Proper gasket selection for fiberglass reinforced plastic (FRP) flanges is critical to the long-term success of the pipe system. However, very little focus is placed on evaluating the performance of low stress-to-seal, PTFE-based gaskets engineered to perform at the lower bolt loads/gasket stresses allowable on FRP flanges. In cooperation with a premier FRP piping/equipment manufacturer, this paper evaluates and compares the sealing performance of new gasket technologies/designs and commercially available low stress-to-seal, PTFE-based gaskets. To quantify the relative performance, each gasket style was tested to ASTM D5421 “Standard Specification for Contact Molded “Fiberglass” (Glass-Fiber-Reinforced Thermosetting Resin) Flanges”. Gaskets that passed the ASTM D5421 testing were then subjected to a mass leakage test to further classify each gasket style’s sealing/tightness performance. Given the current standard requirements, gaskets that did not pass the ASTM D5421 standard testing were determined not to be suitable for FRP service and thus were not subject to the subsequent mass leakage testing. By comparing the collected data using these metrics, the final result of this paper will provide end-users with a comprehensive method of evaluating gasket styles and provide guidance for proper gasket selection for FRP flange services.
{"title":"Evaluating the Sealing Performance of Engineered PTFE Based Gaskets in Fiberglass Reinforced Plastic Flanges","authors":"Tim Rice, Jeffery Wilson","doi":"10.1115/pvp2022-80474","DOIUrl":"https://doi.org/10.1115/pvp2022-80474","url":null,"abstract":"\u0000 Proper gasket selection for fiberglass reinforced plastic (FRP) flanges is critical to the long-term success of the pipe system. However, very little focus is placed on evaluating the performance of low stress-to-seal, PTFE-based gaskets engineered to perform at the lower bolt loads/gasket stresses allowable on FRP flanges. In cooperation with a premier FRP piping/equipment manufacturer, this paper evaluates and compares the sealing performance of new gasket technologies/designs and commercially available low stress-to-seal, PTFE-based gaskets. To quantify the relative performance, each gasket style was tested to ASTM D5421 “Standard Specification for Contact Molded “Fiberglass” (Glass-Fiber-Reinforced Thermosetting Resin) Flanges”. Gaskets that passed the ASTM D5421 testing were then subjected to a mass leakage test to further classify each gasket style’s sealing/tightness performance. Given the current standard requirements, gaskets that did not pass the ASTM D5421 standard testing were determined not to be suitable for FRP service and thus were not subject to the subsequent mass leakage testing.\u0000 By comparing the collected data using these metrics, the final result of this paper will provide end-users with a comprehensive method of evaluating gasket styles and provide guidance for proper gasket selection for FRP flange services.","PeriodicalId":23700,"journal":{"name":"Volume 2: Computer Technology and Bolted Joints; Design and Analysis","volume":"83 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-07-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80347121","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. Fernando, Enzo Falo, Henry Kwok, Millar Iverson, L. Wong, Simon Yuen, L. Chan
Coke drums are subjected to severe cyclic thermal and structural loading, and have therefore become canonical examples of thermo-mechanical fatigue failure. One of the most common locations of fatigue failure is at the skirt-to-shell attachment weld. To increase the fatigue life of the attachment weld, vertical slots and keyholes are often machined in a circumferential pattern near the top of the skirt to increase local flexibility near the weld. While this methodology provides a cost-effective means to improve the fatigue life of the attachment weld, stress concentrations that form at the keyholes result in crack initiation and propagation. As such, frequent repairs are necessary to prevent crack growth at the keyhole locations. In the present investigation, a new keyhole design consisting of N06625 overlay at the keyhole locations as a means of delaying crack initiation has been studied using FEA simulations. To further optimize the new design, a sensitivity study involving keyholes with and without fillets was also performed to determine the effect of fillet size on fatigue life. The results presented herein indicate that increasing the keyhole fillet radii mitigates the effect of stress concentrations on the corners of the keyholes, which delays crack initiation. Furthermore, it has been demonstrated that adding N06625 overlay at the keyhole protects the base metal from excessive plastic strain. In particular, the proposed design has been shown to improve the fatigue life of the keyhole by at least an order of magnitude when compared to analogous keyhole designs with no overlay, which has the potential to improve the overall cost-effectiveness of keyhole implementation by a significant margin.
