ASME PCC-1 (2010) introduced 5 different alternative bolting patterns in contrast to the Legacy Pattern that is commonly known as the “Star Pattern”. For the past 15 years, research has shown that these Alternative Patterns issued by PCC-1 are more efficient than the Star Pattern. However, the research has shown tool movement around the flange to show efficiency, but not actual assembly time and/or assembly time savings from each one of these alternative bolting patterns. While all of these alternative bolting patterns are not appropriate for every gasket type and might not add efficiency for smaller diameter flanges, there are many mid-stream and downstream petrochemical applications that could benefit from further knowledge of these efficiencies. The goal of this paper is to not only determine which one of these alternative patterns is the most efficient but to also compare different types of assembly tools with each pattern. This analysis does not address the accuracy and repeatability of each method and tool type, but its function is to determine the optimum combination of tool and pattern selection to decrease downtime and Lost Profit Opportunity (LPO). This paper will use both bolting patterns and assembly tools on an 18” 600 Class flange, that has (24) 1-1/4” studs to develop a method for determining further testing of bolting pattern and bolting tools.
{"title":"Evaluation of Pipe Flange Connection Assembly Efficiencies Using Common Tools and Patterns","authors":"Shane Szemanek, Scott R. Hamilton","doi":"10.1115/pvp2022-78696","DOIUrl":"https://doi.org/10.1115/pvp2022-78696","url":null,"abstract":"\u0000 ASME PCC-1 (2010) introduced 5 different alternative bolting patterns in contrast to the Legacy Pattern that is commonly known as the “Star Pattern”. For the past 15 years, research has shown that these Alternative Patterns issued by PCC-1 are more efficient than the Star Pattern.\u0000 However, the research has shown tool movement around the flange to show efficiency, but not actual assembly time and/or assembly time savings from each one of these alternative bolting patterns.\u0000 While all of these alternative bolting patterns are not appropriate for every gasket type and might not add efficiency for smaller diameter flanges, there are many mid-stream and downstream petrochemical applications that could benefit from further knowledge of these efficiencies.\u0000 The goal of this paper is to not only determine which one of these alternative patterns is the most efficient but to also compare different types of assembly tools with each pattern.\u0000 This analysis does not address the accuracy and repeatability of each method and tool type, but its function is to determine the optimum combination of tool and pattern selection to decrease downtime and Lost Profit Opportunity (LPO).\u0000 This paper will use both bolting patterns and assembly tools on an 18” 600 Class flange, that has (24) 1-1/4” studs to develop a method for determining further testing of bolting pattern and bolting tools.","PeriodicalId":23700,"journal":{"name":"Volume 2: Computer Technology and Bolted Joints; Design and Analysis","volume":"25 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-07-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80153904","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}
J. Nakai-Chapman, C. Fietek, J. Sakai, Young-Bae Park
Additive manufacturing (AM) has become one of the most revolutionary technologies for the fabrication of metallic parts within the industry; notably, the use of existing metals has significantly eased the adoption of AM in manufacturing. The metal AM method can produce complex parts with effective cost. This process, however, involves rapid heating and solidification, resulting in a high thermal gradient. It causes undesired residual stress and distortion that significantly affects the final product’s integrity. This study investigates the features of a high thermal gradient, structural deformation, and residual stress involved in the powder bed fusion process in virtual environments. Powder bed fusion is an additive manufacturing method that uses a laser or electron beam to melt and fuse the metal material to form a three-dimensional part. A simulation model was developed using layer-to-layer scanning paths based on a 3D geometry in the 3DEXPERIENCE platform. Commercial finite element analysis (FEA) software, Abaqus CAE, is used for the sequentially coupled thermo-mechanical analysis. The temperature history is first calculated in an uncoupled thermal analysis and introduced as a predefined field in the subsequent structural analysis. In the sequentially coupled thermo-mechanical analysis, the thermal evolution of the problem affects the structural response, but the temperature field is not dependent on the stress field. Heat transfer in additive manufacturing is time-dependent, and temperature distribution in an additively manufactured part is non-uniform. Hence a time-dependent heat conduction problem is solved to analyze the process. After the thermal analysis is completed, the quasi-static equilibrium of stress is determined for each time step. An isotropic hardening rule was utilized to consider the evolution of plastic deformation.
