A high pressure carbamate condenser (HPCC) is a shell and tube heat exchanger with low pressure steam/condensate on the shell side and high pressure carbamate solution on the tube side. The inlet channel of the exchanger is protected from the internal corrosive environment by means of an austenitic stainless steel liner. During the first internal inspection after commissioning, a bulge was observed in the liner where a pass partition plate is joined to the liner. Surface-breaking cracks were observed at the partition plate to liner welds in the bulged region. The cracks were removed by shallow grinding, but a fitness-for-service assessment was required to evaluate the suitability of the bulged liner for continued service. Due to the complexity of the geometry, a handheld 3D geometry scanner was used to accurately measure the deformed shape of the bulge. Using the measured geometry, a finite element model was developed and used to perform a level 3 fitness for service assessment. This paper will describe the assessment procedure in detail as well as the complex internal repairs that were ultimately implemented in order to restore the integrity of the equipment.
{"title":"Fitness for Service Assessment and Repair of the Liner of a High Pressure Heat Exchanger","authors":"G. Zyl, Sultan A. Alharthi","doi":"10.1115/PVP2018-85001","DOIUrl":"https://doi.org/10.1115/PVP2018-85001","url":null,"abstract":"A high pressure carbamate condenser (HPCC) is a shell and tube heat exchanger with low pressure steam/condensate on the shell side and high pressure carbamate solution on the tube side. The inlet channel of the exchanger is protected from the internal corrosive environment by means of an austenitic stainless steel liner. During the first internal inspection after commissioning, a bulge was observed in the liner where a pass partition plate is joined to the liner. Surface-breaking cracks were observed at the partition plate to liner welds in the bulged region. The cracks were removed by shallow grinding, but a fitness-for-service assessment was required to evaluate the suitability of the bulged liner for continued service. Due to the complexity of the geometry, a handheld 3D geometry scanner was used to accurately measure the deformed shape of the bulge. Using the measured geometry, a finite element model was developed and used to perform a level 3 fitness for service assessment. This paper will describe the assessment procedure in detail as well as the complex internal repairs that were ultimately implemented in order to restore the integrity of the equipment.","PeriodicalId":384066,"journal":{"name":"Volume 3B: Design and Analysis","volume":"270 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-07-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114938952","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, K. Hayashi
In Japan, the Design Fatigue Curve (DFC) Phase 1 and Phase 2 subcommittees were organized under the Atomic Energy Research Committee in the Japan Welding Engineering Society and have proposed new design fatigue curves 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. In this project, fatigue tests were conducted on large-scale and small-sized specimens, and the test data were provided to the DFC Phase 2 subcommittee. This paper discusses the best-fit curves proposed by the DFC Phase 1 subcommittee, focusing on the results of large-scale fatigue tests for carbon steel and low-alloy steel plates. The fatigue test results for large-scale specimens were compared with the best-fit curve proposed by the DFC Phase 1 subcommittee. This comparison revealed that the fatigue lives given by the proposed curves correspond to those of approximately 1.5–4.0-mm-deep crack initiation in large-scale specimens. In this program, fatigue tests with a mean strain were also carried out on large-scale specimens. These tests found that the fatigue lives were almost equivalent to those of approximately 4.4–7.0-mm-deep crack initiation in large-scale specimens. In determining a design fatigue curve, strain-controlled tests are usually performed on small-sized specimens, and the fatigue life is then defined by the 25% load drop. It is reported that the cracks reach nearly 3–4-mm depth under those 25% drop cycles. The test results confirm that the fatigue lives of large-scale specimens agree with those given by the best-fit curve for carbon and low-alloy steels, and no remarkable size effects exist for the crack depths compared in this study.
