This paper presents a new welding quality evaluation approach depending on the analysis by the fuzzy logic and controlling the process capability of the friction stir welding of pipes (FSWoP). This technique has been applied in an experimental work developed by alternating the FSW of pipes process major parameters: rotation speed, pipe wall thickness and travel speed. variable samples were friction stir welded of pipes using from 485 to 1800 rpm, 4–10 mm/min and 2–4 mm for the rotation speed, the travel speed, and the pipe wall thickness respectively. DMAIC methodology (Defining, Measuring, Analyzing, Improving, Control) has been used as an approach to analyze the FSW of pipes, it depends on the attachment potency and technical commonplace demand of the FSW of pipes process. The analysis controlled the Al 6061 friction stir welded joints’ tensile strength. To obtain the best tensile strength, the study determined the optimum values for the parameters from the corresponding range.