Abstract:
A flexible bag-type pipeline weight, configured to straddle a pipeline, has internal tie means to prevent excessive bulging of the weight after being filled with ballasting material, thus facilitating installation in narrow trenches. Built-in loading loops facilitate filling the weight with ballasting material without need for special loading equipment. The bag-type pipeline weight is formed with a pair of leg sections on either side of a Central, pipeline-receiving recess. Once filled with ballast, the legs remain separated, thus facilitating installation on a pipeline. The filled pipeline weight is also freestanding and stable for purposes of transport and storage prior to installation. Hoisting slings facilitate lifting and manipulation of loaded pipeline weights without the need for spreader bars.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims the benefit, pursuant to 35 U.S.C. 119(c), of Provisional Application No. 61/148,299, filed on Jan. 29, 2009, and said provisional application is incorporated herein by reference in its entirety for continuity of disclosure. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The present invention relates in general to means for anchoring or preventing flotation of pipelines, such as oil and gas pipelines. In particular, the invention relates to bag-type weights for large diameter pipelines. 
       BACKGROUND OF THE INVENTION 
       [0003]    Weights of various types are commonly used to anchor pipelines, particularly for pipelines running through water bodies, marshes, sloughs, or other moisture-laden zones in which pipelines might be upwardly displaced due to buoyancy forces. Bag-type pipeline weights are typically made from a flexible and durable fabric or similar material, with pockets or compartments that can be filled with ballast material (such as gravel) to provide weight as needed. The filled weights are then laid over or attached to a pipeline at spaced intervals. Some known bag-type weights incorporate or require straps of sonic sort, to be wrapped and tied around the pipeline. Other designs simply rely on the ballast mass to keep the weights in place relative to the pipeline. Some known designs are configured to straddle the pipeline, with ballast-filled side lobes extending down each side of the pipeline. Bag-type weights have a particular advantage over other known pipeline weights in that they can be filled with ballast material at or near to a pipeline-laying operation, resulting in considerably lower weight transportation costs as compared to, for instance, precast concrete weights. 
         [0004]    Examples of prior art bag-type pipeline weights may be found in the following patent documents: 
         [0005]    U.S. Pat. No. 3,793,845 (Keith); 
         [0006]    CA 2,075,006 and U.S. Pat. No. 5,385,430 (Connors); and 
         [0007]    CA 2,277,523 and U.S. Pat. No. 6,220,788 (Jewell). 
         [0008]    The problem of providing ballast for larger diameter pipelines (e.g., 16-inch plus) has particular challenges. The volume of a pipe per unit of pipe length (i.e., the cross-sectional area of the pipe) is proportionate to the square of the diameter. Accordingly, the potential buoyancy forces acting on a pipeline, per unit of pipeline length, also vary with the square of the pipeline diameter, and the ballast weight (or anchoring force) required to counteract the potential buoyancy forces is generally proportional to the square of the pipeline diameter as well. For example, the ballast weight required to weigh down a given length of 32-inch diameter pipeline will be about four times greater than for the same length of 16-inch diameter pipe (in similar service conditions). 
         [0009]    Because of their inherent configurations, prior art bag-type weights are not suitable or readily adaptable for ballasting large-diameter pipe. For example, weights such as those taught by Jewell are not readily scalable to accommodate the much greater mass of ballast required for large-diameter pipelines. The Connors design, if scaled up to hold greatly increased amounts of ballast, will be difficult to fill, handle, and install, particularly where it is desired or necessary to install a pipeline in a trench with minimum possible side clearances. 
         [0010]    For the foregoing reasons, there is a need for a bag-type pipeline weight design that is readily adaptable to accommodate the large volumes of gravel or other ballast material required to weigh down large-diameter pipelines. At the same time, there is a need for a bag-type pipeline weight for large-diameter pipelines that is easier to fill, transport, and install than known bag-type weight designs. Furthermore, there is a need for a bag-type pipeline weight for large-diameter pipelines that substantially retains its shape after being filled with ballast and during installation, thus facilitating its use in comparatively narrow pipeline trenches. The present invention is directed to these needs. 
       BRIEF DESCRIPTION OF THE INVENTION 
       [0011]    The present invention provides a flexible bag-type pipeline weight configured to straddle a pipeline, with internal tic means for preventing excessive bulging of the weight during or after being filled with ballasting material, thus facilitating installation in comparatively narrow pipeline trenches. Built-in loading loops facilitate filling the weight with gravel or other ballasting material, without need for special loading hoppers or other complex equipment. The pipeline weight of the present invention is formed with a pair of leg sections on either side of a central, pipeline-receiving recess. Once filled with ballast, the legs remain separated, thus facilitating installation on a pipeline. The filled pipeline weight is also freestanding and stable for purposes of transport and storage prior to installation. Hoisting slings may be used to facilitate lifting and manipulation of loaded pipeline weights without the need for spreader bars. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0012]    Embodiments of the invention will now be described with reference to the accompanying figures, in which numerical references denote like parts, and in which: 
           [0013]      FIG. 1  is a cross-section through a pipeline trench, showing a bag-type weight generally in accordance the present invention being installed over a pipeline in the trench. 
           [0014]      FIG. 2  is a perspective view of a bag-type weight in accordance with one embodiment of the invention being positioned over a pipeline. 
           [0015]      FIG. 3  is a perspective view of a first embodiment of the invention. 
           [0016]      FIG. 4  is a perspective view of a second embodiment of the invention. 
           [0017]      FIG. 5  is a perspective view of a third embodiment of the invention. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0018]      FIGS. 1 and 2  illustrate a pipeline weight  10  in accordance with one embodiment of the present invention, being positioned over a pipeline P in a trench T. Pipeline weight  10  has a nominal overall width A and a nominal length B (parallel to pipeline P). Weight  10  preferably has a plurality of hoisting slings  50  which in  FIGS. 1 and 2  are shown being supported by hoisting means conceptually indicated by lifting hooks H. Weight  10  is fashioned from a suitable flexible fabric or similar material, which in preferred embodiments will be a geotextile. 
         [0019]    Tables 1 and 2 provide data relating to weights and preferred materials for non-limiting examples of embodiments of weight  10  for selected combinations of pipe size, weight width A, and weight length B. 
         [0000]    
       
