Feng Xu, Yongsheng Xu, Jianfei Song, Hongchao Suo, Xin Liu
Aiming at the problem that there is no effective tool to quickly analyze the mechanical response of long-distance buried pipelines, this paper uses the APDL language of ANSYS to compile a rapid solution program for the mechanical response of buried pipelines based on the soil spring model. The program is used to establish the calculation model of 500 m long pipe, and analyze the mechanical response of the pipeline with and without medium and subsidence. The value are compared with those of ABAQUS based on PSI unit and solid contact model. The results show that the calculation value of these three methods are in good agreement. The program can realize rapid modeling and accurate analysis of long-distance buried pipelines, and has high engineering application value.
{"title":"Numerical Simulation Comparative Analysis of Pipe Soil Interaction in Buried Pipeline","authors":"Feng Xu, Yongsheng Xu, Jianfei Song, Hongchao Suo, Xin Liu","doi":"10.1115/pvp2022-84573","DOIUrl":"https://doi.org/10.1115/pvp2022-84573","url":null,"abstract":"\u0000 Aiming at the problem that there is no effective tool to quickly analyze the mechanical response of long-distance buried pipelines, this paper uses the APDL language of ANSYS to compile a rapid solution program for the mechanical response of buried pipelines based on the soil spring model. The program is used to establish the calculation model of 500 m long pipe, and analyze the mechanical response of the pipeline with and without medium and subsidence. The value are compared with those of ABAQUS based on PSI unit and solid contact model. The results show that the calculation value of these three methods are in good agreement. The program can realize rapid modeling and accurate analysis of long-distance buried pipelines, and has high engineering application value.","PeriodicalId":23700,"journal":{"name":"Volume 2: Computer Technology and Bolted Joints; Design and Analysis","volume":"48 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-07-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89073623","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}
Many bolting professionals in the heavy industrial industry rely on the belief that “Washers play an essential role in generating and sustaining integrity in bolted assemblies.” [1] It is believed that washers improve the reliability of bolted joints by providing a consistent K-Factor by introducing a flat even plane on which the nut can rotate. During practical training we noticed that using washers resulted in greater difference in bolt load between studs than experienced without washers. That experience led the authors to hypothesize that washers do not improve the accuracy and repeatability of bolted flange joints. This paper reports the findings of a study conducted to test this hypothesis. The study recorded the variance in measured K-Factor when tightening nuts against various flange surfaces with and without washers and determined that, when properly lubricated, the performance of studs against various flange surfaces did not vary greatly from the performance of studs against washers. Additionally, in some cases washers introduced a source of variance in bolt load. In addition to their perceived benefit in generating and maintaining tension in the bolted flange joint, washers are understood to provide benefits including preventing damage to the flange surface, preventing galling of the flange surface, and preventing nut embedment. This study focused on the use of washers in generating the expected bolt load and did not assess those additional benefits of washer usage.
{"title":"Washers: Are They as Good as We Think?","authors":"Scott R. Hamilton, Dan Meigs","doi":"10.1115/pvp2022-83610","DOIUrl":"https://doi.org/10.1115/pvp2022-83610","url":null,"abstract":"\u0000 Many bolting professionals in the heavy industrial industry rely on the belief that “Washers play an essential role in generating and sustaining integrity in bolted assemblies.” [1] It is believed that washers improve the reliability of bolted joints by providing a consistent K-Factor by introducing a flat even plane on which the nut can rotate.\u0000 During practical training we noticed that using washers resulted in greater difference in bolt load between studs than experienced without washers. That experience led the authors to hypothesize that washers do not improve the accuracy and repeatability of bolted flange joints. This paper reports the findings of a study conducted to test this hypothesis.\u0000 The study recorded the variance in measured K-Factor when tightening nuts against various flange surfaces with and without washers and determined that, when properly lubricated, the performance of studs against various flange surfaces did not vary greatly from the performance of studs against washers. Additionally, in some cases washers introduced a source of variance in bolt load.\u0000 In addition to their perceived benefit in generating and maintaining tension in the bolted flange joint, washers are understood to provide benefits including preventing damage to the flange surface, preventing galling of the flange surface, and preventing nut embedment. This study focused on the use of washers in generating the expected bolt load and did not assess those additional benefits of washer usage.","PeriodicalId":23700,"journal":{"name":"Volume 2: Computer Technology and Bolted Joints; Design and Analysis","volume":"60 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-07-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85522750","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In the published standards, selection criteria for bolt materials for high temperature and high pressure environments (exceeding 540°C (1000°F) and 300 lb) has not been specified. In addition, it seems that there are few studies that summarize how the initial bolt load and the flange nominal diameter affect the change over time of the bolt load under a high temperature environment. This paper proposed formulas to calculate the changes over time in bolt stress and gasket stress easily due to bolt creep by applying the mechanical relationship of bolted flange joint. The changes over time in the bolt stress and the gasket stress calculated by the proposed formulas were fairly good agreement with the FEM and the experiments. By utilizing proposed formulas, it is possible to predict when retightening should be carried out for bolted flange joints operated continuously for a long period of time. Furthermore, in the present paper, the effects of initial bolt load, internal pressure, bolt materials, and flange nominal diameters on the sealing performance under high temperature environments are clarified by utilizing proposed formulas and FEM. As a result, this paper shows that the increasing initial bolt load against bolt creep under a high temperature environment can not be expected to be effective, and that the size of internal pressure and flange nominal diameter has small effects on the change over time of bolt load.
