Fatigue test specimens were prepared and tested with an API 5L X70 spiral welded pipe steel and girth weld. For a few selected specimens, two unloading compliance techniques (elastic compliance and back-face strain compliance) were applied simultaneously to a single specimen for direct comparisons of in-situ crack size estimation. This paper also includes fatigue crack growth rate (FCGR) data of other pipe steels and welds available in the literature. It was observed that most FCGR curves of pipeline steels (X65~X100) remained within the BS 7910 mean and upper bound design curves in the Paris region. On the contrary, the fatigue crack growth rate of the X42 pipeline steel from a reference was high - a very steep slope of the FCGR curve, crossing over the BS 7910 design criteria. It was noted that the FCGR of austenitic stainless pipe steel and girth weld obtained from Arora et al. (2014) showed a very excellent fatigue property.
{"title":"Fatigue Crack Growth Evaluation Of Pipeline Steels And Girth Welds","authors":"D. Park, Jie Liang","doi":"10.1115/1.4063293","DOIUrl":"https://doi.org/10.1115/1.4063293","url":null,"abstract":"\u0000 Fatigue test specimens were prepared and tested with an API 5L X70 spiral welded pipe steel and girth weld. For a few selected specimens, two unloading compliance techniques (elastic compliance and back-face strain compliance) were applied simultaneously to a single specimen for direct comparisons of in-situ crack size estimation. This paper also includes fatigue crack growth rate (FCGR) data of other pipe steels and welds available in the literature. It was observed that most FCGR curves of pipeline steels (X65~X100) remained within the BS 7910 mean and upper bound design curves in the Paris region. On the contrary, the fatigue crack growth rate of the X42 pipeline steel from a reference was high - a very steep slope of the FCGR curve, crossing over the BS 7910 design criteria. It was noted that the FCGR of austenitic stainless pipe steel and girth weld obtained from Arora et al. (2014) showed a very excellent fatigue property.","PeriodicalId":50080,"journal":{"name":"Journal of Pressure Vessel Technology-Transactions of the Asme","volume":null,"pages":null},"PeriodicalIF":1.0,"publicationDate":"2023-08-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42342978","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This paper is concerned with experimental analyses on the vibration behaviors of a horizontal pipe containing gas-liquid two-phase flow with different flow patterns. The effects of flow patterns and superficial velocities on pressure fluctuations and structural responses are evaluated in detail. Numerical simulations on the fluid-structure interactions within the pipe are carried out using the volume of fluid method and the finite element method. A strongly partitioned coupling method is adopted to ensure the compatibility and equilibrium interface conditions between the fluid and the elastic pipe. The accuracy of the numerical solutions is confirmed by comparing with experimental results. It is found that the fluctuation frequency of the pressure fluctuations of the two-phase flow ranges from 0Hz to 5Hz. The standard deviation value of the pressure fluctuation of the two-phase flow increases with an increase in the superficial liquid velocity, and the maximum magnitude appears in slug flows. The vibration responses of the pipe exhibit strong dependence on the momentum flux of the two-phase flow, which mainly excites the fundamental flexural vibration mode of the pipe. The magnitude of vertical vibration response of the pipe is equal to that of the lateral vibration response, and the vibration response measured at the middle of the pipe does not contain the second-order operating mode. Moreover, the STD value of the structural responses of the pipe increases proportionally with an increase in the gas flow rate, while the predominant vibration frequency of the pipe slightly increases.