{"title":"Coke Drum Keyhole Optimization With Alloy Weld Overlay","authors":"J. Fernando, Enzo Falo, Henry Kwok, Millar Iverson, L. Wong, Simon Yuen, L. Chan","doi":"10.1115/pvp2022-78705","DOIUrl":"https://doi.org/10.1115/pvp2022-78705","url":null,"abstract":"\u0000 Coke drums are subjected to severe cyclic thermal and structural loading, and have therefore become canonical examples of thermo-mechanical fatigue failure. One of the most common locations of fatigue failure is at the skirt-to-shell attachment weld. To increase the fatigue life of the attachment weld, vertical slots and keyholes are often machined in a circumferential pattern near the top of the skirt to increase local flexibility near the weld. While this methodology provides a cost-effective means to improve the fatigue life of the attachment weld, stress concentrations that form at the keyholes result in crack initiation and propagation. As such, frequent repairs are necessary to prevent crack growth at the keyhole locations. In the present investigation, a new keyhole design consisting of N06625 overlay at the keyhole locations as a means of delaying crack initiation has been studied using FEA simulations. To further optimize the new design, a sensitivity study involving keyholes with and without fillets was also performed to determine the effect of fillet size on fatigue life. The results presented herein indicate that increasing the keyhole fillet radii mitigates the effect of stress concentrations on the corners of the keyholes, which delays crack initiation. Furthermore, it has been demonstrated that adding N06625 overlay at the keyhole protects the base metal from excessive plastic strain. In particular, the proposed design has been shown to improve the fatigue life of the keyhole by at least an order of magnitude when compared to analogous keyhole designs with no overlay, which has the potential to improve the overall cost-effectiveness of keyhole implementation by a significant margin.","PeriodicalId":23700,"journal":{"name":"Volume 2: Computer Technology and Bolted Joints; Design and Analysis","volume":"34 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-07-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82015586","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}
Scott R. Hamilton, Dan Meigs, Tom Blake, D. Oldiges
Vendors offer PTFE-coated studs to provide corrosion resistance in harshly corrosive environments. Vendors advertise PTFE-coated studs as having reduced K-Factor compared to uncoated studs, and differences of opinion exist on whether or not lubrication is required when assembling joints with PTFE-coated studs. In fact, some end users have adopted the practice of assembling joints with PTFE-coated studs without lubrication when the stud is used for the first time and then applying lubrication when studs are reused. This study tested the K-Factor of a set of studs in different sizes from seven vendors to determine what K-Factor should be expected when using PTFE-coated studs, how much variation in K-Factor one should expect between vendors and sizes, and the effect lubrication has on variability in K-Factor. K-Factors were derived using an automated test fixture that plotted K-Factor vs bolt load across a range of loads from 30 ksi to 80 ksi. This study found there is significant variation in K-Factor from vendor to vendor, from stud size to stud size, and even within individual lots of a single size from a single vendor. The study found that without lubrication, the average K-Factor increased significantly with bolt load, making prediction of gasket stress difficult. The study concluded that properly lubricating PTFE-coated studs during assembly significantly reduces the variability seen in unlubricated studs.
