Abstract:
A vortex-induced vibration (VIV) suppression apparatus including a body having a wall dimensioned to at least partly envelope a tubular member in an interior area of the body; at least one extension member extending from the body; and an anti-fouling member mechanically coupled to at least one of the body or the extension member. A method of manufacturing a vortex-induced vibration (VIV) suppression device including providing a VIV suppression device having a body dimensioned to at least partly envelope a tubular member in an interior area of the body and at least one extension member extending from the body. The method further including attaching an anti-fouling sheet to the VIV suppression device.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     The application is a non-provisional application of U.S. Provisional Patent Application No. 62/066,889, filed Oct. 21, 2014 and incorporated herein by reference. 
     FIELD 
     A vortex-induced vibration (VIV) suppression device having an anti-fouling member, more specifically a VIV suppression device having an anti-fouling layer. Other embodiments are also described herein. 
     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. Both helical strakes and fairings can provide sufficient VIV suppression. 
     Helical strakes and fairings are both popular VIV suppression devices. However, the effectiveness of helical strakes and fairings can be substantially degraded due to the presence of marine growth or other rough elements on its external surface. Presently, the technologies that are applied to prevent marine growth fouling (also known as “anti-fouling” methods) consist of paints or coatings that are applied by spraying the material onto the (helical strake or fairing) surface. 
     Present anti-fouling methods are expensive and often have lifetimes that are insufficient for oil and gas platform tubulars that must resist fouling for periods of 30-50 years or more. In addition, these paints and coatings require multiple applications so that the manufacturing can be increased substantially. Finally, some present methods impose substantial surface roughness onto the strake from particles in the coating, which partially defeats the purpose of using an anti-fouling coating. 
     SUMMARY 
     The present invention consists of anti-fouling methods that incorporate an anti-fouling sheet, such as a copper sheet or film, that is bonded or attached to the surface of the VIV suppression device. The method disclosed herein provides an anti-fouling sheet that is relatively inexpensive to apply and can be effective for a number of years (e.g. 50 years or more). In addition, the anti-fouling sheet may be quick to apply and suitable for keeping the surface of the VIV suppression device relatively smooth. 
     In one embodiment, a vortex-induced vibration (VIV) suppression device is provided. The device may include a body dimensioned to at least partly envelope a tubular member in an interior area of the body. The device may further include at least one extension member extending from the body and an anti-fouling member mechanically coupled to at least one of the body or the extension member. The extension member may be, for example, a fin in the case of a helical strake VIV suppression device or a fin in the case of a fairing. The anti-fouling member may be positioned over an outer surface of a wall of the body and/or the extension member. The anti-fouling member may include a sheet of anti-fouling material. For example, the anti-fouling material may be copper, a copper-nickel alloy, a copper-zinc alloy or a copper-tin alloy. In some embodiments, the sheet of anti-fouling material is mechanically attached to the at least one of the body or the extension member by a fastener. Still further, the sheet of anti-fouling material may be attached to the body by inserting the sheet within a channel along an edge of the body. The body may include at least two sections that fit together to form the body. The extension member may be a fin that includes a slot dimensioned to receive a band for securing the body to a tubular member. 
     In another embodiment, the invention relates to a helical strake assembly including a helical strake having a body section and a fin helically arranged around the body and an anti-fouling sheet coupled to the helical strake. The anti-fouling sheet may be positioned along an exterior surface of the helical strake. The anti-fouling sheet may be coupled directly to the body section and the fin. In some cases, the anti-fouling sheet may be dimensioned to conform to an exterior surface of the helical strake. In one embodiment, the anti-fouling sheet may be coupled to the helical strake by a “C” shaped clamp positioned along an edge of the body section. 
     In another embodiment, the invention relates to a fairing assembly for suppressing a vortex-induced vibration (VIV) of a tubular, the fairing assembly comprising a fairing having a wall forming a body portion, a tail portion and an end portion, and an anti-fouling sheet coupled to an interior surface and an exterior surface of the wall of the fairing. 
