Acoustic-Mechanical coupling effect on piping dynamics is examined on site with measurement and analytical development. In this article, a multi-treater piping system in OCU (Olefin Conversion Unit) plant is subjected to investigation since significant piping vibration prevents the normal operation when some specific combinations of two treaters are operated. There is severe piping and structure vibration problem especially with increased capacity. Measurement in frequency domain shows two peaks so close each other to result in high amplitude in the piping system vibration by beating phenomenon. In search of solution, extra safety valve is manually opened to increase the acoustic volume which changes the acoustic natural frequency in the subjected piping system and decrease the vibration. Analytical study with acoustic analysis software is also conducted and it shows the same results as the actual piping dynamics. Based on the acoustic study, piping modification is designed and applied to the piping system and vibration improvement is achieved as expected.
{"title":"Piping Vibration of Multi-Treater System in OCU Process Plant","authors":"Jaeyeol Park, Man-Soo Kim, Mi-kyung Han","doi":"10.1115/pvp2019-93394","DOIUrl":"https://doi.org/10.1115/pvp2019-93394","url":null,"abstract":"\u0000 Acoustic-Mechanical coupling effect on piping dynamics is examined on site with measurement and analytical development. In this article, a multi-treater piping system in OCU (Olefin Conversion Unit) plant is subjected to investigation since significant piping vibration prevents the normal operation when some specific combinations of two treaters are operated. There is severe piping and structure vibration problem especially with increased capacity. Measurement in frequency domain shows two peaks so close each other to result in high amplitude in the piping system vibration by beating phenomenon. In search of solution, extra safety valve is manually opened to increase the acoustic volume which changes the acoustic natural frequency in the subjected piping system and decrease the vibration. Analytical study with acoustic analysis software is also conducted and it shows the same results as the actual piping dynamics. Based on the acoustic study, piping modification is designed and applied to the piping system and vibration improvement is achieved as expected.","PeriodicalId":150804,"journal":{"name":"Volume 3: Design and Analysis","volume":"2 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-11-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132627948","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}
M. Takanashi, H. Ueda, Toshiyuki Saito, T. Ogawa, Kentaro Hayashi
In Japan, the Design Fatigue Curve (DFC) Phase 1 and Phase 2 subcommittees, which are a part of the Atomic Energy Research Committee of the Japan Welding Engineering Society, have proposed new design fatigue curves and fatigue analysis methods for carbon, low-alloy, and austenitic stainless steels. To confirm the validity of the proposed design fatigue curves, a Japanese utility collaborative project was launched, and the authors conducted fully reversed four-point bending fatigue tests for large-scale specimens of carbon steel and low-alloy steel plates. Subsequently, in a previous paper (PVP2018-84456), the authors reported that the fatigue lives determined by the best-fit curve proposed by the DFC subcommittee corresponded to those of approximately 1.5–7.0-mm-deep crack initiation in large-scale specimens. In this study, the fatigue crack initiation and propagation behavior observed in large-scale specimens was investigated by using a plastic replica and beach mark method. Similar to the case of small-sized specimens, in the large-scale specimens, multiple fatigue cracks initiated at an early stage of testing, and propagated with coalescence to penetrate the specimen width. However, no fatigue cracks were detected at the design fatigue life. Approximately 100-μm-long cracks were observed, albeit only after the specimen was subjected to a number of cycles that corresponded to approximately 3.5 times the design fatigue life. According to NUREG/CR-6909 Rev.1, the crack depths in small-sized round bar specimens at the fatigue lives, which are defined by 25%-stress-drop cycles, are reported to be approximately 3 mm. The results of the large-scale tests indicated that regardless of the specimen size, nearly the same phenomenon occurred on the specimen surface until approximately 3–4-mm-deep crack initiated. The size effect was mainly caused by the stress gradient. The finite element analysis indicated that the stress gradient in the large-scale specimen was gentle owing to the large thickness of the specimen, and the stress in the vicinity of the surface was considered to be uniform. In conclusion, the size effect was not apparent. As the same conclusion can be applied to considerably larger actual components, designers do not need to consider the size effect when designing pressure vessels or piping by using the design fatigue curve determined based on small-sized specimens.