{"title":"Estimation of Bolt Creep Characteristics and Sealing Performance of Flanged Joints","authors":"Hiroshi Yamanaka","doi":"10.1115/pvp2022-78366","DOIUrl":"https://doi.org/10.1115/pvp2022-78366","url":null,"abstract":"\u0000 In the published standards, selection criteria for bolt materials for high temperature and high pressure environments (exceeding 540°C (1000°F) and 300 lb) has not been specified. In addition, it seems that there are few studies that summarize how the initial bolt load and the flange nominal diameter affect the change over time of the bolt load under a high temperature environment. This paper proposed formulas to calculate the changes over time in bolt stress and gasket stress easily due to bolt creep by applying the mechanical relationship of bolted flange joint. The changes over time in the bolt stress and the gasket stress calculated by the proposed formulas were fairly good agreement with the FEM and the experiments. By utilizing proposed formulas, it is possible to predict when retightening should be carried out for bolted flange joints operated continuously for a long period of time. Furthermore, in the present paper, the effects of initial bolt load, internal pressure, bolt materials, and flange nominal diameters on the sealing performance under high temperature environments are clarified by utilizing proposed formulas and FEM. As a result, this paper shows that the increasing initial bolt load against bolt creep under a high temperature environment can not be expected to be effective, and that the size of internal pressure and flange nominal diameter has small effects on the change over time of bolt load.","PeriodicalId":23700,"journal":{"name":"Volume 2: Computer Technology and Bolted Joints; Design and Analysis","volume":"17 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-07-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89584554","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}
Spherical pressure vessels (spheres) are widely used for storing liquids and gases at high pressures. The post plates of column-supported spheres are subjected to additional loads imposed by the supporting columns. The resulting localized stresses at column-to-post plate junction are difficult to analyze using analytical methods. Numerical techniques, such as the finite element method (FEM) are generally used to analyze the local discontinuity stresses. In this work, a finite element parametric study is performed using a wide range of sphere geometries. The stresses at various locations around the column attachment are investigated. The influence of various loadings on the local stresses is also investigated. The internal membrane forces and bending moments obtained from the finite element model are then used to establish the dimensionless curves. A step-by-step procedure and the closed-form equations are provided to calculate membrane stresses, bending stresses and the combined stresses. A table of load factors is included to estimate the maximum vertical and horizontal loads on post plate due to wind or seismic forces. Finally, a sample problem is presented to illustrate the analysis procedure. Using this easy-to-use analysis approach, the design engineers will be able to calculate the localized stresses in sphere post plates without having to utilize the finite element method.