{"title":"Metal Additive Manufacturing Simulation Using Sequentially Coupled Thermo-Mechanical Analysis","authors":"J. Nakai-Chapman, C. Fietek, J. Sakai, Young-Bae Park","doi":"10.1115/pvp2022-84612","DOIUrl":"https://doi.org/10.1115/pvp2022-84612","url":null,"abstract":"\u0000 Additive manufacturing (AM) has become one of the most revolutionary technologies for the fabrication of metallic parts within the industry; notably, the use of existing metals has significantly eased the adoption of AM in manufacturing. The metal AM method can produce complex parts with effective cost. This process, however, involves rapid heating and solidification, resulting in a high thermal gradient. It causes undesired residual stress and distortion that significantly affects the final product’s integrity. This study investigates the features of a high thermal gradient, structural deformation, and residual stress involved in the powder bed fusion process in virtual environments. Powder bed fusion is an additive manufacturing method that uses a laser or electron beam to melt and fuse the metal material to form a three-dimensional part. A simulation model was developed using layer-to-layer scanning paths based on a 3D geometry in the 3DEXPERIENCE platform. Commercial finite element analysis (FEA) software, Abaqus CAE, is used for the sequentially coupled thermo-mechanical analysis. The temperature history is first calculated in an uncoupled thermal analysis and introduced as a predefined field in the subsequent structural analysis. In the sequentially coupled thermo-mechanical analysis, the thermal evolution of the problem affects the structural response, but the temperature field is not dependent on the stress field. Heat transfer in additive manufacturing is time-dependent, and temperature distribution in an additively manufactured part is non-uniform. Hence a time-dependent heat conduction problem is solved to analyze the process. After the thermal analysis is completed, the quasi-static equilibrium of stress is determined for each time step. An isotropic hardening rule was utilized to consider the evolution of plastic deformation.","PeriodicalId":23700,"journal":{"name":"Volume 2: Computer Technology and Bolted Joints; Design and Analysis","volume":"76 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-07-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83854299","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}
Thin-walled cylindrical shell structures are widely used in various engineering fields due to their highly efficient load carrying capacity. This kind of structures is prone to buckling failure when subjected to axial compression loads. Machining the shell into corrugated shape is an effective method to prevent buckling. Rational design of corrugated shells can improve the load carrying efficiency of shell structures. However, there are few studies focused on the effects of various parameters on the longitudinal corrugated cylindrical shell buckling. In this paper, numerical studies are performed to analyze the factors affecting the buckling behaviors of thin-walled longitudinal corrugated cylindrical shells under axial compression loads. The cross section of the corrugated shell is obtained by superposing the sine curve on the reference circle. The critical buckling load, buckling mode and imperfection sensitivity of the longitudinal corrugated cylindrical shells are examined and compared with ordinary cylindrical shells. The effects of shell dimensions and material yield strength are taken into account. In addition, the influence of cross section shape parameters on the critical buckling load is considered, including the amplitude A and wave number k. Results show that the axial load carrying capacity of longitudinal corrugated cylindrical shells is better than ordinary cylindrical shells, and rational design of cross section shape can enhance the stability of corrugated shells. This work can provide some reference for relevant experimental studies. Furthermore, it can also give some guides for the application of thin-walled longitudinal corrugated cylindrical shells in actual engineering.
