i.e., longitudinal) axis  34 . Each of the end faces  39  defines a recessed, annular channel  37  generally centered about the longitudinal axis  34  and configured to receive a gasket  33 . When in opposing, coaxial alignment, the end faces  39  of the respective flanges  32   a ,  32   b  together define a circumferentially extending, continuous recess or groove  30  configured to receive a seal-forming packing, such as, for example, a gasket  33 . 
         [0063]    The packing receiving groove has a generally annularly shaped cross-section (for a cross-section taken transverse to the longitudinal axis  34 ) having an open interior dimensioned to correspond to a interior flow dimension D 1 , D 2  of the tube ends  31   a ,  31   b . As indicated in  FIG. 2 , the groove can have a generally toroidal region formed by the recessed channel  37  and positioned adjacent the interior flow opening  14 . The toroidal region can receive a corresponding bead  38  of an O-ring. A portion of the receiving groove defined by the sealing end face  39  can define a generally flat, cylindrical portion extending radially outward of the toroidal region formed by the recess  37 . 
         [0064]    When the flanges  32   a ,  32   b  are clamped into an opposing, end-to-end relationship as shown in  FIG. 2 , the inner, toroidal portion portion of the groove can open inwardly toward the interior  14  of the central flow passage, in some instances. 
         [0065]    As noted above, the groove can further include a second, axially narrower portion extending radially outward of the toroidal portion. The narrower portion can extend circumferentially of the toroidal portion, such as through 360-degrees. The narrower portion can have a thickness measuring approximately one-third of the cross-sectional diameter of the toroidal portion. 
         [0066]    Positioned within the groove is a gasket  33  formed from a suitably pliable material that will form an effective seal when compressed between the flanges  32   a ,  32   b . Examples of suitably pliable materials for the gasket  33  include, but are not limited to ethylene propylenes, fluorocarbons, silicone rubbers, nitrites, neoprenes, polyethylene and tetrafluoroethylenes, the specific selection being based on a particular intended application. 
         [0067]    The gasket  33  can have a cross-section as illustrated in  FIG. 3 . The shape of the gasket  33  can have different configurations and appearances. As shown in  FIGS. 2 and 3 , the gasket  33  can be ring shaped and include a radially inward portion  38  having a generally circular cross section. The toroidal portion  38  can sealingly engage the walls of the recessed channel  37  and form a primary seal. A radially extending outer portion  40  can have a rectangular cross section (e.g., can be a generally annular disc) and sealingly engage the sealing end face  39 , so as to form a secondary seal. A cross-sectional diameter of the inward portion  38  can be selected relative to a cross-sectional width of the outward portion  40  so that in the assembly of the joint  50 , the gasket  33  will be engaged by the corresponding regions  37 ,  39  of the flanges  32   a ,  32   b.    
         [0068]    When a corresponding gasket member is positioned within the groove and the flanges  32   a ,  32   b  are clasped (or otherwise retained) together, the gasket member  33  can fill, and thereby seal, such a groove. Even to the extent that any part of the toroidal portion  38  of the gasket  33  extends radially inwardly of the tube wall  17  (e.g., into the product zone  14 ), an obtuse (i.e., greater than 90 degrees) angle forms between the wall  17  and a line tangent to the gasket  33  at the point of contact between the gasket and the wall. Thus, a region adjacent an inwardly extending portion of the gasket is much less likely to form a pocket or other region  15  ( FIG. 1A ) that collects and/or retains a process fluid or flowable food. Such a gasket and flange configuration as shown in  FIGS. 2 and 3  provides a much lower likelihood of contamination of subsequent flows of fluids or flowable foods through the joint. 
         [0069]    As is noted in the European Hygenic Engineering and Design Group (EHEDG) Guideline  16  (Hygenic Pipe Couplings, 1997), the thermal expansion of elastomers may be as much as 15-fold greater (for silicone rubber) that that of stainless steel alloys. In the configuration shown in  FIGS. 2 and 3 , gasket expansion is directed to an air space  41  between the gasket and the clamp by the shape of the gasket. For example, the shape of the inner toroidal portion  38  of the gasket limits the gasket&#39;s ability to expand radially inward into the product zone  14 . The air space  41  is vented to the atmosphere at one or more hinge and/or bolt portions of the clamp  20 . Since elevated temperatures that accompany gasket expansion is typically accompanied by elevated internal pipe pressures, especially if steam sterilization is employed, a differential pressure is created that encourages the gasket  33  to expand radially outward towards the air space  41  rather than radially inward into the product zone  14 . 
