【作者】 何旭；

【导师】 黄一；

【作者基本信息】 大连理工大学 ， 船舶与海洋结构物设计制造， 2005， 硕士

【摘要】 海底管道系指设置于海底用于输送原油,天然气,海水或者输送淡水,污水的管道。到目前为止,世界上已有几百条海底管道在使用。随着管线的增多,管龄的增长,管道事故频频发生。各国管道工作对管道运行过程中发生的事故进行统计分析认为,管道的腐蚀是影响管道系统可靠性及其使用寿命的关键因素。 我国已建成的长输油气管道中,通常采用防腐涂层与阴极保护并用的复合防腐系统实施防护。在复合防腐系统中,防腐涂层和阴极保护的作用是相辅相成的。完整的防腐涂层可以提高阴极保护的效率,有效的阴极保护又可以对防腐涂层的破损点提供阴极保护电流,使破损点的管道阴极极化而得以保护。因此,两者之中任意一方出现问题,都会造成防腐系统出现故障。 本文对海底管道阴极保护电场进行了研究,并希望得到可行的方法对海底管道的复合防腐系统的工作状态进行评价。本文的主要内容包括以下几个方面。 首先,在对该课题研究领域做了简要回顾的基础上,提出了本文研究的意义所在。其次,由于本文主要研究的是海底管道的防腐系统,因此在第一章中对海底管道的腐蚀与防护进行了简要的介绍,包括腐蚀原理、腐蚀形态、影响因素,防腐涂层的类型和评价参数,阴极保护的原理和评价参数等。文章的重点是第二、三章。第二章主要是应用边界元方法对在防腐涂层出现损伤情况下的海底管道阴极保护电场进行数值模拟仿真计算,研究海底管道周围环境中的电场状态与牺牲阳极的工作状态、防腐涂层老化状态以及环境诸要素之间的固有关系,并建立一个完备的“阴极保护电场-影响因素数据库”。而在第三章中,根据神经网络的功能特点,应用BP神经网络学习由数值计算得到的样本,实现了由环境电位分布到防腐涂层损伤比率、牺牲阳极剩余重量以及保护电流的映射。最终确定了一个基于环境电场测量的海底管道防腐系统状态评价方法,并开发了相关的软件界面。更多还原

【Abstract】 It is known that hundreds of submarine pipelines are used in the world, which are undertaken the transmission of the rude oil, natural gas, seawater, freshwater and sewage. With the increase of the number of the pipelines and the life span, many accidents happened, therefore, many statistical analyses are carried out concerning to the operational process of pipelines. It is believed that the corrosion of the pipe is the critical factors influencing the reliability and the life span of the pipeline system.The overwhelming majority of long pipelines in China are adopted by the anti-corrosion coating and cathodic protection, which are supplemented each other. The intact anti-corrosion coating can enhance the efficiency of the cathodic protection, which in turn can provide cathodically protecting current to the damage points of the coating protected by the cathodic polarization. Thus one of these two aspects is unsuitable can make the anti-corrosion system failure.In this paper, based on the investigation of the cathodic protection electric field of the marine pipelines, the feasible appraisal method for the working condition of the anti-corrosion coating and cathodic protection of the submarine pipelines is obtained. Concerning the above mentioned aspects, the main work in the thesis is outlined as follows.Firstly, based on the literature review in this research field, the significance of the study is presented. Due to the consideration of the anti-corrosion system of the pipelines, a brief introduction of the corrosion and protection of the submarine pipelines is introduced in Chapter 1, which consists of the corrosion principle, the corrosion morphology, influencing factors; the type and assessing parameters of the anti-corrosion coating; and the principle and estimating parameters of the cathodic protection. Chapter 2 is the main part of the thesis, which the numerical simulation for the cathodic protecting electric field of the submarine pipelines is processed via using the boundary element method, and the inherent relationships of the electric field and sacrificial anodes working condition, and the ageing condition of anti-corrosion coating and other factors in the surroundings, are studied. Consequently, a complete cathodic protection electric field versus influencing factors database has been set up. Whereas Chapter 3 implements the projection from the environmental potential distribution to the coating damage rates, and the residual weight of sacrificial anodes to protection current density by applying the numerical samples calculated from the BP neural network. In the end, an appraisal approach is constructed on the basis of the anti-corrosion condition for the submarine pipelines measured from the environmental electric field, and the relevant software interface is developed.更多还原