     A process of manufacturing a vortex-induced vibration (VIV) suppression device is further provided. The process may include providing a VIV suppression device having a body dimensioned to at least partly envelope a tubular member in an interior area of the body and at least one extension member extending from the body. The process may further include attaching an anti-fouling member to the VIV suppression device. The anti-fouling member may be attached to the device by, for example, fastening the anti-fouling member to the exterior surface of the wall of the body and/or positioning a band around the anti-fouling member and the body of the VIV suppression device. In other embodiments, the anti-fouling member may be positioned within a channel formed along an edge of the wall of the body. In still further embodiments, a thermal or chemical process may be used to attach the anti-fouling member to the exterior surface of the wall of the body. In some embodiments, the anti-fouling sheet is preformed to have a shape of the VIV suppression device prior to attaching the anti-fouling sheet to the VIV suppression device. 
     The above summary does not include an exhaustive list of all aspects of the present invention. It is contemplated that the invention includes all apparatuses that can be practiced from all suitable combinations of the various aspects summarized above, as well as those disclosed in the Detailed Description below and particularly pointed out in the claims filed with the application. Such combinations have particular advantages not specifically recited in the above summary. 
    
    
     
       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. 1A  illustrates a perspective view of one embodiment of a helical strake, consisting of two halves, that is banded to the surface of a cylinder. 
         FIG. 1B  illustrates a perspective view of one embodiment of a helical strake half with an anti-fouling member over the external surface. 
         FIG. 1C  illustrates a side view of the edge of the helical strake half of  FIG. 1B  with one embodiment of a clamp along the edge to secure an anti-fouling member to the helical strake. 
         FIG. 1D  illustrates a side view of the edge of the helical strake half of  FIG. 1B  with another embodiment of a clamp along the edge to secure an anti-fouling member to the helical strake. 
         FIG. 2A  illustrates a perspective view of another embodiment of a VIV suppression device having an anti-fouling member attached thereto. 
         FIG. 2B  illustrates a perspective view of another embodiment of the VIV suppression device of  FIG. 2A  having an anti-fouling member attached thereto. 
         FIG. 3  illustrates one embodiment of a process for manufacturing a VIV suppression device having an anti-fouling member. 
     
    
    
     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. 
     Referring now to the invention in more detail,  FIG. 1A  illustrates a perspective view of one embodiment of a VIV suppression device. In particular,  FIG. 1A  illustrates a helical strake design consisting of helical strake  101  having a body  105  formed by wall  108 . Wall  108  is dimensioned to at least partially, or fully, encircle or envelope an underlying tubular  100 . As can be seen in more detail in  FIG. 1B , wall  108  includes an outer surface  106  and an inner surface  107 . The inner surface  107  faces, and in some cases contacts, the exterior surface of tubular  100  when helical strake  101  is positioned around tubular  100  such that tubular  100  is enveloped by an interior area  110  of helical strake  101 . Wall  108  is separated into two separate sections by gap  111  such that helical strake  101  includes helical strake half  101 A and helical strake half  101 B. Helical strake half  101 A and helical strake half  101 B are banded to tubular  100  using bands  103  which reside in channels  104 . Each of helical strake half  101 A and helical strake half  101 B cover less than an entire circumference of tubular  100 , however, in combination almost entirely encircle tubular  100 . Fins  102  are shown attached to, or part of, helical strake  101 . Fins  102  extend from an outer surface  106  of wall  108  and may therefore also be referred to herein as extension members. In particular, fins  102  may include a base portion  113  which contacts, or otherwise attaches to, wall  108  of helical strake  101  and a protruding portion  116 , which extends from base portion  113  and wall  108 . Fins  102  may be positioned along a length dimension of wall  108  such that they are helically arranged around helical strake  101 . 
     Again referring to  FIG. 1A , while this figure shows helical strake  101  consisting of two halves, the helical strake is not restricted to consisting of two halves and can be of a single piece or of more than two pieces. In  FIG. 1A , bands  103  travel through channels  104  and are put in tension which, in turn, presses helical strake half  101 A and helical strake half  101 B against tubular  100 . This allows helical strake  101  to be constrained from axial motion relative to tubular  100 . 
     Still referring to  FIG. 1A , any number of bands may be used in the helical strake and the fins  102  may be of any size or shape. While  FIG. 1A  shows channels  104  between adjacent fins  102 , fins  102  may be continuous and not have channels  104  present. Fins  102  may also utilize slots that allow bands  103  to travel through fins  102  and thereby, when bands  103  are put into tension, press helical strake  101  against tubular  100 . Fins  102  may be formed separately from helical strake half  101 A and helical strake half  101 B and then attached by any suitable mechanism (this also applies to the copper aspects disclosed herein). 
