Patent Abstract:
An apparatus including a suppression device dimensioned to suppress a vortex induced vibration of a tubular. The apparatus further including an adjustable strap assembly attached to the suppression device, the adjustable strap assembly dimensioned to secure the suppression device to the tubular. Alternatively, the apparatus may include a support arm extending from the suppression device to rotatably attach the suppression device to the tubular, the support arm having a guide member at one end dimensioned to be received by a slot formed around an outer surface of the tubular. A method including positioning a suppression device dimensioned to suppress a vortex induced vibration of a tubular against the tubular and attaching the suppression device to the tubular such that the suppression device is movable about the tubular.

Full Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     The application claims the benefit of the earlier filing date of U.S. Provisional Patent Application No. 61/455,458, filed Oct. 21, 2010 and U.S. Provisional Patent Application No. 61/428,995, filed Dec. 31, 2010 and incorporated herein by reference. 
    
    
     FIELD 
     Suppression devices and attachment assemblies for attaching the suppression device to a tubular. 
     BACKGROUND 
     A difficult obstacle associated with the exploration and production of oil and gas is management of significant ocean currents. These currents can produce vortex-induced vibration (VIV) and/or large deflections of tubulars associated with drilling and production. VIV can cause substantial fatigue damage to the tubular or cause suspension of drilling due to increased deflections. While helical strakes, if properly designed, can reduce the VIV fatigue damage rate of a tubular in an ocean current, they typically produce an increase in the drag on the tubular and hence an increase in deflection. Thus, helical strakes can be effective for solving the vibration problem at the expense of worsening the drag and deflection problem. 
     A better solution is to use fairings as the VIV suppression device. A properly designed fairing can reduce both the VIV and the drag. A problem associated with fairings on drilling risers has been the cost of installation and retrieval of the fairings. If the fairings are excessively large, then handling difficulties can produce long installation times. Sometimes, the economics are such that running the riser without fairings has a higher expected return value than installing the fairings due to these high installation costs. 
     Tail fairings are suppression devices that produce reduction in both VIV and drag, but are lighter and faster to install than traditional full fairings. These fairings consist of only the tail portion of a fairing together with straps at each end to hold the tail to the tubular. 
     Tail fairings, while faster to install than traditional full fairings, can be difficult to install when the brackets and straps do not line up correctly. In addition, tail fairings cannot be used for multiple sized risers, and must be used only for the buoyancy size for which they were designed. Tail fairings also typically require at least one collar per fairing to keep them from sliding down the tubular. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The embodiments disclosed herein are illustrated by way of example and not by way of limitation in the figures of the accompanying drawings in which like references indicate similar elements. It should be noted that references to “an” or “one” embodiment in this disclosure are not necessarily to the same embodiment, and they mean at least one. 
         FIG. 1  illustrates a perspective view of an attachment assembly for attaching a suppression device to a tubular. 
         FIG. 2  is an expanded view of the brackets described in reference to  FIG. 1 . 
         FIG. 3  illustrates an embodiment of an attachment assembly for attaching a suppression device to a tubular. 
         FIG. 4A  illustrates a side view of an embodiment of an attachment assembly for attaching a suppression device to a tubular. 
         FIG. 4B  illustrates an expanded view of one of the support arms and slots illustrated in  FIG. 4A . 
         FIG. 4C  illustrates a top view cross-section of the track illustrated in  FIG. 4A . 
         FIG. 5  illustrates a side view of an embodiment of an attachment assembly for attaching a suppression device to a tubular. 
         FIG. 6  illustrates a side view of another embodiment of an attachment assembly for attaching a suppression device to a tubular. 
         FIG. 7  is a side view of another embodiment of an attachment assembly for attaching a suppression device to a tubular. 
         FIG. 8  illustrates a top view of an embodiment of a suppression device. 
         FIG. 9  illustrates a top view of another embodiment of a suppression device. 
         FIG. 10  illustrates a top view of another embodiment of a suppression device. 
