All-position welding technology of stainless steel thin-walled pipe, CO _ 2 gas shielded welding technology of fixed butt welding of 16MnR steel pipe, welding of heat-resistant steel 1Cr5Mo furnace tube and ZG25 elbow, welding technology of pressure steel pipe 15MnVR steel in hydropower station, application of CO 2 welding technology and construction machinery, comparative analysis of advantages and disadvantages of CO2 welding and manual arc welding, Welding procedure qualification (stretching) of 6mm thick 0Cr 18Ni9 steel plate by covered electrode arc welding, welding of new austenitic heat-resistant steel, reasons for poor quality of one-sided welding and double-sided forming and preventive measures, etc.