material to be welded such as melting temperature, density, thermal conductivity, and tensile strength take an important role in welding. Depending upon how the heat applied is created; we get different types of welding such as thermal welding, gas welding, and electric welding. Here in this chapter, we will discuss only about the electric welding and some introduction to other modern welding techniques. Welding is nowadays extensively used in automobile industry, pipe-line fabrication in thermal power plants, machine repair work, machine frames, etc. ADVANTAGES AND DISADVANTAGES OF WELDING Some of the advantages of welding are: o Welding is the most economical method to permanently join two metal parts. o It provides design flexibility. o Welding equipment is not so costly. o It joins all the commercial metals. o Both similar and dissimilar metals can be joined by welding. o Portable welding equipment are available. Some of the disadvantages of welding are: o Welding gives out harmful radiations and fumes. o Welding needs internal inspection. o If welding is not done carefully, it may result in the distortion of workpiece. o Skilled welding is necessary to produce good welding. ELECTRIC WELDING