Patent Publication Number: US-2019186208-A1

Title: Bend Restrictor Segment and Method of Manufacture

Description:
The present invention relates to a bend restrictor segment and a method of manufacturing a bend restrictor segment. A bend restrictor segment is a segment that is connectable to other segments to form a bend restrictor or vertebrate bend restrictor. In particular, but not exclusively, the present invention relates to a bend restrictor segment for defining a minimum radius of curvature of a portion of an elongate member. 
     BACKGROUND 
     Elongate members, for example cables for the transmission of electricity, fibre optic cables, umbilicals, risers, flowlines or flexible pipes for transportation of production fluids are often used in subsea environments. 
       FIG. 1  illustrates an example of an installation of a cable  100  extending from an offshore structure  102  to a vessel  104 . The cable  100  extends from the offshore structure  102  down towards the seabed  106 , along the seabed  106 , and up to the vessel  104  on the surface of the sea. 
     In such an arrangement the cable  100  may be subject to bending forces and/or tension forces. This may be at regions  108  where the cable  100  approaches or leaves the seabed  106 , where there are undulations  110  along the seabed, or at regions where the cable assumes a wave configuration  112 . Similar bending forces may also occur in a subsea flexible pipe. 
     Most elongate members have a minimum bend radius beyond which bending may cause damage. In some cases, damage caused from excessive bending may be irreparable. For example, in flexible pipes for transporting production fluids, excessive bending may cause the pipe to rupture resulting in spillage of production fluids from the pipe. 
     To help define a minimum bend radius and protect the elongate members from over bending, bend restrictors  114  are often used, specifically along portions of the elongate member that may be more susceptible to excessive bending forces. 
     Bend restrictors  114  may be formed from a plurality of bend restrictor segments, connected together in series and extending around the elongate member. 
       FIGS. 2 to 4  illustrate known bend restrictor segments. 
     The bend restrictor segment  200  shown in  FIG. 2  includes two halves  202 ,  204  that can be connected together using six bolts extending through respective holes  206  in each half  202 ,  204 . Each half  202 ,  204  includes a body portion  208  and a neck portion  210 . Adjacent segments are positioned in series around an elongate member with the body portion  208  over the neck portion  210  of an adjacent segment so as to connect the adjacent segments together. Thus, at least the bolts positioned in the neck portion must be fastened before the next bend restrictor segment is added, because the bolts will not be accessible afterwards. 
       FIG. 3  illustrates another known bend restrictor segment  300 . The bend restrictor segment  300  is similar to the bend restrictor segment  200  of  FIG. 2  but the two halves of the bend restrictor segment  300  are connected differently. In this example, each half includes corresponding teeth  302  that interlock when the two halves are brought together. A bolt  304  is provided on either side of the bend restrictor segment  300  and each bolt  304  extends through a hole in two teeth of each half, thereby securing the two halves together. With this example, the bolt has to be tightened from the neck side of the bend restrictor segment. Thus, the bend restrictor segments  300  must be assembled and the bolts tightened individually before an adjacent bend restrictor segment  300  can be added. 
       FIG. 4  illustrates a further known bend restrictor segment  400 , which does not require any bolts. Instead of bolts, the two halves are held together by an adjacent bend restrictor. A special fitting is required at the end of a string of bend restrictor segments, so as to secure the bend restrictor segments in place at either end of the string of segments. 
     A problem with some known bend restrictor segments is that they each require a large number of components (e.g. two halves and associated bolts) to be held on a vessel prior to installation. Large numbers of components requires increased handling time and lost components can result in higher costs due to replacement or spare parts. 
     Another problem with known bend restrictor segments is that each segment has to be connected and the bolts secured in place before the next segment can be added. This can result in the installation process taking a long time thereby contributing to high installation costs. 
     It would be useful to provide a bend restrictor segment in which installation times and costs can be reduced. 
     BRIEF SUMMARY OF THE DISCLOSURE 
     In accordance with a first aspect of the present invention there is provided a bend restrictor segment for defining a minimum radius of curvature of a portion of an elongate member, comprising:
         a first body portion;   a further body portion;   wherein the first and further body portions are connectable to form an annular body; and   wherein the first body portion further comprises a fixing assembly on an outer circumferential edge of the first body portion, for connecting the first and further body portions together, the fixing assembly being integrally connected with the first body portion.       

     Suitably, each of the first body portion and further body portion further comprises a neck portion extending therefrom. 
     Suitably, each of the first and further body portions are configured to be located over a neck portion of a further bend restrictor segment to connect the bend restrictor segments together in series. 
