奥氏体不锈钢管线开裂失效分析及预防措施

某石化公司一奥氏体不锈钢管线发生腐蚀开裂。本文通过宏观检验、化学成分分析、金相检验和硬度检验等方法进行失效原因分析,确定开裂原因为碱应力腐蚀开裂,并提出了建议措施。     

氧化铝厂建筑防碱腐蚀措施

氧化铝生产过程中有碱腐蚀产生，因跑、冒、滴、漏、设备检修、生产事故等原因腐蚀建筑物，楼面、地面易受碱腐蚀而破坏，影响正常生产。合理皋用防腐蚀材料，如耐碱砼、钢材、聚氯乙烯胶泥等，采取有效的防护措施和防腐蚀构造，防止建筑物被碱腐蚀。     

混凝土碱骨料腐蚀及预防措施

碱骨料腐蚀是一种由碱－骨料反应引起的混凝土腐蚀，是导致混凝土耐久性不足的一个重要因素。通过分析骨料腐蚀的机理和产生的条件，提出了碱骨料腐蚀的预防措施以及在预防碱骨料腐蚀中应注意的几个问题。     

喷气燃料银片腐蚀原因及快速检测技术比较

通过酸、碱、水、汞洗及硝酸银试验,以及卤素、氮化物分析和腐蚀产物分析,表明,喷气燃料对银片腐蚀的原因主要是微量的元素硫和多硫化合物.针对喷气燃料银片腐蚀试验时间过长的难题,研究比较了喷气燃料银片腐蚀电解池法、升温法和微波法的各自特点,提出了能够缩短化验时间、提高腐蚀速度的用微波加热促进银片腐蚀的快速检测方法.     

重油加氢装置脱硫系统再生塔顶空冷器出口管束腐蚀穿孔原因分析

对失效的重油加氢装置脱硫系统再生塔顶空冷器出口 管束进行了外观检查，分别用X射线衍射技术和SEM分析了管束腐蚀产物的相组成、元素含量 与形貌.结果表明，腐蚀减薄穿孔原因是由高温下乙醇胺引起的碱腐蚀所致，硫化氢腐蚀也 起到了辅助作用.     

热强碱介质中耐磨高锰钢冲击韧度的研究

采用浸泡腐蚀试验和腐蚀前后的冲击试验并借助于扫描电镜观察,研究了热强碱介质中高锰钢的腐蚀速率和冲击韧度.结果表明,高锰钢的平均腐蚀速率显著高于中碳铬合金钢,腐蚀过程中高锰钢有较严重的碱脆开裂现象.随着热强碱腐蚀时间的延长,高锰钢的冲击韧度明显降低,碱脆开裂是造成高锰钢冲击韧度下降的主要原因.在伴有冲击的热强碱腐蚀磨损工况,高锰钢有过早失效的危险.     

乙烯EA1123稀释蒸汽发生器腐蚀原因分析

某乙烯装置EA1123稀释蒸汽发生器在最近运行17个月中发生腐蚀泄漏13次。本文从设备、工艺上分析了腐蚀原因,认为工艺水中含有大量硫化物,碱,形成NaOH-H2O和H2S-H2O腐蚀体系。在稀释蒸汽发生器中,腐蚀性介质由于蒸发浓缩产生强酸或强碱性腐蚀而引起换热管外壁局部腐蚀穿孔;提出了工艺防腐蚀措施。     

某碱储罐裂纹成因分析及处理方法

锦州某石化公司添加剂车间一个50 m3立式浓碱储罐的焊接热影响区出现大量严重裂纹。对其产生原因进行了分析,进而提出了处理措施。分析结果表明,该储罐焊接热影响区裂纹是一种碱脆应力腐蚀裂纹。合理选材、选择合适的运行加热方式和温度可以有效地防止碱脆的发生。改造后的碱储罐使用3年多没有再发生渗漏现象。     