         
               
               
               
             
               
               
               
               
               
             
               
               
               
               
               
             
           
               
                 TABLE 1 
               
             
             
               
                   
               
               
                 Bag Dimensions on Pipe 
                 Weights 
                   
               
             
          
           
               
                 Pipe Size 
                 A 
                 B 
                 lb 
                 kg 
               
               
                   
               
             
          
           
               
                 16″ 
                 36″ 
                 84″ 
                 2,500 
                 1,134 
               
               
                 20″ 
                 45″ 
                 96″ 
                 5,000 
                 2,268 
               
               
                 24″ 
                 54″ 
                 96″ 
                 5,000 
                 2,268 
               
               
                 30″ 
                 67″ 
                 96″ 
                 7,000 
                 3,175 
               
               
                 36″ 
                 81″ 
                 96″ 
                 9,000 
                 4,080 
               
               
                 42″ 
                 94″ 
                 96″ 
                 12,500 
                 5,440 
               
               
                 48″ 
                 108″  
                 96″ 
                 12,500 
                 5,440 
               
               
                   
               
             
          
         
       
     
         [0000]    
       
         
               
             
               
               
               
               
             
               
               
               
               
               
             
           
               
                 TABLE 2 
               
             
             
               
                   
               
               
                 Bag Material Data 
               
             
          
           
               
                   
                 Geotextile 
                 Loading Slings 
                   
               
             
          
           
               
                   
                 Pipe Size 
                 Material Weight 
                 Width 
                 Load Rating 
               
               
                   
                   
               
               
                   
                 16″ 
                 200 g/m 2  × 2 Layers 
                 4″ 
                 4 × 6000 lbs 
               
               
                   
                 20″ 
                 200 g/m 2  × 2 Layers 
                 4″ 
                 4 × 6000 lbs 
               
               
                   
                 24″ 
                 200 g/m 2  × 2 Layers 
                 4″ 
                 4 × 6000 lbs 
               
               
                   
                 30″ 
                 200 g/m 2  × 2 Layers 
                 4″ 
                 4 × 6000 lbs 
               
               
                   
                 36″ 
                 200 g/m 2  × 2 Layers 
                 4″ 
                 4 × 6000 lbs 
               
               
                   
                 42″ 
                 200 g/m 2  × 2 Layers 
                 4″ 
                 6 × 6000 lbs 
               
               
                   
                 48″ 
                 200 g/m 2  × 2 Layers 
                 4″ 
                 6 × 6000 lbs 
               
               
                   
                   
               
             
          
         
       
