Comparative life cycle assessment of metal arc welding technologies by using engineering design documentation
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The paper aims to analyze and compare the environmental performances of metal arc welding technologies: gas metal arc welding (GMAW), shielded metal arc welding (SMAW), gas tungsten arc welding (GTAW), submerged arc welding (SAW), and flux-cored arc welding (FCAW). Welding is considered one of the most energy-intensive processes in manufacturing. This study was performed in accordance with the international standard ISO 14040/14044 by using attributional life cycle assessment (aLCA).
The functional unit is defined as the “the development of 1 metre of welding seam (qualified by ASME section IX requirements) to join 25 millimetres thick of metal plates made in carbon steel material and considering a V-bevel configuration.” Different configurations of base/filler materials and standardized bevel geometries have been analyzed as welding scenarios. The inventory considers all inputs (e.g., electric energy and filler material) and outputs (e.g., fume emissions and slags) involved in each welding process. A framework for data collection starting from available project documentation is presented as an innovative solution for the inventory phase. The impact assessment includes the human health, resources (midpoints/endpoint), and ecosystems (endpoint) categories from the ReCiPe (H) and cumulative energy demand (CED) methods.
Results and discussion
This study reveals a notable dominance in terms of the environmental burdens of GTAW and SMAW processes, as they present higher impacts in most of the impact categories. SMAW is the most energy-consuming process, and this aspect is reflected in the environmental performance. Conversely, GMAW presents the least environmental load, accounting for less than one third compared with GTAW in terms of the CED indicator and performing very well in terms of the ReCiPe endpoint indicator. Via analysis of different scenarios, the main outcomes are the following: (i) the use of V bevels significantly increases the environmental load when the metal plate thickness increases and (ii) the use of specific materials such as Inconel alloy exacerbates the environmental concerns associated with welding processes.
The use of project documentation allows robust analysis of welding activity. Sensitivity analysis shows how the range of values for specific parameters (e.g., volts and amps) affects each technology in a different manner. Indeed, those ranges have a limited impact on the result accuracy (up to 20%) for more automatized welding processes (e.g., GMAW, SAW, and FCAW), in which only a small number of parameters are set by the operator, and the operator skills are less influential on the quality of the weld.
KeywordsEnvironmental impacts LCA LCI Metal arc welding Welding technologies
- Douglas CA, Harrison GP, Chick JP (2008) Life cycle assessment of the Seagen marine current turbine. Proceedings of the Institution of Mechanical Engineers, Part M: Journal of Engineering for the Maritime EnvironmentGoogle Scholar
- Goedkoop M, Heijungs R, Huijbregts M, De Schryver A, Struijs J, van Zelm R (2009) ReCiPe 2008: a life cycle impact assessment method which comprises harmonised category indicators at the midpoint and the endpoint level. Report I: characterisation—first edition - VROM–Ruimte en Milieu, Ministerie van Volkshuisvesting, Ruimtelijke Ordening en Milieubeheer. (Retrieved from http://www.lcia-recipe.net, last accessed September 2017)
- Heile RF, Hill DC (1975) Particulate fume generation in arc welding processes. Welding Journal, American Welding Society. Fumes and gases in the welding environment. Deposition efficiency of different welding technologies (available at: http://www.esabna.com)
- International Aluminium Institute (2009) Global aluminium recycling: a cornerstone of sustainable developmentGoogle Scholar
- IPCC (2007) In: Solomon S, Qin D, Manning M et al (eds) Climate change 2007: the physical science basis. Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change. Cambridge University Press, CambridgeGoogle Scholar
- ISO (2006a) 14040:2006 - Environmental management - LCA - Principles and FrameworkGoogle Scholar
- ISO (2006b) 14044:2006 -Environmental management - LCA - Requirements and GuidelinesGoogle Scholar
- Jenney CL, O’Brien A (2001a) Welding handbook volume 1, welding science and technology. American Welding SocietyGoogle Scholar
- Jenney CL, O’Brien A (2001b) Welding handbook, Vol. 1: welding science and technology. American Welding Society, Miami, FloridaGoogle Scholar
- Jungbluth N, Frischknecht R (2010) Implementation of life cycle impact assessment methods—chapter 2: cumulative energy demand, Ecoinvent report No. 3, Swiss Centre for LCI, Dübendorf, CH. (Retrieved from http://www.ecoinvent.org, last accessed September 2017)
- U.S. Energy Information Administration (2017) International energy outlook (IEO)Google Scholar
- U.S. Environmental Protection Agency (EPA) (1994) Development of particulate and hazardous—emission factors for electric arc welding (AP-42, Section 12.19) revised final report, May 20, 1994 (AP-42, Section 12.19)Google Scholar
- Weman K (2012) Welding processes handbook. Woodhead PublishingGoogle Scholar
- Zukauskaite A, Mickeviciene R, Karnauskaite D, Turkina L (2013) Environmental and humane health issue of welding in the shipyard. Proceedings of 17th international conference. Transport MeansGoogle Scholar