Abstract:
A method of assembling a conduit assembly that includes seating a ferrule on a distal end portion of an elongate conduit body; mounting the end portion of the conduit body on a small diameter section of a tubular body insert, the body insert has a hollow body defining a passage through the insert along a symmetrical axis and a large diameter section attached to the small diameter section via a shoulder, such that the shoulder contacts a distal end portion of the ferrule interposed axially between the large diameter section of the body insert and the distal end of the conduit body to inhibit axial contact between the distal end portion of the conduit body and the large diameter section of the body insert; radially compressing a portion of the conduit body between the body insert and the ferrule; and deploying one or more transmission lines into the conduit body.

Description:
PRIORITY CLAIM 
     This application is a divisional application of U.S. patent application Ser. No. 11/270,180, filed Nov. 9, 2005, the entire contents of which are incorporated herein by reference and should be considered a part of this specification. 
    
    
     BRIEF DESCRIPTION 
     1. Technical Field 
     The present invention relates generally to the manufacture of conduit assemblies, and relates more specifically to methods for producing composite conduit assemblies capable of housing electrical cables and/or hydraulic hoses. 
     2. Background 
     A wide variety of cables and hoses are used to transmit electrical and hydraulic power from one location to another. While separate, specifically-designed cables and hoses are often used to separately transmit electrical and hydraulic power, this arrangement often becomes cumbersome when many cables are used. Therefore, composite conduit assemblies have been developed that are configured to house electrical cables and hydraulic hoses in a single conduit. Such composite conduit assemblies are used in a wide variety of applications where electrical and hydraulic power is to be transmitted from one location to another. For example, composite conduit assemblies are often used to provide electrical and hydraulic power to the drilling and pipe handling equipment that is commonly used in the oil industry. 
     SUMMARY 
     Methods for fabricating composite conduit assemblies capable of housing electrical cables and/or hydraulic hoses are described herein. In certain optional embodiments, the methods disclosed herein are capable of producing a composite conduit assembly that has sufficient durability to withstand harsh environmental and operating conditions, while still retaining sufficient flexibility to accommodate the repetitive and cyclical movements associated with drilling and pipe handling equipment. 
     According to one embodiment of the present invention, a method of assembling a conduit assembly comprises positioning a ferrule over an end portion of an elongate conduit body. The method further comprises positioning a body insert into the end portion of the elongate conduit body. The end portion of the elongate conduit body is positioned between the ferrule and the body insert. The method further comprises expanding a portion of the body insert positioned inside the elongate conduit. The method further comprises positioning an elongate cable in the elongate conduit body. The elongate cable is longer than the elongate conduit body. The method further comprises filling at least a portion of the elongate conduit body with a potting material. 
     According to another embodiment of the present invention, a method of assembling a conduit assembly comprises providing an elongate conduit body having a first end and a second end opposite the first end. At least one of the first and second ends has an end fitting fixed thereto. The method further comprises deploying a string through the elongate conduit body. The method further comprises coupling a cord to the string. The method further comprises deploying the cord through the elongate conduit body by removing the string from the elongate body. The method further comprises coupling a wench cable to the cord. The method further comprises deploying the wench cable through the elongate conduit body by removing the cord from the elongate body. The method further comprises coupling a transmission line to the wench cable. The transmission line comprises a hydraulic hose and/or an electrical cable. The transmission line is longer than the elongate conduit body. The method further comprises deploying the transmission line through the elongate conduit body by removing the wench cable from the elongate body. 
     According to another embodiment of the present invention, a method comprises seating a ferrule on an end portion of an elongate conduit body. The method further comprises providing an elongate body insert having a large diameter end and a small diameter end. The method further comprises mounting the end portion of the elongate conduit body on the small diameter end of the body insert, such that the large diameter end of the body insert contacts the ferrule. The method further comprises compressing the elongate conduit body between the body insert and the ferrule. The method further comprises deploying a transmission line into the elongate conduit body. The transmission line comprises at least one of a hydraulic hose and an electrical cable. The method further comprises pouring a potting material into the elongate conduit body. 
     According to still another embodiment, a method of assembling a conduit assembly is provided. The method comprises seating a ferrule on a distal end portion of an elongate conduit body and mounting the end portion of the elongate conduit body on a small diameter section of a tubular body insert, the tubular body insert comprising a hollow body defining a passage through the body insert along a symmetrical axis and a large diameter section attached to the small diameter section via a shoulder, such that the shoulder contacts a distal end portion of the ferrule interposed axially between the large diameter section of the body insert and the distal end of the elongate conduit body to inhibit axial contact between the distal end portion of the elongate conduit body and the large diameter section of the body insert. The method further comprises radially compressing at least a portion of the elongate conduit body between the body insert and the ferrule and deploying one or more transmission lines into the elongate conduit body. 
