本文選題：川氣東送管道 + 陰極保護(hù)��； 參考：《西南石油大學(xué)》2015年碩士論文

【摘要】：川氣東送管道是繼西氣東輸管道又一條貫穿我國(guó)東西部地區(qū)的天然氣管道大動(dòng)脈,其安全運(yùn)營(yíng)至關(guān)重要。管道運(yùn)營(yíng)2年后對(duì)防腐層進(jìn)行檢漏和修復(fù)時(shí),發(fā)現(xiàn)防腐層破損處管道均已出現(xiàn)不同程度的腐蝕,陰極保護(hù)系統(tǒng)并未起到很好地保護(hù)作用。因此弄清楚川氣東送管道的陰極保護(hù)狀況,并對(duì)陰極保護(hù)效果進(jìn)行檢測(cè)與有效性評(píng)價(jià)非常重要。 論文針對(duì)川氣東送管道的陰極保護(hù)現(xiàn)狀,通過(guò)建立陰極保護(hù)電位數(shù)學(xué)模型,選擇了基于邊界元的數(shù)值模擬軟件Beasy CP開展檢查片現(xiàn)場(chǎng)檢測(cè)方案分析,同時(shí)利用極化曲線設(shè)計(jì)檢查片,從而進(jìn)行檢查片現(xiàn)場(chǎng)試驗(yàn),最后基于檢查片檢測(cè)數(shù)據(jù)和陰極保護(hù)準(zhǔn)則來(lái)分析與評(píng)價(jià)川氣東送管道陰極保護(hù)的有效性,并對(duì)陰極保護(hù)不合格管段提出針對(duì)性的整改措施。主要研究成果如下： (1)建立埋地管道陰極保護(hù)電位分布模型,通過(guò)對(duì)比常用數(shù)值解法,最終選擇了基于邊界元法的數(shù)值模擬軟件Beasy CP開展研究,為檢查片檢測(cè)方案分析奠定了基礎(chǔ)。 (2)根據(jù)建立的電位數(shù)學(xué)模型,考慮了川氣東送管道陰極保護(hù)系統(tǒng)的具體參數(shù),運(yùn)用軟件Beasy CP模擬檢查片形狀、檢查片面積、檢查片位置、管道防腐層破損率及土壤電阻率對(duì)管道與檢查片電位的影響,分析了檢查片現(xiàn)場(chǎng)檢測(cè)方案,并提出了對(duì)檢查片設(shè)計(jì)與現(xiàn)場(chǎng)試驗(yàn)時(shí)的建議。 (3)基于檢查片的設(shè)計(jì)原理,總結(jié)了檢查片檢測(cè)的適用范圍,確定了川氣東送管道檢查片的5個(gè)試驗(yàn)周期。測(cè)試了X70鋼在不同pH值的土壤溶液中的極化曲線,根據(jù)鋼質(zhì)檢查片消耗電流的大小值計(jì)算鋼質(zhì)檢查片面積,進(jìn)而確定了檢查片的規(guī)格尺寸。同時(shí)對(duì)檢查片進(jìn)行IR降預(yù)測(cè),從而驗(yàn)證了陰保檢查片面積大小不會(huì)影響真實(shí)電位的測(cè)量,最終確定了川氣東送管道檢查片組的設(shè)計(jì)方案。 (4)根據(jù)檢查片方案分析與設(shè)計(jì)進(jìn)行檢查片現(xiàn)場(chǎng)試驗(yàn),制作檢查片組,布置了沿線40個(gè)檢查片試驗(yàn)的檢測(cè)點(diǎn),對(duì)檢查片進(jìn)行埋設(shè)、定期開挖、通斷電電位測(cè)量、清洗、掃描電鏡(SEM)及XPS能譜分析,形成了一套基于檢查片的陰極保護(hù)檢測(cè)實(shí)施規(guī)程。 (5)基于檢查片檢測(cè)數(shù)據(jù)對(duì)川氣東送管道陰極保護(hù)進(jìn)行有效性分析、評(píng)價(jià)與建議。 1)根據(jù)檢查片檢測(cè)數(shù)據(jù)分析了管道沿線39個(gè)檢測(cè)點(diǎn)的土壤腐蝕性分布,通過(guò)腐蝕產(chǎn)物的宏、微觀分析,從腐蝕產(chǎn)物的角度說(shuō)明了陰極保護(hù)對(duì)管道腐蝕的抑制作用。 2)基于保護(hù)度評(píng)估了管道陰極保護(hù)效果,其合格率為44%。并將保護(hù)度與通斷電電位相聯(lián)系,得出了川氣東送管道的平均IR降為220mV,即保護(hù)電位(Uon)準(zhǔn)則應(yīng)取-1070mV (CSE);而當(dāng)真實(shí)電位(Uoff)達(dá)到-850mV (CSE)時(shí),其對(duì)應(yīng)的最小陰極保護(hù)度不會(huì)低于65%,提供了陰極保護(hù)日常管理維護(hù)的依據(jù)。 3)以陰極保護(hù)檢查片的年腐蝕速率、通電電位和瞬時(shí)斷電電位三大準(zhǔn)則為判據(jù),分析和評(píng)價(jià)了川氣東送管道沿線39個(gè)檢測(cè)點(diǎn)的陰極保護(hù)狀況,其陰極保護(hù)合格率為74.4%,同時(shí)判斷出了10處陰極保護(hù)失效管段。 4)用風(fēng)險(xiǎn)評(píng)價(jià)和危險(xiǎn)矩陣方法,繪制了以環(huán)境腐蝕性對(duì)“不保護(hù)度”作的危險(xiǎn)矩陣圖,評(píng)估了各個(gè)檢測(cè)管段的風(fēng)險(xiǎn)等級(jí),結(jié)果表明,無(wú)試驗(yàn)管段位于最高風(fēng)險(xiǎn)區(qū)(V),且5、22、27和30號(hào)管段位于次高風(fēng)險(xiǎn)區(qū)(Ⅳ)。 5)分析影響川氣東送管道陰極保護(hù)的因素,提出了對(duì)陰極保護(hù)不合格管段具有針對(duì)性的整改措施,并通過(guò)管道電位監(jiān)測(cè)和現(xiàn)場(chǎng)開挖驗(yàn)證了檢查片檢測(cè)技術(shù)的可靠性。
[Abstract]:The East pipeline of Sichuan gas transmission is a large artery of natural gas pipeline which runs through the west east gas pipeline and runs through the eastern and western regions of China. Its safe operation is very important. When the pipeline is operated for 2 years, it is found that the corrosion layer has been corroded in different degrees, and the cathodic protection system has not been well protected. Therefore, it is very important to find out the cathodic protection status of the gas pipeline from east to west, and to detect and evaluate the effectiveness of cathodic protection.
