Patent Publication Number: US-2012024412-A1

Title: Articulated piping for fluid transport applications

Description:
TECHNICAL FIELD 
     This invention relates to articulated piping for the transport of fluids. 
     BACKGROUND OF THE INVENTION 
     Piping is employed for distributing fluids over long distances. The exterior surfaces of the piping may be exposed to inhospitable environments, such as open desert, sea water, jungle, uncontrolled chemical spaces, or an environment maintained at an elevated temperature or an elevated pressure, for example. The interior surfaces of the piping may be exposed to abrasive and/or corrosive fluid that is distributed through the fluid passageway of the piping. In the interest of convenience and storage, operators may prefer to arrange such piping on a spool for easy deployment and storage. In view of the foregoing, there exists a need to develop and improve upon fluid transport piping in the interest of storage, performance, convenience, manufacturability and safety. 
     SUMMARY OF THE INVENTION 
     According to one aspect of the invention, an articulated pipeline assembly for the transport of fluids is provided. The articulated pipeline assembly comprises a fluid conduit for transporting fluid and an articulating shell assembly that is positioned to encapsulate the fluid conduit. The articulating shell assembly includes a plurality of articulating shell segments, whereby each articulating shell segment comprises both a ball and a socket. The ball of each articulating shell segment is engaged with a socket of an adjacent articulating shell segment to form a ball and socket joint and the socket of each articulating shell segment is engaged with a ball of an adjacent articulating shell segment to form a ball and socket joint. Each articulating shell segment is configured to rotate with respect to an adjacent articulating shell segment by virtue of the ball and socket joint. 
     According to another aspect of the invention, each articulating shell segment includes two discrete, separable components that are configured to be mated together. 
     These and other aspects of the present invention will become clear from the detailed discussion below when taken into consideration with the drawings. It is to be understood that the following discussion is intended merely to illustrate the preferred embodiments of the present invention. 
    
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
       The invention is best understood from the following detailed description when read in connection with the accompanying drawing. It is emphasized that, according to common practice, the various features of the drawing are not to scale. Included in the drawing are the following figures: 
         FIG. 1  depicts an elevation view of a segment of a pipeline comprising a fluid conduit encapsulated within an articulated shell assembly, according to one exemplary embodiment of the invention, wherein a portion of the articulated shell is cut-away to reveal the fluid conduit. 
         FIG. 2  depicts a cross-sectional view of the pipeline of  FIG. 1  taken along the lines  2 - 2 . 
         FIG. 3A  depicts an elevation view of a segment of a pipeline comprising a fluid conduit encapsulated within an articulated shell assembly, wherein each articulated shell segment is a two-piece assembly, according to yet another exemplary embodiment of the invention. 
         FIG. 3B  depicts a cross-sectional view of the pipeline of  FIG. 3A  taken along the lines  3 B- 3 B. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     This invention will now be described with reference to several embodiments selected for illustration in the drawings. It will be appreciated that the scope and spirit of the invention are not limited to the illustrated embodiments. 
     As used herein, the term fluid is non-limiting and may refer to any type of fluid such as liquids, gasses or slurries, for example. 
       FIG. 1  depicts an elevation view of a segment of a pipeline comprising a fluid conduit encapsulated within an articulated shell assembly, according to one exemplary embodiment of the invention. The segment of the pipeline is denoted by the numeral ‘ 10 .’ The pipeline  10  generally comprises a flexible fluid conduit  12  encapsulated within an articulated shell assembly  13 . The articulated shell assembly  13  comprises a series of interlinked articulated shell segments  14   a - 14   c  (collectively referred to as an articulated shell segments  14 ). In  FIG. 1 , a portion of the shell segment  14   b  is cutaway to reveal the fluid conduit  12 . 
       FIG. 2  depicts a cross-sectional view of the pipeline  10  of  FIG. 1  taken along the lines  2 - 2 . The fluid conduit  12  is a hollow structure for transporting fluid that is encased in the articulated shell assembly  13 . Each articulated shell segment  14  is a rigid body that is configured to protect the fluid conduit  12  from outside abrasion and support the fluid conduit  12  when internal pressures are relatively high. 
     Each shell segment  14  is defined by a substantially cylindrical hollow body. According to this exemplary embodiment, the shell segments  14  are unitary, however, in another embodiment each shell segment is composed of two pieces. Both the shape and size of each shell segment  14  are substantially equivalent. 
     The shell segments  14   a - 14   c  interlock through a series of ball and socket joints. Each shell segment  14  includes a ball  16   b  on one end and a socket  16   a  on an opposing end thereof. Each ball  16   b  is configured for mating with a socket  16   a  of an adjacent shell segment. 