     
    
    
     DETAILED DESCRIPTION 
     In this section we shall explain several preferred embodiments with reference to the appended drawings. Whenever the shapes, relative positions and other aspects of the parts described in the embodiments are not clearly defined, the scope of the embodiments is not limited only to the parts shown, which are meant merely for the purpose of illustration. Also, while numerous details are set forth, it is understood that some embodiments may be practiced without these details. In other instances, well-known structures and techniques have not been shown in detail so as not to obscure the understanding of this description. 
       FIG. 1  illustrates a perspective view of a strap for holding a VIV suppression device in place around a tubular. VIV suppression device  102  is held in place around tubular  101  by straps  103 . Straps  103  are attached at each end to opposite sides of VIV suppression device  102 . In this aspect, straps  103  encircle tubular  101  and hold VIV suppression device  102  against tubular  101 . Straps  103  have a length sufficient to allow VIV suppression device  102  to weathervane around tubular  101 . In the illustrated embodiment, VIV suppression device  102  is shown as a substantially triangular shaped tail fairing. It is contemplated, however, that VIV suppression device may be any type of VIV suppression device capable of producing a reduction in VIV. For example, suppression device  102  may be a helical strake, a fairing, a splitter plate, or any other device where it is desirable for the device to have some rotational capability around tubular  101 . 
     Brackets  104  are attached to suppression device  102  to facilitate attachment of straps  103  to suppression device  102 . In one embodiment, one or more of brackets  104  are attached to suppression device  102  with a pin  105  inserted through each of brackets  104  and straps  103 . In some embodiments, straps  103  may include hinges  106  positioned at one or more locations on straps  103 . 
     Hinges  106  allow straps  103  to bend making straps  103  easier to install into a receptacle or bracket  104  and/or brought into the desired position for attachment to the suppression device  102 . Hinges  106  may be located at both sides of each of straps  103  and/or may also be located near the midpoint between the two ends of the straps  103 . Hinges  106  may also allow one end of each of straps  103  to be pre-attached to suppression device  102  before installation offshore, so that only one connection with pins  105  into brackets  104 , or other attachment, is required offshore. It is contemplated that any number of hinges  106  may be used to allow sufficient freedom of movement of straps  103  so that the straps  103  may easily be attached to suppression device  102 . Hinges  106  may be made of any material suitable for use in seawater and with sufficient toughness to withstand offshore installation. For example, hinges  106  may be made of metal such as stainless steel, aluminum, or copper; thermoplastic, fiberglass; or any materials subsequently discovered. Hinges  106  may be molded into straps  103 , fastened to the straps  103  via bolts, screws, clamps, rivets, chemical bonding agents, or attached by any other suitable means sufficient to withstand a marine environment. Hinges  106  may be external to straps  103  or internal to straps  103 . 
     In some embodiments, recesses  110  dimensioned to receive strap  103  are molded into suppression device  102 . Brackets  104  may be positioned within recesses  110  and straps  103  attached to brackets  104  within recesses  110  using pins  105  as previously discussed. Representatively, when one of straps  103  is inserted into one of recesses  110 , pin  105  is inserted into suppression device  102  and through strap  103  and bracket  104  to retain strap  103  in position. Alternatively, brackets  104  may be positioned over straps  103  positioned within recesses  110  to hold straps  103  in place. Recesses  110  may be, for example, from about 3 inches to about 5 inches tall, for example about 4 inches tall. Recesses  110  may be from about 3 to about 6 inches deep, for example, about 4 or 5 inches deep. The tolerance between the straps  103  and recesses  110  is somewhat close, so that the straps  103  do not sag or bind on the tubular  101 . Pins  105  must fully and tightly engage brackets  104 , suppression device  102 , and straps  101 . In this aspect, in some embodiments, pins  105  may be O-rings to ensure a tight fit. Alternatively, any type of pin like structure may be used to ensure a tight fit, for example, a nut and bolt. 
