The area of complex cracking in piping components and its effects on the fracture behavior and leak-before-beak evaluations has been highly researched. Several researchers have conducted experiments to quantify the behavior through complex cracked piping experiments starting from the 1980s and also more recently in dissimilar metal welds (DMWs). The area has also seen several contributions on the modeling aspects to characterize the crack initiation as well as the ductile crack growth behavior. In this work, the crack growth in complex-crack geometries is revisited through a novel laboratory specimen model, developed by modifying a Single-Edge Notch Tension SEN(T) specimen that is routinely used to obtain the fracture toughness values for both crack initiation as well as crack growth/tearing behavior. Details on the cell size used in the finite element analysis (FEA), and the effects on the predictability of the experimental observations are highlighted. The effects of constraint based on the relative levels of complex-cracking (aspect ratios) are discussed. While the results are precursors to the understanding of the correlations of constraints and fracture for these complex-cracked geometries, they provide guidelines for path forward towards development of methodologies to treat these when making reliable comparisons between material fracture resistance and crack driving forces that are routinely employed in fracture-based leak-before-break assessments for piping and piping components.
{"title":"Crack Growth Modeling and Constraint Behavior Observations in Complex Crack Geometries","authors":"S. Kalyanam, L. Hill, G. Wilkowski, F. Brust","doi":"10.1115/pvp2022-84841","DOIUrl":"https://doi.org/10.1115/pvp2022-84841","url":null,"abstract":"\u0000 The area of complex cracking in piping components and its effects on the fracture behavior and leak-before-beak evaluations has been highly researched. Several researchers have conducted experiments to quantify the behavior through complex cracked piping experiments starting from the 1980s and also more recently in dissimilar metal welds (DMWs). The area has also seen several contributions on the modeling aspects to characterize the crack initiation as well as the ductile crack growth behavior. In this work, the crack growth in complex-crack geometries is revisited through a novel laboratory specimen model, developed by modifying a Single-Edge Notch Tension SEN(T) specimen that is routinely used to obtain the fracture toughness values for both crack initiation as well as crack growth/tearing behavior. Details on the cell size used in the finite element analysis (FEA), and the effects on the predictability of the experimental observations are highlighted. The effects of constraint based on the relative levels of complex-cracking (aspect ratios) are discussed. While the results are precursors to the understanding of the correlations of constraints and fracture for these complex-cracked geometries, they provide guidelines for path forward towards development of methodologies to treat these when making reliable comparisons between material fracture resistance and crack driving forces that are routinely employed in fracture-based leak-before-break assessments for piping and piping components.","PeriodicalId":434925,"journal":{"name":"Volume 4A: Materials and Fabrication","volume":"41 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-07-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128001110","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
High temperature hydrogen attack (HTHA) is a known degradation mechanism in the refining industry for carbon and low alloy steels operating at temperatures above 400°F in hydrogen service. Historically the integrity of operating equipment subject to these conditions has been ensured by using the empirically derived Nelson Curves to identify safe operating regions. This approach was largely successful, but failures still occurred and, in some cases, required overly conservative operational limits. Additionally, this approach did not allow for a defect tolerance approach to fitness for service (FFS) assessments. An on-going joint-industry project (JIP) has been addressing these issues by generating laboratory crack growth data and developing models to apply the acquired knowledge in FFS assessments. A testing program was conducted on three (3) C-0.5 Mo steels to generate crack growth data in hydrogen at a range of temperatures (316 to 399°C [600 to 750°F]), 5.52 MPa (800 psig H2) hydrogen pressure, and stress intensity values between (10.5 to 35.4 MPa√m [9 to 32 ksi√in]). These results were used to validate and refine a crack growth model based on the creep crack growth fracture mechanics approach, C*. The results of the test program and modeling efforts are described in detail.