{"title":"Development of New Design Fatigue Curves in Japan: Discussion of Best-Fit Curves Based on Large-Scale Fatigue Tests of Carbon and Low-Alloy Steel Plates","authors":"M. Takanashi, H. Ueda, Toshiyuki Saito, T. Ogawa, K. Hayashi","doi":"10.1115/PVP2018-84456","DOIUrl":"https://doi.org/10.1115/PVP2018-84456","url":null,"abstract":"In Japan, the Design Fatigue Curve (DFC) Phase 1 and Phase 2 subcommittees were organized under the Atomic Energy Research Committee in the Japan Welding Engineering Society and have proposed new design fatigue curves 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. In this project, fatigue tests were conducted on large-scale and small-sized specimens, and the test data were provided to the DFC Phase 2 subcommittee. This paper discusses the best-fit curves proposed by the DFC Phase 1 subcommittee, focusing on the results of large-scale fatigue tests for carbon steel and low-alloy steel plates. The fatigue test results for large-scale specimens were compared with the best-fit curve proposed by the DFC Phase 1 subcommittee. This comparison revealed that the fatigue lives given by the proposed curves correspond to those of approximately 1.5–4.0-mm-deep crack initiation in large-scale specimens. In this program, fatigue tests with a mean strain were also carried out on large-scale specimens. These tests found that the fatigue lives were almost equivalent to those of approximately 4.4–7.0-mm-deep crack initiation in large-scale specimens. In determining a design fatigue curve, strain-controlled tests are usually performed on small-sized specimens, and the fatigue life is then defined by the 25% load drop. It is reported that the cracks reach nearly 3–4-mm depth under those 25% drop cycles. The test results confirm that the fatigue lives of large-scale specimens agree with those given by the best-fit curve for carbon and low-alloy steels, and no remarkable size effects exist for the crack depths compared in this study.","PeriodicalId":384066,"journal":{"name":"Volume 3B: Design and Analysis","volume":"31 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-07-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115021128","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}
Bulk hydrogen production in a petroleum refinery by steam–methane reforming utilizes high temperatures, moderate pressures and catalyst – filled tubes which generate high tube temperatures of up to 1,690 °F [920 °C] imposing relatively harsh performance demands on system components which are not usually encountered in other refinery or petrochemical plant equipment. Creep rupture and high temperature cycling place a severe service duty on the catalyst tubes, tube outlet pigtails, the subheader train and the downstream steam generator leading to ruptured pigtails, cracking in sub-headers and break up of the ceramic tube sheet ferrules at the steam generator inlet tubesheet. Although the industry has developed specific fit-for-purpose design practice standards augmented with detailed technical reports, reliability issues persist and regularly force premature shutdown of the reformer heater and downstream heat recovery equipment. Among these practices are API Standard 530 and API TR 942-A. API 530 assists designers in the selection of materials and determination of pressure design thickness of heater tubes while API TR 942-A attempts to reconcile the contradictory industry experience where some operators have little or no problems while others suffer premature degradation and cracking of outlet pigtails and manifold components. A reconciliation between application of industry design practices and equipment performance is presented in this paper to determine whether systemic issues contribute to the apparent situation; and, recommendations are made for pressure component design and material selection for steam-methane reformers.