     In accordance with yet another embodiment, a method of assembling a conduit assembly is provided. The method comprises positioning a ferrule over an end portion of an elongate conduit body, and positioning at least a portion of a tubular body insert into the end portion of the elongate conduit body such that the end portion of the elongate conduit body is positioned radially between the ferrule and the body insert, the tubular body insert comprising a hollow body defining a passage through the body insert along a symmetrical axis. The method further comprises compressing at least a portion of the end portion of the elongate conduit body radially between the ferrule and the body insert, inserting one or more elongate cables into the elongate conduit body, and filling at least a portion of the elongate conduit body with a potting material. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Example embodiments of the methods for constructing composite conduit assemblies are illustrated in the accompanying drawings, which are for illustrative purposes only. The drawings comprise the following figures, in which like numerals indicate like parts. 
         FIG. 1  is a perspective view of an exterior portion of an example partially assembled end fitting. 
         FIG. 2  is a cross-sectional view of the partially assembled end fitting taken along line  2 - 2 . 
         FIG. 3  is a side view of an example elongate conduit body having a ferrule installed over one end. 
         FIG. 4  is a cross-sectional view of the elongate conduit body having the ferrule installed over one end, taken along line  4 - 4 . 
         FIG. 5  is a cross-sectional view of the end fitting of  FIG. 1  having the conduit body and ferrule of  FIG. 3  installed thereon. 
         FIG. 6  is a partial cutaway view of an example variable frequency drive cable including a separated insulated grounding cable. 
         FIG. 7  is a flowchart illustrating selected steps in an example process for deploying bundled hoses and/or cables into a conduit body. 
         FIG. 8  is a schematic illustration of an example layout for filing a composite conduit assembly with a potting material. 
         FIG. 9  is a cross-sectional view of the composite conduit assembly of  FIG. 8  taken along line  9 - 9 . 
     
    
    
     DETAILED DESCRIPTION 
     Disclosed herein are techniques for fabricating composite conduit assemblies capable of housing electrical cables and/or hydraulic hoses. The assembly techniques disclosed herein are usable to produce composite conduit assemblies ranging from less than a meter in length to over 100 meters in length. In certain embodiments, these composite conduit assemblies have sufficient durability to withstand harsh environmental and operating conductions while still retaining sufficient flexibility to accommodate repetitive and cyclical bending movements, such as those associated with drilling and pipe handling equipment. 
       FIG. 1  is a perspective view of an exterior portion of an example partially assembled end fitting  10  for use with a composite conduit assembly.  FIG. 2  is a cross-sectional view of the partially assembled end fitting  10  taken along line  2 - 2 . As illustrated, the end fitting  10  includes a flange  12  joined to a body insert  14  by an exterior weld  16  and an interior weld  20 . In certain embodiments, the exterior weld  16  and the interior weld  20  are formed using a tungsten inert gas welding technique, although other welding techniques are used in other embodiments. In such embodiments, a ⅛-inch stainless steel rod is used to form the exterior weld  16 , and a 1/16-inch stainless steel rod is used to form the interior weld  20 , although other materials and dimensions can be used as well. 
     Still referring to the example embodiment illustrated in  FIGS. 1 and 2 , the flange  12  includes a plurality of threaded holes  18 , as well as a large, unthreaded central hole  30 . In an example embodiment, the flange  12  comprises hot rolled and annealed steel, although other materials are used in other embodiments. The body insert  14  defines a hollow tubular body that is aligned with the central hole  30 ; the tubular body has a varying inner and outer diameter. Specifically, as illustrated in  FIG. 2 , the body insert  14  has a larger outer diameter and a larger inner diameter in a first end portion  14   a  that is adjacent to the flange  12 , as compared to a second end portion  14   b  that is distal to the flange  12 . In an example embodiment, the second end portion  14   b  includes an exterior serrated surface  32 . The body insert  14  comprises low carbon steel, although other materials are used in other embodiments. In an example embodiment the central hole  30  and the body insert  14  inner diameter are sized to allow an appropriate quantity of electrical cables and/or hydraulic hoses to be positioned therein, based on the specifications for a particular application. 
