Jaws for heating thermoplastic pipe to be butt welded over a sleeve in - to ensure alignment of joints welded in the field

摘要

Thermoplastic pipes are joined by using a linked pair of split annular clamps to draw the pipes over opposite ends of a slightly biconic and serrated sleeve insert which has been heated by a split annular heating iron. The iron has divergent jaw faces so that the centre of the sleeve and the converging pipe ends are heated more than the ends of the sleeve and the adjacent zones of the pipe. Used esp for butt welding of e.g. polyolefin pipes in situ in trenches etc, to ensure and maintain alignment of the pipe ends. The internal sleeve protects the weld from direct contact with the pipe contents and helps to support external compressive or tensile stresses.