重庆某输气管道地铁杂散电流干扰检测评价与防护案例研究

重庆某输气管道沿线与多条地铁、轻轨交叉并行,管道阴极保护系统受干扰严重。为了认识管道沿线阴极保护水平和真实干扰情况,对其阴极保护参数进行了现场测试。根据测试结果,分析获得了管道沿线干扰大小的分布情况。基于分析结果,利用智能抗干扰恒电位仪开展现场馈电试验。结果表明,在合理分布辅助阳极地床的情况下,利用强制电流阴极保护和牺牲阳极相结合的方法可以将管道的干扰水平控制在可接受范围内。该研究成果可为油气管道动态直流干扰的分析和防护设计提供参考。     

Impressed current cathodic protection

Development of optimum system configurations for ships using scale models (physical scale modelling) The purpose of this fundamental study was to establish optimum cathodic corrosion protection system configurations for ship hulls. Comprehensive surveys were conducted in order to develop a better understanding of the electrochemical processes occurring on a ship hull in a seawater electrolyte. The results obtained show that the performance of a system can only be evaluated when it is installed on a real object. However, once installed the location of the impressed current anodes and the reference electrodes cannot be changed if the potential distribution over the underwater hull is not optimal. Hence, a procedure had to be established that permits the development and optimisation of system configurations for future objects. A validated, experimental laboratory technique using scale ship models was established to determine the fundamentals of cathodic corrosion protection and to develop a theoretical understanding of the underlying mechanisms. The findings obtained in practice could be applied to the models. The model studies were conducted in a systematic manner and under defined conditions in German standard (DIN) artificial seawater and in a natural electrolyte. The experiments clearly showed the functional correlation between the geometric configuration of the reference electrodes on the hull and the locations of the anodes. The results reflect the interrelationships between the electrochemically more positive bronze propeller and the steel. The configuration developed in the course of the experiments provided an optimum distribution of the protection current over the entire hull model. The data from the model study were applied to the design features of the Class 123 Frigate. Subsequently, the efficiency of this procedure was evaluated on a real object in a real electrolyte. The results obtained clearly demonstrate that physical scale modelling is a rational, scientific method for the evaluation and design of impressed current cathodic protection systems.     

杂散电流对海底管道表面电位影响预测方法研究

目的：外加电流阴极保护技术逐渐应用于船舶和海洋结构物防腐领域,但随之而来的杂散电流很可能使平台附近的海底管道本身或者其牺牲阳极阴极保护系统产生电化学腐蚀,缩短海底管道使用寿命,甚至破坏管道本身结构而造成严重的生产事故,因此需要预测外加电流阴极保护系统对附近海底管道及其牺牲阳极阴极保护系统可能造成的不利影响。方法提出一种基于边界元法的预测海底管道杂散电流影响的数值模拟方法,建立包括域内控制方程和对应的边界条件的数学模型,可以计算得到海底管道受杂散电流影响区域的位置和范围,并且得到受影响区域表面保护电位的分布情况。结果通过实验室海底管道模型杂散电流试验测量结果与数值模拟结果进行比较,验证该方法预测海底管道杂散电流影响的准确性,数值模拟仿真结果与试验测量结果最大误差百分比约为1.7%,平均误差百分比小于0.2%。数值模拟计算结果准确地预测了海底管道模型表面保护电位分布情况,预测了导管架平台模型外加电流阴极保护系统对海底管道模型杂散电流的影响情况。结论使用的边界元阴极保护数值模拟技术可以准确预测海底管道杂散电流的影响情况,为海底管道杂散电流影响预测研究提供了有力工具。     

杂散电流干扰和阴极保护作用下碳钢腐蚀规律研究

目的探讨杂散电流和阴极保护二者共同作用对碳钢腐蚀的影响。方法在碳钢管表面手工涂刷涂层并制造小块破损点,研究Q235碳钢在涂层破损后,受单纯直流杂散电流干扰、单纯阴极保护以及二者共同作用时随时间变化的电化学交流阻抗图谱(EIS),通过图谱信息以及图谱数据拟合进行分析。结果所有条件下,Bode图低频阻抗和Nyquist图容抗弧半径都随时间延长而逐渐增加。通过图谱和数据拟合发现,单纯杂散电流条件下,杂散电流越大,电化学阻抗越小,浸泡15天时,20 m A杂散电流条件下的极化电阻达到200 m A条件下的4倍。阴极保护对杂散电流腐蚀具有防护作用,无论是单独施加阴保,还是杂散+阴保共同作用,-1000 m V(vs.CSE)与-850 m V(vs.CSE)横向对比,总是-1000 m V条件下的极化电阻更高。一定程度上,阴保电位越负,极化电阻越大,保护效果越好。结论在一定范围内,不论是单独施加,还是共同作用,总是杂散电流越小,阴极保护电位越负,对碳钢的保护效果越好,腐蚀程度越轻。利用电化学交流阻抗技术监测管道腐蚀状况是可行的。     