{"title":"Crack Growth in Carbon and C-0.5Mo Steels in High Temperature Hydrogen: Laboratory Data and Fitness for Service Modelling","authors":"B. C. Rollins, Nathaniel Sutton","doi":"10.1115/pvp2022-84906","DOIUrl":"https://doi.org/10.1115/pvp2022-84906","url":null,"abstract":"\u0000 High temperature hydrogen attack (HTHA) is a known degradation mechanism in the refining industry for carbon and low alloy steels operating at temperatures above 400°F in hydrogen service. Historically the integrity of operating equipment subject to these conditions has been ensured by using the empirically derived Nelson Curves to identify safe operating regions. This approach was largely successful, but failures still occurred and, in some cases, required overly conservative operational limits. Additionally, this approach did not allow for a defect tolerance approach to fitness for service (FFS) assessments. An on-going joint-industry project (JIP) has been addressing these issues by generating laboratory crack growth data and developing models to apply the acquired knowledge in FFS assessments.\u0000 A testing program was conducted on three (3) C-0.5 Mo steels to generate crack growth data in hydrogen at a range of temperatures (316 to 399°C [600 to 750°F]), 5.52 MPa (800 psig H2) hydrogen pressure, and stress intensity values between (10.5 to 35.4 MPa√m [9 to 32 ksi√in]). These results were used to validate and refine a crack growth model based on the creep crack growth fracture mechanics approach, C*. The results of the test program and modeling efforts are described in detail.","PeriodicalId":434925,"journal":{"name":"Volume 4A: Materials and Fabrication","volume":"52 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-07-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134447624","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The nozzle corner region in a pressure vessel experiences stress concentration under various loading such as internal pressure and thermal transients. There are many situations in which a postulated or detected flaw at the nozzle corner needs to be addressed for life assessment and fitness-for-service determinations which require stress intensity factor (KI) solutions. To assess the remaining life, the crack growth calculation of nozzle corner crack is typically performed with KI assuming a semi-circular or semi-elliptical crack shape which are limited to KI values at the deepest and surface points of the crack. However, due to the complex geometry of the nozzle corner crack, it is desired to compute KI along the entire crack front. To that end, the extended finite element method (XFEM) which can simulate cracks without the need for modeling the crack-tip can be used to calculate KI along the entire crack front for arbitrary crack shapes. Using the KI values calculated from XFEM, ‘natural’ crack growth can be simulated. The objective of this paper is to perform a feasibility study in evaluating the fatigue crack growth behavior of a nozzle corner crack using XFEM. For this purpose, an initial circular nozzle corner crack was used for benchmarking the KI values from XFEM against those from a traditional 3-D finite element model. In the next step, the XFEM model was subjected to cyclic internal pressure to grow the crack where the ‘natural’ crack behavior was studied. Using the fatigue crack growth equation (i.e., Paris Law), the succeeding crack profile was calculated for a given number of cycles using the K values from the previous step and the updated crack profile was then used as an initial crack in the next step. This iterative procedure is automated using Python Script in ABAQUS® and the final crack shape is determined for total number of cycles. Finally, the XFEM based fatigue crack growth results were validated using existing experimental data and were also compared against the crack growth results using an existing KI solution.
