本文選題：天然氣管道 + 破損內(nèi)涂層�。� 參考：《西南石油大學(xué)》2017年碩士論文

【摘要】：天然氣管道涂覆內(nèi)涂層不僅能夠提高輸量,而且具有相應(yīng)的防腐效果。環(huán)氧內(nèi)涂層大量應(yīng)用于國內(nèi)外天然氣管道中。但是,國內(nèi)外普遍采用的內(nèi)腐蝕直接評估方法(ICDA)不能適用于這類內(nèi)涂層天然氣管道,同時國內(nèi)外針對內(nèi)涂層局部破損天然氣管道的內(nèi)腐蝕機(jī)理及規(guī)律研究較少。因此,開展天然氣管道破損內(nèi)涂層的局部腐蝕規(guī)律研究,可為內(nèi)涂層天然氣管道的內(nèi)腐蝕直接評估方法的建立及內(nèi)涂層改性方案的制定提供依據(jù)。根據(jù)實際天然氣管道工程概況,確定了腐蝕實驗試樣采用X80管線鋼/環(huán)氧內(nèi)涂層體系。在系統(tǒng)分析了實際天然氣管道工程內(nèi)檢測數(shù)據(jù)分布規(guī)律的基礎(chǔ)上,合理確定了環(huán)氧內(nèi)涂層的典型破損尺寸。從金屬電化學(xué)腐蝕的熱力學(xué)和動力學(xué)理論出發(fā),篩選出了溫度、壓力和Cl-濃度為影響破損內(nèi)涂層處金屬腐蝕的主要環(huán)境因素�；谖^(qū)掃描測試系統(tǒng)(Tafel極化曲線/EIS/SKP)、動態(tài)反應(yīng)釜與腐蝕產(chǎn)物測試平臺(SEM/EDS),研究了不同破損尺寸、溫度、壓力和Cl-濃度下的破損環(huán)氧內(nèi)涂層的局部腐蝕規(guī)律,確定了相應(yīng)的宏觀與微觀參數(shù)、特征,提出了減小內(nèi)涂層破損可能性的氧化石墨烯(GO)改性方案并評價了其防腐效果。通過研究得到的主要結(jié)論如下:(1)破損內(nèi)涂層為寬縫時(3mm× 1mm),破損內(nèi)涂層處的金屬處于開放的腐蝕環(huán)境中,電荷轉(zhuǎn)移更容易進(jìn)行,金屬腐蝕過程持續(xù)發(fā)生。(2)溫度越高,破損內(nèi)涂層處的金屬腐蝕速率比相同溫度下無涂層X80裸鋼越快。EIS結(jié)果表明20℃、30℃時電極反應(yīng)受擴(kuò)散過程控制。SEM結(jié)果表明10℃時生成的腐蝕產(chǎn)物結(jié)構(gòu)較稀松;而30℃時,雖然腐蝕產(chǎn)物增多且致密,但可能形成了氯化物復(fù)鹽,導(dǎo)致腐蝕產(chǎn)物部分溶解,金屬基底重新裸露。(3)管道壓力從1MPa變化至8MPa的過程中,H_2O和腐蝕介質(zhì)的傳輸動力增大,加快了內(nèi)涂層剝離失效,破損內(nèi)涂層處的腐蝕電流密度是無涂層X80裸鋼的2～2.5倍,金屬基底腐蝕更嚴(yán)重。SEM結(jié)果表明8MPa下腐蝕產(chǎn)物表面存在較大孔洞,這些孔洞將成為腐蝕介質(zhì)向金屬基體表面擴(kuò)散的通道,從而為點蝕或坑蝕發(fā)生提供了條件。(4)在0.05mol/LNaCl濃度下,X80管線鋼/破損環(huán)氧內(nèi)涂層體系的局部腐蝕行為最活躍。EIS結(jié)果表明Cl-濃度越高,溶液導(dǎo)電性越好,離子交換越容易,金屬腐蝕受擴(kuò)散過程控制的時間越早。SKP掃描結(jié)果表明隨著浸泡時間的延長,界面兩側(cè)的電勢差由約520mV增大至900mV,局部腐蝕向涂層內(nèi)部轉(zhuǎn)移的趨勢明顯。(5)提出了氧化石墨烯(GO)內(nèi)涂層改性方案,GO的存在使得改性內(nèi)涂層具有更高的硬度和抗劃傷性能,并且能夠有效阻隔H_2O和Cl-向涂層內(nèi)部滲透,將金屬腐蝕活動限制在破損涂層處并形成一層較厚的保護(hù)膜。
[Abstract]:The inner coating of natural gas pipeline can not only increase the quantity of transportation, but also have the corresponding anticorrosive effect. Epoxy coating is widely used in natural gas pipelines at home and abroad. However, ICDAA, which is widely used at home and abroad, can not be applied to this kind of inner coating natural gas pipeline. At the same time, there are few researches on the internal corrosion mechanism and law of the internally coated local damaged natural gas pipeline at home and abroad. Therefore, the study on the local corrosion law of damaged inner coating of natural gas pipeline can provide the basis for the establishment of direct evaluation method of internal corrosion of inner coating natural gas pipeline and the formulation of modification scheme of inner coating. According to the general situation of natural gas pipeline engineering, X80 pipeline steel / epoxy inner coating system was determined. Based on the systematic analysis of the distribution of testing data in natural gas pipeline engineering, the typical damaged size of epoxy coating is reasonably determined. Based on the thermodynamic and kinetic theory of electrochemical corrosion of metals, temperature, pressure and Cl-concentration were selected as the main environmental factors affecting metal corrosion in damaged inner coatings. Based on the Tafel polarization curve / EIS / SKP and the dynamic reactor and corrosion product testing platform, SEM / EDSU, the local corrosion behavior of damaged epoxy coatings with different damage sizes, temperatures, pressures and Cl-concentration was studied. The corresponding macro and micro parameters and characteristics were determined. The modification scheme of graphene oxide (GOO) to reduce the possibility of internal coating damage was put forward and its anticorrosive effect was evaluated. The main conclusions obtained from the study are as follows: (1) when the damaged inner coating is a wide seam, the metal in the damaged inner coating is in an open corrosion environment, the charge transfer is easier, and the corrosion process of the metal continues to occur at a higher temperature. The results of EIS show that the electrode reaction at 20 鈩，

本文編號：1938631