{"title":"Investigation On Gas-Liquid Two-Phase Flow-Induced Vibrations Of A Horizontal Elastic Pipe","authors":"H. Su, Y. Qu, Z. Peng","doi":"10.1115/1.4063241","DOIUrl":"https://doi.org/10.1115/1.4063241","url":null,"abstract":"\u0000 This paper is concerned with experimental analyses on the vibration behaviors of a horizontal pipe containing gas-liquid two-phase flow with different flow patterns. The effects of flow patterns and superficial velocities on pressure fluctuations and structural responses are evaluated in detail. Numerical simulations on the fluid-structure interactions within the pipe are carried out using the volume of fluid method and the finite element method. A strongly partitioned coupling method is adopted to ensure the compatibility and equilibrium interface conditions between the fluid and the elastic pipe. The accuracy of the numerical solutions is confirmed by comparing with experimental results. It is found that the fluctuation frequency of the pressure fluctuations of the two-phase flow ranges from 0Hz to 5Hz. The standard deviation value of the pressure fluctuation of the two-phase flow increases with an increase in the superficial liquid velocity, and the maximum magnitude appears in slug flows. The vibration responses of the pipe exhibit strong dependence on the momentum flux of the two-phase flow, which mainly excites the fundamental flexural vibration mode of the pipe. The magnitude of vertical vibration response of the pipe is equal to that of the lateral vibration response, and the vibration response measured at the middle of the pipe does not contain the second-order operating mode. Moreover, the STD value of the structural responses of the pipe increases proportionally with an increase in the gas flow rate, while the predominant vibration frequency of the pipe slightly increases.","PeriodicalId":50080,"journal":{"name":"Journal of Pressure Vessel Technology-Transactions of the Asme","volume":null,"pages":null},"PeriodicalIF":1.0,"publicationDate":"2023-08-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46146264","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Fragility function, which defines the conditional probability of exceeding a limit state given an intensity measure (IM) of the earthquake, is an essential ingredient of modern approaches like the performance-based earthquake engineering methodology. However, the generation of such curves generally entails a high computational effort to account for epistemic and aleatory uncertainties associated with structural analysis and seismic load. Moreover, a certain probability function, such as the log-normal distribution, is usually assumed in order to carry out the conditional probability of failure of a structure, without any prior information on the correct probability distribution. In this paper, an artificial neural network (ANN) model is proposed to carry out fragility curves in order to avoid the aforementioned problems. In this respect, this paper investigates the following aspects: (i) implementation of an efficient algorithm to select proper seismic intensity measures as inputs for ANN, (ii) derivation of surrogate models by using the ANN techniques, (iii) computation of fragility curves by means Monte Carlo Simulations and (iv) validation phase.
{"title":"Artificial Neural Network Technique For Seismic Fragility Analysis Of A Storage Tank Supported By Multi-Storey Frame","authors":"G. Quinci, F. Paolacci, H. Phan","doi":"10.1115/1.4063242","DOIUrl":"https://doi.org/10.1115/1.4063242","url":null,"abstract":"Fragility function, which defines the conditional probability of exceeding a limit state given an intensity measure (IM) of the earthquake, is an essential ingredient of modern approaches like the performance-based earthquake engineering methodology. However, the generation of such curves generally entails a high computational effort to account for epistemic and aleatory uncertainties associated with structural analysis and seismic load. Moreover, a certain probability function, such as the log-normal distribution, is usually assumed in order to carry out the conditional probability of failure of a structure, without any prior information on the correct probability distribution. In this paper, an artificial neural network (ANN) model is proposed to carry out fragility curves in order to avoid the aforementioned problems. In this respect, this paper investigates the following aspects: (i) implementation of an efficient algorithm to select proper seismic intensity measures as inputs for ANN, (ii) derivation of surrogate models by using the ANN techniques, (iii) computation of fragility curves by means Monte Carlo Simulations and (iv) validation phase.","PeriodicalId":50080,"journal":{"name":"Journal of Pressure Vessel Technology-Transactions of the Asme","volume":null,"pages":null},"PeriodicalIF":1.0,"publicationDate":"2023-08-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41818525","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Non metallic composite pipes are one of the most effective ways to transport hydrogen. Basalt fiber materials can be used on hydrogen pipes, simulation models of composite pipe under plate and spherical indenter loads were established to study the effects of structure parameters on the pipe's mechanical behavior and failure modes. The results show that the matrix is the weakest part of the composite pipe under spherical indenter load, the failure areas of each fiber layer change for winding angle. The ultimate load decreases with the increasing of diameter-thickness ratio, and that increases with a deviation of the fiber winding angle from the axial direction, the indent depth increases with the increasing of diameter-thickness ratio. Under plate load, the final deformation of composite pipe is affected by the fiber winding angle and diameter-thickness ratio. The weak part of composite pipe changes due to the fiber winding angle, but the failure areas start from the plastic line area. The ultimate load and total absorbed energy of composite pipes under plate load is proportional to the winding angle and inversely proportional to the diameter-thickness ratio.
