分馏塔顶空冷换热器腐蚀的实验研究

本文对催化裂化装置分馏塔顶的空冷器管束内侧的腐蚀行为进行了分析研究。炼油厂催化裂化分馏塔顶空冷器管束腐蚀的主要影响因素有氯离子、硫离子、温度和p H值等。本文选择了现场常用的3种管束材料(10#钢、20#钢、304不锈钢),在模拟实际工况的介质溶液中,研究了氯离子与硫离子含量对材料腐蚀行为的影响,为系统的腐蚀防护提供参考。     

循环水中304不锈钢发生点蚀的Cl~-浓度阈值研究

采用电化学法研究了循环水中304不锈钢点蚀电位(Eb)、蚀孔深度、蚀孔数量与氯离子浓度的关系。结果表明,常温下304不锈钢的Eb总是随着氯离子浓度的增大而减小,当氯离子质量浓度小于800 mg/L时,增大氯离子浓度易导致点蚀敏感,而大于该值时增大氯离子浓度不会明显增大点蚀倾向;从蚀孔深度和表面蚀孔数量得出的304不锈钢点蚀倾向由大变小的氯离子质量浓度阈值为770 mg/L。     

长输管道输油换热设备的腐蚀特性研究

长输管道输油换热设备主要受到由CO_2-H_2O引起的均匀腐蚀、应力腐蚀开裂,由处理引起的点蚀等的影响。本文对目前常用的3种换热设备材料20#钢、304不锈钢、316不锈钢进行腐蚀行为研究,在不同pH值及温度条件下测得其极化曲线,对3种材料进行腐蚀性能对比,确定此3种材料的腐蚀性能,总结出在不同pH值下的规律。     

20#碳钢和304不锈钢在高温环烷酸中的腐蚀研究

采用高温高压反应釜进行高温环烷酸腐蚀试验,改变试验温度、介质浓度和流速等因素,研究了20#碳钢和304不锈钢在高温条件下的腐蚀行为。结果表明,温度、介质浓度和流速对环烷酸的腐蚀速率有显著的影响。两种材质在环烷酸中的腐蚀速率随温度升高,均呈现先增加后减小的规律,20#碳钢的腐蚀速率远大于304不锈钢。280℃时,20#碳钢的腐蚀速率与环烷酸浓度呈线性增加关系。同条件下,304不锈钢的腐蚀速率存在明显的拐点,酸值浓度为5～10 mg KOH·g~(-1)时,其腐蚀速率呈高梯度的增加。碳钢的环烷酸腐蚀速率对流速的变化敏感,腐蚀梯度随介质流速增加而明显增大。304不锈钢的腐蚀速率较低,流速为3.40m·s~(-1)时,其腐蚀速率仅为0.0632mm·a~(-1)。     

浅谈反应釜搅拌桨腐蚀的处理措施

针对反应釜1Crl8Ni9Ti不锈钢搅拌浆在使用含氯物料生产中的腐蚀破坏现象,选用4种材料进行现场挂片试验。得出腐蚀是氯离子的点蚀造成的,并建议使用含钼较高的1Crl8Ni9TiMo不锈钢或20号钢作搅拌浆。     

两种钢在高温环烷酸中腐蚀行为的研究

采用高温高压反应釜,考察温度、酸值和转速对20#碳钢、304不锈钢腐蚀速率的影响。结果表明:在220~300℃随着温度的升高,20#碳钢腐蚀速率先增大后减小,在280℃达到最大值0.654 mm/a,304不锈钢材料腐蚀速率逐渐较小;随着酸值的增大,20#碳钢腐蚀速率不断上升,在酸值为8~10 mg KOH/g时增速最大,304不锈钢呈直线趋势逐渐减小;在转速为0.8~2 m/s的范围内,20#碳钢腐蚀速率由0.654 mm/a变化到0.56 mm/a,304不锈钢由0.039 6 mm/a变化到0.011 2 mm/a,说明在低转速范围内环烷酸腐蚀影响并不太明显。     

氯离子浓度对16Mn与304不锈钢的电偶腐蚀影响的研究

焊缝因为有异种金属接触,所以会发生电偶腐蚀。温州去昂利用普林斯顿2273电化学工作站中的ZRA零电阻电流计通过正交试验的方法研究了氯离子浓度对16Mn和304不锈钢电偶腐蚀的影响。结果表明16Mn开路电位比304不锈钢低;随着氯离子浓度的增加,16Mn与304不锈钢电偶对的电偶腐蚀效应也越大,其电偶腐蚀程度越大电偶腐蚀越严重。     

