奥氏体不锈钢换热管应力腐蚀开裂分析

为了调查奥氏体不锈钢换热管泄漏的原因,对不锈钢换热管中裂纹宏观形貌、金相组织、管材化学成分和腐蚀产物成分、换热管的力学性能以及换热管服役环境进行了综合分析。分析结果表明:换热管开裂原因为高温蒸汽中氯离子引起的奥氏体不锈钢应力腐蚀,并提出了相应的预防措施。     

大型煤泥蒸汽回转干燥装置换热管应力腐蚀失效分析

针对某大型煤泥干燥项目蒸汽回转干燥装置换热管泄漏的问题,采用X射线荧光光谱仪、扫描电镜和X射线能量色谱仪对泄漏换热管进行化学成分分析、应力腐蚀形貌和腐蚀产物分析研究,探讨加热管泄漏主要原因。结果表明,换热管泄漏的主要原因是管外环境的影响导致的应力腐蚀失效,为蒸汽回转干燥机换热管的设计制造提供有益的参考。     

酸性水气提管束腐蚀失效分析

通过宏观检查、工艺分析、PT检测、腐蚀产物能谱分析、金相检验等手段对换热管的腐蚀部位以及附着产物进行分析,并配以腐蚀机理分析做综合评判,确定316L换热管束腐蚀主要是腐蚀介质与应力集中共同作用的结果。从技术上提出了相应的措施,改变换热管材质,确保设备的长周期运行。     

立式氨冷凝器波纹换热管的失效分析

某公司的立式氨冷凝器波纹换热管采用316 L不锈钢制造,使用1年后陆续发生腐蚀穿孔现象。通过宏观观察、显微检测、水质分析以及工作环境的考察,判断这起失效起源于换热管内壁,冷却水中高含量的氯离子和水垢杂质使钝化膜破坏诱发孔腐蚀的发生。     

煤化工酚氨回收器0Cr18Ni9不锈钢换热管断裂原因分析及对策

针对某煤化工企业使用0Cr18Ni9不锈钢换热管发生腐蚀断裂的现象,利用光学显微镜(OM)、扫描电子显微镜(SEM)、能谱分析仪(EDS)、X射线衍射仪(XRD)等技术手段,对腐蚀开裂的换热管进行了金相组织、元素成分、力学性能、显微硬度、物相组成等的分析。水质监测结果发现,循环冷却水中Cl-离子浓度远超过国标含量小于25mg/L的要求,最高达到了2066mg/L;腐蚀产物成分分析证实了Cl元素的存在;衍射分析中发现了FeCl2相的存在;裂纹扩展前沿微观组织分析表明,裂纹扩展路径穿过奥氏体不锈钢晶粒内部进行,属于穿晶型应力腐蚀开裂(IG-SCC)。损坏位置位于换热器入口折流板附近,其他位置未见损坏。经过综合分析,指出不锈钢换热管腐蚀开裂的原因是由氯离子引发的应力腐蚀开裂,同时温度梯度也影响腐蚀的发展,并在循环水氯离子浓度控制、换热管材质、介质流速设计方面给出了换热器设计防腐蚀建议。     

活性焦脱硫脱硝再生塔换热管腐蚀原因分析

为探究某脱硫再生塔换热管在使用过程中出现腐蚀穿孔问题的原因，观察了腐蚀穿孔管段的内外腐蚀壁面，对管段的截面和内壁面分别进行了金相分析和扫描电镜分析，并对管段腐蚀区域的产物进行了X-RAY能谱分析。结果表明，脱硫再生塔换热管因意外液滴侵入导致管道出现电化学腐蚀和斑块状腐蚀，进而出现穿孔问题，操作过程中防止凝液的出现是解决换热管出现腐蚀穿孔问题最有效的方法。     

蒸汽锅炉节能器管失效机理分析

锅炉在人们日常生活中占据重要地位,燃气冷凝式承压蒸汽锅炉更是具有很高的使用率。某厂使用的锅炉系统中,节能器换热管发生局部腐蚀并引发失效,通过对锅炉系统中水质进行化验,对换热器管用材开展光谱分析,并采用场发射扫描电镜对换热器管内壁腐蚀产物进行能谱分析。结果表明,锅炉给水中氧含量过高,引起氧腐蚀是该锅炉系统失效的主要原因,锅水中高浓度氯离子加剧氧腐蚀,导致节能器管腐蚀穿孔,无法继续使用。     