{"title":"Investigate On Failure Mechanism of Basalt Filament Wound Composite Pipe Under External Loads","authors":"Jie Zhang, Rui Yang, Haoming Sun, D. Xiang","doi":"10.1115/1.4063166","DOIUrl":"https://doi.org/10.1115/1.4063166","url":null,"abstract":"\u0000 Non metallic composite pipes are one of the most effective ways to transport hydrogen. Basalt fiber materials can be used on hydrogen pipes, simulation models of composite pipe under plate and spherical indenter loads were established to study the effects of structure parameters on the pipe's mechanical behavior and failure modes. The results show that the matrix is the weakest part of the composite pipe under spherical indenter load, the failure areas of each fiber layer change for winding angle. The ultimate load decreases with the increasing of diameter-thickness ratio, and that increases with a deviation of the fiber winding angle from the axial direction, the indent depth increases with the increasing of diameter-thickness ratio. Under plate load, the final deformation of composite pipe is affected by the fiber winding angle and diameter-thickness ratio. The weak part of composite pipe changes due to the fiber winding angle, but the failure areas start from the plastic line area. The ultimate load and total absorbed energy of composite pipes under plate load is proportional to the winding angle and inversely proportional to the diameter-thickness ratio.","PeriodicalId":50080,"journal":{"name":"Journal of Pressure Vessel Technology-Transactions of the Asme","volume":null,"pages":null},"PeriodicalIF":1.0,"publicationDate":"2023-08-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44184790","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Abstract Type III accumulator is widely used in hydrogen stations. A high-cost pressure cycle test is mandatory to ensure the safety of the accumulator in present regulations. To reduce the high cost, the aim is to develop a methodology of numerical fatigue life prediction, where an axisymmetric finite element model for the Type III accumulator is created precisely and actual loading process including autofrettage pressure is simulated. The alternating stress intensity is evaluated based on the instructions in KD-3 of 2015 ASME Boiler & Pressure Vessel Code, Section VIII, Division 3. 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.
{"title":"Numerical Fatigue Life Evaluation With Experimental Results for Type III Accumulators","authors":"Sang-Won Kim, Nobuhiro Yoshikawa","doi":"10.1115/1.4063042","DOIUrl":"https://doi.org/10.1115/1.4063042","url":null,"abstract":"Abstract Type III accumulator is widely used in hydrogen stations. A high-cost pressure cycle test is mandatory to ensure the safety of the accumulator in present regulations. To reduce the high cost, the aim is to develop a methodology of numerical fatigue life prediction, where an axisymmetric finite element model for the Type III accumulator is created precisely and actual loading process including autofrettage pressure is simulated. The alternating stress intensity is evaluated based on the instructions in KD-3 of 2015 ASME Boiler & Pressure Vessel Code, Section VIII, Division 3. 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":50080,"journal":{"name":"Journal of Pressure Vessel Technology-Transactions of the Asme","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-08-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135492797","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The mechanical and metallurgical properties of weld play the most important role in the performance of welds which needs to be enhanced. The superimposing external magnetic field to the welding arc provided wonderful and favourable results for improving the shape and properties of weld. In this research, different configurations of specially designed electromagnets were used to investigate their effects on weld characteristics of SA 516 grade 70 welds. It is observed that 0-0-S-N configuration yielded maximum penetration (3.92 mm) compared with other configurations as well as the conventional gas tungsten arc welding (GTAW) process. Tensile test, Charpy impact test and microhardness were performed to investigate the mechanical properties and microstructure analysis was used to determine the metallurgical properties of the weld joints. The result shows that the tensile strength, impact strength, and microhardness of magnetically controlled GTAW (MCGTAW) weld was 620MPa, 275J and 198HV respectively which is 3.16%, 22.76%, and 1.51% higher than weld produced by GTAW process. It has also been observed that electromagnetic stirring refined the microstructure of the weld pool. The average grain size of MCGTAW weld was 31.035µm whereas 42.558µm average grain was obtained in conventional GTAW weld. The electromagnetic stirring enhanced the weld cooling rate resulting formation of more acicular ferrite which is desirable.