     One advantage of having recesses  110  molded into the suppression device  102  is that the amount of external hardware required for the straps  103  to attach to suppression device  102  is minimized. If straps  103  are attached externally to suppression device  102 , an entire bracket assembly must be fabricated and the stresses on pins  105  are increased. Still further, if the dimensions of tubular  101  are consistent along the tubular, then use of recesses  110  in suppression device  102  can eliminate the need for a bracket or elaborate attachment mechanism. 
     Suppression device  102  may be made of plastic, but may also be made of other materials such as wood, fiberglass, composite materials, or even metals such as stainless steel. Straps  103  may be made of any material providing sufficient stiffness. Representatively, if straps  103  are too stiff it is difficult to engage with recesses  110  in suppression device  102 . If straps  103  are too soft they may bind when the suppression device  102  needs to weathervane around tubular  101  due to changes in the ocean current direction. In this aspect, straps  103  may be made from plastic but can be made from other materials such as fiberglass or metals in the form of a chain. Brackets  104  can be made of metals such as stainless steel, plastic, composite material, wood, or any material capable of providing sufficient stiffness and strength. 
       FIG. 2  is an expanded view of the brackets described in reference to  FIG. 1 . From this view, it can be seen that bracket  104  includes bolts or other fasteners  204  that attach the back of bracket  104  to suppression device  102 . Bracket  104  has hinge  201  that allows the section of bracket  104  on a side of hinge  201  opposite fasteners  204  (the free end) to rotate. In particular, this portion of bracket  104  can be rotated towards strap  103  so as to allow easier installation of strap  103 . Bracket  104  also includes an extension member  202  that allows bracket  104  to be lengthened. In this aspect, suppression device  102  can accommodate different strap lengths or variations in the diameter of the tubular to which the suppression device  102  is installed. 
     One advantage of adjustable bracket  104  is that it can accommodate the diameter of a tubular that varies significantly over its length or when the fabrication of the strap length is inconsistent. Another advantage of adjustable bracket  104  is that the system can be very fast to install, since extension member  202  may be rotated and extended to best fit the strap. Extension member  202  of bracket  104  can be attached to suppression device  102  with fasteners, for example fasteners  204 . Extension member  202  may increase or decrease the length of bracket  104  to accommodate straps of varying lengths. In addition, extension member  202  may rotate at hinge  201  to accommodate straps that engage suppression device  102  at various angles. 
     Bracket  104  may be made of a metal such as stainless steel, plastic, fiberglass, or other metals and composites. Bracket  104  may be from about 3 to about 5 inches tall, for example 4 inches tall. Bracket  104  may be from about 3 to 8 inches wide, for example, from about 5 to 6 inches wide in its neutral position. Extension member  202  can be extended or contracted within bracket  104  in a telescoping manner to modify a length of bracket  104  between a length of about 5 inches to about 13 inches, for example between about 7 and about 12 inches, depending upon the functional requirements. Hinge  201  allows the section of bracket  104  opposite fasteners  204  to rotate up to 90 degrees from its nominal position against suppression device  102 , so that it can accommodate a strap that approaches suppression device  102  at a 90 degree angle with respect to the tubular. 
       FIG. 3  illustrates an embodiment of an adjustable strap for attaching a suppression device to a tubular. Adjustable strap  305  may be used to secure a suppression device to an underlying tubular as previously discussed. In this embodiment, adjustable strap  305  includes support members  301  designed to withstand tension forces exerted on strap  305  by drag on the associated suppression device. One or more adjustable sections  302  are positioned around support members  301 . Support members  301 , which are attached at one end to main strap section  306 , are capable of sliding within adjustable section  302 . In this aspect, adjustable section  302  may include a loop type buckle assembly or other similar assembly that can guide and hold support members  301  within adjustable section  302 . Adjustable section  302  is fixedly attached to the associated suppression device to secure strap  305  to the suppression device. In this aspect, adjustable section  302  may include an opening  303  through which a pin or bolt may be inserted to fasten adjustable section  302  to the suppression device. One or more cable stops  304  are used to set the desired length of strap  305  by clamping them onto support members  301  thereby restricting movement of support members  301  through adjustable section  302 . 
