Abstract:
An arrangement that brings all of the separate elements of equipment used to lay product offshore such as pipe, umbilicals, and power cables and assembles them into a single device that can be installed on a vessel of opportunity, and includes functional improvements of each to optimize the use of the arrangement as a unit. A base is used for mounting, integration, and installation of the separate elements onto a vessel. The base receives a movable lay chute, means for moving and stabilizing the lay chute, a movable hang off clamp and work table, a movable access platform, a product support arm and wheel, and a fixed chute.

Description:
FIELD AND BACKGROUND OF INVENTION 
       [0001]    The invention is generally related to laying of product offshore and more particularly to an arrangement for laying products such as pipe, umbilical lines (umbilicals), and power cables. 
         [0002]    A-frames, cranes, and chutes have been used in the past to overboard end terminations of flexible pipes, umbilicals, and power cables (referred to hereinafter as products). In the prior art, these structures have all been separate pieces of equipment and not known to be fully integrated together as a single unit. 
         [0003]    The separate pieces of equipment and their function are briefly discussed below. 
         [0004]    In the most general teens, a vessel is used to transport products to an offshore location where they are to be installed. A tension machine or reel drive arrangement will support the tension generated from the self weight of the product spanning from the installation vessel down to the seabed or between the installation vessel and another fixed or floating platform where the product is being installed to or from. 
         [0005]    A chute is used to control the bend radius of the product during laying operations, and is the means of redirecting the product from a generally horizontal plane, over the side (any side including stern), and into the water in a generally vertical plane. 
         [0006]    While over boarding the second end, or making connections between two products, a crane or A-frame is used to lift the end termination over the chute while maintaining tangency of the product to the chute. 
         [0007]    A hang-off clamp work table is used to support the weight of a product hanging in catenary, while the initiating end of a subsequent product is aligned over the top of the clamped product and the two connected together in a vertical orientation below the chute. The chute is generally fixed at an elevation sufficient to make the connection above the hang-off clamp work table. 
         [0008]    A problem with having many different parts that must work together is that the level of complexity for vessel mobilization is increased when installing and configuring all of the different parts in order to work together properly. The amount of time required for installation and configuration is also increased. 
         [0009]    Thus, it can be seen that there is a need for an improved product laying arrangement that reduces the complexity and time required for installation and configuration. 
       SUMMARY OF INVENTION 
       [0010]    The present invention addresses the shortcomings in the known art and is drawn to an arrangement that brings all of the separate elements discussed above and assembles them into a single device that can be installed on a vessel of opportunity, and includes functional improvements of each to optimize the use of the arrangement as a unit. A base is used for mounting, integration, and installation of the separate elements onto a vessel. The base receives a movable lay chute, means for moving and stabilizing the lay chute, a movable hang off clamp and work table, a movable access platform, a product support arm and wheel, and a fixed chute. 
         [0011]    The various features of novelty which characterize the invention are pointed out with particularity in the claims annexed to and forming part of this disclosure. For a better understanding of the present invention, and the operating advantages attained by its use, reference is made to the accompanying drawings and descriptive matter, forming a part of this disclosure, in which a preferred embodiment of the invention is illustrated. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0012]    In the accompanying drawings, forming a part of this specification, and in which reference numerals shown in the drawings designate like or corresponding parts throughout the same: 
           [0013]      FIG. 1  is an elevation of a vessel with the product lay arrangement installed. 
           [0014]      FIG. 2  is a top view of a vessel with the product lay arrangement installed. 
           [0015]      FIG. 3  is a perspective view of the product lay arrangement. 
           [0016]      FIG. 4  is a detail view of the product lay arrangement showing the hang off clamp and work table in the open position. 
           [0017]      FIG. 5  is a detail view of the product lay arrangement showing the hang off clamp and work table in the closed position. 
           [0018]      FIGS. 6 and 7  illustrate the A-frame and roller being raised and lowered. 
           [0019]      FIG. 8  is a section view of a portion of the movable chute. 
           [0020]      FIG. 9  is the section view of the portion of the chute indicated in  FIG. 8 . 
           [0021]      FIG. 10  illustrates the range of product movement through the fixed chute. 
           [0022]      FIG. 11  is an elevation view that illustrates movement of the A-frame and roller during operation. 