{"title":"Evaluation of Localized Stresses at Spherical Pressure Vessel-to-Column Support Junction Using Closed-Form Equations","authors":"Vivek Manjrekar","doi":"10.1115/pvp2022-84890","DOIUrl":"https://doi.org/10.1115/pvp2022-84890","url":null,"abstract":"\u0000 Spherical pressure vessels (spheres) are widely used for storing liquids and gases at high pressures. The post plates of column-supported spheres are subjected to additional loads imposed by the supporting columns. The resulting localized stresses at column-to-post plate junction are difficult to analyze using analytical methods. Numerical techniques, such as the finite element method (FEM) are generally used to analyze the local discontinuity stresses.\u0000 In this work, a finite element parametric study is performed using a wide range of sphere geometries. The stresses at various locations around the column attachment are investigated. The influence of various loadings on the local stresses is also investigated. The internal membrane forces and bending moments obtained from the finite element model are then used to establish the dimensionless curves. A step-by-step procedure and the closed-form equations are provided to calculate membrane stresses, bending stresses and the combined stresses. A table of load factors is included to estimate the maximum vertical and horizontal loads on post plate due to wind or seismic forces. Finally, a sample problem is presented to illustrate the analysis procedure. Using this easy-to-use analysis approach, the design engineers will be able to calculate the localized stresses in sphere post plates without having to utilize the finite element method.","PeriodicalId":23700,"journal":{"name":"Volume 2: Computer Technology and Bolted Joints; Design and Analysis","volume":"20 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-07-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75012306","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}
W. Vorster, J. Roy, Daniel G. Gilroy, Jack A. Pollock, David M. Clarkson, A. J. Beveridge, Alistair Strong
This paper discusses fitness for purpose (FfP) structural integrity assessments of Safety Relief valve (SRV) vent pipes that were inadequately designed and maintained. The FfP assessments identified several latent errors with the pipework design. The absence of a fault schedule in combination with the latent errors led to a discernable anomaly in the safety case which was finally address but resulted in long outage delays and spiraling costs due to the large number of assessments, inspections and modifications required to achieve and demonstrate integrity. The FfP assessments discussed here consider all failure mechanisms which were identified as being relevant during steam discharge. These include plastic collapse, ratchetting, creep rupture and creep-fatigue and required a series of complex assessments to sentence the SRV pipes for return to service. The Computational Fluid Dynamics (CFD), pipe stress analysis and Finite Element Modeling (FEM) required to demonstrate integrity are discussed. The plant modification and repair solutions required to achieve integrity before the pipes could be returned to service are presented. The method used to apply CFD loads to pipe stress models without double accounting for static pressure stresses in the Finite Element Analyses (FEA), is describe here. Novel analysis techniques used to speed up assessments and the historic plant data reviews that were required to substantiate the claims on historic damage are reviewed.
{"title":"Assessment of Safety Valve Escape Pipework","authors":"W. Vorster, J. Roy, Daniel G. Gilroy, Jack A. Pollock, David M. Clarkson, A. J. Beveridge, Alistair Strong","doi":"10.1115/pvp2022-84858","DOIUrl":"https://doi.org/10.1115/pvp2022-84858","url":null,"abstract":"\u0000 This paper discusses fitness for purpose (FfP) structural integrity assessments of Safety Relief valve (SRV) vent pipes that were inadequately designed and maintained. The FfP assessments identified several latent errors with the pipework design. The absence of a fault schedule in combination with the latent errors led to a discernable anomaly in the safety case which was finally address but resulted in long outage delays and spiraling costs due to the large number of assessments, inspections and modifications required to achieve and demonstrate integrity.\u0000 The FfP assessments discussed here consider all failure mechanisms which were identified as being relevant during steam discharge. These include plastic collapse, ratchetting, creep rupture and creep-fatigue and required a series of complex assessments to sentence the SRV pipes for return to service. The Computational Fluid Dynamics (CFD), pipe stress analysis and Finite Element Modeling (FEM) required to demonstrate integrity are discussed. The plant modification and repair solutions required to achieve integrity before the pipes could be returned to service are presented. The method used to apply CFD loads to pipe stress models without double accounting for static pressure stresses in the Finite Element Analyses (FEA), is describe here. Novel analysis techniques used to speed up assessments and the historic plant data reviews that were required to substantiate the claims on historic damage are reviewed.","PeriodicalId":23700,"journal":{"name":"Volume 2: Computer Technology and Bolted Joints; Design and Analysis","volume":"111 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-07-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86789137","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}
To mitigate the severe effects in the beyond design basis accident (BDBA), the concept of fracture control was proposed in the previous study. The idea of the fracture control is to manage the accident consequence by controlling to cause minor failure prior to the fatal failure. Taking the piping system as an example, boundary failure should be prevented under the BDBA condition, whereas the minor failure, such as support failure which does not affect the function of the piping system, can be acceptable. To realize the fracture control concept on piping system, shaking table tests on piping systems with support are planned. As the first step of the attempt, fundamental experiment on relatively simple piping system and support configuration was conducted. In this experiment, pipe elbows made of simulation material (lead-antimony alloy) were used, and the support was modeled by a plate. Through the experiments, the fracture of support successfully occurred prior to the large deformation of pipe itself. The results showed that the fracture control may be possible when the fracture of support occurred prior to the failure of pipe itself, and the ratio of the input frequency to the specimen’s natural frequency (fR) be over 1.0 after the support failure. The test results demonstrated the possibility of fracture control concept by support failure. As the next step of the attempt, shaking table test on more realistic piping system, which is named as validation test, is now prepared. The preliminary analysis shows that the inelastic behavior of support is expected.