低温甲醇洗装置贫甲醇换热器换热管失效分析

本文针对低温甲醇洗装置中贫甲醇换热器换热管频繁泄漏问题,抽取其中4根泄漏的换热管段作为试样,从工艺参数、宏观检查、化学成分、金相组织、硬度测定、腐蚀形貌及垢物成分等方面进行失效分析,以期找出腐蚀产物及腐蚀机理。通过分析,垢下腐蚀是造成贫甲醇换热器换热管腐蚀穿孔的主要原因。同时结合实际生产情况,提出了解决措施。     

甲醇装置压缩机冷却器腐蚀原因分析及对策

分析了因甲醇水冷器泄漏导致甲醇装置循环水水质恶化、浊度超标、压缩机冷却器腐蚀泄漏的原因。采取过程监测、分析等手段,并逐步将碳钢材料的冷却器换热管更换为防腐涂层专利技术的换热管,保证了设备的长周期运行。     

蒸汽过热器换热管爆管失效原因分析

针对某企业蒸汽过热器12Cr1MoVG钢换热管在服役过程中出现的爆裂失效现象,采用光学显微镜、扫描电子显微镜(SEM)、能量色散谱(EDS)对12Cr1MoVG钢管基体低倍组织观察、非金属夹杂物分析、显微组织观察和晶粒度评级,分析了钢管表面腐蚀产物层显微组织及成分,结合断口表面形貌和裂纹前沿腐蚀产物进行成分分析,指出烟气侧S元素造成的高温硫腐蚀是导致蒸汽过热器爆管的主要原因。另外,换热管显微组织中出现黄块状组织,导致换热管力学性能下降,是蒸汽过热器爆管的次要原因。     

裂解炉对流段二次注汽过热炉管失效原因分析

通过对发生腐蚀穿孔的BA-1104裂解炉对流段二次注汽过热炉管进行了宏观腐蚀形貌分析,对含裂纹部位进行了光学显微镜观察,断口进行扫描电镜观察以及对腐蚀产物的化学成分和金相组织分析,指出造成炉管腐蚀穿孔的决定性因素与操作温度及介质中存在的碱有关。进而提出了腐蚀控制与防范的措施,确保裂解炉的安全运行。     

凝汽器铜管的防腐技术研究

根据某热电厂的水质情况和凝汽器铜管的腐蚀形式及腐蚀原因,采用二氧化氯杀菌剂进行了冷却水杀菌和胶球清洗工作,并选用氧化淀粉与水解聚马来酸酐、锌离子的复配药剂进行阻垢缓蚀研究,表明对凝汽器铜管具有较好的阻垢缓蚀作用,其腐蚀速率可以小于0．0004g／（m^2·h）,阻垢率可达到90％以上,而且氧化淀粉复配药剂具有无毒、无富营养化问题,对环境污染小,适于在电厂推广应用。     

急冷水空冷器管束泄漏分析及预防

某炼油厂三台急冷水空冷器运行十个月后出现泄漏，通过对这三台急冷水空冷器腐蚀部位的外观、急冷水的组成的分析，阐明了介质中硫含量高是造成空冷器泄漏的主要原因，并提出了相应的预防措施，该类设备的安全稳定的运行得到了保证。     

急冷油/稀释蒸汽换热器管子的腐蚀失效分析

某石化公司换热器在检验中发现管子多起腐蚀穿孔而失效.对换热器换热列管进行了涡流检测,采用直读光谱仪和三维体视显微镜(3D SM)等对失效管子材质及凹坑形貌进行了检验和观察,利用离子色谱分析仪(IC)和质谱分析仪(MS)等对工艺水介质进行了成分检测,并用扫描电镜( SEM)与能谱分析仪(EDS)对失效管破口和凹坑进行了微...     