{"title":"K-Factor Testing of PTFE-Coated Studs","authors":"Scott R. Hamilton, Dan Meigs, Tom Blake, D. Oldiges","doi":"10.1115/pvp2022-83608","DOIUrl":"https://doi.org/10.1115/pvp2022-83608","url":null,"abstract":"\u0000 Vendors offer PTFE-coated studs to provide corrosion resistance in harshly corrosive environments. Vendors advertise PTFE-coated studs as having reduced K-Factor compared to uncoated studs, and differences of opinion exist on whether or not lubrication is required when assembling joints with PTFE-coated studs. In fact, some end users have adopted the practice of assembling joints with PTFE-coated studs without lubrication when the stud is used for the first time and then applying lubrication when studs are reused.\u0000 This study tested the K-Factor of a set of studs in different sizes from seven vendors to determine what K-Factor should be expected when using PTFE-coated studs, how much variation in K-Factor one should expect between vendors and sizes, and the effect lubrication has on variability in K-Factor. K-Factors were derived using an automated test fixture that plotted K-Factor vs bolt load across a range of loads from 30 ksi to 80 ksi.\u0000 This study found there is significant variation in K-Factor from vendor to vendor, from stud size to stud size, and even within individual lots of a single size from a single vendor. The study found that without lubrication, the average K-Factor increased significantly with bolt load, making prediction of gasket stress difficult. The study concluded that properly lubricating PTFE-coated studs during assembly significantly reduces the variability seen in unlubricated studs.","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":"83806624","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}
Creep and corrosion are typical damage mechanisms of pressure components operated at high temperatures and they are frequently evaluated using the relevant sections of the API 579-1 [1] standard. When a general or local metal loss is expected or assessed via Non-Destructive-Examination (NDE) on a pressure equipment in the creep regime, the time-dependent corrosive phenomenon has a direct impact on the time and stress-dependent creep residual life and the two damage mechanisms are competing and reinforcing one another. For these cases, an API 579-1 Level 3 creep assessment shall necessarily take into account the metal loss induced by the corrosive environment to be effective in predicting the component residual life. In this work, the impact of corrosion on the creep life evaluated according to API 579-1 and the Larson-Miller theory was evaluated for the special case of a low-alloy piping component exposed to both general and local metal loss with variable corrosion and creep rates. A finite-element model was set-up incorporating the inelastic steady-state creep law, the API 579-1 time-fraction creep damage and the progressive metal loss due to uniform and localized corrosion. A parametric analysis was finally carried out to investigate the role of the corrosion rate, and the related, augmented stress field on the overall API 579-1 creep damage.
{"title":"Impact of General and Local Metal Loss on the API 579-1 Creep Residual Life","authors":"Lorenzo Scano, Francesco Piccini","doi":"10.1115/pvp2022-84642","DOIUrl":"https://doi.org/10.1115/pvp2022-84642","url":null,"abstract":"\u0000 Creep and corrosion are typical damage mechanisms of pressure components operated at high temperatures and they are frequently evaluated using the relevant sections of the API 579-1 [1] standard. When a general or local metal loss is expected or assessed via Non-Destructive-Examination (NDE) on a pressure equipment in the creep regime, the time-dependent corrosive phenomenon has a direct impact on the time and stress-dependent creep residual life and the two damage mechanisms are competing and reinforcing one another. For these cases, an API 579-1 Level 3 creep assessment shall necessarily take into account the metal loss induced by the corrosive environment to be effective in predicting the component residual life. In this work, the impact of corrosion on the creep life evaluated according to API 579-1 and the Larson-Miller theory was evaluated for the special case of a low-alloy piping component exposed to both general and local metal loss with variable corrosion and creep rates. A finite-element model was set-up incorporating the inelastic steady-state creep law, the API 579-1 time-fraction creep damage and the progressive metal loss due to uniform and localized corrosion. A parametric analysis was finally carried out to investigate the role of the corrosion rate, and the related, augmented stress field on the overall API 579-1 creep damage.","PeriodicalId":23700,"journal":{"name":"Volume 2: Computer Technology and Bolted Joints; Design and Analysis","volume":"304 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-07-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86142852","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}
Despite the fact that shell elements more accurately model a piping system, beam elements are mainly used to model piping systems. A beam model makes use of SIFs and flexibility factors to account for local geometries in a piping system. Recent advances in software and computer processing power now make shell modelling a realistic option. This paper will examine some of the practical considerations for how modelling of piping can be improved. This includes improvements to beam modelling as well as shell modelling. Some examples of applications will be presented and discussed. Recommendations and suggestions for using shell elements to model piping are put forward.
