某抽水蓄能电站顶盖联结安全性复核

Safety Review of Head Cover and Seat Ring Connection of a Pumped Storage Power Station

通过对某抽水蓄能电站提升预紧力后的顶盖螺纹联结结构的强度复核,现有顶盖螺栓的预紧安全系数、夹紧力安全系数和螺栓材料安全系数均能满足要求,螺母的强度不能满足预紧要求。本着同螺栓有较好匹配原则,重新选用的螺母强度符合按照ASME分析设计原则校核的强度要求。由于现有顶盖的强度偏低,需在顶盖和螺母之间增加一个20mm厚的垫圈。座环内螺纹的强度也满足要求。提升预紧力需要更换螺栓和螺母,该电站机组已经安全运行一个大修周期,进一步提升预紧力的必要性值得探讨。

Through the strength review of the screw connection structure of the roof after increasing the preload in a pumped storage power station,the preload safety factor and the residual force safety factor and the bolt material safety factor were conform to the requirements,while the strength of the nut could not meet the pre-tightening requirement.Based on the principle of good match with the bolt,the strength of the re-selected nut was conform to the requirement with ASME analysis and design principles.Due to the low strength of the existing top cover,a 20mm thick washer should be added between the top cover and the nut.The strength of the internal thread of the seat ring also met the requirements.The power station unit has been operating safely for a major overhaul period,and the necessity of raising the preload is worth discussing.