{"title":"Premature Degradation and Failure of Steam-Methane Reformer Heater System Components","authors":"John J. Aumuller, V. A. Carucci","doi":"10.1115/PVP2018-84006","DOIUrl":"https://doi.org/10.1115/PVP2018-84006","url":null,"abstract":"Bulk hydrogen production in a petroleum refinery by steam–methane reforming utilizes high temperatures, moderate pressures and catalyst – filled tubes which generate high tube temperatures of up to 1,690 °F [920 °C] imposing relatively harsh performance demands on system components which are not usually encountered in other refinery or petrochemical plant equipment.\u0000 Creep rupture and high temperature cycling place a severe service duty on the catalyst tubes, tube outlet pigtails, the subheader train and the downstream steam generator leading to ruptured pigtails, cracking in sub-headers and break up of the ceramic tube sheet ferrules at the steam generator inlet tubesheet.\u0000 Although the industry has developed specific fit-for-purpose design practice standards augmented with detailed technical reports, reliability issues persist and regularly force premature shutdown of the reformer heater and downstream heat recovery equipment.\u0000 Among these practices are API Standard 530 and API TR 942-A. API 530 assists designers in the selection of materials and determination of pressure design thickness of heater tubes while API TR 942-A attempts to reconcile the contradictory industry experience where some operators have little or no problems while others suffer premature degradation and cracking of outlet pigtails and manifold components.\u0000 A reconciliation between application of industry design practices and equipment performance is presented in this paper to determine whether systemic issues contribute to the apparent situation; and, recommendations are made for pressure component design and material selection for steam-methane reformers.","PeriodicalId":384066,"journal":{"name":"Volume 3B: Design and Analysis","volume":"30 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-07-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116552588","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}
Safety valve closure is employed within power plant piping systems to protect sensitive components from damage due to irregular events causing abrupt pressure variations of the thermal fluid flow. The valve closure creates a sudden obstruction to the flow, generating a pressure wave within the fluid which travels upstream and impacts at the pipe elbows. Such an event is known as steam hammer. This steam hammer pressure wave is capable of producing significant loads and stresses which can disrupt the piping supports as the wave travels throughout the pipe system. Previous studies have shown that the magnitude of these transient loads depend upon the characteristics of the flow, valve closure time, elbow-to-elbow pipe section lengths, the piping system flexibility, and the ‘steepness’ of the pressure transient. The latter effect has been ignored in most steam hammer studies; however, wave steepening has been shown to have a significant effect in cases where the pressure wave travels long distances from the safety valve. This study focuses on Computational Fluid Dynamics (CFD) modeling of rapid valve closure to produce this wave steepening effect and to investigate the significance in terms of transient pipe support loads.
{"title":"Effect of Steam Hammer Pressure Wave Steepening on Pipe Supports","authors":"A. Mayes, Kshitij P. Gawande","doi":"10.1115/PVP2018-84775","DOIUrl":"https://doi.org/10.1115/PVP2018-84775","url":null,"abstract":"Safety valve closure is employed within power plant piping systems to protect sensitive components from damage due to irregular events causing abrupt pressure variations of the thermal fluid flow. The valve closure creates a sudden obstruction to the flow, generating a pressure wave within the fluid which travels upstream and impacts at the pipe elbows. Such an event is known as steam hammer. This steam hammer pressure wave is capable of producing significant loads and stresses which can disrupt the piping supports as the wave travels throughout the pipe system. Previous studies have shown that the magnitude of these transient loads depend upon the characteristics of the flow, valve closure time, elbow-to-elbow pipe section lengths, the piping system flexibility, and the ‘steepness’ of the pressure transient. The latter effect has been ignored in most steam hammer studies; however, wave steepening has been shown to have a significant effect in cases where the pressure wave travels long distances from the safety valve. This study focuses on Computational Fluid Dynamics (CFD) modeling of rapid valve closure to produce this wave steepening effect and to investigate the significance in terms of transient pipe support loads.","PeriodicalId":384066,"journal":{"name":"Volume 3B: Design and Analysis","volume":"66 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-07-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130723079","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}
Sai Deepak Namburu, Lakshmana Rao Chebolu, A. Subramanian, R. Prakash, S. Gomathy
Welding residual stress is one of the main concerns in the process of fabrication and operation because of failures in welded steel joints due to its potential effect on structural integrity. This work focuses on the effect of welding residual stress on the ductile crack growth behavior in AISI 316LN welded CT specimens. Two-dimensional plane strain model has been used to simulate the CT specimen. X-ray diffraction technique is used to obtain residual stress value at the SS 316LN weld joint. The GTN model has been employed to estimate the ductile crack growth behavior in the CT-specimen. Results show that residual stresses influence the ductile crack growth behavior. The effect of residual stress has also been investigated for cases with different initial void volume fraction, crack lengths.
