Reva Cranes were the first to adopt SAW Welding of the Bridge girders of Cranes in North India. And till writing of this article also there would be only few may be less than 5 crane manufacturers throughout India who are using SAW welding for the Bridge Girders. Submerged Arc welding is a wire-fed process typically used with carbon steels, stainless steels and some nickel alloys, and it is best suited for materials that are 1/2-inch to 5-inches thick. It’s a common misconception that SAW is only for thick metals, however. It can be used to weld material as thin as 3/16-inch thick, by accounting for travel speed and heat input to avoid burn-through. In SAW, a granular flux is used to protect the arc from the atmosphere; the Submerged Arc name refers to the fact that the arc itself is buried in the flux. The arc is not visible when parameters are correctly set and the layer of flux is sufficient. The wire is fed through a torch that moves along the weld joint. The arc heat melts a portion of wire, flux and base material to form a molten weld pool. In this area, all important functions of the flux — degassing, deoxidizing and alloying — take place. Behind the arc, molten flux and metal freeze to form a slag-covered weld bead. When the welding process is correctly set, the slag should come off easily. Because of the necessity of the flux coverage, the SAW process is limited to the flat and horizontal positions. https://www.youtube.com/watch?v=XscJJWZGoxQ

Advantages of Submerged Arc Welding

1. Molten flux provides very suitable conditions for high current to flow. Great intensities of heat can be generated and kept concentrated to weld thicker sections with deep penetrations.
2. Because of high heat concentration, considerably higher welding speeds can be caused.
3. Because of high heat concentration and high welding speeds weld distortion is much less.
4. High metal deposition rates can be achieved. Single pass welds can be made in thick plates with normal equipment.
5. Welding is carried out without sparks, smoke, flash or spatter.
6. Weld metal deposit possesses uniformity, good ductility, corrosion resistance and good impact strength and hence the Weld Quality is improved.
7. Very neat appearance and smooth weld shapes can be got.
8. The submerged process can be used for welding in exposed areas with relatively high winds.
9. Practically, no edge preparation is necessary for materials under 12 mm in thickness.
10. High Penetrations : the major benefit of Submerged Arc welding is high penetrations.
11. As per IS: 807 the welds has to be free from defects, otherwise the allowable stress is reduced to 1/2 . to ensure the same it is must to adopt procedure which gives accurate results. The Welding done by SAW Welding is nearly defect free.

Reva Cranes has adopted many such advanced instruments, machines and methods which that enhances the quality of the products being delivered to the customers.