H_(2)S/CO_(2)共存环境中X65钢点腐蚀形成机理及预测方法  

Formation mechanism and prediction method of pitting corrosion of X65 steel in H_(2)S/CO_(2)coexistent environment

作　　者：闫伟[1,2] 刘琬晴 李光聪 张晨[1,2] 邹子琛 Srdjan Nesic YAN Wei;LIU Wanqing;LI Guangcong;ZHANG Chen;ZOU Zichen;Srdjan NESIC(College of Safety and Ocean Engineering,China University of Petroleum,Beijing 102249,China;Key Laboratory of Oil&Gas Safety and Emergency Technology,Ministry of Emergency Management//China University of Petroleum,Beijing 102249,China;Institute for Corrosion and Multiphase Technology,Ohio University,Ohio 45701,USA)

机构地区：[1]中国石油大学(北京)安全与海洋工程学院,北京102249 [2]油气生产安全与应急技术应急管理部重点实验室·中国石油大学(北京) [3]美国俄亥俄大学腐蚀与多相流研究所

出　　处：《天然气工业》2024年第11期161-169,共9页Natural Gas Industry

摘　　要：碳钢管材广泛应用于油气生产系统,在含CO_(2)、H_(2)S、氯离子等多种腐蚀介质共存的多相流环境中,容易发生腐蚀穿孔泄漏,可能造成管道和设备的失效,进而带来安全隐患和经济损失。目前针对H_(2)S/CO_(2)共存环境下金属腐蚀的研究主要集中在较高H_(2)S分压下,多种形式FeS产物的生成规律、产物膜保护特性和点蚀形成机理,很少研究极微量H_(2)S诱发点腐蚀的可能性和发生条件。为此,以X65钢为例,利用大型H_(2)S多相流腐蚀环路实验系统完成了4组测试实验和2组验证实验,研究了40℃、恒定CO_(2)分压环境下,不同H_(2)S分压对低碳钢点腐蚀行为的影响规律,并提出了一种基于热力学理论的预测方法。研究结果表明:①当H_(2)S分压高于50 Pa时,X65钢的腐蚀速率低且表现为全面腐蚀;而当H_(2)S分压低于24 Pa时,随着H_(2)S分压的逐步降低,X65钢的点腐蚀加剧,H_(2)S为2.4 Pa时的点腐蚀速率超过11 mm/a。②当H_(2)S分压极低且马基诺型FeS的过饱和度低于1时,快速形成的FeS膜不能完整覆盖金属表面,暴露表面会在电偶腐蚀的作用下,被饱和CO_(2)溶液快速腐蚀,最终导致低碳钢发生局部点腐蚀。③建立不同H_(2)S分压下低碳钢表面马基诺型FeS过饱和度边界控制曲线,可以准确预测不同条件下碳钢的点腐蚀行为。结论认为,在相关行业标准规定的H_(2)S分压下限以内,H_(2)S/CO_(2)共存环境中极微量的H_(2)S仍然可能会诱发碳钢发生点腐蚀,该认识对于H_(2)S/CO_(2)共存环境下油气管道的局部点腐蚀预测和防腐防护研发具有重要理论和现实意义。Carbon steel pipes are widely used in oil and gas production systems,and they are susceptible to corrosion,perforation and leakage in multiphase flow environments containing various corrosive media such as CO_(2),H_(2)S,and Cl-.This may cause pipeline and equipment failure,thus leading to safety hazards and economic losses.At present,researches on the metal corrosion in H_(2)S/CO_(2)coexistent environments mainly focus on the formation laws of various FeS products,the protective performances of product films,and the formation mechanisms of pitting corrosion under high H_(2)S partial pressures,but seldom on the possibility and occurrence conditions of pitting corrosion induced by extremely trace amount of H_(2)S.Taking X65 steel as an example,this paper carries out 4 sets of testing experiments and 2 sets of verification experiments by using the large-scale H_(2)S multiphase flow corrosion loop experimental system,studies the influence of different H_(2)S partial pressures on the pitting corrosion behavior of low carbon steel under 40℃and constant CO_(2)partial pressure,and proposes a prediction method based on the thermodynamic theory.The following results are obtained.First,when the H_(2)S partial pressure is higher than 50 Pa,X65 steel undergoes general corrosion with a low corrosion rate.When it is lower than 24 Pa,with its gradual decreasing,pitting corrosion of X65 steel intensifies,with the pitting corrosion rate exceeding 11 mm/a at 2.4 Pa of H_(2)S partial pressure.Second,when it is extremely low and the supersaturation of Mackinawite type FeS is less than 1,the rapidly formed FeS film cannot fully cover the metal surface.Thereby under the action of galvanic corrosion,the exposed surface is rapidly corroded by saturated CO_(2)solution,and ultimately local pitting corrosion occurs on low carbon steel.Third,the supersaturation boundary control curve of the Mackinawite type FeS on the surface of low carbon steel under different H_(2)S partial pressures is helpful in the accurate prediction of pitting corro

关 键 词：H_(2)S CO_(2) 共存环境 低碳钢 点腐蚀 腐蚀机理 预测方法 

分 类 号：TB304[一般工业技术—材料科学与工程]