{"title":"Natural Crack Growth of Nozzle Corner Crack Using Extended Finite Element Method (XFEM)","authors":"G. Dominguez, M. Uddin, M. Tran, D. Shim","doi":"10.1115/pvp2022-84876","DOIUrl":"https://doi.org/10.1115/pvp2022-84876","url":null,"abstract":"\u0000 The nozzle corner region in a pressure vessel experiences stress concentration under various loading such as internal pressure and thermal transients. There are many situations in which a postulated or detected flaw at the nozzle corner needs to be addressed for life assessment and fitness-for-service determinations which require stress intensity factor (KI) solutions. To assess the remaining life, the crack growth calculation of nozzle corner crack is typically performed with KI assuming a semi-circular or semi-elliptical crack shape which are limited to KI values at the deepest and surface points of the crack. However, due to the complex geometry of the nozzle corner crack, it is desired to compute KI along the entire crack front. To that end, the extended finite element method (XFEM) which can simulate cracks without the need for modeling the crack-tip can be used to calculate KI along the entire crack front for arbitrary crack shapes. Using the KI values calculated from XFEM, ‘natural’ crack growth can be simulated.\u0000 The objective of this paper is to perform a feasibility study in evaluating the fatigue crack growth behavior of a nozzle corner crack using XFEM. For this purpose, an initial circular nozzle corner crack was used for benchmarking the KI values from XFEM against those from a traditional 3-D finite element model. In the next step, the XFEM model was subjected to cyclic internal pressure to grow the crack where the ‘natural’ crack behavior was studied. Using the fatigue crack growth equation (i.e., Paris Law), the succeeding crack profile was calculated for a given number of cycles using the K values from the previous step and the updated crack profile was then used as an initial crack in the next step. This iterative procedure is automated using Python Script in ABAQUS® and the final crack shape is determined for total number of cycles. Finally, the XFEM based fatigue crack growth results were validated using existing experimental data and were also compared against the crack growth results using an existing KI solution.","PeriodicalId":434925,"journal":{"name":"Volume 4A: Materials and Fabrication","volume":"51 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-07-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128638716","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The last several decades have seen growth in elastic-plastic fracture mechanics and the modeling of the behavior of structural steels employed in the nuclear, oil and gas, and other construction industries. Among these are a particular class of problems that provide challenges in modeling the physical behavior of structural steels using finite element modeling (FEM) approach that are based on microstructural damage and using parameters that depict the strain and stress states in the material region ahead of an existing crack. In this work, a recently experimented and investigated pipeline steel X80 material was modeled through two different fracture specimen geometries, namely single-edge-notch-tension, SEN(T) and compact-tension, C(T) to compare and contrast the predictions from two material damage models (microstructure and continuum based). The predictions from both these damage models that predict the ductile crack growth have been compared to the experimental findings of the crack growth (obtained using a d-c Electric Potential measurement technique), the corresponding load levels, and crack opening displacements (CODs). The points of similarity between the experimental measurements and the fracture surface observations of crack growth and the predictions from the FEM approach have been discussed. The same X80 material properties and damage model parameters were employed to predict the ductile crack growth in the two different fracture specimen geometries, SEN(T) and C(T) with a subtle change of one of the parameter values. This sheds light on the predictability of the crack initiation event and the subsequent ductile crack growth until failure using these damage models. The findings provide credence to the applicability of either model (after they are carefully tuned to arrive at optimized parameters) for piping materials while providing a framework for flaw evaluation methodologies. The investigation also opens the doors for regions where mesh regularization methods and modeling approaches along with mathematical relations can be developed to form a more efficient framework for modeling specimens with diverse constraints efficiently and develop material fracture resistance curves.
