Patent Publication Number: US-2013232767-A1

Title: Crimped or swaged couplings for cable reinforced hoses

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates generally to reinforced hose, more particularly to crimped or swaged couplings for reinforced hose, and specifically to crimped or swaged couplings for cable or wire rope reinforced hoses. 
     2. Description of the Prior Art 
     Typically, blow out preventers (BOPS) are used when oil or gas wells are drilled. Blowout preventers are hydraulically controlled valves used to control well kicks and prevent blowouts. A single well may have three or more preventers, stacked one on top of the other. On a land rig, the stack is located beneath the rig floor at ground level. On an offshore rig the BOP may be located on the seafloor. The top preventer on a stack is usually an annular preventer. The annular preventer may be used to completely seal off the drill well annulus (the space between the drill pipe and the borehole). It also can seal off a drill hole that has no pipe. Below the annular preventer are additional controls called ram preventers. The ram preventers are designed to fit around various sizes of drill pipe to hold, close or seal the mud return annulus. Blind rams are used to seal off an open hole. Pipe rams can seal off the drill pipe and the hole. 
     Rock formations may contain pockets of oil, gas or water under extremely high pressures. A drilled hole may intersect any of these. When any of these high-pressure fluids enter the hole it is referred to as a “kick.” When a well kicks, there are several options for handling the kick. The resulting downhole pressure can be cycled out through the BOP system&#39;s manifolds at the surface. Alternatively, an attempt can be made to force the downhole fluid back into the formation, such as by pumping drilling fluid under high pressure into the hole through a choke and kill line. Choke and kill hose is used for this purpose. A final option is to pump in cement, seal off the hole and abandon the drilling operation. 
     Flexible reinforced pipes and hoses are currently used in Choke and Kill applications on oil rigs. These hoses/pipes and couplings are designed to act as a conduit for the pumping of mud (drilling waste) back down into a well head to block the well head fluid against oil, methane gas and noxious chemicals such as Hydrogen Sulphide, at extreme temperatures and pressures. These hoses typically comprise a rubber polymeric tube and are reinforced using multiple layers of “close wound”, high tensile plated steel cables (or wire rope) to withstand flexing and high pressures encountered in oil field and offshore operations. This cable reinforcement is typically wire stranded rope, which is typically interchangeably referred to as “cable” and/or “wire rope.” These hoses also typically include multiple layers of fabric reinforcement disposed under the hose cover, which may be a modified nitrile resistant to abrasion, corrosion, cutting, gouging, oil and weather. 
     Prior crimped or swaged couplings  100  for choke and kill hose applications typically employ ridged ferrule  101  and barbed stem fitting  102 , such as shown in prior art  FIG. 1 . This ferrule and stem are typically welded together ( 103 ), leaving an opening, which accepts hose  105 . Baldwin, et al., U.S. Pat. No. 7,338,090, employs a “waved” ferrule and stem that joins an end connector to the coke and kill hose. This ferrule and stem are also welded together at the coupling end, leaving an opening, which accepts the reinforced hose. However, in Baldwin, et al., the lands of the ferrule and high points of the stem have a sinusoidal shape, providing the aforementioned “wave.” This wave bends the cable/wire rope reinforcement in the hose but does not significantly distort the cables. The stem is designed to support the hose which is inserted over it and under the ferrule. The ferrule is swaged or crimped down onto the hose to provide compressive forces, sealing the hose against the stem and retaining the hose in the coupling. For use with this sort of coupling the cover of the hose is skived (i.e. stripped away) so that the ferrule is able to press down on the cable reinforcement, directly, without the need to penetrate the rubber cover. Still, in designs like Baldwin coupling retention is dependent upon the properties of the rubber to provide a reaction force to compression preventing the cable reinforced hose slipping out of the couplings, such designs may lose their capability at elevated or reduced temperatures where the properties of the rubber layers change and may provide less support. 
     Other approaches to retaining a fitting on a cable reinforced hose call for unraveling reinforcement cable extending from an end of the hose and welding individual elements (cables) to a coupling. Problematically, such approaches are time consuming, expensive and require qualified welders. 
     API (American Petroleum Institute) 16 C standards testing includes testing such as a thirty-day exposure test at 20,000 psi working pressure, at elevated temperature, for choke and kill hose assemblies. When choke and kill hose assemblies employing the above-described couplings are exposed to theses conditions it was found that the hose-coupling interface is susceptible to temperature extremes. The properties of the rubber material change at elevated temperature and as a result the rubber can flow and allow the compressive forces in the coupling ferrule to drop. This can result in loss of coupling retention which is not acceptable in choke and kill, or similar, applications. 
