WELDING, Gas (Oxy-Acetylene). De velopment of Oxy-Acetylene Processes, Gas welding consists of melting the edges of two of metal so that they run together and solid when cold. A good weld requires a very intense flame, such as is ob tained from acetylene and oxygen. By the oxy acetylene process two sections of like metal can be so united that the two members form a homogeneous whole, so perfect that the weld cannot be distinguished when machined. Ex amination reveals the same uniformity of uwialbe texture throughout the weld. In this important respect oxy-acetylene welds are recognized as the highest examples of the science of welding. Oxyacetylene welding, now generally spoken of as oxwelding, has attained a very important and practically in dispensable place in the iron and steel industry.
It is used in practically all forms of construc tion and manufacture, and is applied to almost countless operations in production and repairs. It is extensively used in low and high pressure pipe-lines and for butt-welding of metal tubing. Ninety per cent of the railroads in the United States use this process in their shops and on the road, and approximately 35,000 locomotives now in service have welded joints that with stand standard steam pressure. The extent to which oxy-acetylene welding was used during the World War of 1914-18 m the manufacture of depth bombs, torpedo casings, poison gas tanks and other supplies and munitions in which speed and volume of production were vital is well known. Practically all of the enormous number of high explosive and other large shells manufactured in America during the war were made from steel billets cut to size by the oxy-acetylene process. In the field, army trucks and repair shops were universally equipped with oxy-acetylene welding and cutting outfits, and in France numerous depots were es tablished where broken and damaged metal parts were quickly repaired by oxyacetylene and put back into service. In peace times the oxy-acetylcne cutting torch is extensively used in the wrecking of steel strictures, in cutting of scrap to sizes for the cupola, in the cutting of armor plate of any thickness, and in fact wherever steel and wrought iron are to he cut. from the largest shipyard down to the smallest industrial plant.
The equipment required for oxy-acetylene welding consists of a cylinder or tank of oxy gen, a tank of acetylene, two regulators or re ducing valves (one each for the acetylene and oxygen tanks), a welding blowpipe and two pieces of hose to connect the blowpipe to the regulators. The cutting equipment is very similar excepting as to the type of the blowpipe used and special hose to sustain the higher oxygen pressure used in cutting. Of the gases adapted to blowpipe use, acetylene and oxygen are by far the most extensively applied, owing to their special fitness industrially, both being obtainable in portable cylinders at low cost. Acetylene contains 1.475 B.T.U.'s, and this very high heat content, together with its endothermic characteristics, conduces to speed in accomplish ing a given quantity of work as well as being a material factor in the excellence of the work.
Acetylene was discovered by Edmund Davy. an English chemist, in 11336; hut it remained a laboratory gas until the development, more than half a century later, of a practical method for producing calcium carbide in commercial quantities Thomas L Willson the American electro-metallurgist, in 1891-92 conducted a series of experiments with a mixture of lime and coal tar heated to high temperature in a Heroult electric furnace, resulting in what may he termed the 'commercial discovery' of cal cium carbide and leading to the establishment. in 11f495, of the first factory in the world for the manufacture of carbide.
In the early years of its commercial applica tion, acetylene generated from carbide was used chiefly as an illuminating gas, and so great was the demand for acetylene for house and town lighting that the industry soon became one of considerable importance. By 1901 calcium car bide was being produced in large quantities and distributing warehouses were established throughout the country. This was shortly followed by development of Prest-O-Lite port able acetylene cylinders containing acetylene dissolved in acetone. The convenience of port able acetylene, rendering the gas available everywhere, created a tremendous demand for acetylene in this form and resulted in the Prest-O-Lite company's becoming an enter prise of large magnitude, with plants in various States and distributing and service depots in every important centre in the country.
Up to 1905 the development of economical processes for obtaining oxygen had been al most entirely neglected; so, while the applica tion of acetylene and oxygen to metal welding and cutting dates experimentally from 1901 and Industrially from 1903, the development of the processes was seriously retarded owing to the cost of oxygen and the difficulty of obtaining an adequate supply. In the early years of the industry the users of the process were largely dependent on their own limited facilities for the production of oxygen from chemicals. Consequently the oxy-acetylene industry was given a tremendous Impulse when, in 1907, a liquid air oxygen plant was put into operation in this country. It is a well-known fact that oxygen produced by the liquid air process is of the highest purity. This was the first unit of what has since become the great system of oxygen plants developed by the Linde Air Products Company, who now maintain produc ing plants and warehouses in more than 50 of the large industrial centres. From that time on the production of both oxygen and acety lene increased amazingly, keeping pace with the rapidly expanding applications of oxy-acetylene welding and cutting. The now almost uni versal adoption of the processes is due to their speed and economy combined with the char acteristic excellence of oxwelding and cutting that is attained by the competent operator using standard equipment. See LIQUEFIED AND COMPRESSED GASES — ACETYLENE.