DOI:10.11973/fsyfh-202212016某电站3B循环水泵连接法兰和螺栓断裂原因刘永成(中国大唐集团科学技术研究院有限公司华中电力试验研究院,郑州450000)摘要:某电站3B循环水泵连接法兰及螺栓发生断裂。采用宏观观察、化学成分分析、显微组织观察、力学性能测试、扫描电镜及能谱分析等方法,分析了法兰及螺栓断裂的原因。结果表明:在海水介质环境中,法兰结合面与螺帽压紧面发生缝隙腐蚀,引起螺栓松动,在螺纹根部形成疲劳裂纹,从而发生疲劳断裂,法兰承受的应力大幅增加,在导流体自重、叶轮转动及流体扰动等共同作用下,最终导致法兰发生过载断裂。关键词:法兰;螺栓;疲劳断裂;缝隙腐蚀中图分类号:TG174文献标志码:B文章编号:1005-748X(2022)12-0100-04FractureCauseofConnectingFlangeandBoltsofa3BCirculatingWaterPumpinaPowerStationLIUYongcheng(HuazhongElectricPowerTestResearchInstitute,ChinaDatangGroupScienceandTechnologyResearchInstituteCo.,Ltd.,Zhengzhou450000,China)Abstract:Theconnectingflangeandboltsofa3Bcirculatingwaterpumpinapowerstationwerefractured.Bymeansofmacroscopicobservation,chemicalcompositionanalysis,microstructureobservation,mechanicalpropertytest,scanningelectronmicroscopyandenergydispersivespectrometeranalysis,thereasonsforthefractureofflangeandboltswereanalyzed.Theresultsshowedthatintheseawatermediumenvironment,crevicecorrosionoccurredbetweentheflangejointsurfaceandthenutpressingsurface,causingtheboltsloosenandfatiguecracksnucleatedattherootofscrewthread,resultinginfatiguefractureandthestressontheflangewasgreatlyincreased.Underthecombinedactionofself-weightofthefluid,therotationofimpellerandfluiddisturbance,theflangewaseventuallybeoverloadedandfractured.Keywords:flange;bolt;fatiguefracture;crevicecorrosion2020年9月,某电站3B循环水泵的振动烈度由1.2mm/s突然升至5.5mm/s,电流由310A升高至398A,并在运行15min后停运。3B循环水泵解体后,发现循环泵内接管导水板上的法兰发生断裂,与法兰连接的螺栓有13根(共16根)发生断裂,螺帽均完好。3B循环水泵为全双相钢结构立式混流泵,于2016年3月完成改造后投入运行。水泵型号为2200VZNM。断裂法兰与螺栓材料均为2205双相不锈钢。为查明法兰断裂的原因,以消除机组金属设备在安装和运行过程中产生的缺陷和安全隐患,...
