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Electrothermal fusion of large diameter pipes by electric heating wire wrapping and sleeve connector

  • US 5,252,157 A
  • Filed: 01/14/1993
  • Issued: 10/12/1993
  • Est. Priority Date: 05/01/1989
  • Status: Expired due to Fees
First Claim
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1. A method of sealingly connecting adjacent ends of a pair of large diameter thermoplastic pipe sections by electric fusion comprising:

  • (a) moving a thermoplastic sleeve connector of constant thickness having a large sleeve interior diameter and a large sleeve exterior diameter and having a linear, longitudinal split extending along the entire length of said sleeve and wherein said split is further characterized by a first substantially straight edge and a second substantially straight edge and wherein said first and second edges have substantially flat first and second faces which define said split over the end and a distance down the length of a first of said thermoplastic pipe sections and reducing said sleeve interior diameter to accommodate the external diameter of said thermoplastic pipe sections;

    (b) placing the second of said pipe sections in alignment with said first pipe section whereby an end of said second pipe section is positioned adjacent an end of said first pipe section;

    (c) after step (b) helically winding an electric resistance heating wire around the external surfaces of said pipe sections next to the adjacent ends thereof so that said electric resistance heating wire is in direct contact with the external surfaces of said pipe sections;

    (d) after step (c) moving said sleeve to a position over the adjacent ends of said pipe sections and over said electric resistance wire wound on said pipe sections and closing said sleeve so that said first flat face and said second flat face meet without overlap to form a substantially continuous sleeve outer surface; and

    (e) applying an electric current to said electric resistance heating wire for a period of time such that the thermoplastic materials making up adjacent portions of said sleeve and pipe sections are sealingly fused together.

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