{"title":"Influence of Weld Residual Stresses on Ductile Crack Behavior in AISI Type 316LN Stainless Steel Weld Joint","authors":"Sai Deepak Namburu, Lakshmana Rao Chebolu, A. Subramanian, R. Prakash, S. Gomathy","doi":"10.1115/PVP2018-84693","DOIUrl":"https://doi.org/10.1115/PVP2018-84693","url":null,"abstract":"Welding residual stress is one of the main concerns in the process of fabrication and operation because of failures in welded steel joints due to its potential effect on structural integrity. This work focuses on the effect of welding residual stress on the ductile crack growth behavior in AISI 316LN welded CT specimens. Two-dimensional plane strain model has been used to simulate the CT specimen. X-ray diffraction technique is used to obtain residual stress value at the SS 316LN weld joint. The GTN model has been employed to estimate the ductile crack growth behavior in the CT-specimen. Results show that residual stresses influence the ductile crack growth behavior. The effect of residual stress has also been investigated for cases with different initial void volume fraction, crack lengths.","PeriodicalId":384066,"journal":{"name":"Volume 3B: Design and Analysis","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-07-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130618008","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}
S. Romo, D. Barborak, J. Bedoya, J. Penso, A. Ramirez
Coke drums are massive pressure vessels used in the oil and gas industry, which are subjected to demanding cyclic thermomechanical loading. Such conditions generate severe plastic deformation that leads to bulging and cracking during service due to low-cycle fatigue. The cracks are often repaired in programed maintenance shutdowns, and the repair procedures can be significantly different depending on the organization and failure characteristics. In this work, two types of weld repairs are evaluated after six months of service: (1) a full-excavation crack weld repair, and (2) a partial-excavation crack weld overlay repair. The repair welds were executed on a 1.25Cr-0.5Mo steel coke drum after 20 years of service. This work evaluates the microstructure of the base material, the fabrication circumferential welds, and the weld repairs. The results show that, after prolonged exposure to elevated temperatures, the originally normalized and tempered heat-treated steel microstructure has undergone severe aging. Thermodynamic equilibrium and para-equilibrium calculations were used to determine the carbide formation sequence, and SEM analysis was used to characterize the carbides present on the as-fabricated and aged microstructures. Analysis of the repaired regions did not reveal new cracks.
{"title":"Microstructural Characterization of Base Material and Welded Joints of Serviced and Non-Serviced Coke Drums","authors":"S. Romo, D. Barborak, J. Bedoya, J. Penso, A. Ramirez","doi":"10.1115/PVP2018-84859","DOIUrl":"https://doi.org/10.1115/PVP2018-84859","url":null,"abstract":"Coke drums are massive pressure vessels used in the oil and gas industry, which are subjected to demanding cyclic thermomechanical loading. Such conditions generate severe plastic deformation that leads to bulging and cracking during service due to low-cycle fatigue. The cracks are often repaired in programed maintenance shutdowns, and the repair procedures can be significantly different depending on the organization and failure characteristics. In this work, two types of weld repairs are evaluated after six months of service: (1) a full-excavation crack weld repair, and (2) a partial-excavation crack weld overlay repair. The repair welds were executed on a 1.25Cr-0.5Mo steel coke drum after 20 years of service. This work evaluates the microstructure of the base material, the fabrication circumferential welds, and the weld repairs. The results show that, after prolonged exposure to elevated temperatures, the originally normalized and tempered heat-treated steel microstructure has undergone severe aging. Thermodynamic equilibrium and para-equilibrium calculations were used to determine the carbide formation sequence, and SEM analysis was used to characterize the carbides present on the as-fabricated and aged microstructures. Analysis of the repaired regions did not reveal new cracks.","PeriodicalId":384066,"journal":{"name":"Volume 3B: Design and Analysis","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-07-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129511684","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 main pipes of reactor coolant systems (RCS) are usually long flexible structures that are connected to multiple key equipment and components of the nuclear system (e.g., reactor pressure vessel, steam generator, main pump, etc.). Mechanical analysis of pipe responses at key elbows and weld seams under static and dynamical load conditions is an essential step to ensure safety and reliability of the whole RCS. Common practice to keep the structural integrity of RCS piping under dynamical load (seismic or shock load) is to impose supporting devices at various locations so that the stiffness