Through synthetically considering the issues of the high-frequency welding like low electrical efficiency, high working voltage, poorsafety, small single-machine power, and prominent groove corrosion, it selects the laser welding as the new welding method, which can both minimize the energy consumption and narrow the heat affected zone, as well as can lowest the deformation caused by

heat conduction;

It overcomes the guttering corrosion of the coiled tubing produced by ERW and the internal burr in the inner wall; and it is the firsttime to use the laser welding technology in the coiled tubing production in China. The coiled tubing manufactured in the way oflaser welding, has narrow weld seam, small heat affected zone and high weld scantling accuracy. It is nature without internal burr,and overcomes the issue that the common coiled tubing with an outer diameter of not more than 2in has the internal burr. The

diameter is increased, and the inner surface is almost round and smooth, so it can be used for complex operations, to make products have higher fatigue resistance without any groove corrosion issue.