1 000MW空冷机组主蒸汽管道焊后热处理工艺

为解决国内1 000MW级超超临界火电机组主蒸汽管道用P92钢焊后热处理工艺的选定问题，采用柔性陶瓷电阻主、辅加热器同时加热管道内外壁、两端封堵的热处理工艺进行主蒸汽管道焊后热处理，得到了焊缝内壁温度达740℃以上、内外壁最小温差为15℃的热处理效果。针对宁夏灵武电厂二期工程1 000MW空冷机组，进行了主蒸汽管道用P92钢进行焊后热处理试验，试验结果表明，采用该热处理工艺对P92钢进行焊后热处理，特别是对厚壁管道进行焊后热处理，可以保证恒温过程中焊缝内壁温度符合P92钢回火温度要求，从而保证了焊接接头综合机械性能的均匀性。

Postweld Heat Treatment Process of Main Steam Pipe in 1 000 MW Air Cooling Units

According to the postweld heat treatment (PWHT) for main steam pipe using P92 steel in 1000 MW ultra-supercritical thermal power units, the heat treatment process with the main and auxiliary heaters made of flexible ceramic resistance heating at the same time, measuring the temperature both on inner and outer wall, and plugging both ends is applied, by which the inner wall temperature of welding could be up to 740 ℃ and the minimum temperature difference between inner wall and the outer wall is 15 ℃. The PWHT test was carried out on the main steam pipe using P92 steel in 1000 MW air cooling unit of Ningxia Lingwu Phase II Project. The test results show that, for P92 steel, especial the PWHT of thick pipe, the heat treatment process could make the inner wall temperature of weld seam meet the requirements of tempering temperature of P92 steel isothermal process and ensure the uniformity of mechanical properties of welded joints.