     According to one exemplary method of assembling the articulated shell assembly  13 , the front face  17  of the socket  16   a  of a shell segment (such as shell segment  14   b ) is aligned with the rounded edge  25  of an adjacent shell segment (such as shell segment  14   b ). The rounded edge  25  of the ball  16   b  is configured to guide insertion of the socket  16   a  onto the ball  16   b . The revolved interior surface  27  of the socket  16   a  is then pushed over the revolved exterior surface  29  of ball  16   b . The socket  16   a  and/or ball  16   b  may deflect as the socket  16   a  translates over the ball  16   b . Once the surface  21  of the ball  16   b  abuts the interior surface  23  of the socket  16   a , the shell segments  14  are linked together, i.e., mated. Although not shown, an o-ring may be provided at the interface between the revolved interior surface  27  of the socket  16   a  and the revolved exterior surface  29  of ball  16   b  to limit the ingress of contaminants into the shell segments  14 . The o-ring is an optional component of the design and may be omitted. 
     Although not shown, the revolved interior surface  27  of the socket  16   a  may include one or more openings, slots or slits to facilitate deflection of the socket  16   a  as it is pushed over the ball  16   b . Moreover, the revolved exterior surface  29  of ball  16   b  may also include one or more openings, slots or slits to facilitate deflection of the ball  16   b  as the socket  16   a  is pushed over the ball  16   b.    
     Each ball and socket joint is configured to permit rotation of adjacent shell segments  14 . The revolved exterior surface  29  of the ball  16   b  is capable of rotating within the revolved interior surface  27  of the socket  16   a . The rotation afforded by the ball and socket joint enables spooling of the pipeline  10  onto a reel. 
     Referring still to  FIG. 2 , the interior diameter D 1  of the revolved interior surface  27  of the socket  16   a  is sized to tightly encapsulate the outer diameter D 2  of the revolved exterior surface  29  of the ball  16   b . The relative sizes of diameters D 1  and D 2  are tailored to limit inadvertent separation of mated shell segments  14 , while permitting relative rotation of the mated shell segments  14 . The maximum gap ‘G’ between the surfaces  21  and  23  is also tailored to permit relative rotation of the mated shell segments  14 , while limiting interplay (e.g., clearance) between those shell segments  14 . Excessive interplay between the assembled shell segments  14  could potentially create a weak point in the pipeline  10  upon spooling the pipeline  10  onto a reel. By way of example, the angle of rotation of one shell segment  14  with respect to an adjacent shell segment  14  may be about 0.5 to 2.5 degrees, for example. The radius of the balls  16   b  and the sockets  16   a  may be varied to achieve a desired bend radius of the pipeline  10 . 
     A gap may exist between the inner surface of the shell segments  14  and the outer revolved surface of the fluid conduit  12 . The size of the gap may vary from that shown and described herein without departing from the spirit and scope of the invention. The gap between the inner surface of the shell segments  14  and the outer revolved surface of the fluid conduit  12  is sufficiently large to permit relative rotation of the shell segments  14  if the conduit  12  is semi-rigid and to permit the fluid conduit  12  and the shell segments  14  to move somewhat relative to each other, yet is small enough to support and restrain the fluid conduit  12  when internal pressures are relatively high. 
     The length ‘L’ (see  FIG. 2 ) of each shell segment may be any desired length. By way of example, the entire length of the pipeline  10  may be one to three kilometers, or any other desired length. The length ‘L’ of each shell segment impacts the total bend radius of the pipeline  10 . Increasing the length ‘L’ of each shell segment increases the bend radius of the pipeline  10 . The length of each shell segment may be tailored to meet a specific bend radius. 
     The outer diameter ‘D’ (see  FIG. 1 ) of each shell segment may be about 0.125 inches to 10 inches, for example, or any other desired diameter. The diameter ‘D’ of each shell segment also impacts the total bend radius of the pipeline  10 . Increasing the diameter ‘D’ of each shell segment increases the bend radius of the pipeline  10 , and vice versa. The wall thickness of each shell segment may be about 0.1 inches to 0.75 inches, for example, or any other desired wall thickness. 
     Several ways exist to assemble the articulated shell  14  onto the fluid conduit  12 . By way of example, the shell segments  14  may be assembled onto a free end of the fluid conduit  12  during manufacture of the pipeline  10  or at any time a free end of the fluid conduit  12  is readily available. If the fluid conduit  12  is already spooled on a reel, one method of assembling the shell segments  14  onto a spooled fluid conduit  12  is as follows: (i) assemble a string of shell segments  14  and spool the assembled shell segments  14  onto a second reel, (ii) feed a free end of the spooled fluid conduit into several shell segments  14 , and (iii) unwind the fluid conduit  12  from its reel causing the fluid conduit  12  to travel through the assembled shell segments  14 . Once the fluid conduit  12  has travelled through the assembled shell segments  14  the pipeline  10  is formed. 