{"title":"Overview of Piping Stress Analysis Using Shell Elements","authors":"R. Weyer, Milad Haji Mohammad Karim","doi":"10.1115/pvp2022-83681","DOIUrl":"https://doi.org/10.1115/pvp2022-83681","url":null,"abstract":"\u0000 Despite the fact that shell elements more accurately model a piping system, beam elements are mainly used to model piping systems. A beam model makes use of SIFs and flexibility factors to account for local geometries in a piping system.\u0000 Recent advances in software and computer processing power now make shell modelling a realistic option. This paper will examine some of the practical considerations for how modelling of piping can be improved. This includes improvements to beam modelling as well as shell modelling. Some examples of applications will be presented and discussed. Recommendations and suggestions for using shell elements to model piping are put forward.","PeriodicalId":23700,"journal":{"name":"Volume 2: Computer Technology and Bolted Joints; Design and Analysis","volume":"183 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-07-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80462386","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 presents a series of studies on header boxes and the attached inlet or outlet nozzles for air-cooled heat exchangers and associated data from API-661. Unlike cylindrical or spherical vessels, the rectangular-shaped cross section of a header box does not have a simple thickness equation that allows for determining the minimum required wall thicknesses from pressure. Though pressure vessel codes and relevant API standards provide certain design tool or fabrication data, a definite and consistent assessment procedure with necessary details is still not available. In many occasions this often imposes difficulties and confusion when conducting inspections and integrity assessments on air-cooled heat exchangers. In this study, stress analysis methods for vessels with rectangular cross sections and the attached nozzles are reviewed and applied to assessments of air-cooled heat exchangers. Minimum nominal thicknesses from API-661 are examined and compared to analysis data for a variety of conditions to investigate the applicability and restrictions of the standard on inspection and integrity assessments of header boxes and attached nozzles. As a result, FFS assessment procedures in three different levels, which are consistent with API-579 general assessment methodology, are developed and presented for header boxes and nozzles. This study may serve as a practical addition to integrity assessments and inspection of air-cooled heat exchangers.
{"title":"On API-661 and Assessment Procedures of Header Boxes and Nozzles for Air-Cooled Heat Exchangers","authors":"Mingxin Zhao","doi":"10.1115/pvp2022-80413","DOIUrl":"https://doi.org/10.1115/pvp2022-80413","url":null,"abstract":"\u0000 This paper presents a series of studies on header boxes and the attached inlet or outlet nozzles for air-cooled heat exchangers and associated data from API-661. Unlike cylindrical or spherical vessels, the rectangular-shaped cross section of a header box does not have a simple thickness equation that allows for determining the minimum required wall thicknesses from pressure. Though pressure vessel codes and relevant API standards provide certain design tool or fabrication data, a definite and consistent assessment procedure with necessary details is still not available. In many occasions this often imposes difficulties and confusion when conducting inspections and integrity assessments on air-cooled heat exchangers.\u0000 In this study, stress analysis methods for vessels with rectangular cross sections and the attached nozzles are reviewed and applied to assessments of air-cooled heat exchangers. Minimum nominal thicknesses from API-661 are examined and compared to analysis data for a variety of conditions to investigate the applicability and restrictions of the standard on inspection and integrity assessments of header boxes and attached nozzles. As a result, FFS assessment procedures in three different levels, which are consistent with API-579 general assessment methodology, are developed and presented for header boxes and nozzles. This study may serve as a practical addition to integrity assessments and inspection of air-cooled heat exchangers.","PeriodicalId":23700,"journal":{"name":"Volume 2: Computer Technology and Bolted Joints; Design and Analysis","volume":"22 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-07-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83348819","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 development of Fiber Reinforced Plastic (FRP) composite pressure vessels and pipping has greatly advanced in the past decades in the residential and industrial sectors to combat corrosion and chemical attacks. FRP composite flanges are known for their anisotropic behavior. In the ASME code section X, FRP composite flanges are treated using an analytical approach derived from that of metallic flanges in addition to the fact that the geometries are made to fit them as much as possible and not designed independently. This is known to have caused structural flaws for certain FRP flange classes and sizes. Using a recently developed anisotropic FRP flange approach, it is proposed to identify the most critical flanges by analyzing the flange parameters such as flange ring rotation and stresses in their different parts; flange ring, hub and shell subjected to pressure loading. The study on the strength of flanges described in ASME section X RD-620.1 table, will reveal the most critical size and class flanges and their highly stressed locations. To conduct such a study, the selected flange material is an E glass/Vinyl Ester laminate composite. The study shows that FRP flanges of class 25 and 50 are most vulnerable and should be less loaded.