In view of the current situation of cathodic protection in the pipeline for East Sichuan gas transmission, the paper selects the numerical simulation software Beasy CP based on the boundary element to carry out the analysis of the inspection scheme of the inspection film by setting up the mathematical model of the cathodic protection potential. At the same time, the check sheet is designed by using the polarization curve to carry out the field test of the check sheet. Finally, the inspection data is based on the inspection piece. The cathodic protection criterion is used to analyze and evaluate the effectiveness of the cathodic protection of the East Sichuan gas transmission pipeline, and to put forward the corrective measures for the unqualified cathodic protection tubes. The main research results are as follows:
(1) the distribution model of buried pipeline cathodic protection potential is established. By comparing the common numerical methods, the numerical simulation software Beasy CP based on boundary element method is selected to carry out the research, which lays the foundation for the analysis of inspection scheme.
(2) according to the established potential mathematical model, the specific parameters of the cathodic protection system of the Sichuan Gas East pipeline are considered, and the software Beasy CP is used to simulate the shape of the film, check the area of the sheet, check the position of the sheet, the damage rate of the pipe anticorrosion layer and the soil resistivity on the potential of the pipeline and check sheet, and analyze the on-site inspection scheme of the check sheet, and propose the method. Suggestions for the design of the check sheet and the field test are made.
(3) based on the design principle of the check sheet, the scope of application of check sheet detection is summarized, and the 5 test cycles of the Sichuan Gas East pipeline inspection piece are determined. The polarization curve of the X70 steel in the soil solution with different pH values is tested. The area of the steel check sheet is calculated according to the value of the consumption current of the steel inspection sheet, and the specifications of the check sheet are determined. At the same time, the IR drop prediction is also used to verify that the area size of the negative check sheet will not affect the measurement of the real potential. Finally, the design of the Sichuan Gas East pipeline inspection sheet group is determined.
(4) according to the analysis and design of the checkout program, the inspection film field test is carried out, the inspection sheet group is made, and the test points of the 40 check sheets are arranged along the line, the inspection film is buried, the electric potential measurement is regularly excavated, the cleaning, the scanning electron microscope (SEM) and the XPS spectrum are separated and analyzed, and a set of cathodic protection detection implementation rules based on the inspection sheet is formed. Cheng.
(5) based on the inspection data, the effectiveness analysis, evaluation and suggestions for cathodic protection of the gas pipeline from Sichuan to East are put forward.
1) according to the inspection data of the inspection piece, the soil corrosivity distribution of the 39 detection points along the pipeline was analyzed. Through the macro and micro analysis of the corrosion products, the inhibition effect of the cathodic protection on the corrosion of the pipeline was explained from the angle of corrosion products.
2) based on the protection degree, the cathodic protection effect of pipeline is evaluated. The qualified rate is 44%. and the protection degree is connected with the through electric potential. The average IR of the East Sichuan gas pipeline is reduced to 220mV, that is, the protection potential (Uon) criterion should be -1070mV (CSE), and when the real potential (Uoff) reaches -850mV (CSE), the corresponding minimum cathodic protection degree will not be low. At 65%, it provides the basis for daily management and maintenance of cathodic protection.
3) the cathodic protection of 39 detection points along the East Sichuan gas pipeline was analyzed and evaluated by the three criteria of the annual corrosion rate of the cathodic protection check sheet, the electric potential and the instantaneous electric potential, and the cathodic protection rate of the cathodic protection was 74.4%. At the same time, 10 cathodic protection failure tubes were judged.
4) using risk assessment and risk matrix method, we draw a hazard matrix map of environmental corrosivity to "non protection", and evaluate the risk grade of each detection section. The results show that the non test pipe segment is located at the highest risk area (V), and the 5,22,27 and No. 30 pipe segments are located in the sub high risk zone (IV).
5) analyze the factors that affect the cathodic protection of the East Sichuan gas pipeline, and put forward the corrective measures for the unqualified cathodic protection, and verify the reliability of the inspection technology through the pipeline potential monitoring and the site excavation.
【學(xué)位授予單位】：西南石油大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2015
【分類號(hào)】：TE88

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