{"title":"Computational Mechanics Based Validation of Crack Growth Approaches for Fracture Specimen Predictions","authors":"S. Kalyanam, L. Hill, G. Wilkowski, F. Brust","doi":"10.1115/pvp2022-84898","DOIUrl":"https://doi.org/10.1115/pvp2022-84898","url":null,"abstract":"\u0000 The last several decades have seen growth in elastic-plastic fracture mechanics and the modeling of the behavior of structural steels employed in the nuclear, oil and gas, and other construction industries. Among these are a particular class of problems that provide challenges in modeling the physical behavior of structural steels using finite element modeling (FEM) approach that are based on microstructural damage and using parameters that depict the strain and stress states in the material region ahead of an existing crack. In this work, a recently experimented and investigated pipeline steel X80 material was modeled through two different fracture specimen geometries, namely single-edge-notch-tension, SEN(T) and compact-tension, C(T) to compare and contrast the predictions from two material damage models (microstructure and continuum based). The predictions from both these damage models that predict the ductile crack growth have been compared to the experimental findings of the crack growth (obtained using a d-c Electric Potential measurement technique), the corresponding load levels, and crack opening displacements (CODs). The points of similarity between the experimental measurements and the fracture surface observations of crack growth and the predictions from the FEM approach have been discussed. The same X80 material properties and damage model parameters were employed to predict the ductile crack growth in the two different fracture specimen geometries, SEN(T) and C(T) with a subtle change of one of the parameter values. This sheds light on the predictability of the crack initiation event and the subsequent ductile crack growth until failure using these damage models. The findings provide credence to the applicability of either model (after they are carefully tuned to arrive at optimized parameters) for piping materials while providing a framework for flaw evaluation methodologies. The investigation also opens the doors for regions where mesh regularization methods and modeling approaches along with mathematical relations can be developed to form a more efficient framework for modeling specimens with diverse constraints efficiently and develop material fracture resistance curves.","PeriodicalId":434925,"journal":{"name":"Volume 4A: Materials and Fabrication","volume":"43 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-07-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116360770","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In this work, conventional Friction Stir Welding (FSW) was used to investigate the weldability of recycled hybrid Aluminum Matrix Composites (AMCs). The novel composites were developed by squeeze stir casting process of scrap aluminum alloy wheels of cars as matrix and 4 wt.% of graphite, and 5 wt% of alumina as reinforcements. The casting parameters optimized from our previous work, such as squeeze pressure of 100 MPa, squeeze time of 45s, die preheating temperature of 250°C, and stirrer speed of 525 rpm, were used while casting the hybrid AMC rods. 4 mm plates were cut from each rod and subjected to an in-air friction stir welding process using a cylindrical tool of 16 mm diameter and 3 mm pin depth. Two-pass welding with a tool rotation of 1600 rpm and feed rates of 24 mm/min and 55 mm/min were used for FSW of samples. The welded section was cut out and subjected to mechanical tests such as tensile and Brinell hardness tests. It was observed that the samples welded at lower feed rates exhibited a higher tensile strength of 154 MPa and Brinell Hardness number of 61. The weldability of the recycled composites was successfully tested using FSW, a sustainable welding process. The work shows that hybrid recycled AMCs can be used for piping’s and structures prone to wear.
{"title":"Friction Stir Welding of Hybrid Recycled Metal Matrix Composites","authors":"John Victor Christy, Abdel Hamid Ismail Mourad","doi":"10.1115/pvp2022-84429","DOIUrl":"https://doi.org/10.1115/pvp2022-84429","url":null,"abstract":"\u0000 In this work, conventional Friction Stir Welding (FSW) was used to investigate the weldability of recycled hybrid Aluminum Matrix Composites (AMCs). The novel composites were developed by squeeze stir casting process of scrap aluminum alloy wheels of cars as matrix and 4 wt.% of graphite, and 5 wt% of alumina as reinforcements. The casting parameters optimized from our previous work, such as squeeze pressure of 100 MPa, squeeze time of 45s, die preheating temperature of 250°C, and stirrer speed of 525 rpm, were used while casting the hybrid AMC rods. 4 mm plates were cut from each rod and subjected to an in-air friction stir welding process using a cylindrical tool of 16 mm diameter and 3 mm pin depth. Two-pass welding with a tool rotation of 1600 rpm and feed rates of 24 mm/min and 55 mm/min were used for FSW of samples. The welded section was cut out and subjected to mechanical tests such as tensile and Brinell hardness tests. It was observed that the samples welded at lower feed rates exhibited a higher tensile strength of 154 MPa and Brinell Hardness number of 61. The weldability of the recycled composites was successfully tested using FSW, a sustainable welding process. The work shows that hybrid recycled AMCs can be used for piping’s and structures prone to wear.","PeriodicalId":434925,"journal":{"name":"Volume 4A: Materials and Fabrication","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-07-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130319376","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Failure Assessment Diagrams (FADs) are, in practice, the main engineering tool for the analysis of structural components containing cracks. They are utilised in well-known structural integrity assessment procedures, such as BS7910 and API 579 1/ASME FFS 1, and their reliability has been proven by numerous laboratory tests and industrial applications. However, they have been defined and validated in metallic materials, so their application in other types of materials requires demonstrating that the different assumptions taken when analysing metals are also valid for the particular material (non-metallic) being analysed. At the same time, additive manufacturing (AM) is a growing technology that allows complex geometries to be fabricated through a quite simple process. Among the different AM techniques, fused deposition modelling (FDM) is one of the most widely used, and consists in the extrusion of heated feedstock plastic filaments through a nozzle tip. The resulting printed materials have quite specific characteristics and properties, which are highly dependent on the printing parameters (e.g., raster orientation, printing temperature, etc.) and on the resulting state of internal defects. This paper provides FAD analyses for two additively manufactured (FDM) polymers: ABS and PLA. The results show that the FAD methodology may be applied for these two particular polymers, as long as linear-elastic fracture toughness values are used.