     
         [0020]      FIG. 3  illustrates in detail the construction of one particular embodiment of a pipeline weight  10  in accordance with the present invention. In general configuration, pipeline weight  10  resembles an open-topped bag with an arch-like recess R formed in a bottom region to allow weight  10  to straddle a pipeline P, with pipeline P disposed within recess R (as shown in  FIGS. 1 and 2 ). In the embodiment shown in  FIG. 3 , weight  10  has an overall width A and can be considered as divided into four rectilinear sections, as follows:
       a pair of leg sections  20 , each having a width E and a length B, and extending in height from a floor panel  26 , at a bottom level L B , to an upper intermediate level L 2 ;   a central section  30  extending between leg sections  20  and having a width F and a length B, and extending a height H 2  from a floor panel  36 , at a lower intermediate level L 1 , to upper intermediate level L 2 ; and   a top section  40  having a width A and a length B, and extending a height H 3  from upper intermediate level L 2  to a perimeter top edge  43  at a top level L T .         
         [0024]    Each leg section  20  has an inner sidewall  23  of length B, extending a height H 1  from bottom level L B  to lower intermediate level L 1  (i.e., between floor panels  26  and  36 ): an outer sidewall  24  of length B, extending from bottom level L B  to upper intermediate level L 2  (i.e., a total height of H 1  plus H 2 ); and a pair of opposing endwalls  22  of width E, extending from bottom level L B  to upper intermediate level L 2  (i.e., a total height of H 1  plus H 2 ). Central section  30  has a pair of opposing endwalls  32  of width F and height H 2 , which are contiguous with corresponding endwalls  22  and which extend a height H 2  from lower intermediate level L 1  (i.e., from floor panel  36 ) to upper intermediate level L 2 . 
         [0025]    Top section  40  has a pair of opposing sidewalls  44  of which have length B and are contiguous with outer sidewalls  24 ; and a pair of opposing endwalls  42  (of width A) which are contiguous with corresponding endwalls  22  and  32 , and which extend between sidewalls  44 . Endwalls  42  and sidewalls  44  extend a height H 3  from upper intermediate level L 2  to perimeter top edge  43  at top level L T . Perimeter top edge  43  defines a top opening  45  through weight  10  can befilled with ballast material. Perimeter top edge  43  is preferably fashioned and adapted to incorporate a drawstring  47  or other suitable means for substantially closing top opening  45  after weight  10  has been filled with ballast material to a desired level, which will typically be around upper intermediate level L 2  (but in alternative configurations may be above or below that level). Since upper section  40  in typical applications will not receive a large amount of ballast material (if any), endwalls  42  and sidewalls  44  may if desired be made of a lighter material than other portions of weight  10 . 
         [0026]    The interior of central section  30  is in fluid communication with the interiors of leg sections  20  across the region above inner sidewalls  23  between lower intermediate level L I  and upper intermediate level L 2 . As well, the interior of top section  40  is in fluid communication with central section  30  and leg sections  20  across the plane of upper intermediate level L 2 . Accordingly, when a ballast material is introduced into weight  10  through top opening  45  it can flow into all four sections of weight  10 . 
         [0027]    In preferred embodiments, when leg sections  20  are charged with ballast, inner sidewalls  23  are maintained at a substantially uniform lateral spacing from their corresponding outer sidewalls  24  by first tie means extending between each inner sidewall  23  and its corresponding outer sidewall  24 . In the embodiments shown in  FIGS. 3 ,  4 , and  5 , the first tie means take the form of a plurality of cables or cords  82  extending between sidewalls  23  and  24  through tie openings  81  in sidewalls  23  and  24 . Preferably, sidewalls  23  and  24  incorporate reinforcing bands  80  made of a heavy fabric or other suitable material in the region of tie openings  81 , as shown in  FIGS. 3 ,  4 , and  5 . The first tie means thus have the effect of maintaining sidewalls  23  and  24  generally parallel to each other after being filled with ballast, thus preventing excessive bulging of leg sections  20  and facilitating or enabling installation of weight  10  over a pipeline P in a trench T in situations where the space between pipeline P and the adjacent trench sidewall is as little as width E of leg section  20 . 
         [0028]    To further prevent or minimize excessive bulging of weight  10  after filling, second tie means in the form of one or more crossties  60  preferably extend between central section endwalls  32  (and/or between leg section endwalls  22 , and/or between top section endwalls  42 ) at or near upper intermediate level L 2 , as shown in  FIGS. 3. 4 , and  5 . Similarly, third tic means in the form of one or more lateral ties  62  preferably extend between outer sidewalls  24  of leg sections  20  (and/or between top section sidewalls  44 ) at or near upper intermediate level L 2 , as shown in  FIGS. 3 ,  4 , and  5 . As shown in the Figures, crossties  60  and lateral ties  62  preferably form a grid or lattice pattern, with spaces between adjacent crossties  60  and adjacent lateral ties  62 , so as to interfere as little as possible with the flow or passage of ballast material into leg sections  20  and central section  30  when weight  10  is being filled. Preferably, crossties  60  and lateral ties  62  are connected (such as by stitching or riveting) where they cross. 
