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48 2H. O = GH, +CA (OH):.-As acety- lene is so rich in carbon--containing 92.3 per cent--it is possible, when mixed with air in a Bunsen burner to obtain 3100 degrees Fahr. and when combined with oxygen 6300 degrees ES EES Yip B SRE UY HEEN SR OHISSER/ EIS SSE PENS WELDED STEEL TANK, s Fahr. is produced which is the hottest flame: known as a product of combus- tion and nearly equals the electric AEC, This is about 1200 degrees higher than the oxy-hydrogen blowpipe flame. In lighting the blowpipe, the acety- lene is first turned on full; then the oxygen is added until the flame has only a single cone. At the apex of this _cone is a temperature of 6300 degrees Fahr. In welding this point is held from ¥% in. to % in. distant from. the metal to be welded. Too much acety- _dioxide formed by reaction ' at white heat, THe MARINE REVIEW of one volume of acetylene. Practi- cally however, with the oxy-acetylene blowpipe the best welding results are obtained with 1.7 volumes of oxygen to one volume of acetylene. The acetylene is, therefore, not completely burned with the blowpipe, according to the reaction--(1) 2 CH, + Sao, = 4 CO, b 2H. 4 vol. 10 vol. ' but it is incompletely burned according to the reaction -- (2) CoHe ae Os 2CO + FH, 2°vol,..2 vol : This is understood when we consid- er that at the intense heat produced by this combustion, the water and carbon (1h) are completely dissociated. To this last fact is chiefly due the success of the oxy-acetylene flame as'a welding. agent. To establish the proper conditions for autogenously welding two metals it is necessary to bring them to their melt- ing point without oxidizing or carbur- ating. As shown by the formula, this flame consists largely of carbon- monoxide which is being converted at its extremity into carbon dioxide. This, with the hydrogen, form a relatively, cool jacket which protects the molten metal and the inner cone from loss' of heat. : At the moment of initial combustion, when the acetylene is decomposed into: elements of carbon' and hydrogen, about 300 B. T. U. per cubic ft. of the gas are generated. | The total heat, however, generated per cubic ft. of acetylene is about 1500 B. T. U. which, aside from the initial decompositon is furnished mainly by the combustion in oxygen of the carbon into carbon dioxide and in lessen degree by the combustion of hydrogen into water vapor. Pure acetylene at a pressure of less than 30 Ibs. even when passed through pipes is perfectly safe, os when mixed with oxygen (or airy 1 dangerous. An explosive gas ieee enclosed in a pipe does not inflame at once throughout the entire pipe but from one end of the pipe, ignition tray- els at a certain speed which increases as the square of the pipe section; therefore to render safe the use of ened with water, is used simply to pre- > vent the volatilized zinc from being © deposited on the joint and destroying the weld. This process welds by fusion. forming a perfect metallic union of the: parts, which is imperceptible after fin- ishing. It is not brazing. The Worcester Pressed -Steel Co, employ it in place of riveting and sold- ering and for other forms of metal - construction not heretofore possible. Two sheets of metal may be welded by placing their edges in contact and following along the seam with a blow- _ pipe. Tanks 'of almost any shape may be made by forming the body and ends separately and, in assembling, tracing the seams (joints | butt and flush)" with a blowpipe. To insure strength, the joint is slightly overloaded by: melting a 'wire or rod of same material as metal to be welded, at the same time the edges are -- fused. The unfinished joint is stronger 'than the body of the metal and the finished joint is practically the same. Any shaped hole can be easily cut in steel plates up to 6 in. in' thickness, as with the blowpipe the operator-can accomplish cutting -feats impossible with a saw. In cutting the flame is proportionately elongated by: pressure to penetrate to the bottom of the cut. The intense' heat is so localized that the kerf is practically the same as if a saw were used. Not only is this process adapted for making tanks, boilers, tubing, cylin- ders, pipe joints and angles and for replacing brazing and riveting in many instances, but it effectively welds cast iron. In the foundry this apparatus saves defective castings in iron, steel, brass, copper, etc., for the blowholes can be readily filled and broken castings welded as strongly as new. In repair work it is especially valuable and. many expensive castings, forgings and machined parts may be saved from the junk pile by an hour's use of this blow- pipe. An operaton of average ability can weld steel or copper sheets at the rate and cost for gas approximately as fol- lows: 0:035¢ 0.062" Ones" 0.3778 (about 1-32) 288" (about 1-16) 200" (about 1-8 ) 120" (about 3:8: 560" oxygen and acetylene in the blowpipe flame, the gas mixture is given a speed by pressure greater" than' the rate of propagation of the flame. No flux or molds are required to weld metals such as iron, steel and copper, but for alloys viz., brass, bronze, etc: a little borax or boracic acid, moist- $0.0031 0.0065 0.016 0.075 Metals %4 and less in thickness can ordinarily be welded cheaper than riveted. .Steel and copper tanks | for high and low pressure of almost any dimensions, are effectively welded in place of riveting; broken steel shafts and other forgings repaired; cast iron : welded. with copper or steel and blow- inch. inch. inch. inch. hour, hour, hour, hour, per per per per per per per' per _ STEEL TUBE WELDED INTO BOILER SHELL, lene produces two cones and a white color; an excess of oxygen is indicated by flame assuming a violet tint. : Theoretically, 214 volumes of oxygen are required for complete combustion