     Still referring to  FIG. 1A , all parts shown may be made of any suitable material including, but not limited to, plastic, metal, rubber or elastomer, ceramic, wood, composite, and synthetics. 
     Referring now to  FIG. 1B , helical strake half  101 A, which also has channels  104  present, is shown covered with anti-fouling member or sheet  151 . In one embodiment, anti-fouling sheet  151  is attached to helical strake half  101 A using fasteners  121 . Anti-fouling sheet  151  may be mechanically attached to an outer surface  106  of helical strake half  101 A. The outer surface  106  may be a surface which faces away from tubular  100 , when helical strake half  101 A is positioned around the tubular  100  as shown in  FIG. 1A . Fasteners  121  may be any type of fastener suitable for attaching two structures together, for example, fasteners  121  may be screws or pins which are inserted through openings in anti-fouling sheet  151  and corresponding openings within helical strake half  101 A. 
     Again referring to  FIG. 1B , anti-fouling sheet  151  is shown as a single sheet but can consist of multiple pieces to cover helical strake half  101 A (anti-fouling sheet may be used to cover helical strake half  101 B shown in  FIG. 1A , and can be used to cover any or all of helical strake  101  shown in  FIG. 1A - FIG. 1B .  FIG. 1B  simply illustrates one embodiment of how anti-fouling sheet  151  may cover a portion of a helical strake. Anti-fouling sheet  151  may cover all or part of a helical strake half or section (for example, different sections of anti-fouling sheet  151  may be used to cover each of the fins and other sections may be used to cover the base portion of the strake). Different pieces of anti-fouling sheet  151  may overlap (or underlap) and may, or may not, cover the ends or underside of helical strake half  101 A. Representatively, in one embodiment, anti-fouling sheet  151  may be a short piece of copper that covers ⅓ of the circumference of helical strake  101  and several of these pieces are assembled axially along helical strake  101  to cover helical strake  101 . In addition, anti-fouling sheet  151  may, in some embodiments, be preformed to the strake shape prior to installing on the helical strake  101 . 
     While  FIG. 1B  shows anti-fouling sheet  151  attached to helical strake half  101 A using fasteners  121 , other attachment means may be used in addition to, or in place of the use of fasteners  121 . Any suitable attachment means may be used, including bands (such as bands  103  in  FIG. 1A ), adhesives, any fastening methods such as screws, bolts, nuts, rivets, or clamps, or other structural members (which may also be used to assist with adhesive attachment means). Any combination of methods may also be utilized. The anti-fouling material (e.g. copper) may also be plated to helical strake half  101 A or attached by other thermal means to form a anti-fouling sheet. It should be understood, however, that the anti-fouling sheet  151  as disclosed herein is different from other anti-fouling methods in which a liquid including an anti-fouling material (e.g. copper particles) is applied to a VIV device, such as by painting, to form a coating over the VIV device surface. In other words, the anti-fouling sheet  151  is different form a coating in that it is a solid sheet of material that is mechanically attached to the helical strake and can maintain the desired shape without the presence of the helical strake it is attached to. Other existing methods of applying anti-fouling particles such as painting or coating, however, may be used in conjunction with the subject invention. Anti-fouling sheet  151  may be fairly soft and manually formed to the shape of the helical strake or may be relatively hard and formed to the helical strake by a heating method such as vacuum forming or drape molding. Parts of anti-fouling sheet  151  may be relatively soft and manually formed to the helical strake and other parts of anti-fouling sheet  151  may be hard and heated to the desired shape. For example, anti-fouling for the fins may be formed separately. 
     Still referring to  FIG. 1B , anti-fouling sheet  151  may be of any suitable thickness and does not have to be of constant thickness and various sections or pieces of anti-fouling sheet  151  may be of different sizes or thicknesses. Anti-fouling sheet  151  will typically be of a thickness ranging from 3 mils to 125 mils. Fasteners  121  may be of any size, shape, type or quantity, and any of the various attachment methods may be used to permanently attach anti-fouling sheet  151  to helical strake half  101 A or may be used temporarily, for example to hold anti-fouling sheet  151  in place until bands may be attached. Anti-fouling sheet  151  may have holes or openings. For example, if the fins are continuous then slots may be cut in both the fins and in anti-fouling sheet  151  so that bands may travel through the slots for installation. Multiple holes or openings may also be present in anti-fouling sheet  151  so that it resembles netting or meshing (with no limit on the porosity of anti-fouling sheet  151 ). 
