Patent Publication Number: US-2021190251-A1

Title: Lead Pipe Spudding Prior To Extraction Or Remediation

Description:
FIELD 
     The present invention relates generally to expansion of ductile pipes. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a cutaway side view showing a wire rope passing through a section of pipe. Distances between beads attached to the rope are shortened for clarity. 
         FIG. 2  is a side view of a section of pipe. 
         FIG. 3  is an end view along cross-section  3 - 3  showing the pipe with a wire rope disposed within. 
         FIG. 4  is a cutaway side view showing the wire rope and pipe of  FIG. 1 . Two beads have been pulled through a crushed section of the pipe. 
         FIG. 5  is a cutaway side view of the expanded pipe with a larger wire rope within. 
         FIG. 6  is a perspective view of an unexpanded length of pipe. 
         FIG. 7  is a perspective view of an expanded length of pipe. 
         FIG. 8  is a perspective view of the expanded length of pipe of  FIG. 7 , with a slip-lined pipe disposed within. 
     
    
    
     SUMMARY 
     The invention is directed to a method. The method comprises placing a first wire rope having a first diameter and comprising at least one bead into a pipe. The at least one bead is disposed on a first side of a collapsed section of the pipe. The collapsed section has an effective diameter. The method further comprises pulling the wire rope through the collapsed section of pipe such that the at least one bead passes through the collapsed section to upsize the effective diameter of the collapsed section. 
     The invention is also directed to a system. The system comprises a ductile pipe, a first wire rope, and at least one bead disposed on the first wire rope. The ductile pipe is characterized by an original inner diameter and a crushed section having an effective inner diameter smaller than the original inner diameter. The first wire rope is disposed within the ductile pipe. 
     DETAILED DESCRIPTION 
     Ductile pipes, made of materials such as lead, have been used to connect main water supply lines to residential lateral connections. Lateral connections, such as pipe  10  in  FIGS. 1-5 , connect a potable water supply to a residence. Many such pipes  10  were manufactured from lead, and are proven sources of lead contamination of municipally supplied drinking water. Removal or remediation of lead laterals is desirable for health reasons but has proven difficult as a result of inability to apply sufficient axial force to extract the pipe from the surrounding soil. 
     Pipe pullers using wire rope have been developed to apply such axial force. One such apparatus is shown in U.S. Pat. No. 7,128,499, issued to Wentworth, the contents of which are incorporated herein by reference. The device in the Wentworth reference uses a wire rope disposed within the pipe to attach to an end cap to provide pulling force at the distal end of a pipe. The rope may also pull a replacement pipe behind the pipe being replaced. Additionally, a pair of jaws crimps the removed pipe and provides pulling force. While this and similar devices minimize excavation required, some practical difficulties remain. 
     Ductile pipe, such as lead pipe, has properties that invite damage during installation. Such pipe has a low yield strength—in one embodiment, 1200 psi. This material property allows lead pipe to be formed with bends to facilitate follow an excavated trench. 
     The bends, made without a mandrel for controlling bend cross section, reduce the cross section of the pipe and act as an obstruction to the passage of a wire rope in one or more locations. Additionally, scale may build up within the pipe, restricting the optimal inner diameter B of the pipe  10 . Finally, damage may occur during installation, creating an obstructed section of pipe. 
     Whatever the reason, the pipes  10  often comprise a collapsed section  12  as shown in  FIG. 2 . The collapsed section  12  has a length D and an effective diameter E, as shown in  FIG. 3 . The effective diameter E of the crushed section  12  is not large enough to pass a wire rope for conventional pipe pulling processes. However, because the lateral pipe  10  is large enough to pass water, a smaller wire rope  14  may be able to pass through. 
     In  FIGS. 1 and 3 , a small wire rope  14  is shown passed through the pipe  10 , including collapsed section  12 . The small wire rope  14  has a smaller effective diameter than the effective diameter E of the crushed section  12 . The small wire rope  14  may in one embodiment have a diameter of ¼″ in a 1″ lead pipe  10 . The small wire rope  14  is preferably attached at its end in the direction A to a spool or other conventional cable puller. 
