本文關(guān)鍵詞：含內(nèi)腐蝕缺陷高強鋼輸氣管道剩余強度的評估方法研究　出處：《北京交通大學》2015年博士論文　論文類型：學位論文

  更多相關(guān)文章： 高強鋼 輸氣管道 流固耦合 腐蝕速率 失效壓力 強度評價

【摘要】：高強鋼輸氣管道因具備耐腐蝕、大口徑、及耐高壓等特點,將逐步取代現(xiàn)有的普通鋼級管道,成為承擔全球天然氣輸送的主力管道。正因為高強鋼輸氣管道大口徑、高壓輸送以及薄壁的特點,當管道出現(xiàn)內(nèi)部腐蝕缺陷時其較之普通鋼級管道將面臨更嚴峻的挑戰(zhàn),嚴重時甚至造成泄漏爆炸等災難性事故。當前對于高強鋼管道腐蝕模型及剩余強度評價的研究開展仍較片面,沒有考慮管道在輸運過程中內(nèi)部流體的影響,缺乏針對高強鋼長輸輸氣管道重點位置的內(nèi)腐蝕缺陷強度評價方法。因此考慮高強鋼管道運營過程中輸運氣體流場對內(nèi)腐蝕模型的影響,引入流固耦合下高強鋼管道產(chǎn)生內(nèi)腐蝕缺陷后的強度分析,對于高強鋼輸氣管道剩余強度與運營狀態(tài)的快速評估具有重大意義。 論文以現(xiàn)有的建立較完善的管道內(nèi)腐蝕模型及管道剩余強度評價方法為依托,探討了天然氣流場對于管道內(nèi)腐蝕及內(nèi)腐蝕缺陷評價的影響,將理論分析、模型實驗、數(shù)值模擬與現(xiàn)場數(shù)據(jù)相結(jié)合,提供了一種比較快速、全面的高強鋼輸氣管道內(nèi)腐蝕速率模型及含內(nèi)腐蝕缺陷高強鋼輸氣管道剩余強度評價方法。 首先,根據(jù)雷諾數(shù)相似性設計了高強鋼試片沖刷試驗平臺,并進行了高強鋼試片X80的沖刷磨損試驗,得到了高強鋼試片在不同沖刷角度下的磨損結(jié)果,分析了流場變化對高強鋼沖刷形貌的影響；同時基于顆粒動力學采用有限元方法引入雙流體模型對試驗進行了仿真計算,分析了高強鋼試片沖刷過程中對其沖刷影響較大的流體參數(shù),在模擬計算的流場參數(shù)分布(速度與湍動能)與試驗中的高強鋼沖刷缺陷形狀相似。 然后,進行了高強鋼X70與X80試件成分、屈服強度及抗拉強度的測定與含半橢圓缺陷下的X90試件的拉伸試驗,試驗得到缺陷深度的變化對于其屈服強度時最大拉力的影響較大,而在本實驗范圍內(nèi)(15mm-55mm)缺陷長度的變化對于拉伸試件屈服強度處的最大拉力影響基本不變；在與有限元計算的對比分析中得到了拉伸試件的缺陷位置存在的一定局部范圍內(nèi)的應力集中現(xiàn)象。圓滑過渡后半橢圓缺陷表面應力狀態(tài)比之圓滑過渡前缺陷更能精確、有效地反映拉伸樣件的破壞失效狀態(tài)。 在管道內(nèi)湍流可壓縮流體方程的基礎(chǔ)上,進行了不同傾角下高強鋼輸氣管道內(nèi)部流場參數(shù)分析,推導了長輸管道的壓降公式并在De waard腐蝕模型的基礎(chǔ)上,完成了高強鋼輸氣管道內(nèi)腐蝕速率隨流場參數(shù)變化公式。得到管道高程的起伏會造成管道內(nèi)壓的變化,而管道內(nèi)CO2分壓則成為影響管道沿程平均內(nèi)腐蝕率高低的最重要參數(shù)之一；在引入的流場參數(shù)中,輸運氣體速度與湍流動能數(shù)值變化可代替傾角變化描述對高強鋼輸氣管道沿程平均內(nèi)腐蝕率的影響,根據(jù)修正后的公式預測出的管道重點位置處內(nèi)腐蝕形貌大致呈半橢圓片狀分布。 同時,針對含半橢圓缺陷的X70高強鋼直管道建立了三維有限元模型,模擬了流固耦合下管道內(nèi)流場參數(shù)及應力的變化。得到相對于純內(nèi)壓作用下管道,流場的存在會增高管道內(nèi)壁缺陷處的應力值：在10MPa的操作壓力下,半橢圓缺陷深度對于管道內(nèi)壁最大應力分布影響最大,缺陷長度在超過100mm時管道內(nèi)壁應力值變化范圍不大,而缺陷寬度的變化對于管道內(nèi)壁面應力值的影響很小；對于X70管線鋼,超過其壁厚50%以上的缺陷深度會對管道的失效壓力造成惡劣的影響。而對于含雙橢圓缺陷高強鋼管道,雙缺陷處最大等效應力隨雙缺陷間距離呈反比變化；當雙缺陷間距離超過一定長度時,可忽略雙缺陷間應力的交互影響。 最后,根據(jù)不同缺陷參數(shù)對高強鋼輸氣管道的應力影響,采用Marquardt方法進行數(shù)據(jù)的分段擬合,并提出了流固耦合下的管道失效壓力模型,在與純壓力載荷下的爆管實驗參數(shù)的對比下,提出管道失效壓力模型,其預測結(jié)果分布穩(wěn)定。同時基于論文提出的高強鋼輸氣管道內(nèi)腐蝕速率分析,以流固耦合下的含內(nèi)腐蝕缺陷高強鋼輸氣管道失效壓力為評定準則,提出了流固高強鋼輸氣管道剩余壽命預測模型,可對長輸管道的重點位置進行針對性分析。 在含流體參數(shù)的高強鋼輸氣管道內(nèi)腐蝕速率分析與流固耦合下含內(nèi)腐蝕缺陷高強鋼管道破壞失效壓力分析的基礎(chǔ)上,提出了含內(nèi)腐蝕缺陷高強鋼輸氣管道剩余強度的評價方法,可對高強鋼輸氣管道進行重點檢測位置的劃分、管道產(chǎn)生內(nèi)腐蝕缺陷后的強度校核計算以及管道的再評估間隔預測,為保證高強鋼輸氣管道的可靠運行提供理論基礎(chǔ)。 論文形成了一套進行在役高強鋼輸氣管道內(nèi)腐蝕缺陷強度評價的較為完整的評價體系,使對在役高強鋼輸氣管道內(nèi)腐蝕缺陷評價更為快速精準,可為高強鋼輸氣管道的安全運營提供技術(shù)支撐。