沙特波斯湾沿海混凝土结构阴极保护电流密度研究

钢筋的腐蚀对钢筋混凝土结构的使用寿命影响极大,外加电流阴极保护系统能较好地控制钢筋锈蚀,尤其适用于沿海地区受氯盐侵蚀所引起的钢筋腐蚀,本工作重点介绍了在沙特波斯湾沿海一座混凝土结构中所采用的外加电流阴极保护情况,以位于取水口和排水口的阴极保护分区为研究对象,在工场现场对保护电流进行了研究,并对相关的技术参数进行了分析。结果显示,在中东严酷海洋腐蚀环境中的钢筋混凝土结构,外加电流阴极保护系统给混凝土结构提供相对于钢筋表面电流密度大小为5mA/m2的保护最为合适。     

舰船缩比模型外加电流阴极保护系统表面电位的研究

采用缩比模型理论建立舰船外加电流阴极保护系统,研究船体表面电位分布的影响因素之间关系.结果表明,单区阴极保护系统辅助阳极位置决定船体表面电位曲线的形状,参比电极影响曲线电位值的大小.     

Localised corrosion of cathodically protected pipeline steel under the effects of cyclic potential transients

Cathodic protection (CP) may lose its effectiveness for protecting buried steel pipeline from soil corrosion due to the effects of potential excursions caused by stray currents. In this work, dynamic localised corrosion processes of buried steel due to the effects of cyclic potential transients have been visualised using an electrochemically integrated multi-electrode array, often referred to as the wire beam electrode (WBE). The focus has been on the understanding of the effect of cathodic transients. The WBE maps suggest that the amplitude of cathodic transient, as well as the ratio of anodic cyclic to cathodic cyclic, can significantly affect the corrosion rates and patterns. In particular, if the cathodic transient leads to a very negative potential, e.g. ?1350?mV_vs.CSE, rapid corrosion would occur on buried steel surface. These results have implications for CP parameter selection for preventing stray current-affected buried steel pipelines.     

海船保护发展现状

论述了国内海船涂层保护,阴极保护,电解防潮等防蚀防污技术的发展现状,并介绍了国内近年来在船舶舱的腐蚀防护,管防污防蚀以及控制船体杂散电流腐蚀等方面的研究进展及成果。     

Assessing the long term benefits of Impressed Current Cathodic Protection

This experimental field study interrupted the protection current offered by Impressed Current Cathodic Protection (ICCP) to ten in-service reinforced concrete structures. The study aimed to identify the long-term effects of ICCP after it was recognised that some of the systems are now reaching the end of their design life and require a significant level of maintenance. It was found that after five or more years of ICCP, the steel remained passive for at least 24 months after interrupting the protection current despite chloride contamination that would represent a corrosion risk.     

天然气管道杂散电流排流效果评定实例

杂散电流是指在管道周围土壤环境中漫流的一种大小、方向都不固定的电流,这种电流对金属管道的腐蚀称为杂散电流腐蚀,属于电解腐蚀范畴。杂散电流在管道中的流动会加速管道的腐蚀,对管道的安全性产生极大的影响。有杂散电流干扰的管道中,需要对管道实施排流保护,排除管道中的杂散电流。而杂散电流的排流工程是否合理充分,则需要应用相应的检测手段来测定。本文是在已经采取杂散电流排流保护的管道上,通过测量管道上的阴保电位、交流电压和交流电密度来判定管道的杂散电流排流情况。     

Ship impressed current cathodic protection – modulations of system current outputs by propeller/shaft rotation on physical scale model hull

Abstract

Physical scale modelling was employed to examine the effect of propeller/shaft rotation on the current outputs of ship impressed current cathodic protection (ICCP). When a one-hundredth scale metal hull was protected in diluted sea water, propeller rotation produced low frequency modulations of output. Two propellers rotating resulted in two sinusoidal frequencies, the higher frequency ‘carrier’ being amplitude modulated by a lower frequency envelope. There was only the ‘carrier’ waveform present when only one propeller was rotated. The ‘carrier’ frequency (4·67–0·83 Hz) was related to the speed of shaft rotation and was apparently determined by the faster propeller. Envelope frequencies (0·48 and 0·42 Hz) corresponded to differences in speed of the two propellers. Possible causes of this corrosion control phenomenon are proposed, together with the requirement for further experimental investigation and waveform analysis.     

