FLUX SHIELDED ARC WELDING
This process is popularly known as Submerged Arc Welding (SAW).This is a fully mechanised welding process. The electrode is a continuous metallic solid wire in the form of coil. It is fed automatically in to the arc at a constant speed. A layer of flux covers the arc. The power source used is generally a constant potential power source, transformer or a transformer - rectifier. It is of high capacity varying from 750 to 3000 amps. Since, the process employs such large currents, to protect the welder from arc heat, the arc is completely submerged in the layer of flux. Since the welder is fully comfortable, the process is successfully employed all over India.The welding head is mounted on a trolley, which travels along the joint. Alternately the welding head is stationary and the job is moved under it. The wire diameter varies from 2.4 mm to 6.3 mm. The feed rate varies from 5 m / min to 15 m / min. The welding wire is always connected to positive polarity of the power supply. The wire can be solid cored or flux cored. The process gives very high productivity and excellent weld quality. This process is ideal for heavy thickness. Generally used for welding boiler pipes, drums, cross country pipelines, offshore platforms and piping. It is popularly used in fabrication of ships, plate girders, pressure vessels, pipes and penstocks, for welding, surfacing and strip cladding. In strip cladding wire is in the form of strips of size say 1.6 mm x 75 mm wide. To achieve better deposition rates out of this process, tandem welding with two or more torches are used.