at weak spots can be improved. Nevertheless, the introduction of supporting devices, especially the mechanical stops, may cause significant increase of thermal stress due to the block of thermal expansion path of the piping. Hence, cooperative design and optimization of RCS piping supports by jointly considering the piping responses under static and dynamical load cases becomes quite a necessity. In this paper, such an optimal design task is formulated as a multi-objective optimization problem (MOP) with the stress level at key elbows and weld seams of the main pipes as objectives; and various parameters of each supporting device as design variables. The key feature of such MOP is that the number of design variables is unknown in prior. A single support sampling strategy is first proposed to observe the influence of one supporting device. Clustering algorithms are then applied to discover patterns from the single support sampling pool. A 3-snubber-3-stop main pipe support layout is determined via unsupervised clustering algorithms. We perform the surrogatemodel based parameter optimization once the optimization framework is fixed. Simulation results of the optimal piping support design show good satisfactions of stress level according to ASME boiler and pressure vessel code (BPVC) under both static and dynamical load cases. The data-driven design and optimization procedures presented in this paper suit the optimal design with conflicting objectives and unclear number of design variables.
{"title":"Cooperative Design and Optimization of Reactor Coolant System Piping Supports Under Static and Dynamical Load Conditions","authors":"F. Xiong, Bin Lan","doi":"10.1115/PVP2018-84026","DOIUrl":"https://doi.org/10.1115/PVP2018-84026","url":null,"abstract":"The main pipes of reactor coolant systems (RCS) are usually long flexible structures that are connected to multiple key equipment and components of the nuclear system (e.g., reactor pressure vessel, steam generator, main pump, etc.). Mechanical analysis of pipe responses at key elbows and weld seams under static and dynamical load conditions is an essential step to ensure safety and reliability of the whole RCS. Common practice to keep the structural integrity of RCS piping under dynamical load (seismic or shock load) is to impose supporting devices at various locations so that the stiffness at weak spots can be improved. Nevertheless, the introduction of supporting devices, especially the mechanical stops, may cause significant increase of thermal stress due to the block of thermal expansion path of the piping. Hence, cooperative design and optimization of RCS piping supports by jointly considering the piping responses under static and dynamical load cases becomes quite a necessity. In this paper, such an optimal design task is formulated as a multi-objective optimization problem (MOP) with the stress level at key elbows and weld seams of the main pipes as objectives; and various parameters of each supporting device as design variables. The key feature of such MOP is that the number of design variables is unknown in prior. A single support sampling strategy is first proposed to observe the influence of one supporting device. Clustering algorithms are then applied to discover patterns from the single support sampling pool. A 3-snubber-3-stop main pipe support layout is determined via unsupervised clustering algorithms. We perform the surrogatemodel based parameter optimization once the optimization framework is fixed. Simulation results of the optimal piping support design show good satisfactions of stress level according to ASME boiler and pressure vessel code (BPVC) under both static and dynamical load cases. The data-driven design and optimization procedures presented in this paper suit the optimal design with conflicting objectives and unclear number of design variables.","PeriodicalId":384066,"journal":{"name":"Volume 3B: Design and Analysis","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-07-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130037660","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}
A number of large heavy wall reactors showed severe stress corrosion cracking in the high strength low alloy steel shells. The stress corrosion was mainly caused by the fact that no PWHT was performed which resulted in very high hardness of the Heat Affected Zone; this made the HAZ extremely sensitive for stress corrosion cracking in the feed water environment. The extent of the cracking was such that replacement of all reactors was unavoidable. The redesign and fabrication of the new reactors would take over a year. Fitness for Service methodologies were used keep the reactors running safely until the replacements were installed with minimized down time. This resulted in large economic benefits over several years. The paper covers the FFS assessments performed, the special NDT methods required to get the necessary crack size information at operating conditions as well as failure mode and repair options. It demonstrates an application and the benefits of Fitness for Service assessments on key equipment.