     If for any reason, a free end of the fluid conduit  12  is not readily accessible, a shell segment  14  can not be assembled onto the fluid conduit  12  due to the closed geometrical shape of the shell segments  14 . For at least that reason, a helical shell or a multi-piece shell segment may be particularly useful in instances where a free end of the fluid conduit  12  is not readily accessible. A multi-piece shell segment may also be particularly useful for replacing a damaged shell segment  14  with a new shell segment without having to remove all of the assembled shell segments  14  from the pipeline  10 . 
       FIG. 3A  depicts an elevation view of a segment of a pipeline  60  comprising a fluid conduit  12  that is encapsulated within an articulating shell assembly  62 , according to another exemplary embodiment of the invention. The articulating shell assembly  62  comprises a series of interlinked articulated shell segments  64 A- 64 C (collectively referred to as articulated shell segments  64 ). A portion of the shell segment  64 B is cutaway to reveal the position of the fluid conduit  12 . The pipeline segment  60  is substantially the same as the pipeline segment  10  of  FIGS. 1 and 2 , with the exception that each articulating shell segment  64  of  FIG. 3A  is a two-piece assembly. Like the shell segments  14   a - 14   c  of  FIG. 1 , the articulated shell segments  64 A- 64 C interlock through a series of ball and socket joints such that the shell segments  64 A- 64 C are capable of rotation with respect to one another. 
       FIG. 3B  depicts a cross-sectional side view of the pipeline  60  of  FIG. 3A  taken along the lines  3 B- 3 B. Each shell segment  64  comprises two portions  66  and  68  that are mated together either releasably or permanently. The shell segment portions  66  and  68  are substantially identical. The shell segment portions  66  and  68  include a semi cylindrical, revolved body and a flange  70  and  72 , respectively. The flanges  70  and  72  have mating surfaces that are positioned to meet at a common interface  76 . As best shown in  FIG. 3A , the flanges  70  and  72  extend along a portion of the length of the shell segments  64  so as not to interfere with the ball and socket joint. The flanges  70  and  72  are optional features of the shell segment  64  and may be omitted. 
     A mechanical fastener  74 , in the form of a self-threading mechanical screw, is engaged with both flanges  70  and  72  of each shell segment  64  to join the shell segment portion  66  to the shell segment portion  68  together. The fastener  74  is threadedly engaged with holes (not explicitly shown) that are provided in the flanges  70  and  72 . Those skilled in the art will recognize that numerous ways exist to mount or join the shell segment portions  66  and  68  together. The shell segment portions  66  and  68  may also be mated together by a clip, a connector, a pin, a barb, a hook, a socket, an adhesive, a weld, a clamp, a rivet, a magnet, a bolt, a screw, or any other fastening mechanism known to those skilled in the art. Although not shown, an environmental gasket may be provided at the interface  76  between the shell segment portions  66  and  68  to limit the ingress of contaminants into the pipeline  60 . 
     Although not shown, in lieu of fasteners  74 , the shell segment portion  66  may include a barb extending from flange  70  and the shell segment portion  68  may include an aperture defined on flange  72  that is sized to receive the barb of the shell segment portion  66 . Mating the barb with the aperture either permanently or releasably mates the shell segment portions  66  and  68  together. Depending upon the wall thickness of the portions  66  and  68 , as well as the size of the barb and/or the aperture, the flanges  70  and  72  may be omitted. 
     Each two-piece articulating shell segment  64  may be assembled onto the fluid conduit  12  at any point along the length of the conduit  12  by virtue of the two-piece arrangement of the articulated shell segment  64 . Such an embodiment of the shell segment is particularly advantageous in an instance where the fluid conduit  12  is already deployed in the field and a free end of the conduit  12  is not readily accessible. The two-piece articulating shell segment  64  is also useful for replacing a damaged shell segment  14  (see  FIG. 1 ) with a new shell segment  64  without having to remove all of the assembled shell segments  14  from a pipeline. 
     According to another exemplary embodiment of the invention that is not illustrated herein, instead of each shell segment having both a ball and a socket as is depicted in  FIGS. 1-3B , two types of shell segments are contemplated whereby one shell segment has a ball at each end and the other shell segment has a socket at each end. The shell segment types would be alternated along the length of the piping, forming a ball and socket joint at each interface. 