         [0029]    Preferred embodiments of pipeline weight  10  incorporate lift means preferably in the form of multiple slings  50  as shown in  FIGS. 3 ,  4 , and  5 . The locations, lengths, and heights of slings  50 , and the materials from which they are fashioned, may be selected and varied to suit specific configurations and installation conditions of weight  10 . Typically, slings  50  will be made from a heavy fabric or other strong and flexible material, and securely attached to weight  10  by means of stitching, riveting, or other suitable connection means, optionally in association with reinforcing bands  84  attached to weight  10 . 
         [0030]    In preferred embodiments, weight  10  has, on each side thereof, a plurality of loading loops  70  securely attached to the inner (or outer) faces of top section sidewalls  44  (or leg section outer sidewalls  24 ) at or in the general vicinity of upper intermediate level L 2 .  FIGS. 3 ,  4 , and  5  show either two or three loading loops  70  on each side of weight  10 , but this is for illustration only; there is no inherent limit to the number of loading loops  70  that may be provided. Loading loops  70  may be used to facilitate the filling of weight  10  with ballast material in a number of alternative ways. In order to use loading loops  70 , endwalls  42  and sidewalls  44  of upper section  40  are bunched or folded down as necessary to expose and provide ready access to loading loops  70 . The forks of a fork lift (not shown) may then be inserted through loading loops  70 , whereupon the fork lift used to lift the empty weight  10  and position it over a pipe stub of a diameter matching that of a pipeline P over which the filled weight  10  is to be installed. The use of a pipe stub facilitates filling of weight  10  for optimal fit over pipeline P. 
         [0031]    With empty weight  10  being suspended from the forklift, with floor panels  26  of leg sections  20  being at or near ground level (or other supporting surface), gravel or other ballast material can be introduced into weight  10  using a mobile loader or other suitable materials handling equipment. After weight  10  has been filled to a desired level, weight  10  will be free-standing on filled leg sections  20 , such that the forklift forks can be withdrawn from loading loops  70 . Endwalls  42  and sidewalls  44  of upper section  40  can then be raised as necessary to allow drawstring  47  to be tightened, thus completely or substantially closing off top opening  45 , whereupon suitable hoisting and transport equipment (e.g., wheeled loader, fork lift, or mobile crane) can be used to hoist the loaded weight  10  by means of hoisting slings  50  and to install loaded weight  10  in a desired location over a pipeline P (or to a weight storage area for later installation). 
         [0032]    In an alternative loading method, loading loops  70  of an empty pipeline weight  10  are positioned over brackets or lugs of a suitable filling stand or frame instead of the forks of a fork lift. The weight-loading procedure is otherwise generally similar to the procedure using a forklift. After weight  10  has been filled with ballast to the required level, loading loops  70  can be removed from the filling stand so that drawstring  47  can he tightened and loaded weight  10  can be lifted out of the filling stand and moved to the installation area or a storage area. 
         [0033]      FIGS. 4 and 5  illustrate only two of many possible hoisting sling arrangements that can be used with pipeline weights in accordance with the present invention.  FIG. 4  shows an alternative pipeline weight embodiment  110  that is similar in all respects to weight  10  shown in  FIG. 3  except for the location and length of hoisting slings  50 .  FIG. 5  shows a further embodiment  210  that is similar in all respects to weight  110  shown in  FIG. 4  except for the presence of additional hoisting slings  50 , and optional sling retainer loop  55  which can be used to gather multiple hoisting slings  50  together and thus facilitate engagement of hoisting slings  50  with crane hooks or other hoisting equipment. The components and construction details of pipeline weights  110  and  210  will be substantially identical to corresponding components and details shown in  FIG. 3 , so for purposes of simplicity and clarity, reference characters are largely omitted from  FIGS. 4 and 5 . 
         [0034]    It will be readily appreciated by those skilled in the art that various modifications of the present invention may be devised without departing from the essential concept of the invention, and all such modifications are intended to come within the scope of the present invention and the claims appended hereto. It is to be especially understood that the invention is not intended to be limited to illustrated embodiments, and that the substitution of a variant of a claimed element or feature, without any substantial resultant change in the working of the invention; will not constitute a departure from the scope of the invention. For example, although the illustrated embodiments of bag-type pipeline weights are of generally rectilinear configuration in whole or in part, alternative embodiments may incorporate one or more non-rectilinear sections or portions without departing from the fundamental concepts of the invention. 
         [0035]    In this patent document, the word “comprising” is used in its non-limiting sense to mean that items following that word are included, but items not specifically mentioned are not excluded. A reference to an element by the indefinite article “a” does not exclude the possibility that more than one of the element is present, unless the context clearly requires that there be one and only one such element. Any use of any form of the terms “connect”, “attach”, or any other term describing an interaction between elements is not meant to limit the interaction to direct interaction between the subject elements, and may also include indirect interaction between the elements such as through secondary or intermediary structure.