Root protection in special welding process

The welding torch provides inert gas coverage of the top of the melting area, but unless precautions are taken there is no coverage of the welding root. The use of inert gases or mixtures of reducing gases allows to obtain a clean and shiny cord, even on the opposite side to the electric arc, guaranteeing cleanliness and avoiding the casting bath melting.

Carbon steel, stainless steel, duplex and superduplex, aluminium, and many other gases have different metallurgical characteristics and reactivity to air.

The choice of the inert gas or reducing mixture, must be made by following the compatibility criterion of the material to weld and critical aspects of the atmosphere generated inside the tank- tube to weld. There are on the market, devices and analysers allowing a correct and safe use of the reducing gas, thus avoiding waste of gas or incorrect use, which voids the operating result.

We recommend the use of nitrogen or argon gas-based mixtures with small percentages of hydrogen depending on personal experience. It is also essential to pay specific attention when working on pipes or welding storage tanks. In these cases, safety equipment cases must be adequate to constantly assess the risk of triggers. Even the flushing equipment is essential for correct use and significant savings of the quantities of gas applied. In this application, it’s fundamental to manage the flow, wich must be laminar and no turbulent. To obtain this effect the gas flow must be low.