     The small wire rope  14  may fail at high tensile force, and thus is not strong enough to pull the pipe  10  from the ground in direction A. However, due to the ductile nature of the pipe  10 , the small wire rope  14  is strong enough to pull a bead through the collapsed section  12 . 
     As shown in  FIG. 1 , at least one bead  16  is attached to the small wire rope. The bead  16  has a conical or spherical shape. In the embodiment of  FIG. 1 , the beads  16  are conical. 
     The bead  16  is harder than the ductile pipe  10 . The low yield strength of the lead material causes the pipe  10  to conform to the circumference of the bead  16 . Thus, the bead  16  pushes the crushed section  12  apart, increasing the effective diameter E of the crushed section. 
     In one embodiment, a bead  16  may expand the crushed section  12 . A second bead  16  with a slightly larger diameter may then be pulled through the crushed section. Progressively larger beads  16  may be used until the crushed section  12  has a desired larger effective diameter. 
     Alternatively, as shown in  FIG. 1 , a series of beads  16  may be utilized on the small wire rope  14 . As shown, the beads  16  may be sized such that each bead  16  is progressively larger moving away from the wire rope pull direction A. The beads may be spaced a distance apart that is greater than the length D of a typical obstruction. In one embodiment, the beads  16  are spaced apart at least six inches. Only one bead  16  encounters the crushed section  12  at any one time. Thus, each bead  16  performs only a small part of the expansion operation. 
     By reducing the expansion work at each bead  16 , the maximum tensile stress on the small wire rope  14  drawing the beads  16  through the pipe  10  is reduced. Reducing the tensile stress on the small wire rope  14  reduces the likelihood of wire rope tensile failure. 
     In one embodiment, four beads  16  are used. A first bead  16 A has a minimum effective diameter just larger than the effective diameter E of the collapsed section  12 . A second bead  16 B is larger than the first bead  16 A. A third bead  16 C is larger still. A fourth bead  16 D is larger still. The fourth bead  16 D may be followed by one or more additional beads, or may be the final bead. In any case, the final bead will have an effective diameter that is greater than or equal to the desired diameter of the pipe  10  after the expansion process is complete. 
     The following dimensions are given as an example of one embodiment, and are not intended to be exclusive of dimensions that could be utilized with this invention. In this embodiment a crushed section  12  may allow a 0.250″ diameter small wire rope  14  to pass. The first bead  16 A is sized at 0.38″ max diameter, the second  16 B at 0.44″, the third  16 C at 0.50″ and the fourth and final bead  16 D at 0.56″. The expansion process forces are minimized by the use of progressive upsizing and a longer length of rope  14  between beads than the length D of the crushed section  12 . 
     In  FIG. 4 , the second bead  16 B is shown within the crushed section  12 . As the expansion work of beads  16 A and  16 B is complete, the crushed section  12  has an effective diameter F, larger than the diameter E, but smaller than optimal inner diameter B. In the embodiment where the diameter of the first bead is 0.44″, the effective diameter F of crushed section  12  is approximately 0.44″ in  FIG. 4 . 
     As shown in  FIG. 5 , after the pipe  10  is upsized, a larger wire rope  20  may be placed through the pipe for conventional extraction. The larger wire rope  20  may be drawn through the pipe behind the final bead  16 D and attached to the small wire rope  14 . The larger wire rope  20  is of sufficient tensile strength to perform conventional extraction operations. Further, the larger wire rope  20  may pull a product pipe (not shown) in place behind the extracted pipe  10 . 
     The effective diameter of the pipe  10  through the crushed section  12  is G after expansion is complete. Diameter G is greater than the diameter of the larger wire rope  20 , and approximately the same dimension as the fourth bead  16 D. 
     After drawing the beads  16  through the pipe  10  and installing the larger wire rope  20 , the pipe  10  may be broken loose from surrounding soil. Tensile forces to break the friction associated with long residence time in soil may be, for example, in the 6-10 ton range. After breaking the friction, the large diameter wire rope  20  may be removed and a lower strength, and therefore lower cost tensile strand such as a smaller wire rope or low cost polyester pulling tape, can be used to produce the much lower forces required to complete the pull. Use of such smaller diameter towing strand allows the lead pipe  10  to be cut into sections or folded. 