{"title":"Development of New Design Fatigue Curves in Japan: Discussion of Crack Growth Behavior in Large-Scale Fatigue Tests of Carbon and Low-Alloy Steel Plates","authors":"M. Takanashi, H. Ueda, Toshiyuki Saito, T. Ogawa, Kentaro Hayashi","doi":"10.1115/pvp2019-93393","DOIUrl":"https://doi.org/10.1115/pvp2019-93393","url":null,"abstract":"\u0000 In Japan, the Design Fatigue Curve (DFC) Phase 1 and Phase 2 subcommittees, which are a part of the Atomic Energy Research Committee of the Japan Welding Engineering Society, have proposed new design fatigue curves and fatigue analysis methods for carbon, low-alloy, and austenitic stainless steels. To confirm the validity of the proposed design fatigue curves, a Japanese utility collaborative project was launched, and the authors conducted fully reversed four-point bending fatigue tests for large-scale specimens of carbon steel and low-alloy steel plates. Subsequently, in a previous paper (PVP2018-84456), the authors reported that the fatigue lives determined by the best-fit curve proposed by the DFC subcommittee corresponded to those of approximately 1.5–7.0-mm-deep crack initiation in large-scale specimens.\u0000 In this study, the fatigue crack initiation and propagation behavior observed in large-scale specimens was investigated by using a plastic replica and beach mark method. Similar to the case of small-sized specimens, in the large-scale specimens, multiple fatigue cracks initiated at an early stage of testing, and propagated with coalescence to penetrate the specimen width. However, no fatigue cracks were detected at the design fatigue life. Approximately 100-μm-long cracks were observed, albeit only after the specimen was subjected to a number of cycles that corresponded to approximately 3.5 times the design fatigue life.\u0000 According to NUREG/CR-6909 Rev.1, the crack depths in small-sized round bar specimens at the fatigue lives, which are defined by 25%-stress-drop cycles, are reported to be approximately 3 mm. The results of the large-scale tests indicated that regardless of the specimen size, nearly the same phenomenon occurred on the specimen surface until approximately 3–4-mm-deep crack initiated. The size effect was mainly caused by the stress gradient. The finite element analysis indicated that the stress gradient in the large-scale specimen was gentle owing to the large thickness of the specimen, and the stress in the vicinity of the surface was considered to be uniform. In conclusion, the size effect was not apparent. As the same conclusion can be applied to considerably larger actual components, designers do not need to consider the size effect when designing pressure vessels or piping by using the design fatigue curve determined based on small-sized specimens.","PeriodicalId":150804,"journal":{"name":"Volume 3: Design and Analysis","volume":"48 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-11-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126829195","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}
Printed Circuit Heat Exchangers (PCHEs) are well-suited for Very High Temperature Reactors (VHTRs) due to high compactness and efficiency for heat transfer. The design of PCHE must be robust enough to withstand possible failure caused by cyclic loading during high temperature operation. The current rules in ASME Code Section III Division 5 to evaluate strain limits and creep-fatigue damage based on elastic analysis method have been deemed infeasible at temperatures above 650°C. Hence, these rules are inapplicable for temperatures ranging from 760–950°C for VHTRs. A full inelastic analysis method with complex constitutive material description as an alternative, on the other hand, is time consuming; hence impracticable. Therefore, the simplified Elastic-Perfectly Plastic (EPP) analysis methodology is used as a solution in ASME Code Section III Division 5. The current literature, however, lacks any study on the performance evaluation of PCHE through EPP analysis. To address these issues, this study initiates the pathway of EPP evaluation of an actual size PCHE starting with elastic orthotropic analysis in the global scale. Subsequently, preliminary planning for analyzing intermediate and local submodels are provided to determine channel level responses to evaluate PCHE performance against strain limits and creep-fatigue damage using Code Case-N861 and N862 respectively.