           [0023]      FIG. 12-16  schematically illustrate operations during handling and installation of bend restrictors. 
           [0024]      FIGS. 17 and 18  illustrate the support of the movable work platform. 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0025]    As seen in  FIGS. 1 and 2  the offshore product lay arrangement  10  (referred to as “product lay arrangement” hereinafter) is installed on a vessel  12 . As seen in  FIG. 3 , the product lay arrangement  10  includes a base  14 , a movable A-frame  16  with a product support wheel  18 , a movable lay chute  20 , a movable hang off clamp and work table  22 , a fixed chute  24 , and a movable work platform  26 . 
         [0026]    As seen in  FIG. 3 , the base  14  and equipment thereon are designed to be self contained for ease of installation onto a vessel, as seen in  FIGS. 1 and 2 , as well as removal when the product lay arrangement  10  is no longer required on a particular vessel or needed on a different vessel. The base  14  and equipment thereon are formed from a suitable material such as steel. The base  14  is the structural support that distributes the weight and operation loads of the invention onto the working deck of the vessel  12  and is designed for a balanced and fully assembled lift of the invention onto or off of a vessel. The base  14  controls the spacing of all components and aligns them for safe and optimal performance. 
         [0027]    As seen in  FIGS. 3 ,  6 ,  7 , and  11 - 16 , the A-frame  16  has two arms, with each arm pivotally mounted on the base  14 . At each arm of the A-frame  16  is a hydraulic ram  28  that has one end pivotally mounted on the base  14  and the opposite end pivotally mounted on the arm of the A-frame  16 . This allows selective movement of the A-frame  16  during product laying operations to obtain the optimum angle and height of product support wheel  18  for supporting and laying product. Product support wheel  18  is rotatably mounted between the arms of the A-frame at the end away from the base  14 . The A-frame  16  may also have adjustable length arms to better accommodate a larger size variety of products and accessories attached to the products. 
         [0028]    Movable lay chute  20  receives and guides product being laid. While movable lay chute  20  preferably has a fixed radius of curvature, it is seen in FIGS.  3  and  11 - 18  that it is mounted for selective movement on the frame  14  to change the relative position of the lay chute  20  to obtain the optimum angle and height for laying product. As best seen in  FIG. 12-18 , movable lay chute  20  is mounted on a triangular frame  30 . The movable lay chute  20  is flared progressively and tangentially aligned with the curvature of the fixed lower chute  24 . The geometry of the lay chute  20  allows the product to be radius controlled with the lay chute  20  in any position. 
         [0029]    The long side  31  (best seen in  FIG. 12-16 ) of the triangular frame  30  is pivotally mounted (indicated by numeral  32 ) on the base  14 . For ease of illustration and aid in understanding the invention, the pivot connection  32  is illustrated separately from the base  14  in  FIG. 12-16 . A hydraulic ram  34  has one end connected to the base  14  and the opposite end connected to a brace  36  on the triangular frame  30 . A sliding chute support  38  (seen in  FIGS. 3 and 18 ) has its lower end rigidly attached to the base  14  while its upper end slidably receives the lay chute  20 . The support  38  stabilizes the lay chute  20  in the horizontal direction. A curved rail on the support  38  is preferably centered at the rotation point of the lay chute  20  to provide support at any achievable position of the lay chute  20 . The combination of the pivot connection  32 , the hydraulic ram  34 , and chute support  38  allow selective, stable movement of the lay chute  20  during product laying operations as required for supporting the product and movement of equipment such as pipe line end terminations or branches attached to the product. 
         [0030]    As seen in  FIG. 8 , the sides of the lay chute  20  are provided with water spray nozzles  40  that serve to cool the product as it slides on the surface of the chute  20 . While only one nozzle  40  is shown in the cross section of  FIG. 8  on each side of the lay chute  20  for ease of illustration, it should be understood that a series of water nozzles  40  are preferably provided along the length of the lay chute  20 . 
         [0031]    As seen in  FIG. 8 , the surface of the lay chute  20  in contact with the product is preferably curved (concave) for better retention and guidance of the product. As seen in  FIGS. 8 and 9 , the surface of the lay chute  20  in contact with the product is also preferably lined with a friction reducing material  46  such as polymeric sheeting. 
