交流干扰影响下的最小阴极保护电位

通过模拟试验装置,采用恒电位和恒电流极化试验研究了交流干扰影响下埋地管道阴极保护系统的破坏机理,探究新的确定阴极保护电位的方法。结果表明,可以根据保护电流密度曲线的趋势制定新的阴极保护准则。根据试验结果确定了0～100A·m-2干扰电流密度范围内的最小阴极保护电位限值公式。     

交流干扰下新的保护电位准则的探讨

交流干扰可对埋地管道阴极保护系统的正常运行产生影响。本工作通过实验室模拟装置来探讨交流干扰环境下埋地碳钢管道的新的保护电位准则。结果表明,在环境中存在交流干扰电场的作用时,可以通过提高阴极保护电位(即更负的保护电位)来达到抑阻金属腐蚀、实现保护的要求。一般而言,交流干扰作用越大,作为有效性判据的阴极保护电位也越负。当把阴极保护电位提高的一个较大值时,如-1200 mV(CSE)时,在试验条件下,阴极保护电流几乎不发生震荡。     

交流干扰对埋地管线阴极保护的影响

随着基础建设的加速,高压交流输电线路和交流电气化铁路对埋地金属管道产生的交流干扰日益严重。国外大量案例表明,传统的阴极保护判据无法有效抑制交流腐蚀,而围绕交流干扰和阴极保护之间的相互影响及作用机理目前尚未达成共识。本文综述了目前该方面的研究现状,包括交流干扰下阴极保护有效电位的确定,综合考虑交流干扰和阴极保护相互作用的电流密度判别指标,以及相关交流干扰与阴极保护交互作用机理的讨论,为交流干扰下阴极保护参数的选取提供参考。     

埋地钢质管道交流干扰测试与评价

高压交流输电线路及交流电气化铁路对与其临近铺设的埋地钢质管道会引起交流干扰,产生交流腐蚀,并对阴极保护系统的安全运行带来不利影响。因此,埋地钢质管道中交流干扰的检测与评估是必要的。国内外对于埋地金属管道受交流干扰的测试与分析,主要围绕交流干扰电压、交流电流密度、腐蚀速率等参数的测试来开展。在交流干扰及阴极保护有效性评价方面,国外以交流电流密度及交/直流电流密度比为主要参量。本工作通过对交流干扰下的管地电位信号时频特征研究,得出管地电位信号时频特征与交流干扰源频率存在一致性,为检测和判定埋地钢质管道上的交流干扰提供了一定的依据。     

IR降对埋地管线阴极保护电位影响规律研究

针对新疆油田油气储运公司管线IR降对埋地管线阴极保护电位影响进行现场测量和研究。结果表明,土壤IR降严重影响埋地管线阴极保护电位的测量和评价,消除IR降后的管地电位能有效的对阴极保护效果进行评价。建议定期对所有埋地管线进行消除土壤IR降的测量,以确保各埋地管线阴极保护电位的正确施加和调试,从而确保埋地管线的安全运营。     

管道阴极保护电位无线遥测系统设计

埋地管道阴极保护电位的实时监测,对于保障管道安全具有重要意义。目前阴极保护电位人工定期录取方式的不足,开发采集埋地金属管道阴极保护电位的无线遥测系统,该系统由数据采集模块和监控中心组成,可方便实现对埋地管道测试桩阴极保护电位的无线采集。     

埋地管线钢缝隙腐蚀的机理与防护研究进展

通过对埋地管线钢缝隙腐蚀的机理及防护进行综述,总结了阴极保护下缝内的电位电流分布规律,缝口保护电位、缝口尺寸、溶液导电率与缝内极化电位电流的关系及环境因素对缝隙腐蚀的影响。表明了埋地管线钢的缝隙腐蚀规律研究方面的重大意义。     

交流杂散电流干扰对埋地管道阴极保护电位的影响

设计室内干扰试验,模拟现实中各类因素下交流杂散电流干扰对管道阴极保护电位的影响。通过数据采集系统对电位信号的采集,滤波系统对交、直流信号的分离,分析得到交流干扰下管道真实阴极保护电位的变化。结果表明:在交流干扰下的管道阴极保护电位会产生较大的IR降,使得管道真实的阴极保护电位偏离地表参比法测得的电位值;同时,在交流杂散电流干扰的瞬间,将会有一个较强的电位信号产生,可能会对恒电位仪及管道防腐蚀层产生不利影响。     

站场埋地管阴极保护电位测量与评估的影响因素

建立了站场埋地管试验场,模拟了站场实施阴极保护电位测量的一系列典型应用场景,通过对比试验研究了IR降、金属材料搭接干扰、牺牲阳极材料、阴极保护电位测量方法、防腐层材料及破损等多项因素对阴极保护电位测量与评估结果的影响规律,为开展站场埋地管阴极保护电位测量与评估提供了参考.     