{"title":"Numerical Study on Buckling Behaviors of Thin-Walled Longitudinal Corrugated Cylindrical Shells Under Axial Compression Loads","authors":"He Ma, Zhiping Chen, P. Jiao, Xinyi Lin","doi":"10.1115/pvp2022-84396","DOIUrl":"https://doi.org/10.1115/pvp2022-84396","url":null,"abstract":"\u0000 Thin-walled cylindrical shell structures are widely used in various engineering fields due to their highly efficient load carrying capacity. This kind of structures is prone to buckling failure when subjected to axial compression loads. Machining the shell into corrugated shape is an effective method to prevent buckling. Rational design of corrugated shells can improve the load carrying efficiency of shell structures. However, there are few studies focused on the effects of various parameters on the longitudinal corrugated cylindrical shell buckling. In this paper, numerical studies are performed to analyze the factors affecting the buckling behaviors of thin-walled longitudinal corrugated cylindrical shells under axial compression loads. The cross section of the corrugated shell is obtained by superposing the sine curve on the reference circle. The critical buckling load, buckling mode and imperfection sensitivity of the longitudinal corrugated cylindrical shells are examined and compared with ordinary cylindrical shells. The effects of shell dimensions and material yield strength are taken into account. In addition, the influence of cross section shape parameters on the critical buckling load is considered, including the amplitude A and wave number k. Results show that the axial load carrying capacity of longitudinal corrugated cylindrical shells is better than ordinary cylindrical shells, and rational design of cross section shape can enhance the stability of corrugated shells. This work can provide some reference for relevant experimental studies. Furthermore, it can also give some guides for the application of thin-walled longitudinal corrugated cylindrical shells in actual engineering.","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":"80579540","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 Reactor Inner Zone Inlet Header (RIZIH) temperatures have raised more rapidly in the CANDU units in general, compared to the original aging predictions. This adverse trend is caused by a degradation mechanism that affecting heat exchange efficiency in certain areas of the process systems. The main contributor to the RIZIH temperature increase is the fouling in the preheaters and steam generator/boilers due to magnetite deposits on tube internal diameters. The RIZIH temperature rise had caused units de-rates to ensure the reactor safety and comply with the regulatory requirements. As reported in a previous PVP paper (PVP2017-65096), multiple design alternatives were considered and evaluated to address the adverse condition, the best design option with a piping modification by adding external feedwater bypass of high pressure heater was selected to improve RIZIH temperature control. Following the conceptual engineering, preliminary design and detail design, the engineering change was implemented in two CANDU reactor units between 2018 and 2019. This paper reports out the field physical implementations and discusses the effectiveness of the design change on mitigating the RIZIH temperature rise, it also presents the operational and financial benefits actualized through observations of the two implementing units.
{"title":"Design Modification Implementations for Mitigating the Reactor Inner Zone Inlet Header Temperature in CANDU Reactor Units","authors":"Preston Tang, Bing Li, Akash Bhatia, Leon Cramer","doi":"10.1115/pvp2022-85985","DOIUrl":"https://doi.org/10.1115/pvp2022-85985","url":null,"abstract":"\u0000 The Reactor Inner Zone Inlet Header (RIZIH) temperatures have raised more rapidly in the CANDU units in general, compared to the original aging predictions. This adverse trend is caused by a degradation mechanism that affecting heat exchange efficiency in certain areas of the process systems. The main contributor to the RIZIH temperature increase is the fouling in the preheaters and steam generator/boilers due to magnetite deposits on tube internal diameters. The RIZIH temperature rise had caused units de-rates to ensure the reactor safety and comply with the regulatory requirements. As reported in a previous PVP paper (PVP2017-65096), multiple design alternatives were considered and evaluated to address the adverse condition, the best design option with a piping modification by adding external feedwater bypass of high pressure heater was selected to improve RIZIH temperature control. Following the conceptual engineering, preliminary design and detail design, the engineering change was implemented in two CANDU reactor units between 2018 and 2019. This paper reports out the field physical implementations and discusses the effectiveness of the design change on mitigating the RIZIH temperature rise, it also presents the operational and financial benefits actualized through observations of the two implementing units.","PeriodicalId":23700,"journal":{"name":"Volume 2: Computer Technology and Bolted Joints; Design and Analysis","volume":"52 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":"73486010","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}
