本文關(guān)鍵詞： 西二線 X80鋼 內(nèi)腐蝕 電化學(xué) 剩余強(qiáng)度　出處：《西南石油大學(xué)》2015年碩士論文　論文類型：學(xué)位論文

【摘要】：隨著長輸天然氣管道服役時間增加,管道內(nèi)腐蝕問題日益凸顯。管道內(nèi)腐蝕達(dá)到一定程度,將會引起管道產(chǎn)生裂縫或穿孔,造成天然氣的泄露,嚴(yán)重的甚至發(fā)生爆炸,對人身和財產(chǎn)安全帶來嚴(yán)重隱患。西氣東輸二線(以下稱西二線)輸送的天然氣主要來自土庫曼斯坦和哈薩克斯坦兩個氣源。上述兩氣源均是經(jīng)脫硫后滿足西二線輸送標(biāo)準(zhǔn)的天然氣,雖然只含有微量的H2S(小于20mg/m3),但存在的硫組分仍會使管道內(nèi)腐蝕影響因素更加復(fù)雜,內(nèi)腐蝕程度更加嚴(yán)重,且內(nèi)腐蝕穿孔后的后果也更加嚴(yán)重,故需要對西二線的內(nèi)腐蝕狀況進(jìn)行評估,進(jìn)而研究西二線的剩余強(qiáng)度,以保證西二線的安全高效運(yùn)營。本文針對西二線的內(nèi)腐蝕狀況及剩余強(qiáng)度評估進(jìn)行了以下幾個方面的研究： (1)采用室內(nèi)實(shí)驗(yàn)的方法,對收集的西二線12組清管產(chǎn)物進(jìn)行了總硫含量和Cl-和S042-測試,對39組沿線氣體樣品進(jìn)行了H2S含量測試。結(jié)合調(diào)研的西二線沿線高程,氣質(zhì)組分、管材等整體概況,確定了發(fā)生內(nèi)腐蝕的關(guān)鍵管段為霍爾果斯至精河壓氣站管段以及精河至烏蘇壓氣站管段。 (2)對西二線管材X80管線鋼進(jìn)行了電化學(xué)腐蝕實(shí)驗(yàn),根據(jù)電化學(xué)原理,通過對電化學(xué)過程中的極化曲線和電化學(xué)阻抗進(jìn)行擬合分析,得到相應(yīng)的腐蝕電流密度和極化電阻。研究了X80鋼在西二線清管產(chǎn)物模擬溶液(Cl-和SO42-)中的電化學(xué)腐蝕行為。 (3)利用高壓釜,對X80管線鋼在模擬西二線天然氣及管液組成、運(yùn)行壓力、溫度范圍條件下進(jìn)行了實(shí)驗(yàn),測定了西二線X80鋼的腐蝕速率。采用SEM和EDS對X80管線鋼腐蝕產(chǎn)物進(jìn)行了分析,研究了西二線X80鋼的腐蝕機(jī)理。 (4)基于霍爾果斯至精河壓氣站、精河至烏蘇壓氣站兩條管段的內(nèi)檢測報告數(shù)據(jù),對管道的內(nèi)腐蝕缺陷的數(shù)量、類型、深度、相鄰缺陷軸向間距進(jìn)行了統(tǒng)計和分析,確定了三種代表性的內(nèi)腐蝕缺陷形式。分別針對三種缺陷類型,統(tǒng)計了腐蝕缺陷的尺寸、面積,得到相應(yīng)的分布規(guī)律,初步完成了對西二線關(guān)鍵管段內(nèi)腐蝕缺陷的整體評估,對進(jìn)一步進(jìn)行西二線管道剩余強(qiáng)度的研究提供依據(jù)。 (5)基于西二線內(nèi)腐蝕缺陷統(tǒng)計分析,將三種缺陷類型：軸向凹槽、軸向凹溝、坑狀金屬損失合理簡化為三種物理模型：平底方形、同底方形、球形坑蝕,采用ANSYS有限元、B31G準(zhǔn)則、DNV-PR-F101準(zhǔn)則三種方法進(jìn)行剩余強(qiáng)度的評估,并進(jìn)行結(jié)果對比分析,提出針對不同管材、內(nèi)腐蝕缺陷類型的管道安全評估時兩種準(zhǔn)則的選擇依據(jù)。 (6)依據(jù)計算所得的西二線管道剩余強(qiáng)度、臨界失效腐蝕深度和腐蝕速率,分析預(yù)測西二線管道的使用年限,并結(jié)合西二線工況運(yùn)行條件等情況,提出延長管道使用年限的措施。 本論文對高鋼級天然氣長輸管道的內(nèi)腐蝕狀況及剩余強(qiáng)度評估方面有一定的意義。
[Abstract]:With the increase of service time of long distance natural gas pipeline, the corrosion problem in pipeline becomes more and more serious. If the corrosion in pipeline reaches a certain degree, it will cause crack or perforation of pipeline, cause natural gas leakage, and even explode seriously. Serious danger to personal and property safety. Natural gas from Turkmenistan and Kazakhstan mainly comes from Turkmenistan and Kazakhstan. These two gas sources are both desulphurized and satisfied with the west second gas source after desulphurization of the second line of natural gas transmission from the west to the east (hereinafter referred to as the second line of the west second line). Line conveys standard natural gas, Although it contains only a small amount of H _ 2s (less than 20 mg / m ~ (-3)), the presence of sulfur components will make the corrosion factors in the pipeline more complex, the degree of internal corrosion more serious, and the consequences of internal corrosion perforation more serious. Therefore, it is necessary to evaluate the internal corrosion of the second west line and study the residual strength of the second line. In order to ensure the safe and efficient operation of the West second Line, this paper studies the internal corrosion status and residual strength evaluation of the West second Line in the following aspects:. 