Patent ID: 6758668
Filing Date: 2004-07-06
Classification: B23K

Abstract:
For use with a pipe to be welded, which pipe is in a surrounding concentric relationship and which requires preheating to an elevated temperature for a specified interval, a preheating apparatus comprising:(a) a supporting cylindrical casting sized to fit within a pipe to be preheated, said cylindrical casting including a bottom portion and defining a cavity; (b) a combustible solid fuel mixture supported in said casting and having a generally cylindrical elongate outer surface conforming to the cavity defined by said cylindrical casting, said mixture further being made of a material which burns at a controlled temperature for a specified interval to liberate heat in the form of upwardly flowing gases; (c) a deflector plate having upper and lower face surfaces positioned above and spaced from said casting defining a gap there between, said deflector plate extending outwardly and arranged concentrically within the pipe to deflect the upward flow of heated gases radially toward the surrounding pipe; (d) a grooveway imbedded within and disposed radially around an upper portion of said solid fuel mixture and facing the lower face side of said deflector plate; (e) an oxygen liberating pre-starter compound housed within said grooveway for uniformly igniting said combustible solid fuel mixture thereunder; (f) integrally cast chain means adapted to support and position said cylindrical casting in the pipe; and (g) wherein said cylindrical casting is formed of a frangible material.