PECULIARITIES OF WELDING AND CONTROL IN MANUFACTURE OF HEAT-EXCHANGE MODULES OF EXHAUST-HEAT BOILER OF STEAM-GAS ELECTRIC PLANT OF 150 MW CAPACITY

摘要

Manufacture of exhaust-heat boiler of steam-gas plant of 150 MW capacity for Alchevsk Iron & Steel Works allowed using the secondary metallurgical gases as alternative to the nature gas. Its modular design, high closeness of arrangement in heat-exchange blocks of thin-walled small-diameter pipes of heating surfaces decreased the dimensions of the plant and increased its efficiency factor up to 44.6%. Due to a narrow gap between the pipes the butts of these pipes occurred to be hard-to-reach for welding and control. This caused the increase in the amount of inadmissible defects in welds, and also made the welded joints of pipes almost not suitable for the repair. The making of welded joints on different stands by applying methods of argon-arc and combined welding allowed improving the quality, gave an opportunity to perform repair and to realize their X-ray, ultrasonic and visual-optic control. The manufactured heat-exchange blocks withstood the hydraulic test without appearance of leakage in welded joints, were installed and put into service.