     Strap  305  may be constructed in serial sections, with a portion used for the main strap section  306  and then fastening support members  301  for adjustable sections  302  to main strap section  306 . Alternatively, support members  301  can run the entire strap length with both main strap section  306  and adjustable strap section  302  attached to the support members  301 . To fix the strap length upon installation, clamps such as cable stops  304  may be used or support members  301  may be attached to each other or to the tail in such as way as to prevent further change to the location of adjustable section  302 . 
     Main strap section  306  and adjustable section  302  may be made of any suitable material capable of providing the proper level of stiffness and suitable for use in seawater. Support members  301  may be made of synthetic or wire rope, chain, or cable. Support members  301  may be attached to main strap section  306  and adjustable section  302  by fasteners such as screws, bolts, and rivets. Alternatively, support members  301  may be located interior to main strap section  306  and adjustable section  302  so that they combine to form a composite strap  305 . 
     An overall length of strap  305  will typically be large enough to provide an annulus between strap  305  and the underlying tubular sufficient to allow the associated suppression device to rotate around the tubular freely but not so large as to cause large sagging of strap  305 , which could produce binding of strap  305  when the suppression device tries to weathervane due to changes in the ocean current direction. Representatively, the annulus may be between ½ inch and 1½ inches. Strap  305  must be strong enough to withstand the tension forces produced by drag on the suppression device from the ocean current. It is also important that strap  305  does not stretch significantly as this can cause the suppression device to move downstream away from the tubular which can reduce the effectiveness of the fairing system. Representatively, strap  305  is designed to accommodate tensions ranging from 0 lb to 300 lb of tension. 
       FIG. 4A  illustrates a side view of an embodiment of an attachment assembly for securing a suppression device to a tubular. In this embodiment, straps are omitted and instead, suppression device  401  is attached to tubular  402  by support arms  404  which can be inserted within complimentary slots  403  formed along an exterior of tubular  402 . Slots  403  may extend around all or part of the circumference of tubular  402  such that suppression device  401  is free to rotate around tubular  402  as support arms  404  slide within slots  403  around tubular  402 . Other hardware may be present in slots  403  to assist with rotation of suppression device  401  around tubular  402 . 
     Slots  403  may be as deep and as tall as necessary to allow rotation of suppression device  401  around tubular  402 . Suppression device  401  may be any type of suppression device including a helical strake, a fairing, a splitter plate, or any other device where it is desirable for the device to have some rotational capability around tubular  402 . Slots  403  may be rectangular, elliptical, round, trapezoidal, or of any suitable shape in cross section suitable to receive and hold ends of support arms  404  within slots  403 . Support arms  404  may be made of a single piece structural member or consist of a multitude of structural members that allow suppression device  401  to be maintained in position when ends of support arms  404  are inserted into slots  403 . Representatively, support arms  404  may be “I”, “T” or “L” shaped structures. Bracket  404  may be attached to suppression device  401  by mechanical means such as nuts and bolts, or by chemical bonding, welding, or any other suitable methods. 
     Tubular  402  may be made of metal (such as steel or aluminum), fiberglass or other composite structure, plastic, wood, or any suitable material. In some embodiments, tubular  402  may be a bundle of tubulars such as umbilicals, and does not have to be round. Tubular  402  may have an outer component such as buoyancy, insulation, or other material. Slots  403  may be formed within the outer component or formed within tubular  402 . The outer component can be present solely to contain the slot or it may have one or more other purposes such as providing buoyancy or thermal insulation. Support arms  404  may be made of metal (such as stainless steel or Inconel), fiberglass, plastic, or other synthetic or composite materials. 