{"title":"Analysis of the Load Bearing Capacity of Cracked Additively Manufactured Polymers Using Failure Assessment Diagrams","authors":"S. Cicero, V. Martínez-Mata, S. Arrieta","doi":"10.1115/pvp2022-78280","DOIUrl":"https://doi.org/10.1115/pvp2022-78280","url":null,"abstract":"\u0000 Failure Assessment Diagrams (FADs) are, in practice, the main engineering tool for the analysis of structural components containing cracks. They are utilised in well-known structural integrity assessment procedures, such as BS7910 and API 579 1/ASME FFS 1, and their reliability has been proven by numerous laboratory tests and industrial applications. However, they have been defined and validated in metallic materials, so their application in other types of materials requires demonstrating that the different assumptions taken when analysing metals are also valid for the particular material (non-metallic) being analysed.\u0000 At the same time, additive manufacturing (AM) is a growing technology that allows complex geometries to be fabricated through a quite simple process. Among the different AM techniques, fused deposition modelling (FDM) is one of the most widely used, and consists in the extrusion of heated feedstock plastic filaments through a nozzle tip. The resulting printed materials have quite specific characteristics and properties, which are highly dependent on the printing parameters (e.g., raster orientation, printing temperature, etc.) and on the resulting state of internal defects.\u0000 This paper provides FAD analyses for two additively manufactured (FDM) polymers: ABS and PLA. The results show that the FAD methodology may be applied for these two particular polymers, as long as linear-elastic fracture toughness values are used.","PeriodicalId":434925,"journal":{"name":"Volume 4A: Materials and Fabrication","volume":"109 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-07-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133855879","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The American Society of Mechanical Engineers (ASME) Power Piping Code B31.1 discusses operation and maintenance piping system program requirements in Chapter VII. These program requirements for covered piping systems (CPS) operating in the creep range include the process of piping system walkdowns and the assessment of piping system integrity. For CPS operating in the creep range, this paper provides a methodology to justify extending examination intervals for girth welds subject to low stresses and high remaining useful lives (RULs) considering the observed field anomalies. Piping system walkdowns frequently reveal piping support issues such as bottomed-out, topped-out, or broken spring hangers (Cohn, M.J., Gialdini, R.J., and Nye, O.B., 2021). These unintended field anomalies should be evaluated to determine the possible impact at the piping system girth welds. The author’s strategy assumes that the unexamined girth welds have no significant fabrication defects, that future operation is similar to the past, that there are no future malfunctioning supports, and that there is no future significant off-design event. Evaluation of the first set of nondestructive examination (NDE) results will provide higher confidence in subsequent RUL estimates. The assessment of the piping system integrity for malfunctioning supports includes calculating the highest ranked locations of consumed creep life and implementing applicable NDE at the selected high priority locations. The author’s strategy is to select locations with estimated RULs less than 20 years for NDE during the next scheduled outage. Locations with estimated RULs between 20 and 50 years are medium priority ranking and may be examined during the next scheduled outage, depending on the available resources. Locations with estimated RULs beyond 50 years can have much longer examination intervals. The process of 1) comprehensive piping system walkdowns, 2) simulation as-found stress analyses to the observed field displacements, 3) NDE at the minimum remaining creep life locations, and 4) determining the next set of minimum creep life locations has been used to evaluate the current piping system integrity and provide additional confidence in safely operating the piping system until the next scheduled outage. Several case studies are discussed to illustrate the piping system integrity evaluation process. This strategy typically identifies a few critical girth welds to be examined during the next scheduled outage and provides justification to extend examinations of girth welds with estimated remaining creep rupture lives beyond 50 years.
