Development of Ultra Compact Orbital Welding Machine for Thermal Power Generating Boiler

An ultra compact orbital welding machine for butt welding of water-wall tubes of power generating boilers on erection sites has been developed. The minimum radial clearance of the welding head is 20 mm, and this value is below the half of the existing orbital welding machines. To achieve the 20 mm radial clearance, the new arc length control mechanism and the flat welding torch of 7 mm thickness have been developed. The high quality of welds was achieved by installing arc length control function to adopt new structural differential motion mechanism. To make the flow of the shielding gas a uniform flow, the metal fiber filter was set up at the gas blow exit of the thin torch.Using the developed orbital welding machines, several thousand joints of water-wall tubes of power generating boiler have been successfully welded on erection site.