Welding; theory, practice, apparatus and tests, electric, thermit and hot-flame processes . Fig. 74.—Clamps in position. Draw Pin Pipe-welding by thermit. The thermit portion, about 2 pounds, is poured into a smallcup crucible, which is lined with magnesia and operated witha pair of tongs. Allow the crucible to stand half a minute afterfiring, so that the slag and steel can separate. Then pour overthe lip of the crucible so that the slag comes out first. Beginpouring at one end of the lip of the mold and travel to the otherend. As the thermit slag is poured in on a cold surface of pipe, Pourin
Welding; theory, practice, apparatus and tests, electric, thermit and hot-flame processes . Fig. 74.—Clamps in position. Draw Pin Pipe-welding by thermit. The thermit portion, about 2 pounds, is poured into a smallcup crucible, which is lined with magnesia and operated witha pair of tongs. Allow the crucible to stand half a minute afterfiring, so that the slag and steel can separate. Then pour overthe lip of the crucible so that the slag comes out first. Beginpouring at one end of the lip of the mold and travel to the otherend. As the thermit slag is poured in on a cold surface of pipe, Pouring Gate. Fig. ^Mold for pipe-welding with thermit. it forms a hard shell around the metal, and the liquid whichfollows distributes its heat evenly through this shell, which is apoor conductor. During the pouring, the operators assistantpresses the handles of the mold together to keep the mold in closecontact with the pipe. About one minutes time is allowed forthe iron of the pipe to reach welding heat. The draw pins are THE THERMIT PROCESS 139 put in the sockets of the clamps and screwed tight. If the pipeends are plastic and ready to weld, the operator can feel it byscrewing the draw pins. The nuts on both pins are given twofull simultaneous turns by the operator and his assistant. Thisis enough to force the pipe ends together and complete the the operator desires, he can force enough metal into the upsetby giving the draw nuts another turn, to make the joint con-siderably stronger than the pipe itself. The mold is taken off at once by tapping the upper jaw loosewith a hammer. The
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Keywords: ., bookcentury1900, bookdecade1910, bookpublishernewyo, bookyear1910
