Autogenous Welding

AUTOGENOUS WELDING (from Greek autogenes—self-originating), in contrast to forge welding, is performed without preliminary heating of the objects to be welded in a furnace. The principle of such welding consists in the gradual melting, by the action of a concentrated heat source (acetylene-oxygen flame or electrodes), of small sections of the objects being welded with the addition of molten metal. Thus, in this case, there is, strictly speaking, not welding, but fusion of the seam. Furthermore, the autogenous method can also be used to cut metal. Autogenous welding can be applied to a wide variety of metals, whereas only iron is amenable to forge welding. Autogenous welding, both in the USSR and, especially, abroad, has now become very widespread; moreover, besides the manual method of performing the work, there are special machines for this purpose. There are two types of autogenous welding—gas (acetylene-oxygen) and electric, although it is incorrectly accepted here to call only the former autogenous. From the point of view of labor protection, two types of dangers of autogenous welding should be noted: firstly, for the workers performing this operation, and secondly, from the point of view of the strength of the resulting weld, when welding is applied to such critical parts of equipment as steam boilers, aircraft engines, etc. A substandard seam in these cases can have the most tragic consequences for the persons operating these parts of the equipment. (Regarding the dangers of the first type, see Acetylene.) To date, there are still no methods for checking the quality of autogenous welded seams. This quality depends, mainly, directly on the skill of the welder. Therefore, special schools for welders are currently being created abroad (in the U.S.A., for example, in 1923: 42 for acetylene welding, 2 for electric, and 13 for both). In the USSR, there are no courses for welders yet. Some factories manufacture boilers entirely with welded seams, while others allow welding only in places not subject to bending. Autogenous welding is currently very widely used in the repair of boilers, but only with a sufficiently experienced welder can its use be considered not only economical but also safe.