阴离子和硫酸盐还原菌作用下管线钢腐蚀行为的研究进展

Corrosion Behavior of Pipeline Steel Under Anions and Sulfate-Reducing Bacteria:a Review

近年来,在油气输送过程中,管线泄漏事故屡次发生,这不仅会威胁管线的安全运行,而且会造成环境的污染和巨大的经济损失。腐蚀是造成管线泄漏事故的主要原因。管线钢被广泛地铺设于土壤或海底等环境中,而这些环境通常具有十分复杂的腐蚀特性,如腐蚀性阴离子、微生物、温度、溶解氧、pH值等多种因素都会对管线钢的腐蚀造成影响。因此,在这些因素的共同作用下,管线钢的腐蚀问题不可避免。其中阴离子和硫酸盐还原菌(Sulfate-reducing bacteria,SRB)是造成管线钢腐蚀最主要的因素。在管线钢服役环境中,可能存在Cl^-、SO_4^(2-)、CO_3^(2-)、NO_3^-、S^(2-)等腐蚀性阴离子,其中Cl^-与SO_4^(2-)最为普遍,相关研究较为充分。有关Cl^-对管线钢腐蚀影响规律的研究结果较统一,即随着Cl^-浓度的升高,管线钢的腐蚀速率加快。而有关SO_2-4对管线钢腐蚀的影响规律,目前的观点尚不统一。此外,研究者们在SRB对管线钢腐蚀行为影响方面也做了大量的研究工作。部分研究结果表明,SRB的新陈代谢会加速管线钢腐蚀,还有研究认为SRB会在管线钢表面生成生物膜保护金属,减缓管线钢腐蚀的发生。如今,研究者们意识到管线钢腐蚀的影响因素是多种环境因素共同作用的结果,不能取决于单一环境因素。因此,阴离子与SRB的协同作用对管线钢腐蚀行为的影响成为了目前学术界的研究焦点。研究发现,当阴离子与SRB共同存在时,阴离子会改变SRB的活性,进而影响管线钢的腐蚀行为。目前研究主要集中于Cl^-与SRB共存时,Cl^-浓度反映介质中的盐度,盐类可以通过改变微生物水中的渗透压,影响细菌物质运输,从而改变微生物活性。当腐蚀介质中Cl^-含量较高时,SRB的生长繁殖会被抑制,大部分SRB细胞脱水死亡,不会发生明显的微生物腐蚀,但在Cl^-含量不高且适宜SRB生长的环境中,SRB会与Cl^-共同作用,导致金属发生明显的微生物腐蚀。本文分别综述了阴离子与SRB对管线钢腐蚀行为的影响,总结了SRB与阴离子的协同作用对管线钢腐蚀行为影响的研究现状,提出了当前研究的缺陷与不足并对未来的研究进行了展望。

In recent years,pipeline leakage accidents occurred frequently in the process of oil and gas transportation,which not only threatens the safe operation of pipelines,but also causes environmental pollution and huge economic losses.Corrosion is the main reason of pipeline leakage.Pipeline steels are widely laid in soils and undersea environments.There are always complex corrosion characteristics in these environments.Corrosive anions,microbes,temperature,dissolved oxygen,pH,and other factors can cause the corrosion of pipeline steels.Therefore,under the combined action of these factors,corrosion of pipeline steels is unavoidable.Among them,anions and sulfate-reducing bacteria(SRB)are the main reason for the corrosion of pipeline steels.In the service environment of pipeline steel,there may be corrosive anions like Cl-,SO 4 2-,CO 3 2-,NO 3-,S 2-,etc.Among them,Cl-and SO 4 2-are the most common,and related researches on these two kinds of anions are more adequate.There is a gene-ral consensus among the researchers about the effect of Cl-on the corrosion of pipeline steel.Namely,with the increase of Cl-concentration,the corrosion rate of pipeline steel will be accelerated.However,there is still no unified view regarding to the effect of SO 4 2-on the corrosion of pipeline steel.Besides,great efforts have been put into the research work about the influence of SRB on the corrosion behavior of pipeline steel.Some results indicate that the metabolism of SRB will accelerate the corrosion of pipeline steel,and others suggest that SRB will generate biofilm on the surface of pipeline steel,protecting metal and slowing down the corrosion of pipeline steel.Nowadays,researchers begin to realize that the influencing factors of pipeline steel corrosion are the result of the combination of environmental factors instead of a single environmental factor.Therefore,the synergistic effect of anions and SRB on the corrosion behavior of pipeline steel has become the focus of current research.It has been found that when anions coexist with SRB,anions can affect the corrosion behavior of pipeline steel by changing the activity of SRB.The current research mainly focuses on the coexistence of Cl-and SRB.The salinity of the medium can be reflected by Cl-concentration,and the salts can alter the microbial activity by changing the osmotic pressure in water containing microorga-nisms,affecting the transport of bacterial substances.When the content of Cl-in the corrosive medium is high,the growth and reproduction of SRB will be inhibited,most of the SRB cells will dehydrate and die,and no obvious microbial corrosion occur.While in the environment where the content of Cl-is not high enough for the growth of SRB,SRB will work together with Cl-to induce significant microbial corrosion of metals.In this article,the effects of anions and SRB on corrosion behavior of pipeline steels are reviewed.The synergistic effects of SRB and anions on the corrosion behavior of pipeline steel are summarized.The existed defects and deficiencies were analyzed and the further research direction on these issues was also prospected.