{"title":"Pathway to Evaluate Printed Circuit Heat Exchanger Based on Simplified Elastic-Perfectly Plastic Analysis Methodology for High Temperature Nuclear Service","authors":"U. Devi, Machel Morrison, T. Hassan","doi":"10.1115/pvp2019-93468","DOIUrl":"https://doi.org/10.1115/pvp2019-93468","url":null,"abstract":"\u0000 Printed Circuit Heat Exchangers (PCHEs) are well-suited for Very High Temperature Reactors (VHTRs) due to high compactness and efficiency for heat transfer. The design of PCHE must be robust enough to withstand possible failure caused by cyclic loading during high temperature operation. The current rules in ASME Code Section III Division 5 to evaluate strain limits and creep-fatigue damage based on elastic analysis method have been deemed infeasible at temperatures above 650°C. Hence, these rules are inapplicable for temperatures ranging from 760–950°C for VHTRs. A full inelastic analysis method with complex constitutive material description as an alternative, on the other hand, is time consuming; hence impracticable. Therefore, the simplified Elastic-Perfectly Plastic (EPP) analysis methodology is used as a solution in ASME Code Section III Division 5. The current literature, however, lacks any study on the performance evaluation of PCHE through EPP analysis. To address these issues, this study initiates the pathway of EPP evaluation of an actual size PCHE starting with elastic orthotropic analysis in the global scale. Subsequently, preliminary planning for analyzing intermediate and local submodels are provided to determine channel level responses to evaluate PCHE performance against strain limits and creep-fatigue damage using Code Case-N861 and N862 respectively.","PeriodicalId":150804,"journal":{"name":"Volume 3: Design and Analysis","volume":"209 3","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-11-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114096156","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}
Continuous development of oilfields fosters a growing need for the simplification of oilfield surface process systems (SPSs) to reduce operating and management costs. Wells, testing stations, transferring stations, and central processing facilities are the main facilities in an SPS; pipelines are used to connect these stations. In this system, production radius (PR) is an important index to determine which transferring station can a testing station be linked to. Different simplification plans will lead to different operating and management costs in the following production period. Therefore, the simplification plan should be carefully designed to minimize cost and facilitate management. This paper proposes an optimization method for the simplification of SPSs in oilfields. First, an evaluation model is developed based on fuzzy analytical hierarchy process (FAHP) to select the transferring stations that need to be decommissioned. Second, hydraulic and thermal calculations are performed to get the data for the calculation of PRs. Third, the PRs, including oil gathering radius, water flooding radius, and hot water washing radius are computed to determine the linkage between the transferring stations and the testing stations. Finally, a construction plan is obtained for new pipelines of the testing stations. A case study is conducted to verify the effectiveness of this method. The results show that this method is suitable for the simplification of SPSs in oilfields.
{"title":"Optimal Simplification for the Surface Process System in Oilfields","authors":"Yongtu Liang, Bohong Wang, Jianqin Zheng, Tiantian Lei, Zhang Xin, H. Zhang","doi":"10.1115/pvp2019-93028","DOIUrl":"https://doi.org/10.1115/pvp2019-93028","url":null,"abstract":"\u0000 Continuous development of oilfields fosters a growing need for the simplification of oilfield surface process systems (SPSs) to reduce operating and management costs. Wells, testing stations, transferring stations, and central processing facilities are the main facilities in an SPS; pipelines are used to connect these stations. In this system, production radius (PR) is an important index to determine which transferring station can a testing station be linked to. Different simplification plans will lead to different operating and management costs in the following production period. Therefore, the simplification plan should be carefully designed to minimize cost and facilitate management. This paper proposes an optimization method for the simplification of SPSs in oilfields. First, an evaluation model is developed based on fuzzy analytical hierarchy process (FAHP) to select the transferring stations that need to be decommissioned. Second, hydraulic and thermal calculations are performed to get the data for the calculation of PRs. Third, the PRs, including oil gathering radius, water flooding radius, and hot water washing radius are computed to determine the linkage between the transferring stations and the testing stations. Finally, a construction plan is obtained for new pipelines of the testing stations. A case study is conducted to verify the effectiveness of this method. The results show that this method is suitable for the simplification of SPSs in oilfields.","PeriodicalId":150804,"journal":{"name":"Volume 3: Design and Analysis","volume":"13 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-11-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115906569","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}
