A carbon-arc welding process named for one of its inventors, Nikolas de Benardos, of Russia.
The process was based on the principle that if an electric circuit in which the current is flowing is interrupted, the current will continue to flow across the gap in the circuit until the distance across the gap exceeds the force (voltage) driving the current. The gases in the gap offer such great resistance to the flow of current that they are heated to incandescence. This heat melts the base metal to make the weld. As cumbersome as Benardos’ equipment might have been, it paved the way for future developments in arc welding.
Benardos and his associate, Stanislav Olszewski, were granted a British patent in 1885 for a welding process employing carbon electrodes. Benardos patented the process in Russia in 1887, and is credited with the first patent on arc welding, In the Benardos process, the work was connected to the positive pole of a d-c power source, and the carbon rod was connected to the negative pole. The rod was fitted with an insulated handle so it could be manipulated by hand.
To start the weld, the carbon electrode was touched to the work to complete the electrical circuit, then the tip of the electrode was withdrawn a slight distance to establish the arc. The gap was usually between 3 and 12 mm (1/8 and 1/2 in.). Usually there was insufficient material in the workpiece to fill a joint, so a rod of similar composition was melted by the arc to supply the material necessary to fill the joint.