美国机械工程师学会(ASME)动力管道规范B31.1在第七章中讨论了操作和维护管道系统程序要求。这些在蠕变范围内运行的覆盖管道系统(CPS)的程序要求包括管道系统故障分析过程和管道系统完整性评估。对于在蠕变范围内工作的CPS，本文提供了一种方法来证明在低应力和高剩余使用寿命(RULs)下延长环焊缝检查间隔的合理性，考虑到观察到的现场异常。管道系统检查经常会发现管道支撑问题，如底部拔出、顶部拔出或弹簧吊架断裂(Cohn, m.j.， Gialdini, r.j.， and Nye, o.b.， 2021)。应对这些意外的现场异常进行评估，以确定对管道系统环焊缝的可能影响。作者的策略假设未经检查的环焊缝没有重大的制造缺陷，未来的操作与过去类似，未来没有故障支撑，并且未来没有重大的非设计事件。对第一组无损检测(NDE)结果的评估将为随后的RUL估计提供更高的信心。故障支架的管道系统完整性评估包括计算消耗蠕变寿命最高的位置，并在选定的高优先级位置实施适用的无损检测。作者的策略是在下一次计划停运期间选择估计rl小于20年的地点进行NDE。估计rur在20到50年之间的位置是中等优先级，可能会在下一次计划停机期间进行检查，具体取决于可用资源。估计rur超过50年的地点可以有更长的检查间隔。1)全面的管道系统运行，2)对观察到的现场位移进行模拟发现应力分析，3)在最小剩余蠕变寿命位置进行无损检测，以及4)确定下一组最小蠕变寿命位置的过程已用于评估当前管道系统的完整性，并为管道系统的安全运行提供额外的信心，直到下一次计划停机。讨论了几个案例来说明管道系统完整性评估过程。该策略通常确定在下一次计划停运期间需要检查的几个关键环焊缝，并提供理由延长环焊缝的检查，估计剩余蠕变断裂寿命超过50年。
{"title":"Technical Justification to Extend Girth Weld Examination Intervals","authors":"M. Cohn","doi":"10.1115/pvp2022-85728","DOIUrl":"https://doi.org/10.1115/pvp2022-85728","url":null,"abstract":"\u0000 The American Society of Mechanical Engineers (ASME) Power Piping Code B31.1 discusses operation and maintenance piping system program requirements in Chapter VII. These program requirements for covered piping systems (CPS) operating in the creep range include the process of piping system walkdowns and the assessment of piping system integrity. For CPS operating in the creep range, this paper provides a methodology to justify extending examination intervals for girth welds subject to low stresses and high remaining useful lives (RULs) considering the observed field anomalies.\u0000 Piping system walkdowns frequently reveal piping support issues such as bottomed-out, topped-out, or broken spring hangers (Cohn, M.J., Gialdini, R.J., and Nye, O.B., 2021). These unintended field anomalies should be evaluated to determine the possible impact at the piping system girth welds.\u0000 The author’s strategy assumes that the unexamined girth welds have no significant fabrication defects, that future operation is similar to the past, that there are no future malfunctioning supports, and that there is no future significant off-design event. Evaluation of the first set of nondestructive examination (NDE) results will provide higher confidence in subsequent RUL estimates.\u0000 The assessment of the piping system integrity for malfunctioning supports includes calculating the highest ranked locations of consumed creep life and implementing applicable NDE at the selected high priority locations. The author’s strategy is to select locations with estimated RULs less than 20 years for NDE during the next scheduled outage. Locations with estimated RULs between 20 and 50 years are medium priority ranking and may be examined during the next scheduled outage, depending on the available resources. Locations with estimated RULs beyond 50 years can have much longer examination intervals.\u0000 The process of 1) comprehensive piping system walkdowns, 2) simulation as-found stress analyses to the observed field displacements, 3) NDE at the minimum remaining creep life locations, and 4) determining the next set of minimum creep life locations has been used to evaluate the current piping system integrity and provide additional confidence in safely operating the piping system until the next scheduled outage.\u0000 Several case studies are discussed to illustrate the piping system integrity evaluation process. This strategy typically identifies a few critical girth welds to be examined during the next scheduled outage and provides justification to extend examinations of girth welds with estimated remaining creep rupture lives beyond 50 years.","PeriodicalId":434925,"journal":{"name":"Volume 4A: Materials and Fabrication","volume":"49 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-07-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127614378","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Zhou Fang, Puan Shi, Zhe Wang, Gang Wu, Qia Liu, Yongming Wang
