输气管道环焊缝表面裂纹管道极限载荷计算方法
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摘要
为了便于对天然气长输管道环焊缝缺陷进行准确快速的安全评估,建立了考虑裂纹尖端奇异性的含环焊缝缺陷的有限元模型,计算了不同缺陷尺寸下的管道环焊缝裂纹J积分,分析了焊缝匹配系数及材料硬化指数对J积分的影响,进而研究了基于J积分理论的含缺陷管道的极限载荷影响因素,并在此基础上提出了适用于特定匹配系数和材料硬化指数情况下能够实现J积分及极限载荷快速求解的工程计算公式。研究结果表明:①根据有限元计算结果拟合的工程计算公式具有较高的精度,可以满足较大缺陷几何尺寸范围内J积分求解,实现含环焊缝裂纹缺陷的管道极限载荷求解;②含环焊缝缺陷管道的裂纹J积分与缺陷尺寸、材料属性以及焊缝匹配系数密切相关,含缺陷管道的极限载荷会随着裂纹尺寸的增加而降低,而随着材料硬化指数的增大而增大;③对含环焊缝中心线处表面裂纹的X80钢制管道而言,低匹配焊接管道极限承载能力要弱于高匹配或等匹配焊接管道。结论认为,该研究成果可为现役输气管道的安全评价及完整性管理提供参考。
In this paper, a finite element model with girth weld defects considering crack tip singularity was established in order to facilitate the accurate and rapid safety assessment on girth weld defects of long-distance gas line pipes. Then the J-integral of girth weld cracks in line pipes with different defect sizes was calculated, and the influence of weld matching coefficient and material hardening index on J-integral is analyzed. Furthermore, the factors affecting the limit load of pipelines with defects based on the J-integral theory were studied. Based on this, the engineering calculation formula which can calculate J-integral and limit load rapidly in the situations with specific matching coefficient and material hardening index was proposed. And the following research results were obtained. First, the engineering calculation formula based on the fitting of finite element calculation results is of higher accuracy, and it can calculate the J-integral in the geometry range of large defects and the limit load of the pipes with girth weld cracks. Second, the J-integral of cracks in line pipes with girth weld defects is closely related to defect size, material properties and weld matching coefficient, and the limit load of pipes with defects decreases with the increase of crack size and increases with the increase of material hardening index. Third, for the X80 pipes with surface cracks at the centerline of the girth weld, the load carrying capacity of the line pipe with low-strength matched weld(matching coefficient < 20%) is lower than that with high-strength or equivalent-matched weld(matching coefficient > 20%). In conclusion, the research results can be used as reference for the safety evaluation and integrity management of in-service gas pipelines.
In this paper, a finite element model with girth weld defects considering crack tip singularity was established in order to facilitate the accurate and rapid safety assessment on girth weld defects of long-distance gas line pipes. Then the J-integral of girth weld cracks in line pipes with different defect sizes was calculated, and the influence of weld matching coefficient and material hardening index on J-integral is analyzed. Furthermore, the factors affecting the limit load of pipelines with defects based on the J-integral theory were studied. Based on this, the engineering calculation formula which can calculate J-integral and limit load rapidly in the situations with specific matching coefficient and material hardening index was proposed. And the following research results were obtained. First, the engineering calculation formula based on the fitting of finite element calculation results is of higher accuracy, and it can calculate the J-integral in the geometry range of large defects and the limit load of the pipes with girth weld cracks. Second, the J-integral of cracks in line pipes with girth weld defects is closely related to defect size, material properties and weld matching coefficient, and the limit load of pipes with defects decreases with the increase of crack size and increases with the increase of material hardening index. Third, for the X80 pipes with surface cracks at the centerline of the girth weld, the load carrying capacity of the line pipe with low-strength matched weld(matching coefficient < 20%) is lower than that with high-strength or equivalent-matched weld(matching coefficient > 20%). In conclusion, the research results can be used as reference for the safety evaluation and integrity management of in-service gas pipelines.
引文
[1]帅健,董绍华.油气管道完整性管理[M].北京:石油工业出版社,2017.Shuai Jian&Dong Shaohua.Oil and gas pipeline integrity management[M].Beijing:Petroleum Industry Press,2017.
[2]Budden PJ,Sharples JK&Dowling AR.The R6 procedure:Recent developments and comparison with alternative approaches[J].International Journal of Pressure Vessels and Piping,2000,77(14/15):895-903.
[3]Zahoor A.Ductile fracture handbook,Volume 1:Circumferential through-wall cracks[R].EPRI Report NP-6301-D,Palo Alto,CA:Electric Power Research Institute,1989.
[4]Lei Y&Budden PJ.Limit load solutions for thin-walled cylinders with circumferential cracks under combined internal pressure,axial tension and bending[J].The Journal of Strain Analysis for Engineering Design,2004,39(6):673-683.