The ASME BPVC, Section III, Appendix XI [1] regulates the flange calculation for class 2 and 3 components in Suisse nuclear power plants, and it is also used for class 1 flanges. The most common European Standard for the design of bolted flanged joints is EN 1591-1 [2], the required gasket characteristics for this calculation procedure are defined in EN 13555 [3]. These characteristics can be determined experimentally and they are not only used in EN 1591-1 but also in more realistic finite-element calculations. Finite element calculations are carried out for a certain number of combinations of flange and gasket materials as well as bolt types in order to prove compliance with the integrity and tightness of the connections in the assembly and subsequent operational states, taking into account the tightening torques. A total of almost 400 different combinations of flange, bolt and gasket geometries and materials were examined. The focus is laid on flange types fabricated according to European standards which are generally thinner — looking at the wall thickness or flange ring in the same pressure range — than in the ASME world. In this paper the bolting-up torque moments determined with the European standard EN 1591-1 for the flange connections, are assessed with twice elastic slope method, limit load and elastic-plastic stress analysis according to ASME BPVC, Section VIII, Div. 2. [4] Proof of acceptability of the nonlinear finite element-calculations are conducted according to ASME standard procedures like ASME SECTION III, Appendices EE and FF for the level D.
{"title":"Comparison Between Different Calculation Methods for Determining Bolting-Up Torque Moments","authors":"Alexander Mutz, M. Schaaf, S. Hufnagel","doi":"10.1115/pvp2022-86163","DOIUrl":"https://doi.org/10.1115/pvp2022-86163","url":null,"abstract":"\u0000 The ASME BPVC, Section III, Appendix XI [1] regulates the flange calculation for class 2 and 3 components in Suisse nuclear power plants, and it is also used for class 1 flanges.\u0000 The most common European Standard for the design of bolted flanged joints is EN 1591-1 [2], the required gasket characteristics for this calculation procedure are defined in EN 13555 [3]. These characteristics can be determined experimentally and they are not only used in EN 1591-1 but also in more realistic finite-element calculations.\u0000 Finite element calculations are carried out for a certain number of combinations of flange and gasket materials as well as bolt types in order to prove compliance with the integrity and tightness of the connections in the assembly and subsequent operational states, taking into account the tightening torques. A total of almost 400 different combinations of flange, bolt and gasket geometries and materials were examined. The focus is laid on flange types fabricated according to European standards which are generally thinner — looking at the wall thickness or flange ring in the same pressure range — than in the ASME world.\u0000 In this paper the bolting-up torque moments determined with the European standard EN 1591-1 for the flange connections, are assessed with twice elastic slope method, limit load and elastic-plastic stress analysis according to ASME BPVC, Section VIII, Div. 2. [4] Proof of acceptability of the nonlinear finite element-calculations are conducted according to ASME standard procedures like ASME SECTION III, Appendices EE and FF for the level D.","PeriodicalId":23700,"journal":{"name":"Volume 2: Computer Technology and Bolted Joints; Design and Analysis","volume":"134 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-07-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83419503","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}
Low-stress spiral wound gaskets are marketed as an alternative to standard spiral wound gaskets, requiring less torque to seat the gasket. Spiral wound gaskets are common commodities used in piping reliability staff are constantly looking for different alternatives. Multiple manufacturers offer a low-stress version of spiral wound gaskets. Do these spiral wound gaskets offer a low-stress solution, and do they perform better than a standard spiral wound gasket? This paper will go beyond the marketing of “low-stress” spiral wound gaskets and examine the construction and engineering behind these gasket designs. Manufacturers of spiral wound gaskets have made subtle changes and the “low-stress” technology has become a common theme throughout the spiral wound gasket market. Multiple chemical and petrochemical plants use these designs in their piping systems and sometimes as replacements for ASME recommended spiral wound gaskets with inner rings. Low-stress spiral wound gaskets have multiple designs from additional graphite in the filler to an anti-buckling design which are marketed as requiring less initial preload to seat. This paper will examine the validity of these gaskets and determine if they are low-stress and if they provide a credible seal in a bolted flanged joint. [1]