     Suitably, the fixing assembly comprises a bolt rotatably connected at a first end region to the outer circumferential edge of the first body portion. 
     Suitably, the first end region of the bolt extends through a through-hole in a first bar, wherein the first bar is rotatable within a cavity formed in the outer circumferential edge. 
     Suitably, the through-hole in the first bar is threaded, for threaded engagement with the first end region of the bolt. 
     Suitably, the fixing assembly further comprises a further bar comprising a through-hole, wherein a further end region of the bolt extends through the through-hole of the further bar. 
     Suitably, the further body portion comprises a cavity in an outer circumferential edge, the cavity configured to receive the further bar. 
     Suitably, the first and further body portion are hinged together substantially opposite the fixing assembly, such that the first and further body portions can hinge between an open position and a closed position to form the annular body. 
     Suitably, the bend restrictor segment further comprises a further fixing assembly on an outer circumferential edge of the first or further body portion, for connecting the first and further body portions together, the fixing assembly being integrally connected with the first or further body portion at a position substantially opposite the first fixing assembly. 
     In accordance with a second aspect of the present invention there is provided a kit of parts comprising a plurality of bend restrictor segments according to the first aspect. 
     In accordance with a third aspect of the present invention there is provided an assembly comprising a plurality of bend restrictor segments according to the first aspect, each of the plurality of bend restrictor segments connected together in series, and an elongate element, the plurality of connected bend restrictor elements extending around the elongate element. 
     In accordance with a fourth aspect of the present invention there is provided a method of manufacturing a bend restrictor segment for defining a minimum radius of curvature of a portion of an elongate member, comprising:
         forming a first body portion;   forming a further body portion;   wherein the first and further body portions are connectable to form an annular body; and   integrally connecting a fixing assembly on an outer circumferential edge of the first body portion, for connecting the first and further body portions together.       

     Certain embodiments provide a bend restrictor segment that is of fewer parts than the known bend restrictor segments. Thus, assembly is made relatively easier and simpler for an engineer. 
     Certain embodiments provide bend restrictor segments that can be assembled with unfettered access to fixing points, thereby allowing the assembly process to be faster and easier than previous methods. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Embodiments of the invention are further described hereinafter with reference to the accompanying drawings, in which: 
         FIG. 1  illustrates an underwater cable installation; 
         FIG. 2  illustrates a known bend restrictor segment; 
         FIG. 3  illustrates a further known bend restrictor segment; 
         FIG. 4  illustrates a yet further known bend restrictor segment; 
         FIG. 5 a    illustrates a front view of an example of a bend restrictor segment; 
         FIG. 5 b    illustrates a side view of the bend restrictor element segment of  FIG. 5   a;    
         FIG. 5 c    illustrates a section view through line B-B of the bend restrictor segment of  FIG. 5   b;    
         FIG. 6 a    illustrates a front view of the bend restrictor segment of  FIGS. 5 a  to 5 c   , in an open configuration; 
         FIG. 6 b    illustrates a side view of the bend restrictor segment of  FIG. 6   a;    
         FIG. 6 c    illustrates a section view through line A-A of the bend restrictor segment of  FIG. 5   b;    
         FIG. 7  illustrates a perspective view of the bend restrictor segment of  FIGS. 5 a  to 6 c    in a closed configuration; 
         FIG. 8  illustrates a further perspective view of the bend restrictor segment of  FIGS. 5 a  to 6 c   , in an open configuration; 
         FIGS. 9 and 10  illustrate a yet further perspective views of the bend restrictor segment of  FIGS. 5 a  to 6 c   , in a closed configuration; 
         FIG. 11  illustrates a plurality of bend restrictor segments connected together in series; 
         FIG. 12  illustrates a close up of a portion, C, of  FIG. 11 ; 
         FIG. 13  illustrates a perspective view of a plurality of bend restrictor segments connected together in series; 
         FIG. 14  illustrates another bend restrictor segment; and 
         FIG. 15  illustrates another plurality of bend restrictor segments. 
     
    
    
     DETAILED DESCRIPTION 
     Referring now to the drawings,  FIGS. 5 a  to 5 c    illustrates a bend restrictor segment  500  in an open configuration, and  FIGS. 6 a  to 6 c    illustrate the same bend restrictor segment  500  in a closed configuration. 