     SUMMARY 
     The present invention is directed to systems and methods of crimped or swaged couplings for cable or wire rope reinforced hoses where rubber material properties are taken out of the coupling retention mechanism. In order to achieve this, a short length of the internal tube and external cover of the hose is skived. The result of this short length of skiving is that the wire/cable reinforcement can be gripped alone without a need to compress and penetrate the tube or cover. With a relatively short length of cable exposed, a stem and ferrule of the present invention, which forms a reinforcement cable (or wire rope) trap, can be swaged or crimped onto the hose end, gripping the hose without reliance upon rubber properties. In particular, the cable reinforcement is preferably trapped directly between the stem and the ferrule. Specifically, the cable is retained between a raised portion of the stem which incorporates a depression and a serration in the ferrule. Unlike prior approaches, rather than merely bending the cable, maintaining its integrity, the short length of skived cable is squeezed between stem and ferrule in the present systems and methods. This results in distortion of the cable, providing a mechanical lock between the coupling and the hose. Additional retention may be achieved by using a more aggressive ferrule design where the ferrule is forced to flow around the cable when the connection is swaged or crimped. 
     In accordance with various embodiments of the present invention a hose coupling for fitment to an end of a cable reinforced hose, such as a blowout preventer choke and kill hose, might include a unitary stem and a unitary ferrule, which may be welded, staked or otherwise secured together. Various embodiments of the stem have an inner bore and a termination portion for attaching the coupling and hose on which it is swaged or crimped, such as by welding to a flange, or the like. The stem preferably defines a cable trap groove, which may have a generally trapezoidal, or other polygonal, shape. The root of this groove preferably has an outside diameter that is greater than an inside diameter of a tube of the hose. The outside diameter of the groove root is also preferably less than an inside diameter of the hose with the tube skived from the hose, that is less than the inside diameter of the cable reinforcement layer of the hose. An insert portion of the stem is adapted for insertion into the tube of the hose. The insert preferably defines a plurality of external lands and has an outside diameter generally corresponding to an inside diameter of the tube of the hose. 
     The unitary ferrule has an outer surface and a first and second inside diameter. The first inside diameter of an unstaked or uncrimped ferrule, is preferably greater than an outside diameter of the wire stranded cable reinforced hose. The second inside diameter of the unstaked, uncrimped or unswaged ferrule may be less than the outside diameter of the cable reinforced hose, but greater than an outside diameter of the hose with material covering the cable skived from the hose, that is greater than the outside diameter of the cable reinforcing layer of the hose. An inner surface portion of the ferrule has a portion that has the first diameter. This portion defines a plurality of ridges, positioned to inter-index with the lands of the stem. Another portion of the inner surface of the ferrule defines at least one generally cable trap rib, shaped and positioned to correspond to the cable trap groove in the stem. This cable trap rib has the second inside diameter and is narrower than the groove. Preferably, the groove has a width that is at least the width of the rib plus twice the diameter of a cable reinforcing the hose and the width of the rib is greater than a diameter of a cable reinforcing the hose, such as on the order of multiple diameters of the cable reinforcing the hose. When the ferrule is secured to the stem, such as by welding or staking the termination portion of the stem preferably extends from the ferrule and the cable trap groove and the insert of the stem are disposed in the ferrule. 
     In accordance with the present invention prior to disposition of the ferrule of the coupling over an end of the hose, the outside layers of the hose covering the cable reinforcement portion is skived from a distal extent of the end of the hose. The stem is disposed with the insert inserted inside the tube of the hose and the cable trap groove is inserted inside the distal extent of the hose with the tube skived away from the distal extent of the hose. 