{"title":"A Critical Understanding of “Low-Stress” Spiral Wound Gaskets","authors":"Alton Jamison","doi":"10.1115/pvp2022-84739","DOIUrl":"https://doi.org/10.1115/pvp2022-84739","url":null,"abstract":"\u0000 Low-stress spiral wound gaskets are marketed as an alternative to standard spiral wound gaskets, requiring less torque to seat the gasket. Spiral wound gaskets are common commodities used in piping reliability staff are constantly looking for different alternatives. Multiple manufacturers offer a low-stress version of spiral wound gaskets. Do these spiral wound gaskets offer a low-stress solution, and do they perform better than a standard spiral wound gasket? This paper will go beyond the marketing of “low-stress” spiral wound gaskets and examine the construction and engineering behind these gasket designs. Manufacturers of spiral wound gaskets have made subtle changes and the “low-stress” technology has become a common theme throughout the spiral wound gasket market. Multiple chemical and petrochemical plants use these designs in their piping systems and sometimes as replacements for ASME recommended spiral wound gaskets with inner rings. Low-stress spiral wound gaskets have multiple designs from additional graphite in the filler to an anti-buckling design which are marketed as requiring less initial preload to seat. This paper will examine the validity of these gaskets and determine if they are low-stress and if they provide a credible seal in a bolted flanged joint. [1]","PeriodicalId":23700,"journal":{"name":"Volume 2: Computer Technology and Bolted Joints; Design and Analysis","volume":"125 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-07-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83437273","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 CANDU nuclear reactors, pressure tubes reside within a calandria tube with separation maintained by helical springs installed in the annular space. Evaluation of material degradation due to the unique operating environment requires testing of ex-service spring material by compressing short spring segments by two diametrically opposed forces. The load vs. displacement results combined with the geometry allows for the stress-strain behavior to be derived. The test specimens are effectively unmodified from the as-received condition so accurate characterization of the geometry is required. Since the test response is mainly bending, error in the radial section dimension is augmented by powers of 2 and 3 when calculating bending stress and specimen stiffness respectively. Additional complications come from nonuniform loading of the coils due to end effects. Detailed analysis that accounts for end effects is applied to the linear elastic portion of the load curve to accurately quantify the specimen dimensions. With geometry determined, the nonlinear portion of the tensile curve is adjusted to reproduce the entire load curve up to the failure point. Examples are presented to demonstrate how the load corresponding to the yield point and outer fiber stress at the failure point can be determined.
{"title":"Analysis to Relate Data From Radial Compression Tests on Helical Springs to Tensile Material Properties","authors":"André Gagnon, D. Metzger","doi":"10.1115/pvp2022-84892","DOIUrl":"https://doi.org/10.1115/pvp2022-84892","url":null,"abstract":"\u0000 In CANDU nuclear reactors, pressure tubes reside within a calandria tube with separation maintained by helical springs installed in the annular space. Evaluation of material degradation due to the unique operating environment requires testing of ex-service spring material by compressing short spring segments by two diametrically opposed forces. The load vs. displacement results combined with the geometry allows for the stress-strain behavior to be derived. The test specimens are effectively unmodified from the as-received condition so accurate characterization of the geometry is required. Since the test response is mainly bending, error in the radial section dimension is augmented by powers of 2 and 3 when calculating bending stress and specimen stiffness respectively. Additional complications come from nonuniform loading of the coils due to end effects.\u0000 Detailed analysis that accounts for end effects is applied to the linear elastic portion of the load curve to accurately quantify the specimen dimensions. With geometry determined, the nonlinear portion of the tensile curve is adjusted to reproduce the entire load curve up to the failure point. Examples are presented to demonstrate how the load corresponding to the yield point and outer fiber stress at the failure point can be determined.","PeriodicalId":23700,"journal":{"name":"Volume 2: Computer Technology and Bolted Joints; Design and Analysis","volume":"205 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-07-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88576209","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}
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