       FIG. 4B  illustrates an expanded view of one of the support arm and slots illustrated in  FIG. 4A . Although a single slot and support arm are described, it is contemplated that the following description may apply to each of the slots and support arms illustrated in  FIG. 4A . From this view, it can be seen that track  405  may be inserted into slot  403  to contain guide member  406 , which extends from an end of support arm  404 . Track  405  may be, for example, a bracket type assembly dimensioned to fit within slot  403  and receive guide member  406 . Optional anti-friction pads  407  may be located on guide member  406  to facilitate sliding of guide member  406  within slot  403 . An end of support arm  404  opposite guide member  406  may include a plate member  408  dimensioned to be attached to suppression device  401  by fastening members  409 . 
     Slot  403  is dimensioned to keep track  405  from sliding axially along the length of tubular  402 . Since guide member  406  is attached to suppression device  401  and inserted into track  405 , this also keeps suppression device  401  from sliding axially along the length of tubular  402 . Anti-friction pads  407  reduce the friction between guide member  406  and track  405  so that the system remains as free to rotate as possible. A roller guide or any other suitable guide that produces low friction can be used in addition to or instead of guide member  406 . Similarly, a rail or other track device can be substituted for track  405 . An example would be a rail with a T-shaped cross section and a guide member  406  with a cross section similar to the C-shaped track  405  of  FIG. 4B . While track  405  is shown having a substantially C-shaped profile, it can be made of any suitable shape that is able to contain guide member  406 . Optional anti-friction pads  407  may be positioned within track  405  at various locations depending upon the shape of track  405 . 
     Track  405 , guide member  406 , support arm  404 , and fasteners  409  may be made of metals such as steel, aluminum, copper, or Inconel; fiberglass or other composite structures, plastic, or any other suitable material. Anti-friction pads  407  may be made of Teflon or any other suitable low-friction material. Fasteners  409  may consist of mechanical fasteners such as bolts or screws, chemical bonding, welding, or any other suitable fastening mechanism. Guide member  406  may be fastened to support arm  404  or integrally formed with support arm  404  as a custom bracket with a T-shaped or I-shaped cross section. 
       FIG. 4C  illustrates a top view cross-section through track  405  positioned around tubular  402 . From this view, it can be seen that removable section  410  is attached to track  405  and can be removed to facilitate insertion of guide member  406  into track  405 . Since track  405  is typically quite stiff, it must be made in multiple sections in order to place it in slot  403  formed around tubular  402 . In this aspect, connecting brackets  411  may be used to connect adjacent sections of track  405  as well as removable section  410 . Connection brackets  411  are connected to track  405  or removable section  410  by fasteners  412 . 
     Once the sections of track  405  are placed around tubular  402 , they may be connected to connecting brackets  411  by fasteners  412 . After guide members  406  of suppression device  404  are inserted into track  405 , removable section  410  may be attached to connection bracket  411  to complete the circuit for track  405 . Track  405  does not have to necessarily make a complete loop around tubular  402  but it is shown as a complete loop in  FIG. 4C . Track  405  does not have to be round and can be made of any shape that allows the guides to traverse its length. Track  405  may consist of as many sections as desired and removable section  410  may be of any suitable size. Similarly connecting brackets  411  may be made of any suitable size and shape. Fasteners  412  may consist of mechanical fasteners such as bolts or screws, chemical bonding, welding, a combination of one or more means, or by any suitable fastener method. More than one removable section  410  may be used for inserting the guides, or for any other desired reason such as inserting auxiliary lines in a drilling riser. 