     Still referring to  FIG. 1B , while anti-fouling sheet  151  is presumably made of anti-fouling, the anti-fouling does not need to be pure copper and can consist of various copper alloys such as copper-nickel alloys, copper-zinc alloys (brass), and copper-tin alloys (bronze). Fasteners  121  may be made of any suitable material including, but not limited to, metal, plastic, composite, and synthetics. 
     Referring now to  FIG. 1C , this figure illustrates a possible modification to one or more edges of a VIV suppression device to facilitate attachment of an anti-fouling sheet to the VIV suppression device. Representatively, in this embodiment, anti-fouling sheet  151  may be held in place along an edge of a helical strake half  101 A, such as that previously described, by a receiving member  170  formed along the edge of the helical strake half  101 A. The receiving member  170  may be, for example, a “C” shaped clamp, which forms a channel  171  along the edge  115  of helical strake half  101 A. In particular, receiving member  170  may include an end portion  172  from which two side arms  173 A,  173 B extend. The channel  171  may be formed by the inner (interfacing) surfaces of end portion  172  and two side arms  173 A,  173 B. Side arms  173 A,  173 B may be spaced a sufficient distance from one another such that channel  171  is wide enough to receive both the end of strake half  101 A and sheet  151  and hold the two pieces together. Representatively, in one embodiment, end portion  172  is positioned along the edge  115  of strake half  101 A such that side arm  173 A is positioned along the outer surface  106  of the wall  108  of strake half  101 A and side arm  173 B is positioned along the inner surface  107  of the wall  108  of strake half  101 A. In other words, side arm  173 B is between strake half  101 A and tubular  100 , for example, adjacent to tubular  100 . To accommodate the positioning of side arm  173 B between strake half  101 A and tubular  100 , a recessed region  180  for receiving side arm  173 B may be formed along the inner surface  107  of the wall  108  of strake half  101 A. 
     Again referring to  FIG. 1C , any number or length of edges of helical strake half  101 A may have receiving member  170  in place. Receiving member  170  may be attached to helical strake half  101 A, to anti-fouling sheet  151 , or to tubular  100 . Receiving member  170  may also be held in place by pressure on helical strake half  101 A and anti-fouling sheet  151  against tubular  100 . This pressure may come from an adjacent location such as from an adjacent band. The pressure may also simply come from an interference fit of the channel  171  of receiving member  170  onto helical strake half  101 A and anti-fouling sheet  151 . 
     Still referring to  FIG. 1C , receiving member  170  may be of any suitable size or shape and may be attached to helical strake half  101 A, to anti-fouling sheet  151 , or to tubular  100  by any suitable means including, but not limited to, banding, clamping, fastening, and chemical bonding. 
     Still referring to  FIG. 1C , receiving member  170  may be made of any suitable material including, but not limited to plastic, metal, elastomer, or composite. 
     Referring now to  FIG. 1D , this figure illustrates another possible modification to one or more edges of the subject invention. Helical strake half  101 A and anti-fouling sheet  151  are held in place at the edge by receiving member  175 , which includes channel  185  and is adjacent to tubular  100 . Receiving member  175  is shown optionally attached to helical strake half  101 A and anti-fouling sheet  151  by screw  181  and nut  182 . 
     Again referring to  FIG. 1D , helical strake half  101 A and anti-fouling sheet  151  have an adjusted shape to accommodate receiving member  175 , screw  181 , and nut  182 . While screw  181  and nut  182  are optional, any suitable means may be used for attaching or connecting receiving member  175  to helical strake half  101 A or anti-fouling sheet  151 . Receiving member  175  may, or may not, contact tubular  100 . 
     Still referring to  FIG. 1D , Receiving member  175  may be made of any suitable size, shape, or quantity. While a C-shape cross section is shown for channel  185 , any suitable shape may be used for channel  185  which may be replaced by other structural shapes and merely illustrates that a structural member may be used to assist with connecting anti-fouling sheet  151  and helical strake half  101 A (this also applies to receiving member  170  in  FIG. 1C ). 
     Still referring to  FIG. 1D , receiving member  170  may be made of any suitable material including, but not limited to plastic, metal, elastomer, or composite. 