G. Imbrogno, S. Marlette, Alexandria M. Carolan, A. Udyawar, M. Gray
A recent increase in operating experience (OE) related to pipe cracking in non-isolable auxiliary piping systems has been realized in the Pressurized Water Reactor (PWR) nuclear power industry. The majority of PWR auxiliary piping systems are comprised of welded stainless steel pipe and piping components. The susceptible piping systems are Class 1 pressure boundary and typically non-isolable from the primary loop. Since they are non-isolable, when a pipe crack or crack indication is identified, an emergent flaw evaluation and/or repair is required. Typically, the evaluations begin with an ASME Section XI IWB-3640 flaw evaluation to determine acceptability of the as-found flaw at the time of shutdown. Subsequent flaw evaluations are performed to demonstrate the possibility of continued operation of the piping component by leaving the flaw as-is without repair. The flaw tolerance evaluation considers the applicable piping geometry, materials, loadings, crack growth evaluations, and the detection capabilities of the non-destructive examination technique. If evaluation of the as-found indication does not produce acceptable results, then a repair/replacement activity per ASME Section XI is considered. Possible repair scenarios include replacement of the piping section or component, or structural weld overlay. The results of the flaw evaluations or repairs must ensure that the auxiliary piping system will continue to operate safely. This paper will discuss the recent experiences of two different piping systems (boron injection tank line and drain line) that experienced cracking, the potential causes for the cracking in the absence of evidence, and the ASME Code flaw evaluations and/or repairs performed to support continued operation of the plant.
{"title":"Recent Operational Experience of Pressurized Water Reactor Safety Injection and Drain Line Cracking and Supporting Flaw Evaluations","authors":"G. Imbrogno, S. Marlette, Alexandria M. Carolan, A. Udyawar, M. Gray","doi":"10.1115/pvp2019-93945","DOIUrl":"https://doi.org/10.1115/pvp2019-93945","url":null,"abstract":"\u0000 A recent increase in operating experience (OE) related to pipe cracking in non-isolable auxiliary piping systems has been realized in the Pressurized Water Reactor (PWR) nuclear power industry. The majority of PWR auxiliary piping systems are comprised of welded stainless steel pipe and piping components. The susceptible piping systems are Class 1 pressure boundary and typically non-isolable from the primary loop. Since they are non-isolable, when a pipe crack or crack indication is identified, an emergent flaw evaluation and/or repair is required.\u0000 Typically, the evaluations begin with an ASME Section XI IWB-3640 flaw evaluation to determine acceptability of the as-found flaw at the time of shutdown. Subsequent flaw evaluations are performed to demonstrate the possibility of continued operation of the piping component by leaving the flaw as-is without repair. The flaw tolerance evaluation considers the applicable piping geometry, materials, loadings, crack growth evaluations, and the detection capabilities of the non-destructive examination technique. If evaluation of the as-found indication does not produce acceptable results, then a repair/replacement activity per ASME Section XI is considered. Possible repair scenarios include replacement of the piping section or component, or structural weld overlay. The results of the flaw evaluations or repairs must ensure that the auxiliary piping system will continue to operate safely.\u0000 This paper will discuss the recent experiences of two different piping systems (boron injection tank line and drain line) that experienced cracking, the potential causes for the cracking in the absence of evidence, and the ASME Code flaw evaluations and/or repairs performed to support continued operation of the plant.","PeriodicalId":150804,"journal":{"name":"Volume 3: Design and Analysis","volume":"27 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-11-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116066997","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}
Fluid induced vibration in high-elevation tower and its piping system is examined with on-site measurement, numerical simulation, and analytical model. In this article, Amine regeneration tower in gas separation plant is subjected to investigation since significant vibration in both tower and its piping system prevents the normal operation especially with increased loading capacity. Measurement in frequency domain for inlet piping system shows single dominant peak as well as small peaks in low frequency range. In search of solution, analytical study with computational fluid dynamics model is conducted to reduce fluid velocity which results in decreased dynamic force in both piping system and regeneration tower and reduces the fluid-induced vibration associated with slug flow. Based on the fluid dynamics study, piping modification is designed and applied to the piping system and tower and vibration improvement is achieved as expected.