     Accordingly, various embodiments of methods for securing a fitting to the end of a cable reinforced hose, such as a blowout preventer choke and kill hose, in accordance with the present invention calls for skiving layers of the hose covering the cable reinforcement from a distal end portion of the end of the hose and skiving a tube from inside the distal end portion of the hose. The unitary stem having an inner bore, a termination for attaching to a fixture, a cable trap groove and an insert portion is inserted into the skived hose with the insert portion inserted inside the tube of the cable reinforced hose and with the cable trap groove inserted inside the skived distal end portion of the hose. The unitary ferrule is preferably deployed over the end of the hose and the stem with the ridges inter-indexing with lands defined on an outside of the insert and with at least the cable trap rib corresponding to the cable trap groove. Such deployment of the ferrule and the stem may occur generally simultaneously if the ferrule is welded to the stem, prior to disposition. Regardless, following disposition of the ferrule and the stem the ferule is compressed, such as by swaging or crimping, resulting in the ridges compressing the hose to seal the tube in the lands and the rib forcing the cable into the groove, trapping the cable reinforcement in the skived area and thereby securing the coupling to the hose in a manner that does not depend on gripping rubber or polymeric material. 
     Thus, in accordance with various embodiments of the present invention a hose assembly, such as a blowout preventer choke and kill hose assembly, may be made up from a length of hose having an inner tube, one or more layers of cable reinforcement and one or more layers of rubber covering the reinforcement, wherein the inner tube and the one or more layers of rubber covering are skived from an end portion of the hose. A coupling, such as discussed above, is preferably swaged or crimped on the end portion and a further length of the hose. In accordance with such embodiments, the coupling comprises a unitary ferrule disposed over the end portion of the hose and the further length of the hose. The ferrule has a first inside diameter greater than an outside diameter of the hose and a second inside diameter that may be less than the outside diameter of the hose, but is greater than an outside diameter of the end portion of the hose with the rubber covering skived from the hose. The ferrule defines an inner surface having a plurality of ridges having the first diameter and disposed over the further length of the hose. The ferrule inner surface also preferably defines at least one cable trap rib having the second inside diameter and disposed over the skived end portion of the hose. The coupling also, as discussed above has a unitary stem, which may be secured to or unitary with the ferrule. The stem is preferably disposed in the end portion of the hose and on into the further, unskived length of the hose. The stem comprises a termination portion for attaching to a fixture (such as a flange, or the like) a cable trap groove, and an insert defining a plurality of lands inter-indexing with the ferrule ridges. The insert has an outside diameter generally corresponding to an inside diameter of the tube of the hose and is inserted into the further portion of the hose from which the tube has not been skived. The cable trap groove corresponds to the cable trap rib and is preferably disposed under the end portion. The groove has a diameter greater than an inside diameter of a tube of the hose, but less than an inside diameter of the hose with the tube skived from the hose. Also, the groove preferably has a width that is at least the width of the rib, plus twice the diameter of cable reinforcing the hose. 
     In accordance with various embodiments, epoxy may be disposed between the tube and the stem, prior to compression of the ferrule, to aid in sealing the tube of the hose against the stem following compression of the ferrule. Alternatively, or additionally, low viscosity epoxy may be injected into the fitting, such as through a weephole, to in between the ferrule and the cable, after compression. 
     Advantageously, the present invention provides better coupling retention, resistance to extreme temperatures and separation of retention from sealing because rubber material properties are taken out of the coupling retention mechanism. Further, in contrast to prior systems, since the diameter of the reinforcing wire rope may slightly expand at elevated temperatures, the cable trap provided by the rib and groove described above bearing directly on the bare cable as a result of skiving of both the cover and the tube preferably tightens. 
     The foregoing has outlined rather broadly the features and technical advantages of the present invention in order that the detailed description of the invention that follows may be better understood. Additional features and advantages of the invention will be described hereinafter which form the subject of the claims of the invention. It should be appreciated by those skilled in the art that the conception and specific embodiment disclosed may be readily utilized as a basis for modifying or designing other structures for carrying out the same purposes of the present invention. It should also be realized by those skilled in the art that such equivalent constructions do not depart from the scope of the invention as set forth in the appended claims. The novel features which are believed to be characteristic of the invention, both as to its organization and method of operation, together with further objects and advantages will be better understood from the following description when considered in connection with the accompanying figures. It is to be expressly understood, however, that each of the figures is provided for the purpose of illustration and description only and is not intended as a definition of the limits of the present invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The accompanying drawings, which are incorporated in and form part of the specification in which like numerals designate like parts, illustrate embodiments of the present invention and together with the description, serve to explain the principles of the invention. In the drawings: 
         FIG. 1  is a fragmented, generally sectional view of a crimped or swaged prior art coupling installed on a cable reinforced hose ; 
         FIG. 2  is a fragmented, generally quarter sectional view of an embodiment of a coupling of the present invention; 
         FIG. 3  is a fragmented, generally quarter sectional view of the embodiment of the coupling of  FIG. 2  deployed, uncompressed, on a cable reinforced hose; 
         FIG. 4  is a fragmented, generally quarter sectional view of the embodiment of the coupling of  FIGS. 2 and 3  installed, compressed, on a cable reinforced hose shown in  FIG. 3 ; and 
         FIG. 5  is an enlarged, fragmented, generally sectional view of the embodiment of a coupling of  FIGS. 2-4  shown installed, compressed, on the hose as shown in  FIG. 4 . 