{"title":"Influence Of External Magnetic Field On Mechanical And Metallurgical Properties Of Pressure Vessel Steel (Sa 516 Grade 70) Welds Using Gas Tungsten Arc Welding","authors":"Paramjeet Shakya, Kulwant Singh, H. Arya","doi":"10.1115/1.4063096","DOIUrl":"https://doi.org/10.1115/1.4063096","url":null,"abstract":"\u0000 The mechanical and metallurgical properties of weld play the most important role in the performance of welds which needs to be enhanced. The superimposing external magnetic field to the welding arc provided wonderful and favourable results for improving the shape and properties of weld. In this research, different configurations of specially designed electromagnets were used to investigate their effects on weld characteristics of SA 516 grade 70 welds. It is observed that 0-0-S-N configuration yielded maximum penetration (3.92 mm) compared with other configurations as well as the conventional gas tungsten arc welding (GTAW) process. Tensile test, Charpy impact test and microhardness were performed to investigate the mechanical properties and microstructure analysis was used to determine the metallurgical properties of the weld joints. The result shows that the tensile strength, impact strength, and microhardness of magnetically controlled GTAW (MCGTAW) weld was 620MPa, 275J and 198HV respectively which is 3.16%, 22.76%, and 1.51% higher than weld produced by GTAW process. It has also been observed that electromagnetic stirring refined the microstructure of the weld pool. The average grain size of MCGTAW weld was 31.035µm whereas 42.558µm average grain was obtained in conventional GTAW weld. The electromagnetic stirring enhanced the weld cooling rate resulting formation of more acicular ferrite which is desirable.","PeriodicalId":50080,"journal":{"name":"Journal of Pressure Vessel Technology-Transactions of the Asme","volume":null,"pages":null},"PeriodicalIF":1.0,"publicationDate":"2023-08-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45763467","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Rajkumar Shufen, Ngangkham Peter Singh, U. S. Dixit
Autofrettage is a widely employed process for strengthening cylindrical or spherical pressure vessels. The process involves applying a uniform load to the inner wall of a vessel to cause a controlled plastic deformation, where the vessel yields starting from the inner wall up to an intermediate radius. When the load is removed, elastic recovery takes place and compressive residual stresses are induced in the vicinity of the inner wall, which strengthen the vessel against high static and pulsating loads during service. Based on the load employed, autofrettage can be of five types- hydraulic, swage, explosive, thermal and rotational. This work analyzes a rotational autofrettage augmented by a thermal load where the load is applied by rotating the cylinder about its axis while maintaining a temperature gradient across the wall. The combined centrifugal and thermally-induced stresses cause plastic deformation in the cylinder. When the cylinder is unloaded by bringing it to rest and cooling down to room temperature, compressive hoop residual stresses are introduced in the vicinity of the inner wall. A finite element method model of the proposed thermally-assisted rotational autofrettage is developed for a cylinder made of AH36 mild steel in a commercial package ABAQUS®. The results indicate that the thermal load reduces the rotational speed required for autofrettage, when compared to a conventional pure rotational autofrettage. The thermal load also mitigates the tensile axial residual stresses, which are typical in a purely rotational autofrettage. A conceptual design of the experimental set up is also presented.
