特殊工况用工艺管道的失效分析及其解决对策

【作者】 钟京；

【导师】 杨振国；

【作者基本信息】 复旦大学 ， 材料学， 2009， 硕士

【摘要】 本文综合应用了失效分析的基础理论、测试技术和表征分析方法,系统研究和解决了工业生产企业所发生的非金属材料和金属材料制特殊工况用工艺管道的失效案例。采用X射线衍射仪(XRD)、红外光谱仪(FT-IR)、X射线光电子能谱(XPS)等方法对两种颗粒改性PTFE软管的组成、结构等进行了表征分析;利用示差扫描量热法测试(DSC)、热重分析测试(TG)、差热分析仪(DTA)等热分析方法对两种颗粒改性PTFE软管的导热系数及其他热性能进行了测试分析;通过两个月的腐蚀介质浸泡试验,对软管的耐腐蚀性能进行了评价;并使用三维体视电镜对其表面形态进行了观察。结果表明国产和进口F4软管均是由基体聚四氟乙烯(PTFE)和填充料石墨粒子所组成的共混材料,进口软管表面质量相对好些。两种软管的热性能基本一致。它们能耐各种化学介质的腐蚀,性能均优异,两者的耐蚀性无明显差异。采用光电直读光谱分析和金相组织检验对高压循环气体冷却器三通夹套管的材质进行了检验分析;利用X射线荧光分析(XRF)、X射线衍射分析(XRD)和热重分析(TGA)等方法对夹套管内壁腐蚀物的化学成分和元素组成进行了表征分析,并通过扫描电镜(SEM)和能谱分析(EDS)对腐蚀物的微区形貌和成分进行了系统观察和深入分析。采用光电直读光谱(OES)、金相组织检验等方法对高压循环气体冷却器内管的化学成分和微观组织进行了表征分析和观察,并通过扫描电镜(SEM)和能谱分析(EDS)方法对内管断口表面形貌及其表面腐蚀物的主要元素组成进行了观察和分析。采用光电直读光谱(OES)和金相组织检验对高压循环气体冷却器内管的材质进行了检验分析,通过扫描电镜(SEM)和能谱分析(EDS)对其爆裂断口的微区形貌和成分进行了系统观察和分析。采用ICP-AES等离子发射光谱、离子色谱和红外光谱(FTIR)对循环冷却水的元素种类、阴离子含量和沉淀物的成分进行了表征分析。结果表明高压循环气体冷却器的夹套管、内管的材质均符合质量评定标准;含有一定比例氯离子的不合格循环冷却水是导致内管腐蚀速率加快、壁厚局部减薄迅速,以致强度不足而发生爆裂的主要起因;冷却器的夹套管和内管弯头在冷却水出口处附近的严重结垢,产生了垢下腐蚀和点腐蚀,并导致水流改变产生了局部冲刷效应,这是内管、夹套管腐蚀加剧、壁厚减薄变快的另一关键原因;冷却器冷却水出口处及其附近的弯头的腐蚀物堵塞,干湿交替介质工况不仅导致腐蚀物的快速脱落和局部腐蚀加剧,而且脱落的腐蚀物又使水流改变流向产生冲刷作用,这是夹套管出口处附近内管腐蚀减薄快速的又一重要原因;冷却器的结垢现象相当严重,数量多、分布广、垢物硬,这是与加入的阻垢剂功能失效和加入量不足密切相关。最后根据上述关于工业生产中所使用的非金属材料和金属材料制特殊工况用工艺管道的失效分析,得出国产颗粒改性PTFE软管的主要性能已达到国外同类产品的水平。针对高压循环冷却器的失效提出了相应的解决对策,从而有效预防了类似事故的再次发生,减少了经济损失,避免了可能的人员伤亡,使企业的生产更加安全、可靠和高效。更多还原

【Abstract】 In this thesis,the fundamental theory,testing technique and evaluating analysis method were comprehensively utilized to systematically investigate and solve two failure cases concerned with two types of pipes that applied in special industrial operating conditions and which made respectively from nonmetal and metal materials, which occurred in corporation of industrial production.The composition and structure of two kinds of particle modified polytetrafluoroethylene(PTFE) flexible tubes were studied by XRD,FT-IR and XPS. The thermal conductivity and other thermal properties of two kinds of particle modified polytetrafluoroethylene(PTFE) flexible tubes were analysed by DSC,TG and DTA.The corrosion resistant properties of the tubes were evaluated by immersing them in chemical corrosion medias.The surface morphology of the tubes was observed by 3D-video electricity microscope system.The results show that both domestic and abroad flexible tubes were composite materials consist of PTFE as a matrix and graphite particle as a filling materials,the surface quality of the abroad one is better.The thermal properties of the two types of flexible tubes are almost at the same level.They both can prevent themselves from corrosion attacked by various chemical substances and have little difference with their excellent corrosion resisting properties.The chemical composition and structure of triple outlet jacketed piping of high pressure circulating cooler were inspected by optical-electrical spectrometer(OES) and metallurgical structure inspection.The chemical and element composition of inner surface corrosion substances of jacketed piping were evaluated by x-ray flourescence analysis(XRF),X-ray diffraction(XRD) and thermogravimetric analysis (TGA).The Analysis such as microscopic morphology inspection and chemical composition analysis were studied by scanning electron microscope(SEM) and energy dispersive spectroscope(EDS) on those inner surface corrosion substances systematically.The chemical composition and structure of inner piping of high pressure circulating cooler were inspected by optical-electrical spectrometer and metallurgical structure analysis.The Analysis such as microscopic morphology inspection and chemical composition analysis were studied by SEM and EDS on the bursting crack of inner piping systematically.The chemical and ion composition of circulating cooling water and the chemical composition of its deposits were evaluated by ICP-AES,ion chromatography and FT-IR.The results show that the materials quality of the jacketed and inner piping of the high pressure circulating cooler are qualified according to the quality evaluating criterion.The aggravation of corrosion,the accelerated wall thinning of the inner piping and the so caused bursting crack were caused by the unqualified circulating cooling water which contains certain content of chlorine ion.The aggravation of corrosion and the accelerated wall thinning of the jacketed and inner piping were caused by corrosion under scaling and pitting corrosion due to serious scaling near the cooling water outlet of the jacketed piping and the bend of the inner piping and the so caused local erosive.Another important reason which caused the accelerated wall thinning of the inner piping near the outlet of the jacketed piping is the obstruction of corrosion substances in the bend near the cooling water outlet of the cooler,which creates a dry-wet alternative environment that result in the fast striping of the corrosion substances and the aggravation of local corrosion,and moreover,erosive is also induced by the current direction change due to the striped corrosion substances. The scaling of the circulating cooler is very serious with a large amount,a wide range of distribution and a hard character of the scaling,that is due to the function failure and dosage shortage of the using scaling inhibitor.Finally,based on results from failure analysis performed respectively on two cases of the pipes made from nonmetal and metal materials which are used in special industrial operating conditions,conclusions were made that most of the properties of domestic modified flexible tubes are almost at the same level of those of the abroad counterparts,corresponding countermeasures aim at the failure of high pressure circulating cooler were put forward.These effective suggestions will not only prevent repeating occurrence similar to the analyzed accidents,reduce unnecessary economic loss and avoid possible personnel casualty,but also make the production of corporation more safe,reliable and effective.更多还原