高铁动态交流干扰下管道钢的腐蚀行为试验研究

利用电化学测试、表面分析及失重分析技术,研究了模拟高铁动态交流干扰下管道钢的腐蚀行为和规律及阴极保护的有效性.结果 表明,动态交流干扰下,阴极保护电位向负方向偏移,交流干扰增大管道的阴极保护电流密度;动态交流干扰下,随干扰水平增加,管道钢腐蚀程度增加,点蚀坑明显加深.阴极保护明显减缓交流干扰试样的腐蚀程度,腐蚀速率降为...     

Study of criterion for assuring the effectiveness of cathodic protection of buried steel pipelines being interfered with alternative current

Interference of alternative current (AC) on corrosion of X65 steel was investigated in soil. It was observed that the unfavorable effect of interfering AC was able to be effectively inhibited by increasing the direct current density of the cathodic protection (CP) system. A clear correlation was established between the CP current density and the tolerable AC current density. This led to a new criterion for assuring the effectiveness of CP of buried pipelines being interfered with AC. Field experimental results on a buried pipeline running below a 500 kV transmission line showed that the criterion could satisfactorily predict the risk of AC interfering on the CP system.     

Effect of alternating current on cathodic protection on pipelines

In this work, the effects of alternating current (AC) on the performance of cathodic protection (CP) and the CP potential readings were investigated on a 16Mn pipeline steel in a simulated soil solution. The presence of AC interference decreases the CP effectiveness to protect the steel from corrosion. Only when CP potential is sufficiently negative, the steel is under a complete protection even when the AC current density is 400 A/m². Moreover, the AC would shift CP potential from the designed value. The effect of AC on the CP performance depends on the cathodic potential applied on the steel.     

埋地管道交流干扰与阴极保护相互作用研究进展

系统地综述了交流干扰对阴保电位、阴保电流密度、牺牲阳极电位、牺牲阳极消耗速率、牺牲阳极效率等参数的影响,同时阐述了交流干扰下阴保评价准则及交流腐蚀机理的最新研究成果。最后指出了目前研究存在的主要问题,展望了该研究领域的发展趋势。     

Effects of alternating current interference on cathodic protection potential and its effectiveness for corrosion protection of pipelines

In this work, the effect of alternating current (AC) interference on cathodic protection (CP) potential on a X65 steel in a near-neutral pH bicarbonate solution was investigated, and the CP performance under AC was evaluated by weight-loss measurements. The CP potential applied on the steel cannot be maintained in the presence of AC interference. The shift of the CP potential depends on the applied CP level and AC current density. No matter if the direct current potential of the steel is shifted negatively or positively upon application of AC, the steel suffers from increased corrosion. The AC decreases the effectiveness of CP for corrosion protection. The CP standard at ?0.850?V (copper sulphate electrode) that does not consider the AC interference is not appropriate for AC corrosion protection.     

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。     

电气化铁路对长输管道的交流干扰及防护

我国电气化铁路的牵引供电系统采用单相工频(50 Hz)25kV交流制式,当长输管道与其近距离并行或交越时,电气化铁路会通过电阻耦合的方式对临近埋地段管道产生不同程度的交流干扰,加剧管道交流腐蚀风险。固态去耦合器接地排流是近年来国内广泛流行的防护方法,日东线排流工程实践表明:采用适当规格的固态去耦合器、以及合理的接地材料和施工方式,可以有效抑制管道的交流干扰,能够满足相关标准要求。     

Integral diagnostic in the failure causes of external corrosion of a natural gas transport pipeline

The objective of this study consisted in investigating the possible causes which give rise to the presence of low wall pipe thicknesses on a 16″ natural gas transport pipeline, even though during the last 12‐year period cathodic protection (CP) potentials were kept in the protection range at which external corrosion should not occur. Results from in‐line inspection from a 16″ natural gas transport pipeline showed 46 indications with more than 80% wall thickness lost due to external corrosion in the second segment of the pipeline. Direct inspection at the indication locations, review of the CP system performance, pipeline maintenance programs and studies, allowed to make an integral diagnostic where it was found out that the main cause of external corrosion was an inappropriate coating application since the pipeline construction, this situation has originated the increase of CP shielding effects through time.     

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。     

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.