A resource-efficient process design for heavy fabrication: A case of single-pass-per-layer narrow gap welding

Abstract

The welding process, omnipresent in the heavy fabrication industry, is a potential source of hazardous emissions. The article is motivated by the need to improve the sustainability of the heavy fabrication processes. Single-pass-per-layer narrow gap welding (NGW) is a potential alternative for reducing carbon footprint in high-thickness joints conventionally fabricated using the multi-pass multi-layers, sometimes even 100 or more layers, which is time-, material-, and energy- consuming. A newly developed mathematical model allows process design based on resource-efficient bead-on-plate welds (i.e., one layer deposited on a substrate). The results of bead-on-plate experiments are firstly utilized to identify the process capabilities in terms of strength, process, and production measures and subsequently coupled with the NGW mathematical model to arrive at feasible process parameters for a given groove design. The proposed approach implemented for a candidate case reveals significant improvement in the utilization of process capabilities, i.e., increase in strength, melting efficiency, and deposition rate and reduction in energy and material consumption. This investigation brings out three fundamental design rules for single-pass-per-layer NGW, namely i) the corresponding width of the bead-on-plate weld should be >1.5 times the groove width, ii) an upper limit on the utilization of process capabilities exists beyond which the productivity goes down drastically, and iii) the upper limit can be realized only at critical layer thicknesses. The design approach can be implemented to achieve more productive, economical, and sustainable design for processes involving high energy and material consumption.