不锈钢304L、316L、SAF2205、SAF2507及钛材TiGi2在溴离子作用下腐蚀性能的比较

本文采用化学实验的方法,将不锈钢304L、316L、SAF2205、SAF2507及钛材TiGi2置于特定的含溴介质中加速腐蚀,在短时间内使上述五种耐蚀材料产生了不同的腐蚀结果。通过对不同材料腐蚀方式、腐蚀失重及其它腐蚀参数的观察与测量,比较了这五种材料在含溴离子介质中的腐蚀特性和腐蚀抗力,并从理论上对试验结果及Cr、Mo元素对不锈钢腐蚀性能的影响进行了分析和讨论,发现由于Cr,Mo元素含量的不同,304L,316L钢在溴离子作用下易产生点腐蚀,二者腐蚀特性不同,腐蚀速率相近,SAF2205,SAF2507抗点蚀性能优异,但对缝隙腐蚀敏感,且腐蚀速率不同。同时,试验证实钛材TiGi2耐蚀性能明显优于不锈钢,在含溴离介质中其钝化膜稳定,不易受溴离子干扰。     

不同温度下CO_2对输油换热设备腐蚀行为的影响

本文针对延长石油管道运输公司换热器进行腐蚀部位取样,对目前常用的3种换热设备材料20#钢、304不锈钢、316不锈钢进行研究,采用极化曲线测试法研究不同pH下温度对腐蚀速率的影响,对3种材料进行腐蚀性能对比,确定此3种材料的腐蚀性能。     

砂粒和氯离子对P110钢冲刷与腐蚀性能的影响

采用旋转圆盘冲蚀仪并辅以腐蚀电化学工作站分别测试了P110钢(26CrMo4)在含不同砂粒粒径和氯离子浓度溶液中的冲刷腐蚀行为。借助扫描电镜形貌观察,分析了不同氯离子浓度与砂粒粒径对P110钢冲蚀速率和腐蚀行为的影响规律。结果表明:砂粒粒径和氯离子浓度对P110钢冲刷和腐蚀过程有着重要影响,均为腐蚀和机械的协同作用所致。粒径较大的砂粒在冲刷时加速了传质过程,引起腐蚀作用的增加,最终导致整个冲刷腐蚀失重率的增加。氯离子的存在致使腐蚀过程中大量点蚀坑的形成,引起局部冲刷作用的加剧,最终导致P110钢的整个冲刷腐蚀失重速率增加。     

应变和氯离子浓度对304不锈钢点蚀敏感性的影响

The effects of strain and chloride concentration on pitting susceptibility for type 304 stainless steel were studied in situ using the electrochemical technology under constant strain. The impact factor fc was brought forward to value the effect of strain on pitting. The pitting behaviors of type 304 stainless steel in various chloride concentrations under the strain levels 0%, 10%, and 30% were investigated. Potentiostatic polarization technology was used to study how the chloride concentration affected corrosion current density. The results indicated that fc increased substantially and pitting potential varied remarkably when chloride concentration was over 90 mg.L . Under the three levels of strain mentioned above, when chloride concentration was below 463 mg.L^-1,121 mg.L^-1, and 98 mg.L^-1 respectively, the pitting potential shifted towards positivity and, the passive film became more stable. When the strain was below 10%, the pitting susceptibility of type 304 stainless steel varied greatly as strain increased, whereas the susceptibility only changed a little when the strain was over 10%.     

PITTING CORROSION OF SAF2205 DUPLEX STAINLESS STEEL IN ACETIC ACID CONTAINING BROMIDE AND CHLORIDE

Development of duplex stainless steels has been linked strongly with the increasing requirements of the industry for resistance of materials to highly aggressive environments. In the present work, the effects of bromide and chloride ion concentrations and temperature on the pitting corrosion of commercial grade SAF2205 duplex stainless steel were studied. Cyclic polarization and scanning electron microscopy (SEM) techniques were used to study the pitting corrosion behavior of this steel in 80%v/v acetic acid solution containing 0.01, 0.1, 0.2, and 0.5 M sodium bromide and sodium chloride, respectively. Pitting potential was found to decrease with the increase of the temperature and bromide ion concentration. In the presence of chloride ions, pitting corrosion was not observed at room temperature. Critical pitting temperature in chloride-containing solutions was estimated to be above 35°C. In the case of pitting, SEM observation revealed that pit initiation is in the austenite phase regions.     

