Research Regarding the Manufacture of Pipelines through Automatic Tandem MAG Welding on Generators

Abstract

The manufacture of pipelines is a complex technological process starting with laminates supply, joints cutting-processing, rolling, welding, calibration, control, packing, delivery. As a rule, the technological welding process is achieved by welding on generators through MAG and submerged arc welding, procedures which generally take place completely automatically, affecting the quality and cost of products. Beside a series of advantages, submerged arc welding also has disadvantages; it does not eliminate the operator’s intervention and implies some high linear energies with implications on the mechanical-metallurgical characteristics of the welded joints. In this paper we present the preliminary results of the experiments which have been carried out on welded joints on X52 steel plate, g = 12 mm, through classical MAG welding, with one wire - filler material on the first layer, and the filling beads through tandem MAG welding, with two wires. We should mention that the plates had a V(30°) joint and the welding was executed unilaterally, horizontally, the wire - filler material being of the same quality G42 4 M G3 SI1 ( EN ISO 14341) and diameter (1.2 mm), and EN ISO 14175 protection gas. The entire technological welding process was carried out in laboratory conditions, fully robotized, using a QIROX-315 welding robot fitted with QUINTO-GLC 603-type tandem MAG welding installations, owned by ICDT-PRO-DD C12 “Advanced welding eco-technologies”, belonging to Transylvania University of Braşov.