基于缩比模型理论的船舶外加电流阴极保护系统水线下表面电位的研究

采用缩比模型理论建立船舶外加电流阴极保护系统,研究船体表面电位分布的影响因素之间关系。结果表明,单区阴极保护系统辅助阳极位置决定船体表面电位曲线的形状,参比电极影响曲线电位值的大小;增加阳极数量能够优化电位分布,降低曲线电位的波动。试验证明,基于缩比模型理论的船舶表面电位测量方法是一种方便、有效的测量手段,为进一步优化外加电流阴极保护系统提供新的研究途径。     

核电站凝汽器管板的腐蚀分析及外加电流阴极保护

大亚湾核电站凝汽器管板存在腐蚀状况,其机理是钛管和铜合金管板在海水中形成电偶腐蚀,采用外加电流阴极保护方法能有效地抑制腐蚀。结果表明,凝汽器增加阴极保护后,保护效果良好,显著提高凝汽器设备的可靠性和机组的安全性。     

钢质海水管道系统外加电流阴极保护的应用与探讨

根据外加电流阴极保护技术在某钢质海水循环水管道系统中的应用情况，结合理论及实践经验，提出了海水管道系统外加电流阴极保护的设计原则，以及应用中存在的问题，对这些带有普遍性的问题进行了探讨。有关的观点和经验可供应用参考。     

Das kathodische Schutzpotential an Fehlstellen in der Rohrumhüllung und in Korrosionsanfressungen

Cathodic protection potential at defective points in the pipe covering and at pit corrosion zones Cathodic corrosion protection of effectively wrapped pipelines requires low mean current densities only. In principle, Cathodic protection is also practicable for major defective zones. However, the different ohmic voltage drops in front of the metal surface to be protected will at first give rise, in the soil, to a non-homogeneous distribution of the potential which will gradually become homogeneous in the Course of time. With cathodic protection, secondary cover layers containing carbonate are formed at the phase boundary between metal and electrolyte, which result in a decrease in current density. After a short time, the cathodic protection potential can also be detected at the bottom of pit corrosion zones. Normally, the voltage drop between edge and bottom of the pit is small. Following a current failure in a pipeline that has been cathodically protected for years, the pipe/soil potential remains with the cathodic protection range for several days. With intermittent protection current, the corrosion rate is lower than without cathodic protection.     

海洋结构物牺牲阳极阴极保护设计方法探讨

阴极保护在腐蚀防护领域被广泛接受和使用,海洋结构物飞溅区以下通常采用阴极保护方式进行防腐.本文在总结国内外各种常用阴极保护设计方法、标准和实际工程应用设计方法基础上,对海洋结构物常用牺牲阳极阴极保护设计方法进行了系统的分析,指出了各种设计方法的优缺点,供从事相关科研、设计工作人员参考.     

管道阴极保护远传与杂散电流排除技术探究

为提高管道阴极保护效果,降低杂散电流对管道阴极保护系统产生负面的影响,以GPRS技术为基础,并对远端数据控制以及数据分析等方面进行综合研究,从而实现管道阴极保护效果的进一步提升。在管道阴极保护系统搭建的基础上,充分利用电容元件、晶闸管等,对管道周围杂散电流以及阴极保护远传等方面进行控制,旨在实现管道保护效果的进一步提升。     

埋地钢质管道强制电流阴极联合保护研究

目的验证阴极保护系统在保护目标管道的同时对临近管道造成的杂散电流腐蚀,对比柔性阳极与阳极地床在保护管道的过程中产生的杂散电流污染情况,确定同沟铺设的不同管道联合保护方案。方法通过同一排流设备对相同区域的不同管线进行统一保护,阴极保护系统中的接地装置作为唯一的阳极,多条埋地管线作为电化学电池的阴极实现保护。结果阳极地床产生的杂散电流干扰明显强于柔性阳极材料;排流保护中,两条20 m埋地金属管道达到排流保护的范围时,柔性阳极的排流电压为1.2~1.52 V,远小于碳钢阳极地床的3.5~15 V,能够有效减少防护过程中电能的使用。结论同一阴极系统同时对多条金属管道或金属构筑物进行排流保护的措施可行。     

Critical questions and answers about cathodic protection

ABSTRACT

Cathodic protection has been in use for almost two hundred years, yet there still exist a number of misunderstandings surrounding its application. In this paper, we question some common statements and beliefs to determine whether they are based on fact or fiction. Our questions include: What is the origin of the ubiquitous ?0.85?V_CSE cathodic protection criterion and why does it work? Does cathodic protection really stop corrosion or simply reduce it to negligible levels? What does the instant off potential tell us and is it really the true polarised potential? Does hydrogen gas cause cathodic disbonding? Do the potential shifts measured during interference testing indicate real interference? The answers to these questions are important because they allow the correct interpretation of field and experimental data, based on a true understanding of the electrochemical and thermodynamic basis of cathodic protection.     

杂散电流腐蚀与防护

由于电气化铁路、以接地为回路的输电系统等的客观存在，不可避免地造成杂散电流的产生，并使埋地管道因杂散电流而产生腐蚀。杂散电流具有强度高、危害大，范围广、随机性强等的特点，文章介绍了对直流杂散电流腐蚀的控制，提出了最大限度地减少干扰泄漏电流、符合安全距离、增加回路电阻、排流保护和其他保护等措施；并对在强电线路、输油管道上、油库等交流杂散电流腐蚀的防护方面提出了数种可采取的保护措施。