         [0032]    The movable hang off clamp/work table  22 , best seen in  FIGS. 3-5  and  10 - 18 , is split into two halves that include the clamp  54  and work surface  56 . The fixed chute  24  is also attached to the lower portion of each half of the clamp/work table  22 . The clamp  54  is used to hold end fittings or other accessories in place during the makeup of mid-line connections (flanged connections between two segments of product). The clamp  54  is shown open in  FIG. 4  and closed in  FIG. 5 . The clamp  54  slides open and closed symmetrically about the centerline of the device. 
         [0033]    The fixed chute  24  is curved outward from top to bottom and designed to protect the product from contact with the hang off clamp supporting structure, thus allowing the invention to lay product in the horizontal direction as seen in  FIGS. 10 and 11 .  FIGS. 10 and 11  illustrate both vertical and horizontal laying of product. 
         [0034]    The movable work platform  26 , best seen in  FIGS. 17 and 18 , pivots about a fixed point  42  on the lay chute  20  and is kept horizontal by means of a linkage  44  that completes an effective mechanical parallelogram. The effective mechanical parallelogram, indicated by dashed line  48 , is created by the stairs  47 , a linkage, and pivot point  42 . The linkage is comprised of two arms  44  and  45 . A first, short arm  44  extends down to and is pinned at the bottom of the stair support strut  50 . A second, long arm  45  is pivotally attached at one end to the first, short arm  44  below pivot point  42  and pivotally attached at its second end to the frame  14  as indicated by numeral  52 . The COG (Center Of Gravity) of the work platform  26  will cause the linkage  44  to work in compression to keep the platform  26  level. For example, a person standing on the platform  26  may cause the COG to shift to the right, and cause the linkage  44  to work in tension. 
         [0035]    In operation, the product  58 , which may be an item such as a pipe or umbilical line, is directed from a loaded position on the vessel  12  over the support wheel  18 , onto the lay chute  20 , and then down through the movable hang off clamp/work table  22 . During movement of the product, the water spray nozzles  40  on the lay chute  20  are used to reduce friction and protect the product and the lay chute. As seen in  FIGS. 6 ,  7 , and  11 - 16  the positions of the A-frame  16  and movable lay chute  20  are adjusted as required to obtain the optimum angle for movement of the product. This can be especially important when the product is pipe which must be maintained within certain specifications relative to its bend radius. The different positions are also used for movement of accessories such as pipeline end terminations, bend restrictor elements, and umbilical termination assemblies.  FIG. 11  illustrates the use and movement of the A-frame  16  and movable lay chute  20  to move the end of an umbilical line and its end fitting  60  into position above the movable hang off clamp/work table  22  such that the end fitting  60  does not contact and damage the movable lay chute  20 .  FIG. 12  illustrates the movement of a bend restrictor assembly  62  to the hang off clamp/work table  22 .  FIGS. 13-15  illustrate the use of the hang off clamp/work table  22  to support the product  58  and bend restrictor assembly  62  in place for attaching additional product  58  and then lowering the combination.  FIG. 16  illustrates the use of the hang off clamp/work table to retain a bend restrictor assembly  62  in place for the attachment of an end termination  64 . 
         [0036]    The invention provides the following advantages. 
         [0037]    The invention can be lifted as a single unit and powered by a single hydraulic power unit (HPU). 
         [0038]    This significantly reduces the mobilization time onto vessels of opportunity by reducing the scope and complexity of the physical work, as well as simplifying the engineering of the interfaces. 
         [0039]    The integrated support base guarantees the device will function properly and safely no matter where it is installed. 
         [0040]    The positions and sizes of all the components are optimized to enable maximum work space below the movable lay chute when needed, and reduces the required length of the A-frame, further reducing the loads in the A-frame since the movable lay chute can be lowered to an optimal position for its use. 
         [0041]    The option for an adjustable length A-frame within the strength capacity of the integrated support base increases the quantity of potential work. 
         [0042]    The compact design enables the invention to be installed on a larger number of available vessels. 
         [0043]    The integrated A-frame provides a means of over boarding up to the maximum load of the device and enables product installation from vessels that would have otherwise been passed over due to insufficient crane capacity. 
         [0044]    While specific embodiments and/or details of the invention have been shown and described above to illustrate the application of the principles of the invention, it is understood that this invention may be embodied as more fully described in the claims, or as otherwise known by those skilled in the art (including any and all equivalents), without departing from such principles.