{"title":"Fitness for Service Assessments on Cracked Heavy Wall Reactors","authors":"J. Keltjens, G. Zyl, Fahad Mudhayeq","doi":"10.1115/PVP2018-84046","DOIUrl":"https://doi.org/10.1115/PVP2018-84046","url":null,"abstract":"A number of large heavy wall reactors showed severe stress corrosion cracking in the high strength low alloy steel shells. The stress corrosion was mainly caused by the fact that no PWHT was performed which resulted in very high hardness of the Heat Affected Zone; this made the HAZ extremely sensitive for stress corrosion cracking in the feed water environment. The extent of the cracking was such that replacement of all reactors was unavoidable. The redesign and fabrication of the new reactors would take over a year. Fitness for Service methodologies were used keep the reactors running safely until the replacements were installed with minimized down time. This resulted in large economic benefits over several years. The paper covers the FFS assessments performed, the special NDT methods required to get the necessary crack size information at operating conditions as well as failure mode and repair options. It demonstrates an application and the benefits of Fitness for Service assessments on key equipment.","PeriodicalId":384066,"journal":{"name":"Volume 3B: Design and Analysis","volume":"86 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-07-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133389293","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}
Yun Wang, Hisamitsu Hatoh, Masato Yamamoto, M. Nakane, A. Hirano, K. Hayashi
Based on the precedent design fatigue curves and recent fatigue data obtained from materials with different mechanical properties, new design fatigue curves with high general versatility in air have been developed by The Japan Welding Engineering Society (JWES). Structural materials with different tensile strength are utilized in fatigue tests to verify the validity of these design fatigue curves and discuss the mean stress effect. The materials employed in this study are austenitic stainless steel (SS) SUS316LTP, carbon steel (CS) STPT370, low-alloy steels (LASs) SQV2A and SCM435H, all of which are used in the structural components of nuclear power plants of Japan. The best-fit curves (BFCs) are formulated by using the parameter of tensile strength to describe the relationship between strain (stress) amplitude and fatigue life [1]. The results of fully reversed axial fatigue tests conducted with small-scale test specimens of those materials in air at ambient temperature show good agreement with the developed BFCs. The results of fatigue tests also indicate that the mean stress effect is remarkable in materials with higher tensile strength. The applicability of Modified Goodman and Smith-Watson-Topper (SWT) approaches to the design fatigue curves is compared and discussed when considering mean stress effect. The correction of mean stress effect with SWT approach shows a good agreement with the developed BFCs.