         [0070]    A longitudinal dimension of the packing groove, as well as alignment of the flanges  32   a ,  32   b  with respect to the center axis  34  can be provided by the clamp  20 . For example, each of the radially extending flange portions  32   a ,  32   b  can each define a clamp engaging region  36  positioned radially outward of the gasket receiving region  37 , the end face  39 , or both. The clamp engaging region can define a surface that is recessed, or angled away, from the sealing face region  39 , such that when a corresponding flange  32   a ,  32   b  is positioned in an opposing relationship, the respective clamp engaging regions  36  define a radially recessed channel (or air space)  41  extending circumferentially of the flanges  32   a ,  32   b.    
         [0071]    A clamp  20  configured to circumferentially overlie such a pair of flanges  32   a ,  32   b  can define a corresponding channel  26   a ,  26   b  configured to matingly engage each respective clamp engaging region  36  of the flanges  32   a ,  32   b . Such a mating engagement can sufficiently longitudinally compress a gasket  33  positioned within the groove as to seal the joint  50  formed between the flanges. The mating engagement can also align the flanges. 
         [0072]    For example, the clamp  20  can define an internal, circumferentially extending and radially recessed groove into which an opposed pair of flanges  32   a ,  32   b  can be seated. The groove can have first and second recessed regions  26   a ,  26   b  longitudinally spaced from each other. The first and second recessed regions  26   a ,  26   b  can be separated by a circumferentially extending flange-engaging ridge  27 . Longitudinally outward of the first and the second recessed regions  26   a ,  26   b , the clamp  20  can define respective first and second clamp ridges  28   a ,  28   b . When such a clamp  20  overlies a pair of corresponding flanges  32   a ,  32   b  having respective clamp engaging regions  36 , the flange-engaging ridge  27  can be positioned between the respective clamp engaging regions. The first and second clamp ridges  28   a ,  28   b  can be positioned longitudinally outward of, and thereby longitudinally retain the clamp engaging regions of the flanges. When the clamp  20  is radially tightened, the clamp engaging portion of each flange  32   a ,  32   b  rides along a corresponding one of the first and second clamp ridges  28   a ,  28   b , urging the flanges  32   a ,  32   b  toward each other longitudinally and thereby compressing the gasket  33 . The flange-engaging ridge  27  can engage the respective flanges  32   a ,  32   b , and limit the extent to which the flanges can approach each other longitudinally in response to urging from the clamp ridges  28   a ,  28   b , thereby limiting the extent to which the gasket  33  can be compressed longitudinally. 
         [0073]    Such engagement of the first and second clamp ridges  28   a ,  28   b  and the flange-engaging ridge  27  with the clamp engaging portions  36  of the flanges  32   a ,  32   b  provides improved axial alignment of the respective flanges (and the corresponding tubes). An internal angle β of the clamp ridges  28   a ,  28   b  relative to a plane oriented perpendicularly to the longitudinal axis  34  can measure approximately 37 degrees, such as between about 32 degrees and about 42 degrees, which is significantly greater than the approximately 20 degree outer angle θ the respective flanges  32   a ,  32   b . Such a difference in angles β, θ also provides improved alignment between the flanges as compared to conventional flange and clamp assemblies. 
         [0074]    Other joint configurations are also possible. For example,  FIG. 4  shows an assembly  60  having an overlying clamp  20 , as described above and opposed flanges  42   a ,  42   b . A gasket  43  is positioned between the opposed flanges  42   a ,  42   b . The gasket  43  defines a generally toroidal inner head  46  and a concentric outer bead  45  outwardly spaced from the inner bead. The outer bead  45  can have a generally circular cross-sectional shape, as shown in  FIG. 4 , or another shape. An axial (relative to the longitudinal axis  44  of the flow passage  14 ) dimension of the outer bead  45  can be less than a corresponding axial dimension of the inner bead  46 . A web  46  of gasket material can span the distance between the beads  45 ,  46  and can sealingly engage a corresponding surface of each flange  42   a ,  42   b . A portion of the gasket  43  can extend radially outward of the outer bead  45  and into the air space  41 . Each of the flanges  42   a ,  42   b  can define a respective pair of recessed channels  47   a ,  48   a  and  47   b ,  48   b  corresponding to the axially extending portions of the inner and the outer beads  45 ,  46 . 