[Abstract]:High strength steel pipeline with corrosion resistance, large diameter and high pressure resistance, etc., will gradually replace the existing ordinary steel pipes, bear the brunt of global natural gas pipeline as transportation. Because of high strength steel gas pipelines of large diameter, thin wall and high pressure conveying characteristics, when the pipeline internal corrosion defects compared with ordinary steel pipe will face more severe challenges, even when serious leaks caused by explosion accidents. The research on high strength steel pipe corrosion model and residual strength evaluation carried out is still relatively one-sided, without considering the influence in the pipeline transport of fluid in the process, in view of the lack of corrosion defect strength evaluation method of transmission the key position of high strength steel gas pipeline of long distance transport. Considering the gas flow field in the process of pipeline operation in high strength steel corrosion effect on the internal model, introducing the fluid solid coupling under high strength steel pipes produced in The strength analysis of corrosion defects is of great significance for the rapid assessment of the residual strength and operation state of high strength steel gas transmission pipeline.
Based on the residual strength evaluation method of the existing pipeline established a model based on the internal corrosion and pipeline, discusses the influence of gas flow and for internal corrosion defects in pipeline corrosion evaluation, theoretical analysis, model experiment, numerical simulation and field data binding phase, provides a fast, comprehensive high strength steel within the gas pipeline corrosion rate and corrosion defect model with high strength steel pipeline residual strength evaluation method of gas pipeline.