{"title":"Plan of a Shaking Table Test on a Piping System Model for Verifying the Fracture-Control Concept","authors":"Izumi Nakamura, N. Kasahara","doi":"10.1115/pvp2022-84266","DOIUrl":"https://doi.org/10.1115/pvp2022-84266","url":null,"abstract":"\u0000 To mitigate the severe effects in the beyond design basis accident (BDBA), the concept of fracture control was proposed in the previous study. The idea of the fracture control is to manage the accident consequence by controlling to cause minor failure prior to the fatal failure.\u0000 Taking the piping system as an example, boundary failure should be prevented under the BDBA condition, whereas the minor failure, such as support failure which does not affect the function of the piping system, can be acceptable.\u0000 To realize the fracture control concept on piping system, shaking table tests on piping systems with support are planned. As the first step of the attempt, fundamental experiment on relatively simple piping system and support configuration was conducted. In this experiment, pipe elbows made of simulation material (lead-antimony alloy) were used, and the support was modeled by a plate. Through the experiments, the fracture of support successfully occurred prior to the large deformation of pipe itself. The results showed that the fracture control may be possible when the fracture of support occurred prior to the failure of pipe itself, and the ratio of the input frequency to the specimen’s natural frequency (fR) be over 1.0 after the support failure. The test results demonstrated the possibility of fracture control concept by support failure.\u0000 As the next step of the attempt, shaking table test on more realistic piping system, which is named as validation test, is now prepared. The preliminary analysis shows that the inelastic behavior of support is expected.","PeriodicalId":23700,"journal":{"name":"Volume 2: Computer Technology and Bolted Joints; Design and Analysis","volume":"73 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-07-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84326800","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}
Class 1 nuclear piping systems, small-bore piping branch connections are susceptible to high thermal fatigue stresses, particularly in cases where harsh thermal transients are present. Calculating the Cumulative Usage Factor (CUF) using the procedure defined in the ASME Boiler and Pressure Vessel Code in Section III NB-3600 can limit the permissible cycle life (i.e., fatigue life) of the piping component. As per NB-3630(c), when a design does not satisfy the requirements of NB-3640 and NB-3650, a more detailed alternative analysis defined in NB-3200 can be used. This work compares the code requirements, analysis methodology, and results of a typical small bore branch connection connected to a piping header that is assessed against the requirements of NB-3600 and NB-3200. Piping is modeled using beam elements by utilizing PIPESTRESS piping analysis software for the NB-3600 based analysis. In comparison, a finite element model in Ansys Workbench is developed for the NB-3200 transient thermal and structural analysis. Representative pressure and thermal transients applicable to the heat transport system of a typical CANDU reactor are utilized in the analysis. The analysis results show that a significant drop in the Cumulative Usage Factor is achieved with the NB-3200 approach when compared with NB-3600.