1) the contents of total sulfur, Cl- and S042- were measured in 12 groups of pipe-clearing products collected from West second Line by laboratory experiment, and the content of H _ 2S in 39 groups of gas samples along the route were tested. According to the general situation of pipe material, the key section of internal corrosion is determined to be the section of Halgos to Jinghe gas pressure station and the section of Jinghe to Wusu gas pressure station. The electrochemical corrosion experiment of X80 pipeline steel was carried out. According to the principle of electrochemistry, the polarization curve and electrochemical impedance of X80 pipeline steel in the electrochemical process were fitted and analyzed. The corrosion current density and polarization resistance of X80 steel were obtained. The electrochemical corrosion behavior of X80 steel in simulated solutions of Cl- and SO42-was studied. Using autoclave, the X80 pipeline steel was tested under the conditions of simulating the composition of natural gas and pipe liquid, operating pressure and temperature range of the second line. The corrosion rate of X80 steel was measured, the corrosion products of X80 pipeline steel were analyzed by SEM and EDS, and the corrosion mechanism of X80 steel was studied. Based on the data of internal inspection report of the two pipe sections from Horgos to Jinghe Gas Station and from Jinghe to Wusu Gas Station, the quantity, type, depth and axial distance of adjacent defects of pipeline are analyzed and analyzed. Three representative forms of internal corrosion defects are determined. The size and area of corrosion defects are counted for the three types of defects, and the corresponding distribution laws are obtained, and the overall evaluation of corrosion defects in key sections of the West second Route is preliminarily completed. It provides the basis for further research on the residual strength of the west second line pipeline. Based on the statistical analysis of internal corrosion defects in the West second Line, three types of defects, namely, axial grooves, axial grooves, crater metal losses, are reasonably simplified into three physical models: square with flat bottom, square with same bottom, and spherical pit. The residual strength is evaluated by using the ANSYS finite element B31G criterion and DNV-PR-F101 criterion, and the results are compared and analyzed. The selection basis of the two criteria for the safety assessment of pipelines with different pipe and internal corrosion defects is put forward. Based on the calculated residual strength, critical failure corrosion depth and corrosion rate of the pipeline, the service life of the pipeline is analyzed and forecasted, and the measures for prolonging the service life of the pipeline are put forward in combination with the operating conditions of the second line. This paper has some significance for internal corrosion and residual strength evaluation of high grade gas pipeline.
【學(xué)位授予單位】：西南石油大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2015
【分類號】：TE988.2

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本文編號：1502693