       FIG. 3  illustrates an elongate, tubular conduit body  22  that has been cut to an appropriate length for a particular application. In an example embodiment, the conduit body  22  comprises styrene butadiene rubber. In other embodiments, the conduit body  22  comprises one or more other materials that provide good abrasion resistance, cracking resistance, oil resistance, and tensile strength. In certain embodiments, the conduit body  22  is resistant to degradation when exposed to ozone, water, light, or other environmental conditions. As an example, many synthetic rubber materials provide certain of these qualities, and such materials are used to form the conduit body  22  in certain embodiments. In an example embodiment, the conduit body  22  has an inner diameter that is approximately equal to or slightly larger than an outer diameter of the second end portion  14   b  of the body insert  14 . 
     Still referring to  FIG. 3 , a ferrule  24  is installed over an end of the conduit body  22 .  FIG. 4  is a cross-sectional view of the elongate conduit body  22  having the ferrule  24  installed over one end, taken along line  4 - 4 . As illustrated, the ferrule  24  has an inside diameter that is approximately equal to an outer diameter of the conduit body  22 . However, the ferrule  24  also has an end portion  28  having a reduced diameter, thereby allowing the end of the conduit body  22  to seat within the end portion  28  upon insertion into the ferrule  24 . In an example embodiment, the ferrule end portion  28  has an inner diameter that is smaller than the body insert first end portion  14   a , but that is larger than the body insert second end portion  14   b.    
     The ferrule  24  optionally includes at least one sight hole  26  positioned adjacent to the reduced diameter end portion  28 , thereby allowing an assembler to see whether the conduit body  22  has seated in the end portion  28  of the ferrule  24 . The ferrule  24  also optionally includes a plurality of teeth  34  on the inner surface thereof, the teeth  34  being configured to grip the conduit body  22 . In an example embodiment, the ferrule  24  comprises low carbon steel, although other materials are used in other embodiments. 
     Once the ferrule  24  is installed on the end of the conduit body  22 , the second end portion  14   b  of the body insert  14  is inserted through the end portion  28  of the ferrule  24  and into the end of the conduit body  22 . The first end portion  14   a  of the body insert  14  acts as a stop, thus preventing the ferrule  24  from contacting the flange  12 . The resulting structure is illustrated in  FIG. 5 , which shows that the end of the conduit body  22  is positioned between the body insert  14  and the ferrule  24 . In embodiments wherein the conduit body  22  is tightly fit over the body insert  14 , the body insert  14  is optionally lubricated, for example using an oil, such as a vegetable oil, to assist in the insertion process. 
     After the conduit body  22  and ferrule  24  are installed onto the body insert  14 , the inner diameter of the second end portion  14   b  of the body insert  14  is internally expanded using, for example, an electric or hydraulic expansion machine and a die. In one embodiment, the inner diameter of the body insert second end portion  14   b  is expanded such that the body insert  14  has a substantially constant inner diameter from the first end portion  14   a  to the second end portion  14   b.    
     Expanding the inner diameter of the body insert second end portion  14   b  causes the outer diameter of the body insert second end portion  14   b  to expand, thus securely pinching the conduit body  22  between the body insert  14  and the ferrule  24 . This also secures the ferrule  24  to the body insert  14  by preventing the reduced diameter end portion  28  from sliding off of the expanded body insert second end portion  14   b . Expanding the inner diameter of the body insert second end portion  14   b  also causes the optional serrated surface  32  and/or optional teeth  34  to be pressed into the conduit body  22 , thus further securing the conduit body  22  to both the ferrule  24  and the body insert  14 . This results in the flange  12 , the body insert  14 , the conduit body  22  and the ferrule  24  all being secured together to form a finished end fitting  10 . Once the end fittings  10  are formed at one or both ends of the elongate conduit body  22 , the electric cables and/or the hydraulic hoses are ready to be deployed within the conduit body. 
     The electrical cables and/or hydraulic hoses to be positioned within the conduit body  22  are bundled together before they are deployed therein. In an example embodiment, this is accomplished by wrapping tape (for example, 1-inch fiber reinforced adhesive tape) around the cables and/or hoses periodically (for example, every 12 inches). This assists in holding the cables and/or hoses in substantially cylindrical bundle, which facilitates their deployment within the conduit body  22 . The process of bundling the cables together is optional; for example, in embodiments wherein only one hose or cable is to be deployed within the conduit body, the bundling procedure is omitted. The cables and/or hoses are optionally wrapped in a plastic sheath before deployment into the conduit body  22 . In an example embodiment, the cables and/or hoses are longer than the conduit body  22 , such that after deployment therein, a length of cable and/or hose extends from one or both ends of the conduit body  22 . This extra length of cable and/or hose is useful, for example, in splicing the cables and/or hoses of the composite conduit assembly to other cables and/or hoses. 