{"title":"Vibration Design of Amine Regenerator Tower and its Piping System","authors":"Jaeyeol Park, Minsung Chae","doi":"10.1115/pvp2019-93471","DOIUrl":"https://doi.org/10.1115/pvp2019-93471","url":null,"abstract":"\u0000 Fluid induced vibration in high-elevation tower and its piping system is examined with on-site measurement, numerical simulation, and analytical model. In this article, Amine regeneration tower in gas separation plant is subjected to investigation since significant vibration in both tower and its piping system prevents the normal operation especially with increased loading capacity. Measurement in frequency domain for inlet piping system shows single dominant peak as well as small peaks in low frequency range. In search of solution, analytical study with computational fluid dynamics model is conducted to reduce fluid velocity which results in decreased dynamic force in both piping system and regeneration tower and reduces the fluid-induced vibration associated with slug flow. Based on the fluid dynamics study, piping modification is designed and applied to the piping system and tower and vibration improvement is achieved as expected.","PeriodicalId":150804,"journal":{"name":"Volume 3: Design and Analysis","volume":"70 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-11-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130098894","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}
Siva Kumar Chiluvuri, Yeswanth Kumar Adusumilli, J. Penso
A typical Fluid Catalytic Cracking Unit (FCCU) generates high temperature flue gas in the process of regenerating the catalyst. This flue gas is diverted to a stack after removal of catalyst fines and excess heat using a Waste Heat Recovery Unit (WHRU) or CO boiler. This flue gas line is a large diameter (1.2 m /2 m) piping and is a combination of Hot Wall (bare SS304H piping with external insulation) upstream of Orifice Chamber and Cold Wall (Carbon steel piping with internal refractory lining) for the downstream side. In a major revamp project, large portion of flue gas line was replaced with some dimensional and design changes. A crack was noticed at the SS304H side of hot wall to cold wall transition joint downstream of Orifice Chamber after approximately 2 years in operation. The line operates around 700 °C and 0.15 Bar(g) at the location of the crack. The initial crack was measured to be approximately 250 mm to 300 mm and grew to a full circumference crack in a short time resulting in minor flue gas leaking with catalyst fines. This paper discusses the details on how the issue was addressed on site and a temporary repair (i.e. welding of a box on high temperature piping) was carried out online safely, while the unit remained in operation. Further, the paper presents the root cause assessment and design modifications implemented for hot wall to cold wall transition joint during a scheduled turnaround.
典型的流动催化裂化装置(FCCU)在催化剂再生过程中产生高温烟气。在使用废热回收装置(WHRU)或CO锅炉去除催化剂细粒和余热后，该烟气被转移到烟囱中。该烟气管道为大直径(1.2 m / 2m)管道，由孔室上游的热壁(带有外保温的裸SS304H管道)和下游的冷壁(带有内部耐火衬里的碳钢管道)组成。在某大型改造工程中，对大部分烟气管道进行了尺寸和设计上的改造。运行约2年后，发现孔室下游热壁到冷壁过渡接头SS304H侧出现裂缝。该生产线在700°C和0.15 Bar(g)的压力下工作。经测量，初始裂纹约为250 ~ 300 mm，并在短时间内扩展为全周裂纹，导致少量含催化剂颗粒的烟气泄漏。本文讨论了如何在现场解决问题的细节，并在机组仍在运行的情况下，在线安全地进行了临时修复(即在高温管道上焊接一个盒子)。此外，本文还介绍了在计划周转期间对热壁到冷壁过渡接头实施的根本原因评估和设计修改。
{"title":"Repair of High Temperature Flue Gas Line in Fluid Catalytic Cracking (FCC) Service","authors":"Siva Kumar Chiluvuri, Yeswanth Kumar Adusumilli, J. Penso","doi":"10.1115/pvp2019-93539","DOIUrl":"https://doi.org/10.1115/pvp2019-93539","url":null,"abstract":"\u0000 A typical Fluid Catalytic Cracking Unit (FCCU) generates high temperature flue gas in the process of regenerating the catalyst. This flue gas is diverted to a stack after removal of catalyst fines and excess heat using a Waste Heat Recovery Unit (WHRU) or CO boiler. This flue gas line is a large diameter (1.2 m /2 m) piping and is a combination of Hot Wall (bare SS304H piping with external insulation) upstream of Orifice Chamber and Cold Wall (Carbon steel piping with internal refractory lining) for the downstream side.\u0000 In a major revamp project, large portion of flue gas line was replaced with some dimensional and design changes. A crack was noticed at the SS304H side of hot wall to cold wall transition joint downstream of Orifice Chamber after approximately 2 years in operation. The line operates around 700 °C and 0.15 Bar(g) at the location of the crack. The initial crack was measured to be approximately 250 mm to 300 mm and grew to a full circumference crack in a short time resulting in minor flue gas leaking with catalyst fines. This paper discusses the details on how the issue was addressed on site and a temporary repair (i.e. welding of a box on high temperature piping) was carried out online safely, while the unit remained in operation. Further, the paper presents the root cause assessment and design modifications implemented for hot wall to cold wall transition joint during a scheduled turnaround.","PeriodicalId":150804,"journal":{"name":"Volume 3: Design and Analysis","volume":"15 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-11-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127836213","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}
