Selection of Joint Preparation Procedure based on Cost-effectiveness and Defects analysis of Double-V SMAW Joint

Abstract

Double sided shielded metal arc welded joint has wide applications in fabrication sector for production of critical joints but the root pass in those joint leads to many defects, mainly due to the sudden cooling because the adjacent base material is at room temperature in the start of welding and compromises the quality of the weldments. In the fabrication industry, root pass removal is a routine practice for producing quality joints using grinding and air carbon arc gouging. In this research, comparative study of cost-effectiveness and defects analysis of the above root pass removal procedures have applied to the double-v mild steel shielded metal arc welded joint for the selection of better procedure. For cost calculation of joints, labor cost (LC), energy cost (EC), material cost (MC) and overhead cost taken into account and defects examined by the visual inspection, liquid penetrant test, radiographic test and optical microscope. The results showed overall 4.7% lower cost and enhanced quality in terms of macro/micro-defects for ground joint. The major contribution to the lower cost of ground joint has given by the consumables and energy but in defects analysis, only width difference in both sides’ reinforcement i.e., front and back have observed for gouged joint and relatively more numbers of micro-defects.