     The bend restrictor segment  500  includes a first body portion  502 , and a further body portion  504 . As shown in  FIG. 6 a   , the first and further body portions  502 ,  504  are connectable to form an annular body. Thus, an elongate member may be placed between the first and further body portions  502 ,  504  when the body portions are in an open configuration and then the first and further body portions  502 ,  504  may be connected together around the elongate member (over the outer surface of the elongate member). 
     In this example, each of the first and further body portions  502 ,  504  are substantially semi-annular (or equal halves). In other examples, one of the first or further body portions  502 ,  504  may be larger than the other, so that together they form a complete annular body. 
     Each of the first and further body portions  502 ,  504  includes a neck portion  506 ,  507  extending from therefrom. The neck portion  506 ,  507  extends from the body portion  502 ,  504  in a substantially axial direction (as best seen in  FIGS. 5 b  and 6 b   ). Each neck portion  506 ,  507  includes an annular flange  512  at an end distal from the body portion  502 ,  504 . Each body portion  502 ,  504 , includes a corresponding annular groove  514  and flange  515  on an inner circumferential edge thereof. 
     When adjacent bend restrictor segments  500  are connected together in series, the annular groove  514  of a first bend restrictor segment  500  extends over and cooperates with a flange  512  of an adjacent bend restrictor segment  500  and the flange  515  on the inner surface of the first bend restrictor segment  500  extends over the neck portion of the adjacent bend restrictor segment  500  to thereby connect adjacent bend restrictor segments together. 
     Each of the first and further body portions  502 ,  504  may be formed from any suitable material as known in the art. For example, the first and further body portions  502 ,  504  may be formed from PU, steel, HDPE, PE, PA, PEEK rubber, or filled polymers. The inner and outer diameters of the annular body will depend on the elongate member for which the bend restrictor segment is intended to be used, and can be readily selected by those skilled in the art. Typically, the outer diameter of the bend restrictor segment may be from 200 mm up to 1 m, for example. 
     The first body portion  502  further includes a fixing assembly  510  on an outer circumferential edge  508  of the first body portion  502  for connecting the first and further body portions  502 ,  504  together. The fixing assembly  510  is integrally connected with the first body portion  502 . That is, the fixing assembly  510  is pre-installed in the first body portion  502  so that the fixing assembly and first body portion are connected as a single component. Thus the fixing assembly and body portion are operably connected. 
     As best illustrated in  FIGS. 7 to 10 , the fixing assembly  510  includes a bolt  520  (or socket head cap screw, SHCS fitting) rotatably connected at a first end region  522  to the outer circumferential edge  508  of the first body portion  502 . 
     As used herein, the term “outer circumferential edge” is not limited specifically to the actual outer edge of the body portion. Rather, it may also encompass a region or surface that is visible or accessible from the outer circumferential edge of the body portion. For example, as shown in  FIGS. 7 and 8 , the fixing assembly is connected within a cavity  524  in the outer circumferential edge  508  of the first body portion  502 . The annular body can be said to have an inner surface (for overlying part of another segment or the elongate element), and an outer surface. The outer surface includes and outer circumferential edge (co-axial with the elongate member) and two side edges that will abut further annular bodies of further segments when joined in series in use. 
     In this example, the fixing assembly  510  includes a first bar  526 . The first bar is provided in a cavity of hole  530  that extends axially (i.e. parallel to a central longitudinal axis of the annular body) and crosses the cavity  524  housing the bolt  520 . The first bar  526  is rotatable within the cavity  524 . In this case the cavity  530  extends to the outer surface side edges of the first body portion  502 . 
     The first end region  522  of the bolt  520  extends through a through-hole  532  in the first bar  526 . The through-hole  532  in the first bar  526  is substantially perpendicular to the central longitudinal axis of the first bar  526 . Thus, when the first bar  526  rotates within the cavity  530 , the bolt  520  rotates about the axis of the first bar  526 . In this example, the cavity  524  allows the bolt  520  to rotate even if the end region of the bolt  520  protrudes beyond the through-hole  532  of the first bar  526 . 
     The through-hole  532  in the first bar  526  is aptly threaded for threaded engagement with the first end region of the bolt  520 . In this example, at least the first end region of the bolt  520  is also threaded, so as to cooperate with the threaded through-hole  532 . 
     The fixing assembly also includes a further bar  528 . The further bar  528  includes a through-hole  534 , through which a further end region  542  of the bolt  520  extends. In this example, the through-hole  534  extends through the further bar  528  so that the further bar  528  lays substantially perpendicular to the axis of the bolt  520 . The through-hole  534  and the further end region of the bolt  520  are unthreaded to allow free movement of the further bar  528  with respect to the bolt. 