       FIG. 5  illustrates a side view of an embodiment of an attachment assembly for securing a suppression device to a tubular. Suppression device  501 , support arm  504  and slot  503  are substantially the same as suppression device  401 , support arm  404  and slot  403  described in reference to  FIG. 4A  except that in this embodiment, slot  503  having track  505  therein are external to tubular  502 . Guide member  506  and support arm  504  are used to hold suppression device  501  in place along slot  503  formed around tubular  502 . Fasteners  509  may be used to attach support arm  504  to suppression device  501  and anti-friction pads  507  can be used to reduce the friction on guide member  506  as it travels along track  505 . Track  505  and/or slot  503  may be attached to tubular  502  by any suitable means. Although slot  503  and track  505  are shown completely exterior to tubular  502 , it is contemplated that slot  503  may be interior, exterior, or both interior and exterior to tubular  502 . 
       FIG. 6  illustrates a side view of another embodiment of an attachment assembly for securing a suppression device to a tubular. Suppression device  601  may be any type of suppression device such as those previously discussed. Straps  604  may encircle tubular  603  and be attached to suppression device  601  at their ends by brackets  605  and fasteners  606  to secure suppression device  601  to tubular  603 . Tubular  603  may have an exterior sleeve  602  that encircles tubular  603 , to for example, provide buoyancy or insulate tubular  603 . Sleeve  602  may be substantially cylindrical or sleeve  602  may have flat sections  607  such as the flat section on drilling riser buoyancy. Channels  610  may be formed within an outer surface of sleeve  602 . Channels  610  may be dimensioned to receive straps  604 . 
     Straps  604  may be dimensioned to keep suppression device  601  sufficiently close to tubular  603  so as to optimize the performance of suppression device  601 . Suppression device  601  must be held close enough to tubular  603  to keep straps  604  from being able to depart from recesses  610  formed within sleeve  602 . Straps  604  must also be sufficiently loose to allow straps  604  to rotate around tubular  603  so that suppression device  601  is free to weathervane with the incoming current. Straps  604  may be made of any suitable geometry and, in some cases, are not completely round. Straps  604  can be made of any of the previously disclosed materials suitable for straps, for example, steel, Inconel, aluminum, plastic, fiberglass or other composites or may be a hybrid of several different materials. 
     Optional brackets  605  can be useful for attaching straps  604  to suppression device  601 . Fasteners  606  attach straps  604  to brackets  605  or directly to suppression device  601 . Brackets  605  can be made of any suitable geometry. Fasteners  606  can include any suitable fastening mechanisms including mechanical fasteners such as bolts or screws, chemical bonding, welding, or any other suitable mechanisms. 
       FIG. 7  is a side view of another embodiment of an attachment assembly for securing a suppression device to a tubular. Tubular  703 , suppression device  701 , straps  704 , brackets  705  and their associated components (e.g. fasteners  706  and  708 ) are substantially similar to those discussed in reference to  FIG. 6  except that in this embodiment, brackets  705  include hinges  707 . Hinges  707  allow for one end of straps  704  to be attached to suppression device  701  prior to final installation. During final installation, the attachment of suppression device  701  to tubular  703  may need to occur as quickly or as easily as possible and having one side of straps  704  already attached to suppression device  701  can fulfill these needs. Note that it is also possible to attach one end of straps  704  to suppression device  701  with other mechanisms such as mechanical fasteners, welding, clamping, chemical bonding or other suitable means and have a hinge somewhere along the span of straps  704  instead. 
     Straps  704  may be connected to brackets  705  by fasteners  706  such as those previously discussed. Brackets  705  may be attached to suppression device by additional fasteners  708 . Other attachment mechanisms are also possible for attaching straps  704  to brackets  705  or hinges  707  including direct attachment of straps  704  to hinges  707  through welding or any other suitable means. In some embodiments, hinges  707  are separate from brackets and may be attached to straps  704  in the absence of brackets  705 . Brackets  705  may be attached to suppression device  701  using any suitable means including welding, clamping, bolting, chemical bonding, or even molding part of the hinge into suppression device  701 . Tubular  703  may have an exterior sleeve  702  that encircles tubular  703 , to for example, provide buoyancy or insulate tubular  703 . Sleeve  702  may be substantially cylindrical or sleeve  702  may have flat sections  712  such as the flat section on drilling riser buoyancy. Once assembled, straps  704  are positioned within channels  710  formed around tubular  703 . 