     In embodiments wherein the composite conduit assembly includes an electrical cable having conductive shielding, a separate grounding cable coupled from the shielding is optionally formed at one or both ends of the shielded cable. For example,  FIG. 6  illustrates a partial cutaway view of a variable frequency drive (“VFD”) cable  38  having a plurality of individually insulated electrical conductors  36 . The conductors  36  are enclosed in a conductive armor  40  which is surrounded by an insulating wrap  42 . In an example embodiment, the conductive armor comprises stainless steel braiding, and the insulating wrap comprises a polymeric material, such as a Mylar®. Other types of VFD cable are used in other embodiments. 
     When using a VFD cable such as that illustrated in  FIG. 6 , the conductive armor  40  is configured to be connected to an electrical ground. When the VFD cable is installed within the conduit body  22 , this ground connection is provided by a separate grounding cable  44 , as illustrated in  FIG. 6 . The grounding cable  44  provides an electrical connection between the conductive armor  40  and the exterior of the conduit body  22 . In an example embodiment, this is accomplished, by removing the insulating wrap  42  from one end of the VFD cable  38 , and combing out a portion of the conductive armor  40 . The individual conductive strands that form the conductive armor  40  are twisted into a plurality of groups, which are then braided into a wire  46 , as illustrated in  FIG. 6 . The wire  46  is coupled into the insulated grounding cable  44  using a soldered bushing  50 . The soldered bushing  50  is optionally enclosed within heat shrink tubing. The insulated grounding cable  44  is then grouped with the other electrical conductors  36  from the VFD cable  38 . 
     In an example embodiment, the insulated grounding cable  44  includes a distinctive indicium, such as a marking  52 , to differentiate it from the other electrical conductors  36 . In a modified embodiment wherein the composite conduit assembly includes a plurality of VFD cables, the grounds for the VFD cables are optionally combined into a single insulated grounding cable. The VFD cable  38  is then ready to be bundled with other cables and/or hoses as described above, and deployed into the composite conduit  22  using the techniques described herein. In an example embodiment, the electrical conductors  38  and the insulated grounding cable  44  extend from one or both ends of the composite conduit. 
     By optionally positioning the soldered bushing  50  and the stripped portion of the insulating wrap  42  within the conduit body  22 , only the electrical conductors  36  and the insulated grounding cable  44  extend from an end of the composite conduit assembly. This advantageously eliminates the need for an end user to splice the individual components of the VFD cable  38 ; instead, the splice is secured within the composite conduit assembly. However, in modified embodiments the VFD cable is not spliced inside the composite conduit assembly. 
     An example process for deploying a hydraulic hose, an electrical cable, or a bundle of hoses and cables into a conduit body  22  is set forth in the flowchart illustrated in  FIG. 7 . In this process, the ends of the conduit body  22  are securely anchored, as indicated by operational block  50 . In example embodiments wherein end fittings  10  have been assembled one the conduit body  22 , this is accomplished by pinning the end fittings  10  between the blades of a forklift, by tying cables between the threaded holes  18  and floor anchors, by a combination of these two techniques, or by using other techniques. 
     Once the ends of the conduit body  22  are secured, a string (for example, a fiber, nylon, metal, or other string type) is deployed through the length of the conduit body  22 , as indicated by operational bock  52 . Preferably, the string is longer than the conduit body  22 , such that the ends of the string extend from the ends of the conduit body  22  when the string is fully deployed. In an example embodiment, the string is deployed by tying one end of a string to a ping-pong ball and blowing the ping-pong ball through the conduit body  22  using compressed air. In this embodiment, string is used (a) to facilitate the passage of the string through the conduit when only compressed air is used as a propellant, and (b) because the string is not subjected to large tensile stresses in subsequent assembly steps. Other techniques are used to deploy the string into the conduit body  22  in other embodiments. For example, in a modified embodiment a first magnet is tied to one end of the string, and a second magnet is passed along the exterior of the conduit body  22 , thereby “dragging” the first magnet along the interior of the conduit body  22  as the string is deployed therein. In yet another modified embodiment, ping pong ball is used, but a vacuum is used to pull the ball from one end of the conduit body  22 . 
     Once the string is deployed through the length of the conduit body  22 , a cord is attached to a first end of the string, as indicated by operational block  54 . In an example embodiment, the cord has a higher tensile strength than the string. A second end of the string is then pulled from the conduit body  22 , thereby removing the string from the conduit body  22  and deploying the cord into the conduit body  22 , as indicated by operational block  56 . Preferably, the cord is longer than the conduit body  22 , such that the ends of the cord extend from the ends of the conduit body  22  when the cord is fully deployed. 