     Each of the components of the fixing assembly  510  (the bolt  520  and the first and further bars  526 ,  528 ) may be manufactured from materials including super duplex (a stainless steel), titanium, or a stainless steel, for example. Other materials may also be suitable, depending on the intended environment for use (including strength requirements or corrosion) and may be readily selected by those skilled in the art. 
     As shown most clearly in  FIGS. 7 and 9 , the further body portion  504  includes a cavity  536  in an outer circumferential edge  509 . The cavity  536  is shaped or configured to receive the further bar  528  of the fixing assembly  510 . As shown in  FIG. 9 , the cavity  536  is formed by a depression in the outer circumferential surface  509  of the further body portion  504 . The depression is sized and configured to receive the further bar  528  and a head portion  521  of the bolt. An edge of the cavity  536  includes an axially extending recess  540  sized and shaped to receive the further bar  528 . In other words, the edge of the cavity is shaped to cup the further bar  528 . Aptly the recess  540  is deep enough to encompass around a quarter of the circumference of the further bar  528 , as shown in  FIG. 7 . More aptly the recess may be deep enough to encompass at least half of the circumference of the further bar. In this way, the further bar  528  can be securely held within the recess  540 . 
     The bolt  520  includes the head portion  521 , which can be used to tighten or loosen the bolt (by screwing the first end region of the bolt further into or out of the first bar  526 ). The head portion is an end of the bolt, aptly wider than the rest, to allow a user to grasp and move the bolt. In other examples, the bolt  520  may include a different shaped head, for example a hexagonal head, or a cross head. 
     To assemble the bend restrictor segment around an elongate member, the first and further body portions  502 ,  504  are placed in an open position (as shown in  FIGS. 5 a  to 5 c    and  8 ). In the open position, the bolt  520  of the fixing assembly is loosely screwed into the through-hole  532  of the first bar  526 , and is hinged outwardly to allow space to insert the elongate member. That is, in the open position the first and further body portions  502 ,  504  are spaced apart so that an elongate element fits through a gap between the first and further body portions  502 ,  504 . In the open position an elongate member can be inserted between the first and further body portions  502 ,  504  (or alternatively the first and further body portions  502 ,  504  may be placed around the elongate member). Once the elongate member is in position between the first and further body portions  502 ,  504 , the first and further body portions  502 ,  504  can be brought together to form an annular body around the elongate member. 
     The bolt  520  and further bar  528  may then be rotated towards the further body portion  504  until the further bar  528  is received in the recess  540  of the cavity  536 . The bolt  520  may then be screwed further into the through-hole  532  of the first bar  526  using an allen key or other suitable tool to rotate the head portion  521 . 
     After tightening of the bolt  520 , the further bar  528  is secured in position in the recess  540  of the further body portion  504 . Thus, the first and further body portions  502 ,  504  can be securely connected together. 
     The first and further body portions  502 ,  504  are also connected together at a second position. In this example, the first and further body portions  502 ,  504  are hinged together substantially opposite the fixing assembly  510 , so that the first and further body portions  502 ,  504  can hinge between the open position and the closed position to form the annular body. 
     In this example, a hinging mechanism  550  is provided substantially opposite the fixing mechanism  510  to hinge together the first and further body portions  502 ,  504 . The hinging mechanism  550  in this example includes a fixing assembly substantially the same as the fixing assembly  510 . However, the fixing assembly forming the hinging mechanism  550  is pre-installed and tightened into position. The first and further body portions are able to rotate about the first and further bars of the hinging mechanism  550 . 
     In another example, rather than a hinging mechanism  550 , a further fixing assembly may be provided substantially opposite the first fixing assembly  510 . The further fixing assembly may be substantially the same as the first fixing assembly  510  and may be provided on the outer circumferential edge of either of the first or further body portions  502 ,  504  and integrally connected with the first or further body portions  502 ,  504 . 
       FIG. 11  illustrates an assembly  1100  including a plurality of bend restrictor segments  500   1-n  connected together in series around an elongate element  1102 . 
     As shown, each of the bend restrictor segments  500   1-n  are connected to an adjacent bend restrictor segment by locating the body portion of a first bend restrictor segment over the neck portion of an adjacent bend restrictor segment. 
     The interlocking of the body portion with an adjacent neck portion allows a predetermined degree of movement between adjacent bend restrictor segments (as shown more clearly in  FIG. 12 ). This method of interlocking adjacent bend restrictor segments to define a minimum radius of curvature of an elongate member, is known in the art, so for brevity will not be described in detail. 