       FIG. 2A  illustrates a perspective view of another embodiment of a VIV suppression device having an anti-fouling member attached thereto. In this embodiment, the VIV suppression device is a fairing  201 , which is dimensioned to suppress VIV of an underlying structure or tubular  210 . Fairing  201  may include a wall  202  that forms a body portion  220  which encircles an underlying structure or tubular  210  and a tail portion  222  that extends from body portion  220  and tapers to form an end portion  224 . The tail portion  222  may also be referred to herein as an extension member. Fairing  201  may be include first section  201 A and second section  201 B that can be separated along opening  204  so that fairing  201  can be positioned around underlying structure or tubular  210 . Once fairing  201  is positioned around tubular  210 , it is free to weathervane with changes of angle of the incoming current. In some embodiments, fairing  201 , including first section  201 A and second section  201 B are integrally formed pieces that are formed together as a single unit. In other embodiments, first section  201 A and second section  201 B of fairing  201  are separate modules, that are formed independently of one another. Fairing  201  can be made of plastic, rubber, wood, fiberglass or other composite materials, metals, or any suitable material that allows it to maintain its approximate shape. 
     Fairing  201  may further include an anti-fouling member  206  attached to the wall  202 . The anti-fouling member  206  may be similar to the anti-fouling member previously discussed in reference to  FIG. 1A - FIG. 1D , except in this case it is dimensioned to cover a fairing  201 . Representatively, anti-fouling member  206  may be a sheet of anti-fouling material that is wrapped around an outer surface  208  of wall  202  of fairing  201 . Anti-fouling member  206  may be attached to wall  202  mechanically using fasteners  205 . Fasteners  205  may be similar to the fasteners  121  previously discussed in reference to  FIG. 1A - FIG. 1D . 
       FIG. 2B  illustrates a perspective view of another embodiment of the VIV suppression device of  FIG. 2A  having an anti-fouling member attached thereto. In this embodiment, however, the anti-fouling member  206  is shown also positioned over the inner surface  207  of wall  202  of fairing  201 . Representatively, anti-fouling member  206  may be wrapped around the outer surface  208  of wall as previously discussed, and then over the end portion  224  such that it extends over the inner surface  207  of fairing wall  202 . Positioning of the anti-fouling member  206  between the fairing wall  202  and tubular  210  helps to impede marine growth between fairing  201  and tubular  210 . In addition, in some embodiments, anti-fouling member  206  may be optionally held in place along fairing wall  202  by an interior support block  212  (shown in dashed lines) positioned within fairing  201 . A tape, or other similar material, may further be positioned around the edges of fairing  201  and anti-fouling member  206  to reduce the sharpness of the edges. 
       FIG. 3  illustrates one embodiment of a process for manufacturing a VIV suppression device having an anti-fouling member. In one embodiment, process  300  includes providing a VIV suppression device (block  302 ). The VIV suppression device may, for example, be helical strake  101 , and include a body having a wall dimensioned to at least partly envelope a tubular member in an interior area of the body and at least one fin protruding outward from an exterior surface of the wall. Process  300  may further include attaching an anti-fouling member to the VIV suppression device (block  304 ). For example, the anti-fouling member may be attached to the VIV suppression device by, for example, fastening the anti-fouling member to the exterior surface of the wall of the body. In other embodiments, the anti-fouling member may be attached to the VIV suppression device by positioning a band around the anti-fouling member and the body of the VIV suppression device. Still further, the anti-fouling member may be positioned within a channel formed along an edge of the wall of the body, such as by receiving member  170  or receiving member  175  previously discussed in reference to  FIG. 1C  and  FIG. 1D . Alternatively, a thermal or chemical bonding process may be used to attach the anti-fouling member to the exterior surface of the wall of the body. In some embodiments, the anti-fouling sheet is preformed to have a shape of the VIV suppression device prior to attaching the anti-fouling sheet to the VIV suppression device. 
     The above aspects of this invention may be mixed and matched in any manner suitable to achieve the purposes of this invention. It is recognized that, while a helical strake has been used to illustrate the invention herein, the concepts presented may be applied to any VIV suppression device such as for a fairing. 
     In broad embodiment, the present invention consists of methods for attaching pieces of anti-fouling sheet to a VIV suppression device. 
     While the foregoing written description of the invention enables one of ordinary skill to make and use what is considered presently to be the best mode thereof, those of ordinary skill will understand and appreciate the existence of variations, combinations, and equivalents of the specific embodiment, method, and examples herein. For several of the ideas presented herein, one or more of the parts may be optional. The invention should therefore not be limited by the above described embodiment, method, and examples, but by all embodiments and methods within the scope and spirit of the invention.