         [0075]    The pair of beads  45 ,  46  provides improved alignment and retention of the gasket  43  in the recessed channels  47   a ,  48   a  and/or  47   b ,  48   b  during assembly of the joint, as compared to a gasket with only a single bead. For example, the gasket  43  can be seated in one pair of channels in a corresponding flange, and the other flange can be brought into opposed axial alignment therewith, in a manner as described above. During such assembly, the second, outer bead  45  helps keep the gasket  43  from buckling or otherwise unseating from the inner recess  48   a ,  48   b  as could occur during assembly if the flanges  42   a ,  42   b  are moved transversely relative to each during assembly. As a result of such a movement, for example, an edge  49   a ,  49   b  of the recess  48   a ,  48   b  could engage (e.g., “catch”) and unseat the inner bead  46  from the recess  48   a ,  48   b  in the absence of, for example, the stiffening effect of the outer bead  45 . If the clamp  20  engages and urges the flanges  42   a ,  42   b  together in such an instance, an unsanitary pocket and/or gasket bulge (not shown) could form adjacent one or both edges  49   a ,  49   b.    
         [0076]    Although such pockets and/or bulges are unlikely using a gasket configured as shown in  FIG. 3  and described above, the likelihood of such pockets and/or bulges is further reduced using a gasket  43  configured as shown in  FIG. 4 . Accordingly, a gasket and flange configuration as shown in  FIG. 4  provides a low likelihood of contamination of subsequent flows of fluids or flowable foods through the joint  60 . 
         [0077]    With systems disclosed herein, it is possible in many embodiments to provide a sanitary joint between pipes (or tubes). Although principles have been described by way of reference to exemplary embodiments having circular cross-sections, other cross-sectional shapes are possible without deviating from the principles disclosed herein. By way of example and not limitation, such alternative cross-sectional shapes include square, rectangular, oval, ellipsoid and arbitrary shapes. References to a “diameter” (or radius) of an interior flow opening can be understood as a reference to a “hydraulic diameter” when considered in the context of a flow cross-sectional shape of other than a circle, and shall be so understood when the context requires. 
         [0078]    This disclosure makes reference to the accompanying drawings which form a part hereof, wherein like numerals designate like parts throughout. The drawings illustrate specific embodiments, but other embodiments may be formed and structural changes may be made without departing from the intended scope of this disclosure. Directions and references (e.g., up, down, top, bottom, left, right, rearward, forward, etc.) may be used to facilitate discussion of the drawings but are not intended to be limiting. For example, certain terms may be used such as “up,” “down,”, “upper,” “lower,” “horizontal,” “vertical,” “left,” “right,” and the like. These terms are used, where applicable, to provide some clarity of description when dealing with relative relationships, particularly with respect to the illustrated embodiments. Such terms are not, however, intended to imply absolute relationships, positions, and/or orientations. For example, with respect to an object, an “upper” surface can become a “lower” surface simply by turning the object over. Nevertheless, it is still the same surface and the object remains the same. As used herein, “and/or” means “and” as well as “and” and “or.” 
         [0079]    Accordingly, this detailed description shall not be construed in a limiting sense, and following a review of this disclosure, those of ordinary skill in the art will appreciate the wide variety of imaging systems that can be devised and constructed using the various concepts described herein. Moreover, those of ordinary skill in the art will appreciate that the exemplary embodiments disclosed herein can be adapted to various configurations without departing from the disclosed concepts. Thus, in view of the many possible embodiments to which the disclosed principles can be applied, it should be recognized that the above-described embodiments are only examples and should not be taken as limiting in scope. I therefore currently claim as my invention all that comes within the scope and spirit of the following claims.