12Cr13热碱泵叶轮失效及影响因素研究

12Cr13钢热碱泵使用短时间内发生严重变形失效,采用SEM、EDS、XRD等检测技术对失效后叶轮表面腐蚀形貌、腐蚀产物物相及组成进行分析,查找失效原因,采用正交实验对各因素的影响程度进行分析。结果表明:叶轮表面发生严重的冲刷腐蚀,腐蚀产物多孔疏松,分布有少量微裂纹,产物中除了可形成钝化膜的Cr_2O_3也含有Fe,Mg和Zn等的化合物,破坏了Cr2O3钝化膜的连续性和致密性,失去对基材的保护作用;大流速冲刷促进腐蚀产物的剥落,加剧局域性碱腐蚀;冲刷腐蚀造成叶轮明显减薄,降低强度,最终导致变形失效。各因素对12Cr13钢腐蚀速率影响从大到小的顺序为:流速、温度、时间、浓度。     

乙烯顺丁橡胶装置溶剂油系统腐蚀分析

乙烯厂顺丁橡胶装置溶剂油回收系统腐蚀严重，通过现场调查，分析了该系统的腐蚀原因，在试验的基础上提出了适当提高强碱浓度或加大注碱量，控制系统内溶剂油pH值，同时采取材质优化的措施，可以控制并改善顺丁橡胶装置的腐蚀状况。     

二次过热器炉管的腐蚀损伤分析与表征

采用金相检验、扫描电镜、三维视频系统及能谱分析等方法，对350MW火力发电机组经13万h运行后二次过热器炉管内表面严重腐蚀损伤进行了检测与表征。结果表明，该炉管内表面的损伤主要是由水中的氯离子及溶解氧作用下引起的点腐蚀所致，为此提出了相应的预防措施。     

一起电站锅炉严重腐蚀的原因分析及处理措施

某电站锅炉水冷壁发生爆管泄漏,通过水冷壁厚度、材质、金相分析及腐蚀产物成分分析,确定水冷壁失效的直接原因是锅炉水质不合格导致的严重腐蚀。根据事故原因提出了具体的应对措施。     

热水锅炉炉管腐蚀破坏事故分析

采用X射线衍射相分析技术对某热水锅炉炉管的腐蚀产物进行了分析，对炉管材质的化学成分，硬度，抗拉强度和显微组织分别进行了检测，并对锅炉给水的含氧量进行了测定，综合分析结果表明，造成锅炉炉管穿孔漏水的主要原因是氧腐蚀。     

Enhancement of Service Life of Steam Generating Tubes in Oil-Fired Boiler for Power Generation Employing Plasma Spray Technology

The effects of Ni-50 mass% Cr alloy coating, that is plasma-sprayed onto the fire-side of steam generating tubes in a heavy oil-fired boiler, on the high temperature corrosion resistance were examined. One of the severe environments in the industrial manufacturing facilities, where thermal sprayed coatings are employed, is the high temperature corrosion such as the oxidation, sulfidation, and low melting fuel ash corrosion in the fire-side of boiler tubes. In the fossil fuel-fired steam generating boiler facilities, the degradation or failure of steam generating tubes that were derived from the contaminants in a lower grade fuel have often occurred. The situation of degradation of the water evaporator and superheater tubes and corrosion-preventing effects of plasma sprayed coating are described. The enhanced effects of plasma sprayed Ni-50 mass% Cr alloy coating for the suppression of hot corrosion failure of the steam generating tubes of boiler are summarized.     

水冷壁管受热面失效分析

通过电子探讨,能谱和Ｘ射衍射等多种分析技术系统分析某电厂锅炉水冷壁管发生局部腐蚀的原因。结果表明,腐蚀产物中硫含量很高,局部区域超过２０（ｗｔ％）,产物主要由铁的氧化物和硫化物组成。水冷壁管受热面腐蚀主要原因是高温硫腐蚀。     

