Fig. 84.—Method of Cutting with Two Welding Torches. Torch A is Adjusted so that a Neutral Flame will do the Preheating, while a Fork in the Oxygen Line Supplies Oxygen only to Torch B, and it does the Cutting.
(151) Frequently the welder has a call for a cutting torch, where none is available, yet an extra welding torch or two may be on hand. If this is the case, two welding torches may be fastened together in such a manner that a temporary job of cutting may be handled. The arrangement shown in [Fig. 84] illustrates this point. If no extra welding torch is available, a carbon burning torch or any piece of copper tubing which has a valve in one end, suitable for taking a hose connection, and the other end free to have a welding tip brazed on, can be used in the same manner. The welding torch will give the neutral flame and the extra line of oxygen will do the cutting. It is well to remember that oxygen, no matter under what pressure, cannot be expected to act upon cold metal. A red heat is absolutely necessary. There are various short cuts, it is true, in obtaining this heat, and where a large shaft is to be cut, the operator would not think of playing his torch upon such a piece of metal until it was red hot in the locality in which he wished to start his cut. This would consume too much time and gas. Generally a hammer and cold chisel are brought into play and a slight curl on the metal is obtained as shown in [Fig. 85]. The moment this becomes red hot, the oxygen jet may be turned on, and the cut commenced. As soon as started, the operator is able to “carry-on” at will.
Fig. 85.—When no Edge is Available to Start the Cut on Large Work, Much Time may be Saved by Making a Curl with a Cold Chisel, as Shown.
(152) An armored hose is generally used on the oxygen line for cutting, as well as on the acetylene line, as there is much more pressure used in cutting than in welding. This type of hose wears much longer and does not kink to the extent that the unprotected hose does. The armor protects both lines from being burned by the melted metal, which is very apt to come in contact with the rubber, were it not protected in some manner.
(153) The question often arises in welding circles, as to why, since the cutting torch contains a series of neutral flames, it would not be just as well to use such a method in welding, as no doubt more heat could be obtained and a greater surface handled. The answer to such a question would be, that the opportunity for oxidation is so great that successful welding could not be expected, although if this were the last means at a welder’s disposal, he would certainly be justified in making a weld in this manner. He should be very careful, however, to see that his extra oxygen supply is completely shut off and that there is no possible chance for that gas leaking into the weld.
(154) To plunge a flame, such as is used in the cutting torch, under water and see it continue to burn while submerged, looks quite marvelous to the average layman. Yet in cutting piling along water fronts this is continually being done. Not only does the torch stay lighted, but it retains much of its efficiency as a cutting tool, and some instances have been recorded where cutting has been accomplished at a depth of thirty feet under the sea. It is true that the water conducts a large part of the heat away very rapidly, but to facilitate such operations, an air line is brought down which ejects air under the torch and clears the water away to some extent, but this is not necessary. In order to explain this phenomenon in a very simple way, it will be stated that nothing will burn unless oxygen is present, and the more oxygen used, up to a certain point, the more rapidly will the burning take place. When submerging the cutting torch, it is presumed that the flame obtains what added oxygen is necessary from the cutting jet and this together with the velocity of the flame and its hydrogen enveloping flame permits the neutral flame to continue burning.
CHAPTER XII
CARBON BURNING
(155) Those who are familiar with gasoline engines will know that after being used for some time, the impurities in the lubrication oil and in the gasoline, which is continually being burned, will form around the top of the piston and cylinder head in the motor. When enough has been deposited and a few high points become overheated through long running, there will be a metallic knock distinctly heard when an extra strain is being exerted by the motor. This layer of impurities is called carbon and its presence means loss of power. Owing to the construction of most cylinder blocks, it is a very difficult matter to reach this portion of the block without dismantling. This requires skilled labor and means much delay. A method of removing this carbon by the oxygen process has been devised, which will save much time and trouble.