含凹陷管道安全性研究
发布时间：2018-12-15 09:26
【摘要】：管道作为石油和天然气主要的运输方式,在工业体系中发挥着重要的作用,维持高水平的管道完整性和可靠性对石油天然气行业至关重要。机械损伤是导致管道失效重要的原因之一,而凹陷是其最典型的类型,它会引起应力和应变集中从而对管道安全运行造成严重的威胁。因此,对凹陷管道进行合理的安全评价是非常必要的并根据评价结果对其采取相应的处理措施。本文针对凹陷管道安全性进行了以下内容的研究:首先,整理归纳凹陷管道安全评价方法,基于PDAM凹陷深度准则和最小伸长率极限判据对球形凹陷管道应变进行了分析。结合韧性断裂失效模型研究了不同参数下球形凹陷管道的损伤程度并对凹陷深度准则进行了验证,同时研究了不同管道内压作用下球形凹陷的临界失效应变,根据临界失效应变选取合适的安全因子确定许用应变,通过应变评价方法确定工程中需要修复或者替换的管段。其次,在球形凹陷管道研究的基础上,针对曲折凹陷管道进行了安全性分析,采用API 579准则规定的临界凹陷深度作为研究对象,分析了不同参数下曲折凹陷的应变及应变分布变化规律,通过最小伸长率极限判据对其进行评估。为了进一步探究基于该准则临界凹陷深度的准确性,结合韧性断裂失效模型研究了不同参数下曲折凹陷管道的损伤程度,根据韧性失效损伤准则判定其是否达到阈值,从而确定其是否发生断裂。随后分析了不同管道内压下曲折凹陷的临界失效应变,根据应变评价流程分析了曲折凹陷的安全性并给出处理意见及建议。最后,根据ASME B31.4标准针对内腐蚀缺陷和凹陷联合作用下缺陷管道的安全性进行了初步探究。在内腐蚀缺陷管道安全运行下通过塑性失效准则探究了不同参数下内腐蚀缺陷管道所能承受压头下压的临界深度;为了进一步验证移除压头后该临界凹陷深度是否准确,通过基于凹陷深度准则和韧性断裂失效模型对内腐蚀凹陷管道损伤程度进行了分析,结果表明基于塑性失效准则得到的临界凹陷深度不可以作为此类缺陷管道的临界凹陷深度,而在一定的条件下基于ASME B31.8凹陷深度准则的内腐蚀缺陷管道是安全的;为探究更为精确的安全凹陷深度,采用ASME B31.8应变评价方法对内腐蚀缺陷管道所能承受的安全凹陷深度进行了分析,结果表明该方法的确比基于凹陷深度准则得到的安全凹陷深度更精确,对此综合两种评价方法提出了针对此类缺陷管道的安全评价流程,这将为工程评估提供参考。
[Abstract]:Pipeline, as the main transportation mode of oil and natural gas, plays an important role in the industrial system. It is very important for oil and gas industry to maintain the high level of pipeline integrity and reliability. Mechanical damage is one of the most important causes of pipeline failure, and depression is the most typical type, which will cause stress and strain concentration and pose a serious threat to the safe operation of pipeline. Therefore, it is very necessary to carry on reasonable safety evaluation to the depressed pipeline and take the corresponding treatment measures according to the evaluation result. In this paper, the safety of the hollow pipeline is studied as follows: first of all, the pipeline strain of the spherical sag is analyzed based on the PDAM depth criterion and the minimum elongation limit criterion. Combined with ductile fracture failure model, the damage degree of spherical sag pipeline under different parameters is studied and the criterion of sag depth is verified. At the same time, the critical failure strain of spherical sag under different internal pressure of pipeline is studied. According to the critical failure strain, the appropriate safety factor is selected to determine the allowable strain, and the pipeline segment that needs to be repaired or replaced is determined by the strain evaluation method. Secondly, based on the research of spherical sag pipeline, the safety analysis of zigzag sag pipeline is carried out, and the critical sag depth stipulated by API 579 criterion is adopted as the research object. The variation of strain and strain distribution in zigzag sag under different parameters is analyzed and evaluated by the limit criterion of minimum elongation. In order to further explore the accuracy of critical depth of sag based on the criterion, the damage degree of the pipeline with different parameters is studied by combining with the ductile fracture failure model, and the threshold value is determined according to the criterion of ductile failure damage. To determine whether it breaks. Then the critical failure strain of the zigzag sag under different pipeline pressure is analyzed and the safety of the zigzag sag is analyzed according to the strain evaluation flow and the treatment opinions and suggestions are given. Finally, according to ASME B31.4 standard, the safety of defective pipeline under the combined action of internal corrosion defect and indentation is preliminarily explored. Under the safe operation of internal corrosion defect pipeline, the critical depth of internal corrosion defect pipeline can withstand the pressure of pressure head under different parameters is studied by plastic failure criterion. In order to further verify the accuracy of the critical depth of the indentation after removing the head, the damage degree of the internal corrosion sag pipeline is analyzed based on the criterion of the depth of the depression and the failure model of the ductile fracture. The results show that the critical indentation depth based on plastic failure criterion can not be used as the critical sag depth of this kind of defective pipeline, but the inner corrosion defect pipeline based on ASME B31.8 indentation depth criterion is safe under certain conditions. In order to find out the more accurate depth of safety sag, ASME B31.8 strain evaluation method is used to analyze the safe indentation depth of the pipeline with internal corrosion defects. The results show that the method is more accurate than the one based on the sag depth criterion. The safety evaluation process for this kind of defective pipeline is put forward for these two comprehensive evaluation methods, which will provide a reference for engineering evaluation.