{"title":"Thermally-Assisted Rotational Autofrettage of Long Cylinders with Free Ends","authors":"Rajkumar Shufen, Ngangkham Peter Singh, U. S. Dixit","doi":"10.1115/1.4063095","DOIUrl":"https://doi.org/10.1115/1.4063095","url":null,"abstract":"\u0000 Autofrettage is a widely employed process for strengthening cylindrical or spherical pressure vessels. The process involves applying a uniform load to the inner wall of a vessel to cause a controlled plastic deformation, where the vessel yields starting from the inner wall up to an intermediate radius. When the load is removed, elastic recovery takes place and compressive residual stresses are induced in the vicinity of the inner wall, which strengthen the vessel against high static and pulsating loads during service. Based on the load employed, autofrettage can be of five types- hydraulic, swage, explosive, thermal and rotational. This work analyzes a rotational autofrettage augmented by a thermal load where the load is applied by rotating the cylinder about its axis while maintaining a temperature gradient across the wall. The combined centrifugal and thermally-induced stresses cause plastic deformation in the cylinder. When the cylinder is unloaded by bringing it to rest and cooling down to room temperature, compressive hoop residual stresses are introduced in the vicinity of the inner wall. A finite element method model of the proposed thermally-assisted rotational autofrettage is developed for a cylinder made of AH36 mild steel in a commercial package ABAQUS®. The results indicate that the thermal load reduces the rotational speed required for autofrettage, when compared to a conventional pure rotational autofrettage. The thermal load also mitigates the tensile axial residual stresses, which are typical in a purely rotational autofrettage. A conceptual design of the experimental set up is also presented.","PeriodicalId":50080,"journal":{"name":"Journal of Pressure Vessel Technology-Transactions of the Asme","volume":null,"pages":null},"PeriodicalIF":1.0,"publicationDate":"2023-08-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43932086","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Buried gas pipelines in karst area is inevitably affected by the geotechnical activities, which is difficult to resist the permanent ground displacement caused by soil dislocation and surface damage. In this paper, ABAQUS finite element software has been used to establish a pipe-soil nonlinear coupling model based on element birth and death technique. The influence rules of various sensitive factors on the stress response of gas pipelines are studied. The work presented in this paper can provide a reference for the design and safety of PE gas pipeline crossing the karst area.
{"title":"Research On Effect Factors Of Mechanical Response Of Pe Gas Pipeline In Karst Area Based On Element Birth And Death Technique","authors":"Q. Li, Junhua Chen","doi":"10.1115/1.4062972","DOIUrl":"https://doi.org/10.1115/1.4062972","url":null,"abstract":"\u0000 Buried gas pipelines in karst area is inevitably affected by the geotechnical activities, which is difficult to resist the permanent ground displacement caused by soil dislocation and surface damage. In this paper, ABAQUS finite element software has been used to establish a pipe-soil nonlinear coupling model based on element birth and death technique. The influence rules of various sensitive factors on the stress response of gas pipelines are studied. The work presented in this paper can provide a reference for the design and safety of PE gas pipeline crossing the karst area.","PeriodicalId":50080,"journal":{"name":"Journal of Pressure Vessel Technology-Transactions of the Asme","volume":null,"pages":null},"PeriodicalIF":1.0,"publicationDate":"2023-07-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42993211","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This study aimed to perform a Fitness-For-Service (FFS) Assessment and investigate the root cause of failure of Grade 14CrMo3 steel seamless tubes typically used in superheaters in power generation plants. Thickness and hardness measurements were taken from the samples, and microstructural analyses were performed using scanning electron microscopy and X-ray diffraction. The results showed the presence of vanadium (V) and sulfur (S) elements on the tubes' external surface (fireside) which is indicative of fuel ash corrosion. The formation of low melting point salts such as Na2SO4, NaVO3, Na2O, and V2O5 and degradation of the protective oxide layer led to loss of tube wall thickness. On the steam side of the tubes, the formation of an iron oxide layer and the presence of water in the steam due to the improper function of the steam drum created an insulated zone leading to the formation of localized hot spots, creep microvoids, and spheroidization of carbides. In addition, a thickness reduction of 18% resulted in a considerable increase in hoop stresses having a detrimental effect on the remaining creep life. To explain the creep damage mechanism and determine the remaining creep life, the Larson-Miller criteria and API 579-1/ASME FFS-1 guidelines were utilized. The effects of the reduction in wall thickness were considered by performing a 3D finite element analysis. The results showed that a temperature increase of only 50C could decrease the life of the tubes from 30 years to less than a year.
