Welding; theory, practice, apparatus and tests, electric, thermit and hot-flame processes . Asbestos WasherSand Head of{Tapping Tin Tap Hole. MagnesiaStone MagnesiaTbimble Tapping EiA Fig. 65.—Thermit crucible with detail of lap hole. The tap hole is the vital part of the crucible. It must remainfluid-tight until tapped, and must then withstand the rush ofmolten steel under pressure. As shown in figure 65, the bottomof the crucible holds a large cylindrical magnesia stone which hasbeen placed in position before the magnesia lining has beentamped in. Resting inside the stone is another conical-
Welding; theory, practice, apparatus and tests, electric, thermit and hot-flame processes . Asbestos WasherSand Head of{Tapping Tin Tap Hole. MagnesiaStone MagnesiaTbimble Tapping EiA Fig. 65.—Thermit crucible with detail of lap hole. The tap hole is the vital part of the crucible. It must remainfluid-tight until tapped, and must then withstand the rush ofmolten steel under pressure. As shown in figure 65, the bottomof the crucible holds a large cylindrical magnesia stone which hasbeen placed in position before the magnesia lining has beentamped in. Resting inside the stone is another conical-shapedmagnesia stone, called the thimble. It is also hollow, and itscore is the channel for the molten steel. An iron tapping pin,having a long shank and a fiat head, is dropped into the hole inthe thimble; its head acts as a plug to the channel. An asbestoswasher is dropped on the head of the tapping pin, then an ironwasher, and next an inch of silica sand is poured on the ironwasher. This makes a plug to the crucible that is fluid-tight forat least a minute, long enough for the reaction to take place. THE THERMIT PROCESS 127 This p
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Keywords: ., bookcentury1900, bookdecade1910, bookpublishernewyo, bookyear1910