     
    
    
     DETAILED DESCRIPTION 
     As noted,  FIG. 2  is a quarter sectional view of an embodiment of coupling  200  of the present invention. In  FIG. 3  coupling  200  is deployed, uncompressed, on cable reinforced hose  305 , which may be a blowout preventer choke and kill hose, or the like. Hose coupling embodiment  200  includes unitary stem  202  and unitary ferrule  201 , which may be welded ( 203 ), staked or otherwise secured together, such as through the use of circular plate  204 , or similar mechanism. 
     Various embodiments of stem  202  may have inner bore  210  and termination structure portion  212  for attaching coupling  200  and hose  305  on which it is swaged or crimped to a fixture, such as a flange, or the like. Termination structure  212  may take the form of a bud, or the like, that may be welded to a flange or the like for fitment using a hammer union, or the like. Stem  202  preferably defines cable trap groove  215 , which is illustrated in  FIGS. 2 through 5  as generally trapezoidal in shape. However, such cable trap grooves may, in accordance with the present invention, be of a number of different shapes, such as, generally rounded, chevron-shaped, generally rectangular, etc. Root  216  of groove  215  preferably has a diameter that is greater than an inside diameter of inner tube  317  of hose  305 . The diameter of groove root  216  is also preferably less than an inside diameter of the hose with inner tube  317  skived from the hose, that is less than the inside diameter of cable reinforcement layer  320  of hose  305 , as may best be seen in  FIG. 3 . An insert portion  225  of the stem is adapted for insertion into inner tube  317  of hose  305 . Insert portion  225  preferably defines a plurality of external lands  227  and has an outside diameter generally corresponding to an inside diameter of inner tube  317  of the hose  305 . When ferrule  201  is secured to stem  202 , such as by welding or staking as discussed above, termination portion  212  of stem  202  preferably extends from ferrule  201  and cable trap groove  215  and insert  225  of stem  202  are disposed in ferrule  201 . 
     Unitary ferrule  201  has an outer surface  230  and an inside having a number of diameters defining a number of features, but primarily a first and second inside diameters, defining a plurality of ridges  232  and a cable trap rib  236 . The first inside diameter of unstaked or uncrimped ferrule  201 , such as shown in  FIGS. 2 and 3  is preferably greater than an outside diameter of wire stranded cable reinforced hose  305 , as best seen in  FIG. 3 . The second inside diameter of unstaked or uncrimped ferrule  201  may be less than the outside diameter of cable reinforced hose  305 , but is preferably greater than an outside diameter of hose  305  with material covering cable reinforcement  320 , such as cover  333 , skived from the hose. In other words the second inside diameter of the ferrule is preferably greater than the outside diameter of cable reinforcing layer  320  of hose  305 , but may be less than the outside diameter of the hose overall. Preferably, ridges  232  are positioned to generally inter-index with lands  227  of stem  202 . Another portion of the inner surface of the ferrule defines at least one cable trap rib  236 , positioned to correspond to cable trap groove  215  in stem  202 . Cable trap rib  236  has the second aforementioned inside diameter and is preferably narrower than groove  215 . Preferably, groove  215  has a width that is at least the width of rib  236  plus at least, or about, twice the diameter of a cable reinforcing hose  305 . Also, preferably, the width of rib  236  is greater than the diameter of a cable reinforcing hose  305 , such as on the order of multiple diameters of the cable reinforcing hose  305 . 
     The embodiment illustrated in  FIGS. 2 through 5  has a single cable trap groove,  215  and a single rib,  216 . However, any number of cable traps can be employed on a coupling in accordance with the present invention. For example, a plurality of cable trap ribs may be employed in conjunction with a corresponding number of cable trap grooves. 
