Welding and Metal-Cutting by the Oxy-Acetone Process.

Progress, Volume VI, Issue 4, 1 February 1911, Page 546

Welding and Metal-Cutting by the Oxy-Acetone Process.

(By G. K. Hansard, Napier.)

Engineering .firms have lately shown considerable interest in the dissolved acetylene process for storing gas under small pressure, as by its means it has become possible to carry out welding work under far superior conditions than existed before. The advantages of its use for welding, metal cutting and illuminating have been brought under the notice of engineers by the Acetone Illuminating and Welding Company of Napier. A mixture of dissolved acetylene and oxygen is used for welding. The oxygen is prepared from a mixture of potassium chlorate and black oxide of manganese, and compressed in cylinders to 120 atmospheres. Dissolved acetylene is acetylene previously washed and dissolved in acetone. Acetone is a liquid which possesses the property of dissolving 25 times its own volume of acetylene for every atmosphere of pressure applied. If the pressure on the gas is released, then the acetone slowly gives off the acetylene it has absorbed. Advantage is taken of this fact, and steel bottles are filled with porous brick which is impregnated with acetone. Acetylene is then forced into the bottles under pressure and dissolved by the acetone. The quantity of acetone the brick will absorb is sufficient to permit of the cylinders holding 10 times more acetylene than a similar sized ordinary gas cylinder would were acetone not employed. All cylinders are compressed to 10 atmospheres so that they contain 100 times their own volume of acetylene at that pressure. The reason for the employment of porous brick is as follows:—It would be impossible to fill the bottle with acetone and then force in acetylene, as space must be left for the expansion of the acetone, which takes place on dissolving the acetylene. This space would contain acetylene under pressure, and this is forbidden by law. This method of storing makes an explosion in the cylinder absolutely impossible, as the pores of the brick not completely filled contain sufficient room for the expansion of the acetylene, which takes place during charging, or during a rise in temperature.

; Acetylene is an eudiothermic gas, consistmg of hydrogen and carbon, and when used in conjunction with oxygen in a properly designed blowpipe dissociated at the base of the flame, the carbon only taking part m the burning owing to the fact that hydrogen will not combine with oxygen at the temperature at which carbon will do so. Ihe hydrogen consequently remains free and forms a protection to the small cone at the nozzle of the blowpipe where the carbon is burning and which is the point of maximum temperature. In practical

which had a crack right across the crown, To enable this to be welded, the top of the water jacket was turned out and may be • seen resting against the cylinder, where will also be seen the two sides of the water jacket, which it was found necessary to remove, as the crack extended clown the walls of the cylinder. The crack, which was opened up by chipping, will be clearly seen. After this crack had been autogenously welded, the pieces, which had been removed, were placed in position and the operation completed by welding them in

cess, whilst pipes can be expeditiously joined at any angle As regards the 'strength of welded joints, tests have shown that the metal does not suffer in any way Experiments in bending welded plates show that their strength is not impaired and welded Yorkshire iron tested in tension failed at 29 tons per square inch. Furthermore, the cost is low. £6O will provide a plant, whilst the cost of recharging a 100 subic foot cvlinder of either gas is only £1 13s 4d Despite the fact that it is little more

welding the quantities of oxygon and acetylene used are about equal, and the working pressure of both gases varies from 5 to 151bs. per square inch for welding, and from 20 to lOOlbs. per square inch for metal cutting, in the case of oxygen, while the same pressure is retained on the acetylene. The accompanying illustration will convey some idea of the apparatus employed, and shows the cylinders of oxygen and of acetone gas, the necessary regulators, tubing and blowpipe, the latter being provided with various sizes of nozzles suitable for different classes of work. A flame of the exceedingly high temperature of 6300 deg. F. is obtained. This is a great deal higher than the oxyhydrogen flame, which is limited by the dissociation temperature of steam, whereas in the oxy-acetone blowpipe the temperature is only limited by the dissociation temperature of carbon monoxide, which is much higher than that of steam. In addition to welding, outfits are supplied for metal cutting by the aid of the same compressed gases in conjunction with a specially designed blowpipe. This blowpipe has two jets, a central jet and an annular jet; the latter is to produce a flame whereby the metal to be cut is heated locally to a bright red. A stream of oxygen is then admitted through the central jet. The plate is completely severed, the cut being barely l/-6in. wide, and having the appearance of a saw cut. At the Addington Workshops recently there could be seen a %in. crown plate of a boiler cut to a curve six feet, in length in six minutes, which operation previously took six hours. Reverting to the welding process, the accompanying illustration provides a good instance of the work which may be done. The photos are of a motor-car cylinder

place. The cost of the work, exclusive of the turning, was £2 10s. The saving of . time and money which results from the application of autogenous Avoiding to marine work is very considerable. A job recently done on the s.s. “Kiripaka” in Wellington is worthy of mention. The bottom place of the boiler’s combustion chamber had become so corroded at the stay bolts that in some places it was no thicker than a penny. This Avas filled with new metal to the thickness of the original plate, and then drilled. The neAv metal, in the form of a Avire, being added as re-

quired. The cost of the oxygen and acetylene used was £B, to which must lie added the operator’s wages. In Spain recently the stern post of a vessel was welded in eight hours for £SO, at a saving of £6OO and 3 weeks’ detention of the vessel. Over 1000 cracks in boilers of 80 different vessels were mended by this process at Marseilles in 1907. Broken crank shafts and all descriptions of castings have been repaired with great sue-

than a year since this process was introduced into New Zealand, the Government Railway "Workshops at Petone, Addington, and Hillside, the Union Steamship Co., of Port Chalmers, and many other engineers have installed the plant.