Oxy acetylene welding

Ten years ago the oxy-acetylene method of welding and cutting metals was hardly more than a laboratory process, but in the course of these few years it has become one of the most important of the methods in the metal-working industries. It has made possible the making of repairs of broken machine parts that previously had to be replaced by entirely new castings or forgings. Not only has the process proved of the utmost importance in repair work, but its application has also been found to be of the greatest value in the manufacture of many articles. Much has been published relating to this process, but a great deal of that which has been placed on record in the past has been descriptive of odd jobs. It is, therefore, believed that the present volume, dealing in a more systematic manner with the principles and practice of the art of oxy-acetylene welding, will be of considerable value to those engaged in the metal trades.

The information here presented on the subjects of oxy-acetylene welding and cutting has been mainly furnished by S. W. Miller, proprietor of the Rochester Welding Works, whose wide experience in the practical application of the process and whose success in the work vouch for the reliability of the information here placed on record. The experience of the author in the oxy-acetylene welding field has been unusually extensive, but having been mostly on repair work, he has written especially for those engaged in a similar line. A great deal of the work done with the oxy-acetylene welding torch is on repairs, and while there are also a great many applications of it in manufacturing work, such applications are more or less special in each case, and sometimes require a great deal of experimenting before success is attained. The general principles here presented, however, apply equally to repair and manufacturing work.

In the publication of this volume the Publishers have also made use of several articles by other authors, especially articles by Julius Springer, which from time to time have been published in MACHINERY. A chapter on "Lead Burning," by James F. Hobart, has also been included. This material has been added in order to give as complete and comprehensive information as possible. In general, time and cost data have purposely been omitted in the chapters on oxy-acetylene welding, because, in the present state of the art, it is difficult, if not impossible, to give accurate cost data on repair work. Two welders, working on repairs of a similar character, will often vary as much as fifty per cent in the time consumed, and, as shop conditions also vary to a great extent, it is almost impossible to give accurate figures regarding cost.

This volume describes the equipment required for oxy-acetylene welding and cutting, deals in detail with the methods used for welding cast iron, malleable iron, steel, copper, brass, bronze, and aluminum, and gives, in addition, special attention to the welding of sheet metal, tank welding, boiler repairs, etc., as well as to the subject of lead burning, which is really a kind of autogenous welding. All of the information given has been obtained from the most authoritative sources, the descriptions of the welding apparatus and gas generators having been furnished by the manufacturers in each case, and has been subjected to careful and painstaking editorial work by the staff of MACHINERY'S Book Department, by whom all the volumes in MACHINERY'S Mechanical Library have been prepared. Hence, the Publishers believe that the present volume on oxy-acetylene welding and cutting equipment and practice will be found to be of very great value in the metal-working field.

During the past fifteen years several valuable processes for joining metal parts have been developed, which, to a consider- able extent, have taken the place of ordinary forge welding, soldering, and brazing, which latter methods are very old and which have been used from time immemorial. Not only have the new processes that have been developed taken the place of the older processes, in many instances, but entirely new fields have been opened up for the application of welding, and today various methods of welding autogenous, electric, and thermit are applied to metals under conditions where the ordinary forge welding process would be wholly inadequate.

Forge welding is applicable only to the joining of parts of wrought iron and low-carbon steel. It is true that high-carbon steel, and some of the other metals, may also be welded by this method, but these welds are not always satisfactory and are never as strong as the metal itself. Soldering can be used only on small light work for joints which are exposed to ordinary temperatures, or temperatures only slightly above the boiling point of water, the reason for this being that the melting point of most soldering alloys is about 400 degrees F. Brazing, that is, the joining of metal parts by the fusion of a so-called "spelter solder," is applicable to iron, steel, copper, brass, and several other metals, but, on many kinds of work, the process is rather uncertain in its results, even when in the hands of experts, unless a good equipment is provided for controlling the heat and manipulating the work. Because of ' these limitations of the older processes, the newer processes have had a very rapid development, and have within comparatively few years become recognized as among the most important of the methods used in the metal-working field. The three most important of these new welding methods are the electric welding process, the thermit welding process, and the autogenous welding process, the latter of which is dealt with in the following chapters.

Fusion Welding. Welding is understood generally to mean the uniting of two pieces of iron or steel by heating them to the temperature at which they become softened or pasty, without melting them, placing them together, and by hammering, or in some other way, bringing them into intimate contact. As is well known, this cannot be done with any of the common metals except wrought iron or steel. The process of fusing and uniting metals by the application of intense heat from a gas flame with- out compression or hammering is generally known as "autogenous welding." The temperature required is obtained by the combustion of a gas containing carbon or hydrogen, or both, by the aid of pure oxygen. Acetylene is the gas generally used, although hydrogen is also employed. The gases are thoroughly mixed in a torch or blowpipe to insure perfect combustion, which takes place at the nozzle or tip. A modification of the welding torch is also utilized for the cutting of iron and steel by heating and burning away the metal by oxidizing it.