{"title":"Development of New Design Fatigue Curves in Japan: Discussion of Best-Fit Curves Based on Fatigue Test Data With Small-Scale Test Specimen","authors":"Yun Wang, Hisamitsu Hatoh, Masato Yamamoto, M. Nakane, A. Hirano, K. Hayashi","doi":"10.1115/PVP2018-84052","DOIUrl":"https://doi.org/10.1115/PVP2018-84052","url":null,"abstract":"Based on the precedent design fatigue curves and recent fatigue data obtained from materials with different mechanical properties, new design fatigue curves with high general versatility in air have been developed by The Japan Welding Engineering Society (JWES). Structural materials with different tensile strength are utilized in fatigue tests to verify the validity of these design fatigue curves and discuss the mean stress effect. The materials employed in this study are austenitic stainless steel (SS) SUS316LTP, carbon steel (CS) STPT370, low-alloy steels (LASs) SQV2A and SCM435H, all of which are used in the structural components of nuclear power plants of Japan. The best-fit curves (BFCs) are formulated by using the parameter of tensile strength to describe the relationship between strain (stress) amplitude and fatigue life [1]. The results of fully reversed axial fatigue tests conducted with small-scale test specimens of those materials in air at ambient temperature show good agreement with the developed BFCs. The results of fatigue tests also indicate that the mean stress effect is remarkable in materials with higher tensile strength. The applicability of Modified Goodman and Smith-Watson-Topper (SWT) approaches to the design fatigue curves is compared and discussed when considering mean stress effect. The correction of mean stress effect with SWT approach shows a good agreement with the developed BFCs.","PeriodicalId":384066,"journal":{"name":"Volume 3B: Design and Analysis","volume":"20 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-07-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123113485","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}
Sang-Won Kim, N. Yoshikawa, Hiroshi Kobayashi, Toshiro Fujisawa, Takeru Sano
Composite Reinforced Accumulator (CRA) is widely used in hydrogen stations. A high-cost pressure cycle test is mandatory to ensure the safety of accumulator in present regulations. To reduce the high cost, the aim is to develop a methodology of numerical fatigue life prediction of CRA with results of pressure cycle tests. An axisymmetric finite element model for the Type III accumulator is created and actual loading process including autofrettage pressure is simulated. Stress amplitude caused by pressure cycle is evaluated based on the instructions in KD-3 of ASME BPVC VIII 3-2015. By comparing stress amplitude distributions with the leak positions after the pressure cycle test, and plotting the results in the design fatigue curve, it could be shown that fatigue life prediction of Type III accumulator can be done by precise finite element analysis of the liner including dome part, where the principal axes of stress change in pressure cycle.
复合增强蓄能器(CRA)在加氢站中应用广泛。在现行规定中，为保证蓄能器的安全，必须进行高成本的压力循环试验。为了降低高成本，研究了基于压力循环试验结果的CRA疲劳寿命数值预测方法。建立了III型蓄能器的轴对称有限元模型，模拟了包括自增强压力在内的实际加载过程。根据ASME BPVC VIII -2015中KD-3的说明对压力循环引起的应力幅值进行评估。通过压力循环试验后应力幅值分布与泄漏位置的对比，并将结果绘制到设计疲劳曲线中，可以通过对应力主轴随压力循环变化的含顶盖部分进行精确的有限元分析来预测III型蓄能器的疲劳寿命。
{"title":"Numerical Fatigue Life Evaluation With Experimental Results for Type III Accumulators","authors":"Sang-Won Kim, N. Yoshikawa, Hiroshi Kobayashi, Toshiro Fujisawa, Takeru Sano","doi":"10.1115/PVP2018-84188","DOIUrl":"https://doi.org/10.1115/PVP2018-84188","url":null,"abstract":"Composite Reinforced Accumulator (CRA) is widely used in hydrogen stations. A high-cost pressure cycle test is mandatory to ensure the safety of accumulator in present regulations. To reduce the high cost, the aim is to develop a methodology of numerical fatigue life prediction of CRA with results of pressure cycle tests.\u0000 An axisymmetric finite element model for the Type III accumulator is created and actual loading process including autofrettage pressure is simulated. Stress amplitude caused by pressure cycle is evaluated based on the instructions in KD-3 of ASME BPVC VIII 3-2015. By comparing stress amplitude distributions with the leak positions after the pressure cycle test, and plotting the results in the design fatigue curve, it could be shown that fatigue life prediction of Type III accumulator can be done by precise finite element analysis of the liner including dome part, where the principal axes of stress change in pressure cycle.","PeriodicalId":384066,"journal":{"name":"Volume 3B: Design and Analysis","volume":"114 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-07-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131432052","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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