Pitting corrosion of Cr–Mn–N steel in sulphuric acid media

The resistance to pitting corrosion of austenitic stainless steel Cr18Mn12N has been studied in model solutions of sulphuric acid (0.5 m) containing chloride ions (0.5 m). The cyclic potentiodynamic method has been employed to investigate the effects of chloride ions and agitation rate on the pitting and repassivation potentials. Electron and optical microscopy, electron diffraction spectroscopy and atomic absorption spectrometry have been used to detect the surface sites for pit formation and the growth of pit nuclei. The results obtained with chromium–manganese–nitrogen steel have been compared with those of austenitic Cr18Ni9 stainless steel. A similarity in pit initiation is established, while steel composition exhibits no significant effect. Cr18Mn12N steel is less prone to repassivation as compared with Cr18Ni9 steel.     

电解清除氧化皮的304不锈钢盘条耐蚀性的电化学评价

研究了电解清洗黑色和蓝黑色氧化皮304不锈钢盘条在盐酸和氯化钠介质中的耐蚀性能。动电位极化曲线方法测试了清洗后盘条的耐点蚀性能;恒电位充电曲线研究了不锈钢盘条的时间有效性。结果表明,电解清洗后不锈钢具有良好的耐蚀性。表面电子能谱测试表明清洗后不锈钢表面有显著的Mn元素富集,并探讨了Mn元素富集对耐蚀性的影响。     

氯离子与冷却水系统中不锈钢的腐蚀

综述了有关氯离子对冷却水系统中不锈钢腐蚀研究的最新进展,涉及冷却水中氯离子引发不锈钢孔蚀、缝隙腐蚀和应力腐蚀开裂的机理,氯离子的限度,以及影响水中不锈钢腐蚀的其他因素.对如何应对冷却水中氯离子的负面效应提出了见解.     

Effects of nitrate ions on the electrochemical synthesis and behavior of polypyrrole films

Effects of nitrate ions on the properties of polypyrrole films electrodeposited in phosphoric acid medium on 304 stainless steel were studied. The presence of nitrate ions enhances the process of oxidation by moving the oxidation potential of monomers toward more cathodic values and increases the current density of oxidation and reduction peaks while it has no effect on the morphology of the films. It is worth mentioning that nitrate ions have doped the formed films as proven by Infrared spectroscopy. Polarization curves and electrochemical impedance spectra performed in 3% NaCl solutions have shown that the doping of polymer films with nitrate ions improves the pitting corrosion resistance of the stainless steel and also increases the ageing time of polypyrrole coating.     

Electrochemical properties and corrosion protection of stainless steel for hot water tank

The state in which a stainless steel (STS) exhibits a very low corrosion rate is known as passivity, which is self-healing in a wide variety of environments. However, for those STS the corrosion includes pitting, crevice corrosion, galvanic corrosion, hydrogen embrittlement and stress corrosion cracking etc. And the corrosion resistance of STS is affected by area ratio, solution temperature and solution condition etc. Corrosion characteristics of STS 304, welding parts STS 316, STS 329 and STS 444 were investigated with parameters such as corrosion potential, galvanic current measurements, cathodic and anodic polarization behaviors as a function of area ratio and solution temperature in solution for hot water tank. It was found that galvanic current is affected by the area ratio, temperature and a kind of STS for hot water tank. Corrosion potential of welding part STS 316 was lower than that of STS 304, STS 329, STS 444 in solution for #1, #2 hot water tank. Therefore, it is suggested that the welding part STS 316 acts as anode for the other STSs. The amplitude of galvanic current between welding parts STS 316 and STS 304, STS 329, STS 444 in #1 solution is smaller than that in #2 solution. This is the reason that chloride ion quantity in #2 solution is more than that for #1 solution. And then welding part STS 316 corrodes easily by acting as anode compared to the other STS.     

十二烷基硫酸钠对不锈钢在循环冷却水中的缓蚀作用

研究了在50℃含有氯离子的模拟循环冷却水溶液中,表面活性剂十二烷基硫酸钠对不锈钢点蚀行为的影响。实验结果表明,十二烷基硫酸钠对不锈钢的点蚀具有一定的缓蚀作用,且随其浓度的增大,缓蚀效果越好;当十二烷基硫酸钠的浓度为6mmol/L,θ为50℃时缓蚀效果最佳。