       FIG. 8  illustrates an embodiment of a suppression device that may be used in connection with any of the previously disclosed assemblies for attaching a suppression device to a tubular. In this embodiment, suppression device is a tail  803 . Tail  803  is constructed from plates  804   a ,  804   b ,  804   c , which are separated and attached to each other by structural members  805 . Strap  802  is attached to tail  803  by any suitable attachment mechanism (e.g. bolts, welding, etc.) at attachment locations  806 . In some embodiments, ends of straps  802  are attached to tail  803  as illustrated in  FIG. 8  while in other embodiments strap  802  extends through plates  804   a ,  804   b ,  804   c  so that tail  803  may be locked to strap  802  or free to slide along strap  802 . Strap  802  and tail  803  are free to weathervane around the tubular  801 . Attachment locations  806  may also be located on the side of the tail  803  that is adjacent to tubular  801 . 
     Plates  804   a ,  804   b ,  804   c  may be connected to structural members  805  by welding, specialized bracket, chemical bonding or other mechanical methods. A tip of the outer plates  804   a  and  804   c  may be tapered to align flush against center plate  804   b  to establish a better connection and/or to improve the tail performance. Structural members  805  may be bars that pass through plates  804   a ,  804   b , and  804   c  and clamps, welds, appurtenances, fasteners, chemical bonding, or other mechanisms may be used to fix plates  804   a ,  804   b , and  804   c  to structural members  805  and keep them from sliding along structural members  805 . Attachment locations  806  may consist of one or more of brackets, plates, pins, studs, screws, chemical bonding, bolts, nuts or other suitable fastening mechanisms. 
     An advantage of tail  803  having plates  804   a ,  804   b ,  804   c  is that plates  804   a ,  804   b ,  804   c  and structural members  805  may be easily constructed and require minimal molding or forming of parts. Plates  804   a ,  804   b ,  804   c  may be made of plastic or other materials sufficiently light in weight and suitable for seawater. Structural members  805  may be made out of plastic, stainless steel, fiberglass, composites, or other suitable materials. 
     Plates  804   a  and  804   c  may have a length sufficient to form an angle substantially tangent to the outer diameter of tubular  801  and should meet at plate  804   b . Plate  804   b  has a length such that it does not contact tubular  801  at one end, however plate  804   b  can be as long as desired to optimize the system performance. Plate  804   b  may have other appurtenances on its exterior to achieve a stable performance of the fairing system. Plates  804   a ,  804   b ,  804   c  may have a height, for example, of from about 1 foot to about 42 feet, more preferably from about 6 feet to about 8 feet, for example 7 feet depending upon the length of the tubular joint to which they are applied. Structural members  805  may run substantially along the length of plates  804   a ,  804   b ,  804   c , but may also have a relatively small cross, such as a cylindrical cross section, and simply act as connectors between adjacent plates  804   a ,  804   b ,  804   c.    
     In some embodiments, structural members  805  may be omitted and a bracket or similar device may be used to connect plates  804   a ,  804   b , and  804   c  together or strap  802  may be used to connect the plates and provide the required structural support. For example, strap  802  can pass through plates  804   a ,  804   b ,  804   c , but may not require fasteners or other devices to keep them from sliding along the strap  802 , since the curvature of strap  802  will often minimize sliding of plates  804   a ,  804   b ,  804   c.    