     An additional embodiment of the method is to pull the full length of the lateral pipe  10  from the soil with the larger wire rope  20  in its interior. The pipe  10  may then be removed from the rope  20  by ripping it lengthwise with a cutting blade, either static or rotating. This method salvages the wire rope  20  for reuse. 
     In another embodiment, rather than extracting the pipe  10 , the pipe may be lined with a resin. Lining techniques generally require a consistently sized large interior. Because ductile pipe  10  has a low strength, it is possible to increase its size to greater than the original pipe diameter using increasing sizes of bead as discussed. 
     The resin coats the inside diameter of the pipe  10 . In this embodiment, the beads  16  upsize the pipe  10  as discussed. Additional sizes of beads  16  may be utilized to restore the pipe  10  to an effective diameter near, at, or greater than the original diameter B of the pipe  10 . 
     When an entire length of pipe  10 , rather than a collapsed section  12  ( FIG. 1 ), is to be expanded, steps may be taken to limit the tensile stress on the wire rope  14 . For example, if collapsed sections  12  have been remediated prior to expanding the entire pipe  10  according to the previous method, the larger wire rope  20  may be used with large beads (not shown) to accommodate the increased forces. Additionally, the beads  16  may be spaced apart such that only one bead is expanding the pipe  10  at any one time. If desired, spacing between beads  16  may be greater than or equal to the length of the lateral pipe  10 . 
     For example, as shown in  FIGS. 6-8 , an unexpanded length of ductile pipe  10 A may have an inside diameter  82  and an outside diameter  81 . As shown in  FIG. 7 , the same pipe  10 B, after expansion, may have an enlarged inner diameter  86 . The inner diameter  86  may conform approximately to the diameter of the largest bead  16  drawn through the pipe  10 . The outer diameter  87  will also expand and the wall of pipe  10 B will become thinner. 
     As shown in  FIG. 8 , expanding the pipe  10 B may allow for placement of a slip lined pipe  95  within its inner diameter. The slip lined pipe  95  may be formed of polyethylene, copper, or HDPE. The outer diameter  93  of the slip lined pipe  95  is smaller than the expanded inner diameter  86  of the expanded pipe  10 B. Further, the inner diameter  94  of the slip lined pipe  95  may be similar or identical to the original unexpanded inner diameter  86  of the unexpanded pipe  10 A ( FIG. 6 ). 
     Expansion of the pipe  10 B will reform deformed areas. It may be advantageous to clean the inner diameter  86  of the pipe  10 B with compressed air and to lubricate the slip lined pipe  95  prior to insertion. Further, it may be advantageous to coat the lead pipe  10 B with a resin or passivation chemical to minimize the chance that lead from the pipe  10 B will pass through the slip lined pipe  95  and into the water supply. Such a passivation may take place prior to installing the slip lined pipe  95 . Alternatively the annulus  91  between the pipe  10 B and slip lined pipe  95  may be filled with a passivation chemical after installation. 
     As successive beads  16  expand the inner diameter  86  and outside diameter  87  of pipe  10 B, its length may also grow. In one example, when the mean circumference of a 0.75″ lead pipe was increased by 14%, the length of the pipe increased by 2.2%. Such lengthwise expansion will provide a gradual break between the outer surface of pipe  10 B and surrounding soil. 
     Therefore, the larger inner diameter  86  not only allows access for the larger wire rope  20 , it also at least partially frees the pipe  10 B from the soil, decreasing required extraction forces. 
     The various features and alternative details of construction of the apparatuses described herein for the practice of the present technology will readily occur to the skilled artisan in view of the foregoing discussion, and it is to be understood that even though numerous characteristics and advantages of various embodiments of the present technology have been set forth in the foregoing description, together with details of the structure and function of various embodiments of the technology, this detailed description is illustrative only, and changes may be made in detail, especially in matters of structure and arrangements of parts within the principles of the present technology to the full extent indicated by the broad general meaning of the terms in which the appended claims are expressed.