With the development of global society and the progress of technology, hydrogen energy is gradually becoming an emerging clean energy source. As a special high-pressure container for storing hydrogen, damage to the hydrogen storage vessel under the impact of dynamic load can cause serious accidents. In order to study the mechanical property changes of hydrogen storage vessel under dynamic load, this paper adopts the equivalent static method to numerically simulate the steel hydrogen storage vessel and analyze the effects of load size and impact location on the stress-strain of hydrogen storage vessel under dynamic load impact, so as to provide theoretical basis for the analysis, evaluation and design of hydrogen storage vessel’s crashworthiness.
{"title":"Finite Element Numerical Simulation of Hydrogen Storage Vessel Under Dynamic Load Impact","authors":"Zhou Fang, Puan Shi, Zhe Wang, Gang Wu, Qia Liu, Yongming Wang","doi":"10.1115/pvp2022-84473","DOIUrl":"https://doi.org/10.1115/pvp2022-84473","url":null,"abstract":"\u0000 With the development of global society and the progress of technology, hydrogen energy is gradually becoming an emerging clean energy source. As a special high-pressure container for storing hydrogen, damage to the hydrogen storage vessel under the impact of dynamic load can cause serious accidents. In order to study the mechanical property changes of hydrogen storage vessel under dynamic load, this paper adopts the equivalent static method to numerically simulate the steel hydrogen storage vessel and analyze the effects of load size and impact location on the stress-strain of hydrogen storage vessel under dynamic load impact, so as to provide theoretical basis for the analysis, evaluation and design of hydrogen storage vessel’s crashworthiness.","PeriodicalId":434925,"journal":{"name":"Volume 4A: Materials and Fabrication","volume":"34 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-07-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128998778","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Gi-bum Lee, Y. Jang, N. Huh, Sung Hoon Park, Noh-hwan Park, Jun-Hui Park, Kyoungsoo Park
Because of the long-term operation of nuclear power plants, the assessment of crack growth in pipelines has become one of the most important issues. Crack growth resistance in operating nuclear power plants is typically evaluated using linear elastic fracture mechanics based on ASME B&PV Section XI. However, the ASME method predicts the results conservatively, for complex shapes and conditions, while the finite element analysis, which is more accurate, consumes a substantial amount of time and cost. In this study, a finite element analysis-based iterative crack growth program was created to evaluate cracks with more accuracy and time efficiency. The verification of the program was carried out in two cases. By comparing the produced program with the test result of the three-point bending of the beam with rivet holes, it was shown that the program simulates crack propagation in the right direction. In addition, by comparing the results of the fatigue crack growth (FCG) test of CCT/SENT specimens, it was shown that the program can be applied to the evaluation of major failure mechanisms in the nuclear power plants such as stress corrosion crack (SCC) growth and FCG.