[5]Kim YJ,Kim JS&Lee YZ.Non-linear fracture mechanics analyses of part circumferential surface cracked pipes[J].International Journal of Fracture,2002,116(4):347-375.
[6]Kim YJ&Shim DJ.Relevance of plastic limit loads to reference stress approach for surface cracked cylinder problems[J].International Journal of Pressure Vessels and Piping,2005,82(9):687-699.
[7]Song TK,Kim YJ,Kim JS&Jin TE.Mismatch limit loads and approximate J estimates for tensile plates with constant-depth surface cracks in the center of welds[J].International Journal of Fracture,2007,148(4):343-360.
[8]HerteléS,Waele WD,Verstraete M,Denys R&'Dowd NO.J-integral analysis of heterogeneous mismatched girth welds in clamped single-edge notched tension specimens[J].International Journal of Pressure Vessels and Piping,2014,119(4):95-107.
[9]Paredes M&Ruggieri C.Engineering approach for circumferential flaws in girth weld pipes subjected to bending load[J].International Journal of Pressure Vessels and Piping,2015,125:49-65.
[10]Souza RF&Ruggieri C.Fracture assessments of clad pipe girth welds incorporating improved crack driving force solutions[J].Engineering Fracture Mechanics,2015,148:383-405.
[11]帅健,辛艳霞.基于失效评定图的油气管线可靠性分析[J].天然气工业,2002,22(2):83-86.Shuai Jian&Xin Yanxia.Reliability analysis of oil and gas pipelines on the basis of failure assessment diagram[J].Natural Gas Industry,2002,22(2):83-86.
[12]孙亮,李培宁,刘长军.任意应力应变关系材料J积分估算的等效原场应力法[J].机械强度,2003,25(4):450-455.Sun Liang,Li Peining&Liu Changjun.Equivalent remote stress method of J integral evaluation for any stress-strain relationship materials[J].Journal of Mechanical Strength,2003,25(4):450-455.
[13]白永强,汪彤,吕良海,帅健,孙亮,陈钢.油气管道内部轴向表面半椭圆裂纹弹塑性断裂分析[J].石油化工高等学校学报,2009,22(3):71-74.Bai Yongqiang,Wang Tong,LüLianghai,Shuai Jian,Sun Liang&Chen Gang.Elastic-plastic fracture analysis for internal axial surface half elliptical cracks in oil and gas pipeline[J].Journal of Petrochemical Universities,2009,22(3):71-74.
[14]白永强,汪彤,吕良海,孙亮,帅健,陈钢.拉弯联合载荷下弹塑性J积分估算方法研究[J].工程力学,2010,27(3):6-9.Bai Yongqiang,Wang Tong,LüLianghai,Sun Liang,Shuai Jian&Chen Gang.Elastic-plastic J integral calculation method for cracks in structures under combined tension and bending[J].Engineering Mechanics,2010,27(3):6-9.
[15]全国石油天然气标准化技术委员会.石油天然气工业管线输送系统用钢管:GB/T 9711-2017[S].北京:中国标准出版,2017.National Technical Committee for Standardization of Oil and Natural Gas.Petroleum and natural gas industries-Steel pipe for pipeline transportation systems:GB/T 9711-2017[S].Beijing:China Standard Publication,2017.
[16]石油工程建设专业标准化委员会.输气管道工程设计规范:GB 50251-2015[S].北京:中国计划出版社,2015.Petroleum Engineering Construction Standardization Commission.Code for design of gas transmission pipeline engineering:GB 50251-2015[S].Beijing:China Planning Press,2015.
[17]Bergman M.Stress intensity factors for circumferential surface cracks in pipes[J].Fatigue and Fracture of Engineering Materials and Structures,2007,18(10):1155-1172.
[18]British Standards Institution.Guide on methods for assessing the acceptability of flaws in metallic structures:BS 7910-2015[S].London:BSI Standards Limited,2015.
[19]马彬.高强度管道极限载荷评价方法研究[D].北京:中国石油大学(北京),2014.Ma Bin.Research on limit pressure assessment method of high strength pipeline[D].Beijing:China University of Petroleum(Beijing),2014.
[20]王晓芳.基于极限载荷的在用含未焊透缺陷压力管道安全性分析[D].杭州:浙江大学,2010.Wang Xiaofang.Research on safety analysis of in-service pressure pipelines containing incomplete welding defects based on limited load[D].Hangzhou:Zhejiang University,2010.
[2]Budden PJ,Sharples JK&Dowling AR.The R6 procedure:Recent developments and comparison with alternative approaches[J].International Journal of Pressure Vessels and Piping,2000,77(14/15):895-903.