{"title":"Fatigue Analysis of Nuclear Class-1 Small-Bore Piping Connections in CANDU Reactors","authors":"S. A. Rehman, Ahmed R. Alian, Najmul H. Abid","doi":"10.1115/pvp2022-84938","DOIUrl":"https://doi.org/10.1115/pvp2022-84938","url":null,"abstract":"\u0000 Class 1 nuclear piping systems, small-bore piping branch connections are susceptible to high thermal fatigue stresses, particularly in cases where harsh thermal transients are present. Calculating the Cumulative Usage Factor (CUF) using the procedure defined in the ASME Boiler and Pressure Vessel Code in Section III NB-3600 can limit the permissible cycle life (i.e., fatigue life) of the piping component. As per NB-3630(c), when a design does not satisfy the requirements of NB-3640 and NB-3650, a more detailed alternative analysis defined in NB-3200 can be used. This work compares the code requirements, analysis methodology, and results of a typical small bore branch connection connected to a piping header that is assessed against the requirements of NB-3600 and NB-3200. Piping is modeled using beam elements by utilizing PIPESTRESS piping analysis software for the NB-3600 based analysis. In comparison, a finite element model in Ansys Workbench is developed for the NB-3200 transient thermal and structural analysis. Representative pressure and thermal transients applicable to the heat transport system of a typical CANDU reactor are utilized in the analysis. The analysis results show that a significant drop in the Cumulative Usage Factor is achieved with the NB-3200 approach when compared with NB-3600.","PeriodicalId":23700,"journal":{"name":"Volume 2: Computer Technology and Bolted Joints; Design and Analysis","volume":"7 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-07-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82863029","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}
This paper proposes an improved transfer matrix method (TMM) algorithm to calculate frequency response function (FRF) for finite periods of periodic composite pipelines structures. Traditional TMM usually generate instable matrix and inaccurate calculation results for Phononic crystals (PCs) pipeline. Under the assumption that periodic distribution of pipeline structure with no intermediate excitation, the main idea of the improved algorithm is to reasonably divide finite periodic pipeline into several effective segments, then the transfer relationship of state vector for each connected pipe part could be expressed individually, thereby realizing the calculation order reduction by expanding the dimension of overall stiffness matrix. This improved algorithm could effectively avoid cumulative error caused by diagonal sparse matrix operations, thus getting true dynamic response to calculate exact FRF curves. Moreover, this algorithm could fundamentally improve the accuracy and stability of traditional TMM calculations. The transverse FRF for finite periods calculated by improved TMM shows excellent consistency with corresponding band gap structures (BGs), validate the correctness of derived theory and algorithm. This improved TMM algorithm supplies an effective method for FRF calculation of finite pipeline periods, and also provide effective verification of BGs for infinite structures, which could guide the vibration and noise reduction design of pipeline system.
{"title":"Algorithm Improvement of Transfer Matrix Method for Vibration Propagation of Periodic Pipeline Structure","authors":"Qingna Zeng, Donghui Wang, F. Zang, Yixion Zhang","doi":"10.1115/pvp2022-85297","DOIUrl":"https://doi.org/10.1115/pvp2022-85297","url":null,"abstract":"\u0000 This paper proposes an improved transfer matrix method (TMM) algorithm to calculate frequency response function (FRF) for finite periods of periodic composite pipelines structures. Traditional TMM usually generate instable matrix and inaccurate calculation results for Phononic crystals (PCs) pipeline. Under the assumption that periodic distribution of pipeline structure with no intermediate excitation, the main idea of the improved algorithm is to reasonably divide finite periodic pipeline into several effective segments, then the transfer relationship of state vector for each connected pipe part could be expressed individually, thereby realizing the calculation order reduction by expanding the dimension of overall stiffness matrix. This improved algorithm could effectively avoid cumulative error caused by diagonal sparse matrix operations, thus getting true dynamic response to calculate exact FRF curves. Moreover, this algorithm could fundamentally improve the accuracy and stability of traditional TMM calculations. The transverse FRF for finite periods calculated by improved TMM shows excellent consistency with corresponding band gap structures (BGs), validate the correctness of derived theory and algorithm. This improved TMM algorithm supplies an effective method for FRF calculation of finite pipeline periods, and also provide effective verification of BGs for infinite structures, which could guide the vibration and noise reduction design of pipeline system.","PeriodicalId":23700,"journal":{"name":"Volume 2: Computer Technology and Bolted Joints; Design and Analysis","volume":"13 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-07-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81902595","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}
Andrew Carlson, C. Narayanan, D. Lakehal, Timo Hermonen, Noora Jokinen, J. Ikävalko
This study is an interesting industrial case study for the application of a validated flashing and hydraulic shock modelling approach to the safety and design of a reactor blow line. The maximum flow rate is important for sizing of downstream components. The high pressure of the blow and flashing of the liquid can result in significant forces on pipe bends and other geometrical features. Analysis and prediction of such forces are of importance for the structural design and anchoring of the piping. Another concern for a liquid blow under high pressure is the potential for condensation-induced hydraulic shock. The collapse of the flashed vapor to the liquid phase creating shock waves of large amplitudes is a serious safety concern. The CFD model used the homogeneous mixture model with a flashing model for phase change of the fluid. The properties of the fluid were defined by a custom function which interpolated between tabulated values of the thermodynamic and transport properties. The CFD simulations confirmed the risk of condensation hydraulic shock when the blow down is initiated with empty pipes and also demonstrated that a hydraulic shock could be prevented with liquid-filled condition. The pipework geometry was also optimized to reduce the forces acting at the junctions. The vapour quality at the outlet as a result of flashing was estimated which is necessary for the design of downstream systems.
