Publisher Summary This chapter gives an overview of maintenance welding. Welding machines and electrodes have been developed to the point where reliable welding can be accomplished under the most adverse circumstances. Besides making quick, on-the-spot repairs of broken machinery parts, welding offers the maintenance department a means of making many items needed to meet a particular demand promptly. The welding involved should present no particular problems if the operators have the necessary training and background to provide them with knowledge of the many welding techniques that can be used. A maintenance crew proficient in welding can fabricate and erect many of the structures required by a plant, even to the extent of making structural steel for a major expansion. Welding can be done either in the plant maintenance department or on the erection site. Standard structural shapes, including pipe, which makes an excellent structural shape, can also be used. Electrodes such as the E6010-11 types are often the welder's first choice for this kind of fabrication welding because of their all-position characteristics. Scrap materials often can be put to good use. When using scrap, however, it is best to weld with a low-hydrogen E7016-18 type of electrode, since the analysis of the steel is unlikely to be known and some high carbon steels may be encountered. Low-hydrogen electrodes minimize cracking tendencies. Structural scrap frequently comes from dismantled structures such as elevated railroads, which use rivet-quality steel that takes little or no account of the carbon content. This chapter also explains gas tungsten arc welding, including its advantages and disadvantages.