     Referring now to the material composition of the components of the pipelines  10  and  60 , the shell segments disclosed herein may be composed of any metallic or polymeric material known to those skilled in the art, including thermoplastic as well as thermoset materials. The shell segments may be composed of OXPEKK® C40C which is manufactured by Oxford Performance Materials Inc. of Enfield, Conn., USA. By way of non-limiting example, other materials suitable for the shell segments include polyetheretherketone (PEEK) and polyetherketoneketone (PEKK), as well as other polyarylketones and polyaryletherketones, which are sufficiently rigid, rated for elevated temperatures (e.g., the continuous use temperature for PEKK is 500 degrees Fahrenheit) and are resistant to either acidic or basic chemicals. Illustrative examples of other suitable engineering thermoplastics include polyphenylene sulfides, polyphenylene oxides and polysulphones. Other structural plastics such as polycarbonates, polyamides, polyesters or polyacetals, for example, may be useful for less aggressive applications. Suitable thermoset materials include epoxy resins and polyester thermoset resins. The polymeric material may be compounded with any of the additives known in the art, such as fillers, reinforcing agents, stabilizers, processing aids and the like. The shell segments may be manufactured using any of the conventional fabrication techniques customarily utilized for shaping materials, including but not limited to injection molding and compression molding. 
     Referring now to material composition of the fluid conduit  12 , the conduit  12  optionally includes a single layer that is composed of fiber reinforced OXPEKK® polyetherketoneketone which is manufactured by Oxford Performance Materials Inc. of Enfield, Conn., USA. By way of non-limiting example, other materials suitable for the fluid conduit  12  are plastics such as Polyvinylidene Fluoride (PVDF, including Kynar® PVDF), Polyolefins (such as Polypropylene), and Polyamides (such as Polyamide 11 or 12). In addition to one or more plastics, the conduit may be comprised of one or more other materials, such as metals, glass or other ceramic materials, as well as other inorganic substances (such as inorganic particulate fillers or carbon fibers), provided the conduit remains sufficiently flexible to permit the pipeline to be deployed in the field. These additional materials (which may be in the form of fibers, particles, wires, or mats, for example) may be embedded in or compounded into a plastic matrix. The material of the fluid conduit  12  may be tailored to enhance its structural integrity or static dissipation properties, for example. The fluid conduit  12  may be composed of any material that meets the following criterion: (i) suitable for fluid transport, (ii) sufficiently flexible for simple deployment of the pipeline in the field, and (iii) becomes sufficiently rigid when pressurized. Those skilled in the art will recognize that numerous materials meet the foregoing criterion. 
     Single-layer fluid conduits may be preferred as they are less expensive to manufacture. Alternatively, the fluid conduit  12  may comprise more than one layer depending upon the particular application. For example, double-layer fluid conduits are envisioned for use with a pipeline where the fluids outside of the conduit are of a different nature than the fluids travelling within the fluid conduit, such that no single material is impervious to both fluids. For example, if the fluids travelling along the interior of the conduit are acidic, but the fluids travelling along the exterior of the conduit are basic, the material of the interior layer of the fluid conduit would be resistant to acids, while the material of the exterior layer of the fluid conduit would be resistant to bases. In such an example, the interior layer of the double-layer fluid conduit may be composed of PVDF, whereas the exterior layer of the double-layer fluid conduit may be composed of polyolefin, for example. 
     Triple-layer fluid conduits are also envisioned for use with a pipeline where the fluids outside of the conduit are of a different nature than the fluids on the inside of the fluid conduit, such that no single material is impervious to both fluids. The internal layer (i.e., sandwiched between the exterior layer and the interior layer) can be employed as a tie layer in the event that the interior layer and/or the exterior layer of the conduit need be integrally attached. For applications where the bend radius of a pipeline need be maintained at a minimum, however, a triple-layer conduit may not be preferred because the third layer may reduce the flexibility of the pipeline. Other circumstances where a triple layer conduit might be advantageous is when an internal layer is needed as an additional barrier for complex fluids, such as gases that might penetrate the interior layer and/or the exterior layer. Additionally, a braid composed of Kevlar® aromatic polyamide fiber, for example, may be applied over the conduit for added protection. 
     Although the invention is illustrated and described herein with reference to specific embodiments, the invention is not intended to be limited to the details shown. While the pipelines disclosed herein might be particularly useful for the transport of fluids for chemical process and petroleum applications, they may be employed for any other application involving wires, lines, cables or conduits. As an example, the articulated shell segments may be applied over electrical cabling in an effort to prevent rodents from chewing, or otherwise harming, the electrical cabling. Various modifications may be made in the details within the scope and range of equivalents of the claims and without departing from the spirit of the invention.