{"title":"CFD Study of Cooking Liquor Blow for Piping Thrust Force and Risk of Condensation Hydraulic Shock","authors":"Andrew Carlson, C. Narayanan, D. Lakehal, Timo Hermonen, Noora Jokinen, J. Ikävalko","doi":"10.1115/pvp2022-79373","DOIUrl":"https://doi.org/10.1115/pvp2022-79373","url":null,"abstract":"\u0000 This study is an interesting industrial case study for the application of a validated flashing and hydraulic shock modelling approach to the safety and design of a reactor blow line. The maximum flow rate is important for sizing of downstream components. The high pressure of the blow and flashing of the liquid can result in significant forces on pipe bends and other geometrical features. Analysis and prediction of such forces are of importance for the structural design and anchoring of the piping. Another concern for a liquid blow under high pressure is the potential for condensation-induced hydraulic shock. The collapse of the flashed vapor to the liquid phase creating shock waves of large amplitudes is a serious safety concern.\u0000 The CFD model used the homogeneous mixture model with a flashing model for phase change of the fluid. The properties of the fluid were defined by a custom function which interpolated between tabulated values of the thermodynamic and transport properties. The CFD simulations confirmed the risk of condensation hydraulic shock when the blow down is initiated with empty pipes and also demonstrated that a hydraulic shock could be prevented with liquid-filled condition. The pipework geometry was also optimized to reduce the forces acting at the junctions. The vapour quality at the outlet as a result of flashing was estimated which is necessary for the design of downstream systems.","PeriodicalId":23700,"journal":{"name":"Volume 2: Computer Technology and Bolted Joints; Design and Analysis","volume":"1 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-07-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83123281","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In the pressure equipment industry, codes of construction stipulate that fastener assemblies shall exhibit thread engagement through the full depth of the nut. In many older facilities and in locations with poor quality control, assemblies may be found on in-service equipment which do not have full thread engagement and do not meet the requirements of the code of construction. This is often found during the routine visual inspection of equipment and is flagged as a construction code deficiency requiring attention. Current post construction code guidance on fastener assemblies is ambiguous on how to handle fasteners with less-than-full thread engagement exceeding one thread of shortfall. The perceived risk of such a lack of thread engagement may lead maintenance organizations to perform costly and high-risk remediation activities, such as in-service “clamping” or “single stud replacement,” also known as “hot-bolting.” However, in many situations, fastener assembly strength can be proven to be sufficient for a given joint through analytical evaluation. Using a combination of innovative and existing thread strength and flanged joint considerations, the minimum required length of engagement, and, thus, the maximum allowable lack of engagement, can be safely determined for most fasteners on flange connections. This paper reviews some of the most important fastener strength considerations to propose a post-construction evaluation technique to determine the fitness for service of less-than-fully engaged fastener assemblies.
{"title":"Stud Bolt Thread Engagement: A Fitness for Service Approach","authors":"Colton M. Cranford","doi":"10.1115/pvp2022-84722","DOIUrl":"https://doi.org/10.1115/pvp2022-84722","url":null,"abstract":"\u0000 In the pressure equipment industry, codes of construction stipulate that fastener assemblies shall exhibit thread engagement through the full depth of the nut. In many older facilities and in locations with poor quality control, assemblies may be found on in-service equipment which do not have full thread engagement and do not meet the requirements of the code of construction. This is often found during the routine visual inspection of equipment and is flagged as a construction code deficiency requiring attention. Current post construction code guidance on fastener assemblies is ambiguous on how to handle fasteners with less-than-full thread engagement exceeding one thread of shortfall. The perceived risk of such a lack of thread engagement may lead maintenance organizations to perform costly and high-risk remediation activities, such as in-service “clamping” or “single stud replacement,” also known as “hot-bolting.” However, in many situations, fastener assembly strength can be proven to be sufficient for a given joint through analytical evaluation. Using a combination of innovative and existing thread strength and flanged joint considerations, the minimum required length of engagement, and, thus, the maximum allowable lack of engagement, can be safely determined for most fasteners on flange connections. This paper reviews some of the most important fastener strength considerations to propose a post-construction evaluation technique to determine the fitness for service of less-than-fully engaged fastener assemblies.","PeriodicalId":23700,"journal":{"name":"Volume 2: Computer Technology and Bolted Joints; Design and Analysis","volume":"47 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-07-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89618856","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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