余热锅炉省煤器管腐蚀原因分析

 对在役使用的余热锅炉省煤器管进行了现场取样,经化学成分分析、机械性能测试,省煤器管束符合材质要求.通过外观检验、壁厚测量、扫描电镜、能谱和X射线衍射,对省煤器管腐蚀原因进行了分析.结果表明,余热锅炉以瓦斯气作为燃料,总硫含量波动大,硫分在燃烧时绝大部分变成了SO2,其中有一部分可进一步氧化成SO3,SO3与水汽作用而在省煤器低温部位凝结成H2SO4.腐蚀产物分析证实蚀坑内腐蚀产物为硫酸铁,管外表面附着物经检测也有其它硫酸盐形式.证实管外表面蚀坑处于易于形成露点的位置管材外表面局部腐蚀是因露点腐蚀造成.露点腐蚀蚀坑深达0.9mm,并已连片出现,难以满足省煤器管使用条件.管内表面腐蚀产物主要为Fe2O3,说明管内表面受除氧水均匀腐蚀.      

船用锅炉过热管束异常破损分析

某型船用主锅炉过热器管束普遍存在短时间非正常破损现象.通过对该主锅炉过热器管束的勘查和腐蚀产物分析,认为破管的主要原因是管壁温度过高、过热蒸气中的氧和氯离子的协同作用结果.据此提出了改进措施和建议.     

Retardation of High-Temperature Fuel Ash Corrosion of Fireside Boiler Tubes via Nanoparticles

The high-temperature corrosion rate of boiler tubes was studied as a function of inhibitor concentration, time, and temperature in the absence and presence of fuel ash. Samples of steel tubes were taken from boilers that operate in Northern Baghdad Station for Electric Power Generation. Fuel ash was collected from the boiler combustion chamber, as well. Normal and nano-MgO were used as a corrosion inhibitor in different mixing ratios. A weight loss technique was used to evaluate the corrosion rates, while scanning electron microscopy was used to study the surface morphology. It was seen that corrosion rates increased with both time and temperature, and decreased with the addition of inhibitors. The maximum inhibitor efficiency was 81 %, obtained via using nano-MgO at mixing weight ratio 2:1, 600 °C, and 10 h. The Presence of fuel ash had harmful effects on the steel surface.     

Mechanistic aspects of carburization in oil-fired power plants

Materials degradation due to surface carburization has been recently reported in connection to failures or high corrosion rates of superheaters or reheater tubes of oil-fired and coal-fired boilers. Reducing conditions to explain carburization process of materials are hardly to expect because fuel is burned with oxygen excess to attain its complete combustion. The formation of sodium carbonate as a carburization catalyst has been proposed in order to explain carburization phenomenon in boilers, however this carburization catalyst has been rarely found in ash deposits on carburized tubes. In order to study the role of some compounds present in boiler deposits as possible carburization catalysts and the corrosion behavior of 304H-type stainless steel in boiler deposits under reducing conditions, pack-carburization experiments were carried out at 650°C by 1000 hours. Mixtures of 60 wt.% carbon and 40 wt. % of different typical compounds of boiler tube deposits were used. The experimental results show that ash deposits and several deposit compounds act as carburization enhancers, they increase carburization of the alloy if carbon is present in ash deposits. Furthermore, corrosion were detected in some cases. However, other mechanisms might be considered to explain carburization of boiler steels. Analysis of these mechanisms is presented. It is concluded that surface deposition of partially burned particles and its further burning supplying carbon monoxide to the local atmosphere is considered as the main mechanism contributing to carburization of boiler tubes.     

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 某化工厂锅炉蒸发器吊挂管在运行了5年后突然发生爆裂失效。对该吊挂管进行了化学成分分析、金相检验、扫描电镜、X射线衍射分析及力学性能测定,结果表明：吊挂管爆口附近的碳含量和力学性能均低于相关标准规定值;管外壁脱碳;内部金相组织为过热组织。这些都是由于管内壁沉积有钙盐和硅酸盐类水垢,造成管体超温运行的结果。严重沉积的水垢还导致管内壁高温氢腐蚀,壁厚由原来的6 mm减至2～3 mm,因此发生了失效爆裂。根据分析结果提出了相应的解决方案。