       FIG. 9  illustrates a top view of another embodiment of a suppression device that may be used in connection with any of the previously disclosed assemblies for attaching a suppression device to a tubular. In this embodiment, tail  903  is connected to tubular  901  by strap  902 . Strap  902  may be substantially the same as any of the previously disclosed strap configurations. Tail  903  is connected to strap  902  by any suitable fastening assembly  904  which can lock tail  903  to strap  902  or allow tail  903  to slide along strap  902  by simply passing strap  902  through fastening assembly  904 . In this embodiment, tail  903  may have any non-triangular shape suitable for suppression VIV about tubular  901 . Representatively, a cross section of tail  903  may be any desired shape, such as round, circular, elliptical, or polygonal, for example, a square or rectangular shape. If polygonal, the corners of the polygon may, or may not, be rounded. For example, tail  903  may be elliptical with the major axis of the ellipse directed towards fastening assembly  904 . If circular, the diameter of tail  903  may be any size desired, for example, the diameter can range from 10 to 70 percent of the diameter of tubular  901 . 
     Fastening assembly  904  may be constructed of any suitable material, for example a metal such as stainless steel, plastic, or composite material. Tail  903  may be attached to fastening assembly  904  by welding, molding, clamping, fastening, or any other suitable means. Fastening assembly  904  may consist of multiple components such as rings, plates, brackets, bearings, blocks, pulleys, pins, nuts, bolts, and other fasteners. Tail  903  may be made of plastic, metal such as stainless steel, or composite material. Tail  903  may be allowed to fill with water, or may be filled with a material to control buoyancy, such as syntactic foam or air. Strap  902  will usually be substantially circular, but can be elliptical with a ratio between the major and minor axes of the ellipse in the range of 1:1 to 4:1. 
       FIG. 10  illustrates a top view of another embodiment of a suppression device that may be used in connection with any of the previously disclosed assemblies for attaching a suppression device to a tubular. In this embodiment, tail  1003  is connected to tubular  1001  by strap  1002 . Strap  1002  may be substantially the same as any of the previously disclosed strap configurations. According to this embodiment, a cross section of tail  1003  may be an equilateral triangle as shown, but may also be of any other triangular shape. Alternatively, the cross section will be an isosceles triangle with two equal sides that are longer than the third side, and with the two equal sides coming to a point furthest from fastening assembly  1004 . 
     Although not illustrated, another possible cross sectional shape of tail  1003  is a rectangle, where the short side of the rectangle is attached to bracket fastening assembly  1004 . This rectangular shape will typically have an aspect ratio (the ratio defined by the length of the longer sides divided by the length of the shorter sides) ranging from 1 to 5, however the rectangle can also consist of a single plate, with the rectangle defined by the plate thickness. Another possible cross sectional shape for tail  1003  may be a trapezoid. In this case, the side attached to fastening assembly  1004  will typically be longer than its opposite side, and the other two sides will be substantially equal to each other in length. The trapezoid may also have rounded corners and edges to smooth the flow past it. All tails may have appurtenances attached to them in order to improve flow quality. These appurtenances may include additional members with cross sections similar to those of tails  903 ,  1003  to help streamline the flow past the tail or additional members such as plates at the tip of the tail furthest from bracket  1004  to assist with weathervaning. Appurtenances may also be added to increase the size of the tail or to accommodate a different sized tubular. 
     It should also be appreciated that reference throughout this specification to “one embodiment”, “an embodiment”, or “one or more embodiments”, for example, means that a particular feature may be included in the practice of the invention. Similarly, it should be appreciated that in the description various features are sometimes grouped together in a single embodiment, Figure, or description thereof for the purpose of streamlining the disclosure and aiding in the understanding of various inventive aspects. This method of disclosure, however, is not to be interpreted as reflecting an intention that the invention requires more features than are expressly recited in each claim. Rather, as the following claims reflect, inventive aspects may lie in less than all features of a single disclosed embodiment. Thus, the claims following the Detailed Description are hereby expressly incorporated into this Detailed Description, with each claim standing on its own as a separate embodiment of the invention. 
     In the foregoing specification, the invention has been described with reference to specific embodiments thereof. It will, however, be evident that various modifications and changes can be made thereto without departing from the broader spirit and scope of the invention as set forth in the appended claims. The specification and drawings are, accordingly, to be regarded in an illustrative rather than a restrictive sense.

Technology Classification (CPC): 5