Offshore pipelines are generally subjected to variable amplitude (VA) loading in service due to waves or ocean currents. Welded joints often represent the most critical locations for fatigue cracking. Use of the current fatigue design guidance, for example, BS 7608, to assess fatigue performance of the welded joints in such structure may lead to inaccurate estimates depending on the nature of the VA loading spectrum. Further studies on the effect of VA loading spectra on fatigue performance of welded joints are needed. In this research, both uniaxial and 3-point bending fatigue tests were performed on non-load carrying fillet welded plates under VA loading spectra to investigate the effects of mean stress and the type of VA loading spectra. The influence of plate thickness was also investigated. Test results suggest that the spectrum with a high constant maximum tensile stress (cycling-down) could significantly degrade fatigue performance of welded joints, with the damage parameter D only at around 0.5. The severity of this type of loading spectrum depends on the mean stress level and the plate thickness. An analytical model has been developed to predict fatigue crack propagation (FCP) by considering the interaction of stresses in the loading spectrum. The model considers the impact of the mean stress generated by the preceding load on FCP in the subsequent cycles. FCP predicted by the model shows a good agreement with the experimental data.
{"title":"Fatigue Performance of Welded Joints Under Variable Amplitude Loading Spectra","authors":"Xu Liu, Yan-Hui Zhang, Bin Wang","doi":"10.1115/pvp2019-93073","DOIUrl":"https://doi.org/10.1115/pvp2019-93073","url":null,"abstract":"\u0000 Offshore pipelines are generally subjected to variable amplitude (VA) loading in service due to waves or ocean currents. Welded joints often represent the most critical locations for fatigue cracking. Use of the current fatigue design guidance, for example, BS 7608, to assess fatigue performance of the welded joints in such structure may lead to inaccurate estimates depending on the nature of the VA loading spectrum. Further studies on the effect of VA loading spectra on fatigue performance of welded joints are needed. In this research, both uniaxial and 3-point bending fatigue tests were performed on non-load carrying fillet welded plates under VA loading spectra to investigate the effects of mean stress and the type of VA loading spectra. The influence of plate thickness was also investigated. Test results suggest that the spectrum with a high constant maximum tensile stress (cycling-down) could significantly degrade fatigue performance of welded joints, with the damage parameter D only at around 0.5. The severity of this type of loading spectrum depends on the mean stress level and the plate thickness. An analytical model has been developed to predict fatigue crack propagation (FCP) by considering the interaction of stresses in the loading spectrum. The model considers the impact of the mean stress generated by the preceding load on FCP in the subsequent cycles. FCP predicted by the model shows a good agreement with the experimental data.","PeriodicalId":150804,"journal":{"name":"Volume 3: Design and Analysis","volume":"45 24","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-11-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"120910622","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}
Yafei Wang, Songyan Hu, G. Cheng, Zao-xiao Zhang, Jianxiao Zhang
The carbide precipitation of 2.25Cr-1Mo-0.25V steel is studied during the head-fabrication heat treatment process using gold replica technique, scanning electron microscopy (SEM), transmission electron microscopy (TEM) and selected area electron diffraction (SAED). Shapes, structures and sizes of carbides before and after heat treatment are analyzed. The dissolution of strip-shaped carbides and the precipitation of granular carbides are confirmed. Amorphous films at the boundaries of carbides are observed by high-resolution transmission electron microscope (HRTEM), which is formed due to the electron irradiation under TEM.