     Once the cord is deployed through the length of the conduit body  22 , a winch cable, or other pulling device, is attached to a first end of the cord, as indicated by operational block  58 . A second end of the cord is then pulled from the conduit body  22 , thereby removing the cord from the conduit body  22  and deploying the winch cable into the conduit body  22 , as indicated by operational block  60 . In an example embodiment, the cord has sufficient tensile strength to pull the winch cable through the conduit body  22 . Preferably, the winch cable is longer than the conduit body  22 , such that the ends of the winch cable extend from the conduit body  22  when the winch cable is fully deployed. 
     Once the winch cable is deployed through the length of the conduit body  22 , the bundle of electrical cables and/or hydraulic hoses to be deployed therein is coupled to a first end of the winch cable, as indicated by operational block  62 . In an example embodiment, this is accomplished using a bundled cable harness that cinches around the bundled cables and includes a hook that is tied to the winch cable. A winch is then used to pull a second end of the winch cable from the conduit body  22 , thereby removing the winch cable from the conduit body  22  and deploying the bundle of electrical cables and/or hydraulic hoses through the conduit body  22 . 
     Once the bundle of electrical cables and/or hydraulic hoses is deployed into the conduit body  22 , a potting material is filled into the conduit body  22 . The potting material unites the bundles cables and/or hoses with the conduit body  22 , thereby reducing or preventing binding or other movement of the cables and/or hoses within the conduit body  22 . In an example embodiment, the potting material is poured into the conduit body  22  using the example gravity-based filling system illustrated in  FIG. 8 . As illustrated, the conduit body  22  is laid out with the end fittings  10  elevated and facing upward, with the cable and/or hose ends  54  deployed in the conduit body  22  extending therefrom.  FIG. 9  is a cross-sectional view of the end fitting  10  illustrated in  FIG. 8 , taken along line  9 - 9 . Once the conduit body  22  is positioned as illustrated in  FIG. 8 , a potting material is poured into one or both ends of the conduit body  22 . Specifically, the potting material is poured into the portion of the conduit body  22  not occupied by the cables and/or hoses, as indicated by region  56  illustrated in  FIG. 9 . 
     In an example embodiment, the potting material comprises two different liquid polymers that, when cured at room temperature between approximately 12 hours and approximately 48 hours, form a relatively tough urethane elastomer that is resistant to petroleum and ozone, and that has superior abrasion resistance. In one embodiment, the potting material retains its mechanical properties over a wide range of operating temperatures, such as between about −20° F. and about +175° F. 
     In an example embodiment, a first liquid polymer is poured into the conduit body  22  first, and is filled to within approximately three feet (or other desired distance) of the end fittings  10 . A second liquid polymer is poured into the conduit body  22  after the first liquid polymer, and is filled to the opening of the end fitting  10 . In an example embodiment, the second liquid polymer has more adhesive properties as compared to the first liquid polymer, whereas the first liquid polymer is more flexible than the second liquid polymer. In a modified embodiment wherein the conduit body is relatively short, the first liquid polymer is filled to less than three feet of the end fittings  10 . In yet another modified embodiment, the first liquid polymer is omitted, and the conduit body is potted using only the second liquid polymer. In yet another modified embodiment, the second liquid polymer is omitted, and the conduit body is potted using only the first liquid polymer. 
     The first and second liquid polymers include a catalyst and a base that are mixed before pouring into the conduit body  22 . In one embodiment, the first liquid polymer is Calthane 1900 (base and catalyst mixed at a 9:1 mass ratio), and the second liquid polymer is Calthane 1300 (base and catalyst mixed at a 6:1 mass ratio), which are both available from Cal Polymers, Inc. (Long Beach, Calif.). 
     After the potting material is filled into the conduit body, the resulting structure is allowed to cure for at least approximately 12 hours. Shorter or longer curing times are used in other embodiments. After the potting material has cured, the resulting composite conduit assembly is ready for use. As expounded herein, the techniques disclosed herein are usable to produce composite conduit assemblies having sufficient durability to withstand harsh environmental and operating conductions yet still retain sufficient flexibility to accommodate repetitive and cyclical bending movements, such as those associated with drilling and pipe handling equipment. 
     While the foregoing detailed description discloses several embodiments of the present invention, it should be understood that this disclosure is illustrative only and is not limiting of the present invention. It should be appreciated that the specific configurations and operations disclosed can differ from those described above, and that the methods described herein can be used in contexts other than the manufacture of composite conduit assemblies.