【学位授予单位】：西南石油大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TE973
本文编号：2380412
[Abstract]:Pipeline, as the main transportation mode of oil and natural gas, plays an important role in the industrial system. It is very important for oil and gas industry to maintain the high level of pipeline integrity and reliability. Mechanical damage is one of the most important causes of pipeline failure, and depression is the most typical type, which will cause stress and strain concentration and pose a serious threat to the safe operation of pipeline. Therefore, it is very necessary to carry on reasonable safety evaluation to the depressed pipeline and take the corresponding treatment measures according to the evaluation result. In this paper, the safety of the hollow pipeline is studied as follows: first of all, the pipeline strain of the spherical sag is analyzed based on the PDAM depth criterion and the minimum elongation limit criterion. Combined with ductile fracture failure model, the damage degree of spherical sag pipeline under different parameters is studied and the criterion of sag depth is verified. At the same time, the critical failure strain of spherical sag under different internal pressure of pipeline is studied. According to the critical failure strain, the appropriate safety factor is selected to determine the allowable strain, and the pipeline segment that needs to be repaired or replaced is determined by the strain evaluation method. Secondly, based on the research of spherical sag pipeline, the safety analysis of zigzag sag pipeline is carried out, and the critical sag depth stipulated by API 579 criterion is adopted as the research object. The variation of strain and strain distribution in zigzag sag under different parameters is analyzed and evaluated by the limit criterion of minimum elongation. In order to further explore the accuracy of critical depth of sag based on the criterion, the damage degree of the pipeline with different parameters is studied by combining with the ductile fracture failure model, and the threshold value is determined according to the criterion of ductile failure damage. To determine whether it breaks. Then the critical failure strain of the zigzag sag under different pipeline pressure is analyzed and the safety of the zigzag sag is analyzed according to the strain evaluation flow and the treatment opinions and suggestions are given. Finally, according to ASME B31.4 standard, the safety of defective pipeline under the combined action of internal corrosion defect and indentation is preliminarily explored. Under the safe operation of internal corrosion defect pipeline, the critical depth of internal corrosion defect pipeline can withstand the pressure of pressure head under different parameters is studied by plastic failure criterion. In order to further verify the accuracy of the critical depth of the indentation after removing the head, the damage degree of the internal corrosion sag pipeline is analyzed based on the criterion of the depth of the depression and the failure model of the ductile fracture. The results show that the critical indentation depth based on plastic failure criterion can not be used as the critical sag depth of this kind of defective pipeline, but the inner corrosion defect pipeline based on ASME B31.8 indentation depth criterion is safe under certain conditions. In order to find out the more accurate depth of safety sag, ASME B31.8 strain evaluation method is used to analyze the safe indentation depth of the pipeline with internal corrosion defects. The results show that the method is more accurate than the one based on the sag depth criterion. The safety evaluation process for this kind of defective pipeline is put forward for these two comprehensive evaluation methods, which will provide a reference for engineering evaluation.
【学位授予单位】：西南石油大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TE973
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