First of all, according to the Reynolds number similarity design of high strength steel specimen erosion test platform, test and erosion wear of high strength steel specimens of X80, the wear test results of high strength steel specimens at different erosion angle, analyzed the influence of flow change on erosion morphology of high strength steel; and the particle dynamics with finite element method the two fluid model of test is simulated based on the analysis of the impact of fluid parameters on the large scour erosion process in high strength steel plate, the flow field distribution in the simulation (velocity and turbulent kinetic energy) and high strength steel shape defects similar erosion test.
Then, the high strength steel X70 and X80 specimens, the yield strength and tensile strength and determination of the defects with semi elliptical X90 under test tensile test pieces, obtained defect depth test changes for the yield strength when the influence of maximum force is large, and in this experimental range (15mm-55mm) changes the defect length the maximum tensile yield strength tensile specimens at the same; in contrast analysis and finite element calculation by the tensile stress concentration phenomenon of certain local defect position in the second half. Smooth elliptic surface defects shall be smooth and stress than before the transition defects more accurately and effectively. The tensile samples reflect failure failure state.
Based in the pipe turbulent compressible fluid equations, the different angle analysis of internal flow field parameters of gas pipeline under high strength steel, deduced the formula of pressure drop of pipeline based on De waard corrosion model, completed the transmission of high strength steel corrosion rate of gas pipeline with the flow field parameters obtained pipeline formula. The elevation fluctuation can cause changes in pipeline pressure, has become one of the influences of corrosion along the average rate in the most important parameters in pipeline CO2 pressure; in the flow field parameter is introduced in numerical transport velocity and turbulent kinetic energy of gas can replace the angle change description of high strength steel gas pipeline along the average corrosion rate in the process, according to the corrosion morphology of pipeline key position correction formula to predict the roughly half elliptical distribution.
At the same time, a three-dimensional finite element model is established for containing semi elliptical defects of X70 high strength steel straight pipe, simulated flow solid coupling flow field parameters of pipeline and stress. Compared to pure pressure inside the pipeline, the flow stress value will increase the pipeline inner wall defects: in the operating pressure of 10MPa under the semi elliptical defect depth for pipe wall maximum stress distribution of the maximum length of the defect in more than 100mm pipe wall stress variation range is not big, but also affected the pipeline wall defect width for stress value is very small; for X70 pipeline steel, more than the wall thickness of more than 50% of the depth of defect will cause bad influence on pipe failure pressure. For high strength steel pipe with double elliptical defect, two defects maximum equivalent stress with two defects is inversely proportional to the distance between the change of distance between the two defects; when more than a certain length of time The interaction of stress between two defects can be ignored.
Finally, according to the influence of different parameters on the stress defects of high strength steel gas pipeline, Marquardt method was used for fitting data, and put forward the failure pressure model of pipeline coupling under flow, and in the pure pressure loading tube explosion experimental parameters contrast, proposed pipeline failure pressure model, the prediction results of distribution stability analysis. The corrosion rate of gas pipeline in high strength steel and the thesis based on the transmission, to flow with internal corrosion defects in solid coupling under high strength steel gas pipeline failure pressure as the criterion of assessment, put forward the high strength steel transmission fluid solid gas pipeline residual life prediction model, but for the analysis of key position of long distance pipeline.
In high strength steel containing fluid parameters transmission gas pipeline corrosion rate and flow solid coupling analysis with internal corrosion defects of high strength steel pipeline failure based on the analysis of failure pressure, put forward the evaluation method with the internal corrosion defects of high strength steel pipeline residual strength of the gas pipeline, the high strength steel pipeline Road Division focuses on the detection of position then, evaluate the pipeline internal corrosion defects produced after the strength calculation and pipeline interval prediction, in order to provide theoretical basis for reliable operation of high strength steel gas pipeline.
A complete evaluation system for evaluating the strength of in-service high-strength steel gas pipeline corrosion defects is formed, which makes the evaluation of corrosion defects in service high strength steel gas pipelines faster and more precise, and provides technical support for the safe operation of high strength steel gas transmission pipelines.

【學位授予單位】：北京交通大學
【學位級別】：博士
【學位授予年份】：2015
【分類號】：TE973;TG142.1

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