本文選題：海底管道 + 管道節(jié)點　； 參考：《大連理工大學》2015年碩士論文

【摘要】：隨著海洋油氣資源的大量開采,海底管道作為海洋資源輸運最重要的途徑,其腐蝕問題已引起了高度的重視。由于海底管道長期處于惡劣的海洋環(huán)境中,其外腐蝕破壞的原因也十分復(fù)雜,而近幾年運行期單層保溫管道腐蝕事故的頻發(fā),也暴露出國內(nèi)對其外腐蝕的原因及事故的應(yīng)對措施研究的不足。因此,本論文擬通過試驗的方法,涉及材料科學,海洋環(huán)境學及化學與化工等學科,結(jié)合工程實際情況,對海底管道的外腐蝕成因進行分析、研究,同時給出各原因的解決方法。本論文通過對國、內(nèi)外大量文獻進行研究的基礎(chǔ)上,對海底管道的故障原因進行了歸納、總結(jié),統(tǒng)計得出海底管道外腐蝕故障發(fā)生的特點及規(guī)律,并進一步深入研究。論文選取其中一條發(fā)生外腐蝕破壞事故的管道進行參數(shù)和腐蝕檢測結(jié)果的分析,并通過設(shè)計實驗室水池試驗對事故進行模擬,從而針對試驗結(jié)果,對事故的原因進行猜想和假設(shè)。本文作者從假設(shè)出發(fā),設(shè)計試驗對管道材料的電化學性能進行研究,利用失重法、表面狀態(tài)觀察、穩(wěn)態(tài)極化曲線法、電極電位測量等方法,探究溫度、酸堿度、鹽度等因素對管線材料抗腐蝕性能的影響,同時,對材料的抗點蝕能力、陰極屏蔽現(xiàn)象及氧濃差電池的加速現(xiàn)象進行分析研究,并給出相關(guān)影響因素的改進方法。本論文的主要結(jié)論有：(1)管線材料X65鋼材的在不同溫度、鹽度及酸堿度的條件下,其耐點蝕性能較好,通過對極化曲線及表面狀態(tài)的分析,材料不存在點蝕傾向；(2)在3.5%的NaCl溶液中,溫度升高會造成自腐蝕電位的負移,腐蝕速率加快；在不同鹽度的溶液中,試驗用的X65鋼材料的腐蝕速率會隨著Cl一濃度的增大而降低：針對鹽度、溫度相同,但pH不同的溶液,pH=3的弱酸性溶液會加速腐蝕的腐蝕行為,使X65鋼的腐蝕速率明顯上升；(3)管線補口處所使用的PE材料熱收縮套和防水帽表面能較低,容易發(fā)生分離引起進水事故；該材料對陰極保護電流的屏蔽效果十分明顯,在其陰極保護的作用下,進水區(qū)域的電極電位接近材料自腐蝕電位,無法對進水區(qū)域的達到保護的效果。因此本文針對PE材料補口的問題,提出了通過使用無屏蔽涂層,從而規(guī)避因陰極屏蔽現(xiàn)象造成的管道外腐蝕；(4)管線鋼材料X65鋼在氧濃差腐蝕電池的作用下,貧氧區(qū)域的金屬做陽極,其腐蝕速率會有明顯的加速,達到正常腐蝕速率的3倍,因此,本文從材料成分的角度進行調(diào)查、研究,得出不同組分對氧濃差腐蝕電池的影響。
[Abstract]:With the exploitation of offshore oil and gas resources, the corrosion of submarine pipelines, as the most important way to transport marine resources, has attracted great attention. Because the submarine pipeline is in the bad marine environment for a long time, the reason of its external corrosion damage is also very complicated, and in recent years, the corrosion accident of the single-layer insulation pipeline occurs frequently in recent years. It also exposed the lack of domestic research on the causes of external corrosion and the measures to deal with the accident. Therefore, this paper intends to pass the experimental method, involving materials science, marine environment science, chemistry and chemical engineering and other disciplines, combined with the actual situation of engineering, the causes of external corrosion of submarine pipelines are analyzed and studied. At the same time, the solutions of various reasons are given. On the basis of studying a lot of domestic and foreign literatures, this paper sums up and summarizes the fault causes of submarine pipelines, and obtains the characteristics and rules of the external corrosion faults of submarine pipelines by statistics, and makes further research on them. In this paper, the parameters and corrosion detection results of one of the pipelines with external corrosion failure are analyzed, and the accident is simulated through the design of laboratory pool test, which aims at the test results. Guess and hypothesize the cause of the accident. Based on the hypothesis, the author designs experiments to study the electrochemical properties of pipeline materials. By means of weightlessness method, surface state observation, steady-state polarization curve method, electrode potential measurement and so on, temperature, pH and alkalinity are investigated. The effects of salinity and other factors on the corrosion resistance of pipeline materials are also analyzed and studied, including the pitting resistance, cathodic shielding and the acceleration of oxygen concentration cells, and the improvement methods of related factors are given. The main conclusions of this paper are as follows: (1) the pitting corrosion resistance of pipeline material X65 steel is better under different temperature, salinity and pH. Through the analysis of polarization curve and surface state, there is no pitting corrosion tendency. (2) in 3.5% NaCl solution, the increase of temperature will result in negative shift of corrosion potential and increase of corrosion rate, and in different salinity solution, the corrosion rate of X65 steel will decrease with the increase of Cl ~ (-) concentration: for salinity, the corrosion rate of X65 steel will decrease with the increase of Cl ~ (-) concentration. The corrosion behavior of X65 steel was accelerated by weak acid solution with different pH and different pH, and the corrosion rate of X65 steel was obviously increased. (3) the surface energy of heat shrink sleeve and waterproof cap of PE material used in pipeline repair was lower. The shielding effect of the material on cathodic protection current is very obvious. Under the action of cathodic protection, the electrode potential in the influent area is close to the self-corrosion potential of the material. Unable to reach the protection effect on the influent area. In order to avoid the pipeline corrosion caused by cathodic shielding phenomenon, this paper proposes to avoid the pipeline corrosion caused by cathodic shielding by using unshielded coating. (4) the pipeline steel X65 steel is under the action of oxygen concentration corrosion cell. The corrosion rate of the metal anode in the oxygen-poor region will be obviously accelerated to 3 times of the normal corrosion rate. Therefore, this paper investigates and studies the effect of different components on the oxygen concentration corrosion cell from the point of view of material composition.
【學位授予單位】：大連理工大學
【學位級別】：碩士
【學位授予年份】：2015
【分類號】：P756.2;P755.3

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