Innovation of quality improvement to reduce weld defect through six sigma methods in the fabrication process of power plant component

This study aims to improve the quality of boiler through six sigma methods. Quality of boiler in the thermal power plant should be maintained with a good performance in order to assure that power plant can operate normally. DMAIC principle, defining, measuring, analyzing, improving, and controlling processes is implemented in this research. The reseach finding that the average rejection rate that exceeds the target rejection rate are Radiography Test (RT) of welding tube- tube, header-header, and header-end caps. Porosity is a type of weld defect that often occurs, around 36%. Project team concluded three critical that influence the output variables the most. These four variables are welder skill, welding fluxes gas, and welding condition. By implemented improvement of six sigma methods, sigma value increased from 4.1 become 5.