{"title":"Crack Growth Simulation Using Iterative Crack-Tip Modeling Technique","authors":"Gi-bum Lee, Y. Jang, N. Huh, Sung Hoon Park, Noh-hwan Park, Jun-Hui Park, Kyoungsoo Park","doi":"10.1115/pvp2022-84684","DOIUrl":"https://doi.org/10.1115/pvp2022-84684","url":null,"abstract":"\u0000 Because of the long-term operation of nuclear power plants, the assessment of crack growth in pipelines has become one of the most important issues. Crack growth resistance in operating nuclear power plants is typically evaluated using linear elastic fracture mechanics based on ASME B&PV Section XI. However, the ASME method predicts the results conservatively, for complex shapes and conditions, while the finite element analysis, which is more accurate, consumes a substantial amount of time and cost. In this study, a finite element analysis-based iterative crack growth program was created to evaluate cracks with more accuracy and time efficiency. The verification of the program was carried out in two cases. By comparing the produced program with the test result of the three-point bending of the beam with rivet holes, it was shown that the program simulates crack propagation in the right direction. In addition, by comparing the results of the fatigue crack growth (FCG) test of CCT/SENT specimens, it was shown that the program can be applied to the evaluation of major failure mechanisms in the nuclear power plants such as stress corrosion crack (SCC) growth and FCG.","PeriodicalId":434925,"journal":{"name":"Volume 4A: Materials and Fabrication","volume":"37 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-07-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132363728","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Zhao Yatong, Shuai Jian, S. Lei, Hu Zijian, Chen Zhanfeng
With the development of oil and gas transmission pipelines towards large diameter, and high strength, high steel grade pipeline steel materials represented by X80 have become the primary choice for oil and gas transmission pipelines. In order to achieve a low-cost and rapid acquisition of fracture toughness of pipeline steel in engineering, the feasibility of Charpy impact testing is investigated. In this paper, the test method of pipe fracture toughness based on instrumented Charpy impact test is investigated in detail, taking X80 pipeline steel as an example, and its fracture mode and expansion law are studied in combination with fracture morphology analysis. The dynamic J-integral of the material was obtained by the rate of change curve method of flexibility, and then the equation for solving the quasi-static J-integral based on the dynamic test method of CVN specimens was established. An innovative empirical equation for solving the J-integral based on the load-displacement curve was established based on the method of dimensional analysis. The results show that the method is suitable for rapid engineering solutions with good results, offering new possibilities for the assessment and study of weld fracture toughness.
{"title":"Study of a Method for Determining the Fracture Toughness of Pipe Steel Based on Instrumented Charpy Impact Testing","authors":"Zhao Yatong, Shuai Jian, S. Lei, Hu Zijian, Chen Zhanfeng","doi":"10.1115/pvp2022-84022","DOIUrl":"https://doi.org/10.1115/pvp2022-84022","url":null,"abstract":"\u0000 With the development of oil and gas transmission pipelines towards large diameter, and high strength, high steel grade pipeline steel materials represented by X80 have become the primary choice for oil and gas transmission pipelines. In order to achieve a low-cost and rapid acquisition of fracture toughness of pipeline steel in engineering, the feasibility of Charpy impact testing is investigated. In this paper, the test method of pipe fracture toughness based on instrumented Charpy impact test is investigated in detail, taking X80 pipeline steel as an example, and its fracture mode and expansion law are studied in combination with fracture morphology analysis. The dynamic J-integral of the material was obtained by the rate of change curve method of flexibility, and then the equation for solving the quasi-static J-integral based on the dynamic test method of CVN specimens was established. An innovative empirical equation for solving the J-integral based on the load-displacement curve was established based on the method of dimensional analysis. The results show that the method is suitable for rapid engineering solutions with good results, offering new possibilities for the assessment and study of weld fracture toughness.","PeriodicalId":434925,"journal":{"name":"Volume 4A: Materials and Fabrication","volume":"1 6 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-07-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130555075","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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