This work presents a systematic approach to the use of friction stir welding for joining pipes Al 6061 aluminum alloy welding was performed on the pipe with different thickness 2 to 4mm, rotational speeds 485 to 1800 RPM and a traverse speed 4 to 10mm/min was applied. The Mechanical properties of welded joints were investigated using different mechanical tests including nondestructive test (visual inspection) and destructive test (tensile strength and hardness ).This paper presents the optimization of friction stir welding for pipe and also highlights the influence of material thickness, rotation speed and travel speed on mechanical properties of FSW 6061 Al alloy. The resultant friction stir welding efficiency increases with increase rotation speed and decreases travel speed and material thickness.