{"title":"Influence of Quenching-Tempering on the Carbide Precipitation of 2.25Cr-1Mo-0.25V Steel Used in Reactor Pressure Vessels","authors":"Yafei Wang, Songyan Hu, G. Cheng, Zao-xiao Zhang, Jianxiao Zhang","doi":"10.1115/pvp2019-93054","DOIUrl":"https://doi.org/10.1115/pvp2019-93054","url":null,"abstract":"\u0000 The carbide precipitation of 2.25Cr-1Mo-0.25V steel is studied during the head-fabrication heat treatment process using gold replica technique, scanning electron microscopy (SEM), transmission electron microscopy (TEM) and selected area electron diffraction (SAED). Shapes, structures and sizes of carbides before and after heat treatment are analyzed. The dissolution of strip-shaped carbides and the precipitation of granular carbides are confirmed. Amorphous films at the boundaries of carbides are observed by high-resolution transmission electron microscope (HRTEM), which is formed due to the electron irradiation under TEM.","PeriodicalId":150804,"journal":{"name":"Volume 3: Design and Analysis","volume":"21 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-11-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121300148","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}
Elbow fittings are manufactured using quenching and tempering heat treatment processes. Such fittings can occasionally exhibit localized regions with lower yield strength than the design target, potentially due to non-uniform heat treatment. This paper presents an analytical methodology to examine the influence of these localized lower yield zones on the load capacity of the affected pipe fitting. In parallel, full-scale testing has been performed to quantify the actual response of the elbows under a combination of different loading conditions. The experimental data is used to validate the analytical approach. Details of the analytical method include a two-fold criterion: a global failure based on elastic–plastic stress analysis and a local failure based on the tri-axial strain limit per ASME Boiler and Pressure Vessel Code Section VIII, Division 2. This paper presents the details of the finite element model development, assessment procedure, validation and parametric analysis of the size and location of the low yield zones in the elbow fittings. The fittings are analyzed for three possible operating scenarios: internal pressure, internal pressure with opening moment and internal pressure with closing moment. To characterize the influence of the low yield zone on the strength of the pipe, a parameter termed as “effective yield strength” is introduced. This approach is further demonstrated and found suitable for predicting burst pressures of components with lower yield zones of various diameters and thicknesses. This assessment method can be further extended to assess other pipeline components that exhibit similar behavior.
{"title":"A Methodology to Assess Elbow Fittings With Localized Material Variations","authors":"Pritha Ghosh, M. Kulkarni, B. Vyvial, J. Ferguson","doi":"10.1115/pvp2019-93746","DOIUrl":"https://doi.org/10.1115/pvp2019-93746","url":null,"abstract":"\u0000 Elbow fittings are manufactured using quenching and tempering heat treatment processes. Such fittings can occasionally exhibit localized regions with lower yield strength than the design target, potentially due to non-uniform heat treatment. This paper presents an analytical methodology to examine the influence of these localized lower yield zones on the load capacity of the affected pipe fitting. In parallel, full-scale testing has been performed to quantify the actual response of the elbows under a combination of different loading conditions. The experimental data is used to validate the analytical approach. Details of the analytical method include a two-fold criterion: a global failure based on elastic–plastic stress analysis and a local failure based on the tri-axial strain limit per ASME Boiler and Pressure Vessel Code Section VIII, Division 2. This paper presents the details of the finite element model development, assessment procedure, validation and parametric analysis of the size and location of the low yield zones in the elbow fittings. The fittings are analyzed for three possible operating scenarios: internal pressure, internal pressure with opening moment and internal pressure with closing moment. To characterize the influence of the low yield zone on the strength of the pipe, a parameter termed as “effective yield strength” is introduced. This approach is further demonstrated and found suitable for predicting burst pressures of components with lower yield zones of various diameters and thicknesses. This assessment method can be further extended to assess other pipeline components that exhibit similar behavior.","PeriodicalId":150804,"journal":{"name":"Volume 3: Design and Analysis","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-11-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115771188","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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