     As shown in  FIG. 11 , at a first end of the series of bend restrictor segments, a centraliser  1110  is provided to seal an annulus  1106  between a J-tube  1104  and the elongate member  1102 . 
     Although the specific bend restrictor segments  500  described above include a neck and body portion to allow connection of adjacent bend restrictor segments, the bend restrictor segments may be differently configured to be connected to adjacent bend restrictor segments. For example, adjacent segments may be connected together via an adapter piece  1501 . An adapter piece  1501  may be used to transition between different diameter bend restrictor segments (as shown in  FIG. 15 ). 
     Rather than the fixing assembly described above with a bolt and bars, another fixing assembly may include a bolt  401 , pivotally attached to a first body portion  1402 , and a head portion  1406  threaded to the bolt ( FIG. 14 ). The head portion may be cupped by a corresponding cavity in the further body portion  1404 . 
     Alternatively, the fixing assembly may include a clasp arrangement with a clasp on an outer circumferential surface of a first body portion and a receiving groove in the further body portion. 
     Although the hinging mechanism described above includes a further fixing assembly, alternative hinging mechanisms (e.g. a plano hinge) may also be suitable. 
       FIG. 13  illustrates a plurality of bend restrictor segments  500   1-4  connected together in series. As shown, both before and after assembly, the fixing assemblies  510  of each of the bend restrictor segments  500  are accessible for tightening or loosening the bolts  520 . Thus, the fixing assemblies may be tightened at any stage during installation. There is no need to individually position connect, and fasten each of the bend restrictor segments before the next adjacent segment can be added. 
     For example, an entire string of bend restrictor segments can be assembled around the elongate member prior to tensioning of the fixing assemblies. This allows, for example, a first team to continue to continually align and install successive bend restrictor segments along the length of the elongate member, whilst a second team follow the first team tensioning the bolt of the assembled bend restrictor segments. This can result in reduced installation times since successive bend restrictor segments can be added simultaneously to previous bend restrictor segments being tightened into position. 
     With the above described arrangement, each bend restrictor segment may be supplied as a single piece, avoiding the requirement for separate fixings or bolts. Thus, numerous loose parts are not needed to be kept safely before installation. Also the costs associated with handling times during installation and spare or replacement parts are reduced compared with known methods. 
     With the above arrangement, the fixing is accessed from an outer circumferential surface only. So, no fixing stage is required that necessitates access to a side surface of the segment (i.e. requiring separate fixing of each segment prior to adding of a further segment). Instead, all fixings may be accessed at any time, and optionally at the same time. 
     With the above described arrangement each of the first and further body portions can be shaped identically or near identically. The fixing assembly (and optionally the hinge assembly) can be fixed to the respective body portions after they are formed. Thus, costs of tooling to manufacture the body portions can be reduced since each portion can be identical, so only one set up of tooling is required for manufacture. 
     The fixing assembly of the above described bend restrictor segments may distribute the load across a larger surface area (across the length of the first and further bars) than traditional bolt and washer assemblies (such as that shown in  FIG. 2 ). In particular, each bar spreads load from the bolt across the cavity surface of each segment. Thus the fixing assembly described above is less likely to damage the first and further body portions and is less likely to fail under excessive loads than known fixing assemblies. 
     Throughout the description and claims of this specification, the words “comprise” and “contain” and variations of them mean “including but not limited to”, and they are not intended to (and do not) exclude other moieties, additives, components, integers or steps. Throughout the description and claims of this specification, the singular encompasses the plural unless the context otherwise requires. In particular, where the indefinite article is used, the specification is to be understood as contemplating plurality as well as singularity, unless the context requires otherwise. 
     Features, integers, characteristics, compounds, chemical moieties or groups described in conjunction with a particular aspect, embodiment or example of the invention are to be understood to be applicable to any other aspect, embodiment or example described herein unless incompatible therewith. All of the features disclosed in this specification (including any accompanying claims, abstract and drawings), and/or all of the steps of any method or process so disclosed, may be combined in any combination, except combinations where at least some of such features and/or steps are mutually exclusive. The invention is not restricted to the details of any foregoing embodiments. The invention extends to any novel one, or any novel combination, of the features disclosed in this specification (including any accompanying claims, abstract and drawings), or to any novel one, or any novel combination, of the steps of any method or process so disclosed. 
     The reader&#39;s attention is directed to all papers and documents which are filed concurrently with or previous to this specification in connection with this application and which are open to public inspection with this specification, and the contents of all such papers and documents are incorporated herein by reference.