     In accordance with various embodiments for securing a fitting, such as fitting  200 , to the end of a cable reinforced hose, such as hose  305 , which may be a blowout preventer choke and kill hose, or the like, layer(s)  333  of hose  305  covering cable reinforcement  320  are skived from an end portion of hose  305  and inner tube  317  is skived from an inside distal extent of the end portion of hose  305 . Generally, this distal extent from which the tube is skived is only a portion of the end of the hose from which the cover is skived. Unitary stem  202 , having inner bore  210 , termination  212  for attaching to a fixture, cable trap groove  215  and insert portion  225 , is inserted into the skived hose. Insert portion  225  is inserted inside (unskived) inner tube  317  of cable reinforced hose  305 , with cable trap groove  215  inserted inside the skived distal extent of hose  305 . Unitary ferrule  201  is preferably deployed over the end of the hose  305  and stem  202 , with ridges  232  of ferrule  201  inter-indexing with lands  227  defined on an outside of insert  225  and with cable trap rib  236  corresponding with, that is generally aligning with, cable trap groove  215 . Such deployment of ferrule  201  and stem  202  may occur generally simultaneously if ferrule  201  is welded to stem  202  prior to disposition. Following disposition of ferrule  201  and stem  202 , ferule  201  is compressed, such as by swaging or crimping, resulting in ridges  232  compressing the end of hose  305  to seal hose inner tube  317  against lands  227  and resulting in rib  236  forcing cable reinforcement  320  into groove  215 . Preferably, this traps cable reinforcement in the double-skived area between rib  236  and groove  215 . Also, in accordance with various embodiments, at least some of the individual cables making up cable reinforcement  320  are deformed by the compression of the cable trap rib, particularly compression of the cable trap rib, with respect to the uncompressed cable trap groove. This deformation of individual cables is best seen in enlarged  FIG. 5 . Entrapment of the cable by the compressed cable trap, comprised of rib  236  and groove  215 , secures coupling  200  to hose  305  in a manner that does not depend on gripping rubber or polymeric material, such as cover  333  and/or inner tube  317 . 
     Thus, in accordance with various embodiments of the present invention, a resulting hose assembly  400  ( FIGS. 4 and 5 ) may be made up from a length of hose  305  having inner tube  317  and rubber covering  333  skived out of and off of end portions of hose  305  and coupling  200 , such as discussed above swaged or crimped on the end of hose  305 . 
     In accordance with some embodiments, epoxy (not shown in Figures for sake of clarity) may be disposed between tube  227  and stem  202 , prior to compression of ferrule  201  to enhance sealing, and/or injected after compression of ferrule  201  to permeate cable reinforcement  320  with the epoxy in the areas where cover  333  and/or inner tube  317  is skived away to provide improved bonding of hose  305  and coupling  100 . 
     For example, in some embodiments, a high temperature epoxy, such as epoxy 4525 from Cotronics Corporation, may be applied to stem  202  prior to insertion in hose  305 . Since the epoxy is in two parts, the epoxy resin and the amine hardener cure in place regardless of the environment, i.e. oxygen, humidity, heat, etc. The epoxy may be placed on two lands  227  of insert  202 , near the end of stem to prevent excess epoxy from entering into the stem or hose tube. Compression of ferrule  201  distributes the epoxy. In particular swaging advantageously moves the adhesive further into tube  227 , along stem  202 . Adding heat may facilitate set-up of the epoxy making the hose useable in a relatively short time frame. 
     In accordance with other embodiments, a high viscosity epoxy, such as epoxy  4461  from Cotronics Corporation, may be injected through weephole  235  to penetrate the interstices of the cables as well as any additional areas between the cable and stem  202 . By filling the coupling and thus gaining access into very small cavities the epoxy will have increased contact surface area, and thus, increased bond strength, as well as enhanced sealing functionality. Advantageously, such low viscosity epoxy may be injected through weephole  235  after compression of ferrule  201 , or before. 
     Although the present invention and its advantages have been described in detail, it should be understood that various changes, substitutions and alterations can be made herein without departing from the scope of the invention as defined by the appended claims. Moreover, the scope of the present application is not intended to be limited to the particular embodiments of the process, machine, manufacture, composition of matter, means, methods and steps described in the specification. As one of ordinary skill in the art will readily appreciate from the disclosure of the present invention, processes, machines, manufacture, compositions of matter, means, methods, or steps, presently existing or later to be developed that perform substantially the same function or achieve substantially the same result as the corresponding embodiments described herein may be utilized according to the present invention. Accordingly, the appended claims are intended to include within their scope such processes, machines, manufacture, compositions of matter, means, methods, or steps.