The word "autogenous," used in connection with the name of this process of welding, is not, however, strictly accurate. Autogenous means "self produced," and this application of the word is not descriptive of a weld made by the oxy-acetylene process. One idea that should be conveyed by any word describing a weld of this kind is that it is made with the same kind of metal as that of which the piece is composed. That is, it is not a joining or soldering process, but, strictly speaking, a welding process. The word "autogenous," however, does not convey this meaning. Another idea that should be conveyed by the name of the process is that it involves the melting of the metal during the making of the weld. Probably there is no word which conveys all of the ideas involved, but "homogeneous" would better explain the uniformity of the character of the weld than "autogenous." This, however, is a long word and is not especially descriptive of the process, as one of the essential features of the process is the melting of the metal, and hence it would seem that the term " fusion welding," which is short, descriptive, and distinctive, should be entirely satisfactory. However, the expression "autogenous welding" has become a term so generally used that it seems doubtful if any other expression, even though more expressive and definite, will ever replace it.

In oxy-acetylene welding the weld may be formed directly between the two adjoining surfaces, but, more commonly, it is formed by fusing in additional material between the surfaces of the joint. This material is in the form of a rod or wire, and may or may not be of the same composition as the material being welded.

Development of Oxy-acetylene Welding Process. Autogenous welding is generally spoken of as a modern development, and this, of course, is true as regards its present commercial application. As a matter of fact, however, it is known that the Romans used a fusion welding method for the joining of lead pipes a century or two before Christ. As they had no knowledge, however, of producing the high temperatures required for the autogenous welding of metals having a high melting temperature, the early application of the fusion welding process was limited to lead, the melting point of which is about 620 degrees F. The process of autogenous welding by means of the oxy acetylene torch or blowpipe dates back only to the year 1900. About that time the process had its inception in France, the first experimenter being Edmund Fouche, of Paris, who, in conjunction with Picard, devised the first practical oxy-acetylene welding torch in 1901, and who, after a couple of years of experimenting, succeeded in producing a commercially successful apparatus.

For some time, however, the process remained more or less of a laboratory method, and the commercial development of oxy-acetylene welding and cutting may be said to have taken place during a brief period beginning about 1905. Considering the short time during which this development has taken place, the process has reached remarkably high perfection and efficiency. Apparatus and equipment for gas welding are now made by a number of manufacturers in the United States and Europe. The principles involved in the use of the apparatus of different makes are practically the same, the differences being mainly in the construction of the torches and the manner in which the gases are generated. Oxygen and acetylene are most generally used, although oxygen and hydrogen are also employed, especially in metal cutting. Great difficulties were at first met with in cheaply producing pure oxygen. The cheap production of acetylene had been generally solved through the extensive development of acetylene lighting; but the means for generating and storing this gas have also been further developed so as to meet all the requirements of metal welding and cutting work. Nevertheless, while these advances have been made, the cost of the gases is still at such a point that there is a vast amount of work that cannot be done by the oxy-acetylene process, which will in future be so done, when the cost of gases is still further reduced.

Application of the Process. The oxy-acetylene welding process is used both in the manufacture of articles, the parts of which would otherwise be riveted or joined by other means, and in repair work. In both fields it has proved to be of exceptional value. In the manufacture of many articles the rapidity with which the joints can be made and the comparatively high efficiency of the welds make it of great importance; in repair work it has made possible the saving of many parts which otherwise would have to be thrown away, such as broken automobile cylinder castings, crankcases, and parts of all kinds of machinery. Some special applications are found in the reclaiming of cracked castings in foundries, the filling of blow-holes in castings, the adding of metal to worn surfaces to secure the original thickness, the welding of piping without removal, the filling of drilled holes that have been incorrectly located, and the sealing of riveted seams to secure absolutely tight joints, which cannot be done effectively by calking. In cutting, the blowpipe is used for cutting out steel-plate shapes, cutting holes in steel plates, cutting off piping, cutting off risers from steel castings, cutting structural beams, and for cutting up steel wreckage, etc.

The importance of the autogenous welding process for producing reliable joints in thousands of manufactured articles which are now brazed, riveted, or bolted together is obvious. In many fields the process has revolutionized past manufacturing methods, decreased cost of production, and made possible the placing on the market of articles that are not only cheaper, but better, more reliable, or more convenient, than those previously made by other methods. The process, of course, has its limitations, as will be pointed out in the subsequent chapters of this treatise on oxy-acetylene welding and cutting, which will deal in detail with the equipment used for producing the required gases and for performing the welding operation, the preparation of the stock for welding, the materials used for filling in at the joints, the fluxes required when welding, and the practice followed in making oxy-acetylene welds in all the common metals to which the process is applicable.


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