Pipe Extraction Assisted By Pre-Stressed Strand

Abstract

A machine for extracting a ductile pipe. The machine has a vise which can grip the pipe, and a wire clamp. Each of the wire clamp and vise are supported on a carriage which is movable relative to a frame. This enables the vise to grip and pull the ductile pipe. Additionally, a wire strand may be disposed through the pipe from a far end to the end at which the machine is placed. The wire clamp allows the machine to pre-stress the strand to improve the extraction of the ductile pipe.

1 . A method comprising:
 disposing a wire strand through an existing pipe, the existing pipe having first and second ends and an underground section disposed between the first and second ends;   securing the wire strand to a pipe puller at the second end of the existing pipe;   gripping the wire strand with a first wire clamp at the first end of the existing pipe;   while the first wire clamp is gripping the wire strand, moving the first wire clamp away from the first end of the existing pipe;   after the step of moving the first wire clamp away from the first end of the existing pipe, securing the wire strand with a second wire clamp;   thereafter, releasing the grip of the first wire clamp and moving the first wire clamp toward the first end of the existing pipe;   thereafter, gripping the wire strand with the first wire clamp; and   thereafter, moving the carriage away from the first end of the existing pipe with the wire strand gripped by the first wire clamp.   
     
     
         2 . The method of  claim 1 , further comprising:
 subsequently, while continuing to grip the wire strand with the first wire clamp gripping the existing pipe with a pipe clamp; and   pulling the pipe with the pipe clamp and the first wire clamp.   
     
     
         3 . The method of  claim 2  wherein the first wire clamp and pipe clamp are supported on a carriage, and wherein:
 the step of pulling the pipe comprises extending a cylinder to translate the carriage. 
 
     
     
         4 . The method of  claim 2  wherein the first wire clamp comprises three jaws having a central passage disposed between the three jaws, and wherein:
 the step of gripping the wire strand with the first wire clamp comprises reducing a space between the jaws. 
 
     
     
         5 . A method comprising:
 disposing a wire through an existing pipe, the existing pipe having first and second ends and an underground section disposed between the first and second ends, wherein a first direction is defined as being from the second end toward the first end;   anchoring the wire to the existing pipe at the second end;   thereafter, pulling the wire in the first direction from the first end without moving the pipe, thereby stretching the wire; and   thereafter, while maintaining the wire in tension, pulling the existing pipe and the wire in the first direction from the first end.   
     
     
         6 . The method of  claim 5  in which the step of pulling the wire from the first end comprises:
 with a first wire clamp, pulling the wire in the first direction; 
 thereafter, with a second wire clamp, gripping the wire and holding it in place; and 
 thereafter, releasing the wire with the first wire clamp. 
 
     
     
         7 . The method of  claim 6  further comprising:
 after releasing the wire with the first clamp, moving the first wire clamp in a direction opposite the first direction; and 
 thereafter, pulling the wire in the first direction prior to the step of pulling the pipe and the wire in the first direction from the first end. 
 
     
     
         8 . The method of  claim 5  in which the step of pulling the existing pipe and the wire in the first direction from the first end comprises:
 gripping the wire with a first wire clamp; 
 gripping the pipe with a pipe vise; and 
 thereafter, while the wire and the pipe are gripped, extending an actuator to move the first wire clamp and the pipe vise in the first direction. 
 
     
     
         9 . The method of  claim 8 , wherein the pipe vise and first wire clamp are supported on a carriage. 
     
     
         10 . The method of  claim 8  in which the step of pulling the wire in the first direction from the first end without pulling the pipe comprises:
 with a first wire clamp, pulling the wire in the first direction; 
 with a second wire clamp, gripping the wire and holding it in place; and 
 thereafter, releasing the wire with the first wire clamp. 
 
     
     
         11 . The method of  claim 10  in which the pipe vise and first wire clamp are supported on a carriage, and the carriage is supported on a stationary support structure. 
     
     
         12 . The method of  claim 11  in which at least a portion of the support structure is interposed between the carriage and the second wire clamp. 
     
     
         13 . The method of  claim 5  further comprising:
 securing a replacement pipe to the second end of the existing pipe; and 
 thereafter, extracting the existing pipe and thereby installing the replacement pipe along substantially the same path previously defined by the existing pipe prior to its extraction. 
 
     
     
         14 . A method of tensioning a wire prior to extraction of a pipe, comprising:
 placing a wire within a pipe, the pipe having a first end and a second end;   at the second end, securing the wire to the pipe;   at the first end, pulling the wire without moving the pipe until the wire is at a desired tension, wherein the desired tension is less than the force required to overcome an adhering bond between the pipe and an underground environment.   
     
     
         15 . The method of  claim 14  in which the step of pulling the wire comprises:
 gripping the wire with a first wire clamp; 
 while gripping the wire, pulling the first wire clamp without moving the pipe; 
 thereafter, gripping the wire with a second wire clamp; and 
 thereafter, releasing the wire with the first wire clamp. 
 
     
     
         16 . The method of  claim 15  further comprising:
 thereafter, moving the first wire clamp toward the first end of the pipe; 
 thereafter, gripping the wire with the first wire clamp; and 
 thereafter, pulling the first wire clamp without moving the pipe. 
 
     
     
         17 . The method of  claim 15  wherein the step of gripping the wire comprises:
 moving a plurality of jaws toward the wire rope such that a space between the plurality of jaws is smaller than the diameter of the wire rope. 
 
     
     
         18 . The method of  claim 15  further comprising:
 providing a pipe pulling apparatus, the pipe pulling apparatus comprising:
 a stationary frame; 
 a carriage movable relative to the stationary frame; 
 a first wire clamp supported on the carriage; and 
 a second wire clamp configured for support on the stationary frame; 
 
 wherein the step of pulling the wire is performed by the pipe pulling apparatus. 
 
     
     
         19 . The method of  claim 18 , further comprising:
 gripping the wire with the first wire clamp;   with the carriage, pulling the first wire clamp away from the pipe;   supporting the second wire clamp on the stationary frame such that the second wire clamp is not permitted to move toward the pipe;   gripping the wire with the second wire clamp; and   thereafter, releasing the wire with the first wire clamp.   
     
     
         20 . The method of  claim 19  in which the second wire is permitted to move away from the pipe when supported on the stationary frame.