Vapour side corrosion in a ME desalination plant at Jebel Dhana

Jebel Dhana, from the Abu Dhabi Water and Electricity Authority (ADWEA), operates two 2 MGD multi-effect thermo-compression distillers commissioned in 1996. Tube failures were first reported approximately 16 months after commissioning. The initial tube failures were from the upper rows, but more recent failures were apparently randomly distributed throughout the tube bundle. Ten tubes were removed and their corrosion morphology was examined macroscopically and microscopically. The corrosion products were analysed by X-ray, EDAX, and EPMA techniques. The copper nickel alloy tubes were found to have suffered from vapour side corrosion; however, there was no sign of any copper oxide deposition, as has often been seen in failed tubes from MSF distillers. The failures took two forms: corrosion fatigue cracking, and pitting corrosion. The corrosion fatigue was in the form of a circumferential crack at a flat portion of the tube in the centre of a tube span. It was believed that the flat surface had developed as a result of fretting against a neighbouring tube, and had been worn away to the point of failure. Unfortunately, the position of the tubes in the tube bundle had not been identified during their removal, but it is suspected that the damaged tube had been in the top row, with the flattened portion directly below one of the two vapour inlet pipes. The other tubes sampled showed pitting corrosion. Some of the pitting had perforated the tube walls whilst others showed pitting on the outer surface only. Some of the pits contained corrosion products whilst others were free of them. This pitting corrosion is attributed to the formation of carbonic acid in the presence of oxygen (air). A weak acid is formed due to the dissolution of CO₂ in the condensing water vapour. The gas concentration varies within the tube bundle, due to the vapour phase, allowing the gas concentration to increase in specific areas of the tube bundle, causing the non-uniformity of attack. There was no immediate tie-up between the pitting corrosion and the two steam inlet pipes due to the unknown position of the sampled tubes within the tube bundle. It is recommended that the oxygen level be reduced by ensuring that the distiller vessels are as air-tight as possible, thus reducing the tendency towards pitting corrosion.     

焦化加热炉炉管失效分析

应用扫描电子显微镜、能谱分析以及X射线衍射仪对焦化加热炉炉管的高温腐蚀形貌,腐蚀物成分以及物相进行了分析,结果表明,尽管加热炉管用材是抗腐蚀性能和高温机械性能均良好的Cr5Mo钢,但由于炉膛操作温度过高,且燃料中含硫,炉管不但发生高温氧化腐蚀,还发生硫化腐蚀,使破坏加速,最终导致炉管失效。提出了预防措施。     

YG系列油管防腐蚀涂料的性能研究

针对井下油管的腐蚀环境和防腐蚀涂覆的需要,研制了YG系列油管防腐蚀涂料,包括YG-01烘烤固化型油管涂料和YG-03常温固化型油管涂料等。性能研究结果表明:YG系列油管防腐蚀涂料具有优异的耐盐雾、耐酸和耐油田污水等耐腐蚀性能;以及在高温高压下耐H2S/CO2腐蚀和耐碱等性能,并具有较好的综合性能,可以满足不同腐蚀环境下井下油管内防腐的涂覆需要。其中YG-01满足国内现有进口油管/钻杆内防腐涂覆作业线的工艺要求。     

石灰软化水pH值对冷却水系统铜管腐蚀结垢的影响

大型火电厂中,作为循环冷却水补充水的石灰软化水出水pH值范围较宽,一些机组凝汽器铜管因此产生腐蚀、结垢问题。通过腐蚀和阻垢试验,考察了石灰软化处理系统出水pH值对火电厂循环冷却水系统腐蚀和结垢的影响,试验表明,石灰软化水系统出水pH值为8.5~9.5时,凝汽器HSn70-1和BFe30-1-1铜管腐蚀均较轻;随pH值增高,冷却水结垢倾向略有增加。     

烷基苯F301加热炉炉管失效初析

对一批使用了５ａ时间就换下的烷基苯脱氢进料加热炉炉管进行了剖析和试验，发现这批炉管虽然组织发生变化，机械性能有所下降，但并不影响其继续使用，而内壁腐蚀造成的壁厚减薄和性能劣化才是本次失效的主要原因。导致炉管内壁出现大量腐蚀凹坑乃至腐蚀斑和沟槽的主要机理之一是由严重渗碳所诱发的金属尘化     

The Effect of Surface Roughness and Composition on Wetting and Corrosion of Al−Si Alloys

This paper presents results of wetting and corrosion of cast Al−Si alloys with composition varying from 7–50 wt% Si in contact with water. The dependency of the wetting angle and corrosion properties on the alloy composition, surface roughness, size of water droplets, and microstructure were studied. An increase in the Silicon content reduced the water contact angle (WCA) while an increase in the roughness and/or droplet size increased the WCA. No systematic variation in corrosion was found due to change in the Silicon content. The results are of interest for the development of lightweight (Al−Si) alloys with non-wetting and corrosion-resistant properties.