Ensuring the required mechanical-technological properties of welds is a critical issue in the application of multi-wire submerged arc welding (SAW) processes in the manufacture of large-diameter pipes made of high-strength fine-grained steels of grade X70 and higher according to API 5L. Excessive heat input of up to 10 kJ/mm is one of the main causes of the formation of microstructural areas in the heat-affected zone (HAZ) with deteriorated mechanical properties, such as impact toughness and tensile strength. In this work, a variant of a five-wire SAW process is proposed that reduces the weld volume and the heat input, while retaining the high process stability and production speed of multi-wire SAW. By adapting the welding wire configuration of a five-wire SAW process and the energetic parameters of the arcs, the high penetration depth of approx. 24 mm and a 10 % reduction in the weld cross-section could be achieved compared to the usual process configuration. This effect was transformed into a higher welding speed, which led to a reduction in the heat input. A concept for process monitoring is proposed in order to maintain constant manufacturing quality in large-diameter pipe production. In addition to the analysis of electrical process signals such as welding current and welding voltage, acoustic process monitoring using vibro-acoustic sensors provides reliable information on the stability of the welding process. The evaluation of characteristic process features is presented and discussed in this article.
Material-adapted and process-reliable multi-wire submerged arc welding of large-diameter pipes
Part of the proceedings of
PE Pipelines – Improvement of Productivity and Safety Using Mobile VFT Welding Trac`s
Effect of welding defects on mechanical properties and fatigue life of girth welds of X80 steel pipe
Case Study On Environmental Cracking Resistance Assessment Of Welded Segments Of An Interconnecting Sour Gas Feed Pipeline