关键词: 超超临界机组, 高压旁路, 主阀门, 阀座, 堆焊

Abstract: In this paper, the restoration of main valve seat of HP bypass pipes in a 1 000-MW coal-fired USC power unit is introduced in detail. Through implementing strict restoration procedure and adopting hot-wire arc welding and nickel-base superalloy as transition material, as well as the flexible robotic welding arms with six-aixs simultaneous motion the problem of surfacing in tight spaces, such as the main valve chamber of HP bypass pipes under high-temperature harsh environmental conditions is tackled, which ensures the quality of surfacing layer to meet the performance requirements of valve seat sealing surface. Meanwhile, the defects such as cracking and blowing loss on the steam valve seat of HP bypass pipes which is built with SA184-F91/F92 are solved completely. Therefore, the reliability and economic efficiency of the power unit are guaranteed. This restoration can provide ideas and methods for solving steam valve leakage under high steam temperature and pressure in coal-fired USC power units.

Key words: USC power unit, HP bypass pipe, main valve, valve seat, surfacing