{"title":"Microstructure Analysis And Fe Modelling For Creep Failure Prediction And Fitness-For-Service Assessment Of Superheater Tubes","authors":"S. Zangeneh, H. Lashgari, R. Moazed","doi":"10.1115/1.4062974","DOIUrl":"https://doi.org/10.1115/1.4062974","url":null,"abstract":"\u0000 This study aimed to perform a Fitness-For-Service (FFS) Assessment and investigate the root cause of failure of Grade 14CrMo3 steel seamless tubes typically used in superheaters in power generation plants. Thickness and hardness measurements were taken from the samples, and microstructural analyses were performed using scanning electron microscopy and X-ray diffraction. The results showed the presence of vanadium (V) and sulfur (S) elements on the tubes' external surface (fireside) which is indicative of fuel ash corrosion. The formation of low melting point salts such as Na2SO4, NaVO3, Na2O, and V2O5 and degradation of the protective oxide layer led to loss of tube wall thickness. On the steam side of the tubes, the formation of an iron oxide layer and the presence of water in the steam due to the improper function of the steam drum created an insulated zone leading to the formation of localized hot spots, creep microvoids, and spheroidization of carbides. In addition, a thickness reduction of 18% resulted in a considerable increase in hoop stresses having a detrimental effect on the remaining creep life. To explain the creep damage mechanism and determine the remaining creep life, the Larson-Miller criteria and API 579-1/ASME FFS-1 guidelines were utilized. The effects of the reduction in wall thickness were considered by performing a 3D finite element analysis. The results showed that a temperature increase of only 50C could decrease the life of the tubes from 30 years to less than a year.","PeriodicalId":50080,"journal":{"name":"Journal of Pressure Vessel Technology-Transactions of the Asme","volume":null,"pages":null},"PeriodicalIF":1.0,"publicationDate":"2023-07-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46608008","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Kazuma Okuno, M. Arai, Kiyohiro Ito, Hidetaka Nishida
In recent years, the role of thermal power plants has shifted from providing a baseload to providing supplemental supply due to fluctuations in the energy output of renewable energy sources. Thus, it is expected that the operation of these plants involves frequent startup and shutdown cycles, which lead to extensive damage caused by creep and fatigue interactions. In addition, the piping utilized in thermal plants is subjected to a combined stress state composed of bending and torsional moments. In this study, a high-temperature fatigue testing machine that is capable of generating such a bending-torsional loading was developed. Creep-fatigue tests were conducted on P91 steel piping with weldment. The obtained results clarified that the creep-fatigue life was reduced by the superposition of the torsional and bending moments and that it was further reduced by a holding load. It was also shown that the creep-fatigue life of piping welds can be estimated accurately by the modified ductile exhaustion rule.
{"title":"Creep-Fatigue Life Property Of P91 Welded Piping Subjected To Bending And Torsional Moments At High Temperature","authors":"Kazuma Okuno, M. Arai, Kiyohiro Ito, Hidetaka Nishida","doi":"10.1115/1.4062973","DOIUrl":"https://doi.org/10.1115/1.4062973","url":null,"abstract":"\u0000 In recent years, the role of thermal power plants has shifted from providing a baseload to providing supplemental supply due to fluctuations in the energy output of renewable energy sources. Thus, it is expected that the operation of these plants involves frequent startup and shutdown cycles, which lead to extensive damage caused by creep and fatigue interactions. In addition, the piping utilized in thermal plants is subjected to a combined stress state composed of bending and torsional moments. In this study, a high-temperature fatigue testing machine that is capable of generating such a bending-torsional loading was developed. Creep-fatigue tests were conducted on P91 steel piping with weldment. The obtained results clarified that the creep-fatigue life was reduced by the superposition of the torsional and bending moments and that it was further reduced by a holding load. It was also shown that the creep-fatigue life of piping welds can be estimated accurately by the modified ductile exhaustion rule.","PeriodicalId":50080,"journal":{"name":"Journal of Pressure Vessel Technology-Transactions of the Asme","volume":null,"pages":null},"PeriodicalIF":1.0,"publicationDate":"2023-07-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43923260","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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