Cost evaluation and life cycle assessment of thick plates using SAW and GMAW

Abstract

With the ever-growing demand for steel structures and the rise in environmental awareness, industries are moving towards more sustainable means of producing steel structures, which entails the use of high strength steel instead of mild steel and more sustainable production process. The objective of this thesis is to present a more economical cutting process for thick steel plates based on analytical data. To propose which welding process is more economical and environmentally friendly, and compare the two grades of steels. Justify the move from mild steel to high strength steel base on cost and environmental impact. The objectives are achieved by two sample materials, S355J2 and S690QC, comparing SAW and GMAW, collecting analytical data from online and similar welding experiments with the same parameters. These data were used to calculate the cost of cutting processes and welding processes to evaluate which was economical. For the life cycle assessment, GaBi 6.0 software was used to estimate the environmental burden of each welding process and compared which is more environmentally friendly. The study gives more support to the use of oxyacetylene cutting for steel plates, the use of submerged arc welding process for a more economical and environmentally friendly welding process, and an upgrade to high strength steel from mild steels. Based on the literature and results gotten from both cost and impact categories, this study concludes that for cutting processes, oxyacetylene is the most economical process for cutting steel plates. Submerged arc welding of high strength steel is cheaper than mild steel. Using submerged arc welding is cheaper than gas metal arc welding. The use of high strength steel for structure is more sustainable and environmentally friendly, and the submerged arc welding process has less environmental burden and more environmentally friendly than gas metal arc welding.