[3]Zahoor A.Ductile fracture handbook,Volume 1:Circumferential through-wall cracks[R].EPRI Report NP-6301-D,Palo Alto,CA:Electric Power Research Institute,1989.
[4]Lei Y&Budden PJ.Limit load solutions for thin-walled cylinders with circumferential cracks under combined internal pressure,axial tension and bending[J].The Journal of Strain Analysis for Engineering Design,2004,39(6):673-683.
[5]Kim YJ,Kim JS&Lee YZ.Non-linear fracture mechanics analyses of part circumferential surface cracked pipes[J].International Journal of Fracture,2002,116(4):347-375.
[6]Kim YJ&Shim DJ.Relevance of plastic limit loads to reference stress approach for surface cracked cylinder problems[J].International Journal of Pressure Vessels and Piping,2005,82(9):687-699.
[7]Song TK,Kim YJ,Kim JS&Jin TE.Mismatch limit loads and approximate J estimates for tensile plates with constant-depth surface cracks in the center of welds[J].International Journal of Fracture,2007,148(4):343-360.
[8]HerteléS,Waele WD,Verstraete M,Denys R&'Dowd NO.J-integral analysis of heterogeneous mismatched girth welds in clamped single-edge notched tension specimens[J].International Journal of Pressure Vessels and Piping,2014,119(4):95-107.
[9]Paredes M&Ruggieri C.Engineering approach for circumferential flaws in girth weld pipes subjected to bending load[J].International Journal of Pressure Vessels and Piping,2015,125:49-65.
[10]Souza RF&Ruggieri C.Fracture assessments of clad pipe girth welds incorporating improved crack driving force solutions[J].Engineering Fracture Mechanics,2015,148:383-405.
[11]帅健,辛艳霞.基于失效评定图的油气管线可靠性分析[J].天然气工业,2002,22(2):83-86.Shuai Jian&Xin Yanxia.Reliability analysis of oil and gas pipelines on the basis of failure assessment diagram[J].Natural Gas Industry,2002,22(2):83-86.
[12]孙亮,李培宁,刘长军.任意应力应变关系材料J积分估算的等效原场应力法[J].机械强度,2003,25(4):450-455.Sun Liang,Li Peining&Liu Changjun.Equivalent remote stress method of J integral evaluation for any stress-strain relationship materials[J].Journal of Mechanical Strength,2003,25(4):450-455.
[13]白永强,汪彤,吕良海,帅健,孙亮,陈钢.油气管道内部轴向表面半椭圆裂纹弹塑性断裂分析[J].石油化工高等学校学报,2009,22(3):71-74.Bai Yongqiang,Wang Tong,LüLianghai,Shuai Jian,Sun Liang&Chen Gang.Elastic-plastic fracture analysis for internal axial surface half elliptical cracks in oil and gas pipeline[J].Journal of Petrochemical Universities,2009,22(3):71-74.
[14]白永强,汪彤,吕良海,孙亮,帅健,陈钢.拉弯联合载荷下弹塑性J积分估算方法研究[J].工程力学,2010,27(3):6-9.Bai Yongqiang,Wang Tong,LüLianghai,Sun Liang,Shuai Jian&Chen Gang.Elastic-plastic J integral calculation method for cracks in structures under combined tension and bending[J].Engineering Mechanics,2010,27(3):6-9.
[15]全国石油天然气标准化技术委员会.石油天然气工业管线输送系统用钢管:GB/T 9711-2017[S].北京:中国标准出版,2017.National Technical Committee for Standardization of Oil and Natural Gas.Petroleum and natural gas industries-Steel pipe for pipeline transportation systems:GB/T 9711-2017[S].Beijing:China Standard Publication,2017.
[16]石油工程建设专业标准化委员会.输气管道工程设计规范:GB 50251-2015[S].北京:中国计划出版社,2015.Petroleum Engineering Construction Standardization Commission.Code for design of gas transmission pipeline engineering:GB 50251-2015[S].Beijing:China Planning Press,2015.
[17]Bergman M.Stress intensity factors for circumferential surface cracks in pipes[J].Fatigue and Fracture of Engineering Materials and Structures,2007,18(10):1155-1172.
[18]British Standards Institution.Guide on methods for assessing the acceptability of flaws in metallic structures:BS 7910-2015[S].London:BSI Standards Limited,2015.
[19]马彬.高强度管道极限载荷评价方法研究[D].北京:中国石油大学(北京),2014.Ma Bin.Research on limit pressure assessment method of high strength pipeline[D].Beijing:China University of Petroleum(Beijing),2014.
[20]王晓芳.基于极限载荷的在用含未焊透缺陷压力管道安全性分析[D].杭州:浙江大学,2010.Wang Xiaofang.Research on safety analysis of in-service pressure pipelines containing incomplete welding defects based on limited load[D].Hangzhou:Zhejiang University,2010.