在过去的几十年里，纤维增强塑料(FRP)复合压力容器和管道的发展在住宅和工业领域取得了很大的进步，以抵抗腐蚀和化学侵蚀。玻璃钢复合法兰以其各向异性特性而闻名。在美国机械工程师协会(ASME)规范第X节中，玻璃钢复合材料法兰采用源自金属法兰的分析方法进行处理，此外，几何形状要尽可能地与金属法兰相适应，而不是单独设计。已知这导致了某些FRP法兰等级和尺寸的结构缺陷。采用近年来发展起来的各向异性玻璃钢法兰方法，通过分析法兰环旋转和各部位应力等参数，识别出最关键的法兰;法兰环、轮毂和壳体承受压力载荷。对ASME X RD-620.1表中描述的法兰强度的研究将揭示最关键的尺寸和等级的法兰及其高应力位置。为了进行这样的研究，选择的法兰材料是E玻璃/乙烯基酯层压复合材料。研究表明，25级和50级FRP法兰最脆弱，应减小载荷。
{"title":"A Study of the Strength of ASME Section X FRP Flanges","authors":"Sofiane Bouzid, A. Bouzid, A. Ngo","doi":"10.1115/pvp2022-81832","DOIUrl":"https://doi.org/10.1115/pvp2022-81832","url":null,"abstract":"\u0000 The development of Fiber Reinforced Plastic (FRP) composite pressure vessels and pipping has greatly advanced in the past decades in the residential and industrial sectors to combat corrosion and chemical attacks. FRP composite flanges are known for their anisotropic behavior. In the ASME code section X, FRP composite flanges are treated using an analytical approach derived from that of metallic flanges in addition to the fact that the geometries are made to fit them as much as possible and not designed independently. This is known to have caused structural flaws for certain FRP flange classes and sizes.\u0000 Using a recently developed anisotropic FRP flange approach, it is proposed to identify the most critical flanges by analyzing the flange parameters such as flange ring rotation and stresses in their different parts; flange ring, hub and shell subjected to pressure loading. The study on the strength of flanges described in ASME section X RD-620.1 table, will reveal the most critical size and class flanges and their highly stressed locations. To conduct such a study, the selected flange material is an E glass/Vinyl Ester laminate composite. The study shows that FRP flanges of class 25 and 50 are most vulnerable and should be less loaded.","PeriodicalId":23700,"journal":{"name":"Volume 2: Computer Technology and Bolted Joints; Design and Analysis","volume":"29 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-07-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89588379","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}
High-temperature design evaluations of 700°C (1292°F) heat exchanger was conducted that would be installed in a large-scale high-temperature thermal energy storage performance test facility under development at KAERI site. The helical tube type sodium-to-air heat exchanger, AHX with 125kWt capacity of Type 316L austenitic stainless steel would be subjected to high-temperature operation at 700°C. Case studies in elevated temperature designs were conducted for the two materials of Type 316L and Type 316L(N) stainless steel codified in French high-temperature design rules of RCC-MRx. Because some significant material properties are not available up to 700°C in RCC-MRx, the lack material properties and design coefficients were determined through high-temperature material tests and relevant determination procedures. Another case studies on design temperatures with 700°C and 650°C (1202°F) in sodium coolant were conducted due to the availability of material properties in the design rules, and comparisons were made among the four cases of the two materials (316L and 316L(N)) and two design temperatures (700°C and 650°C).
{"title":"High-Temperature Design of 700°C Heat Exchanger in a Large Scale High-Temperature Thermal Energy Storage Performance Test Facility","authors":"H. Lee, Jung Yoon, Jewhan Lee, J. Eoh","doi":"10.1115/pvp2022-84895","DOIUrl":"https://doi.org/10.1115/pvp2022-84895","url":null,"abstract":"\u0000 High-temperature design evaluations of 700°C (1292°F) heat exchanger was conducted that would be installed in a large-scale high-temperature thermal energy storage performance test facility under development at KAERI site. The helical tube type sodium-to-air heat exchanger, AHX with 125kWt capacity of Type 316L austenitic stainless steel would be subjected to high-temperature operation at 700°C. Case studies in elevated temperature designs were conducted for the two materials of Type 316L and Type 316L(N) stainless steel codified in French high-temperature design rules of RCC-MRx. Because some significant material properties are not available up to 700°C in RCC-MRx, the lack material properties and design coefficients were determined through high-temperature material tests and relevant determination procedures. Another case studies on design temperatures with 700°C and 650°C (1202°F) in sodium coolant were conducted due to the availability of material properties in the design rules, and comparisons were made among the four cases of the two materials (316L and 316L(N)) and two design temperatures (700°C and 650°C).","PeriodicalId":23700,"journal":{"name":"Volume 2: Computer Technology and Bolted Joints; Design and Analysis","volume":"71 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-07-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"72654477","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 bolted joints used in mechanical structures loosen owing to, for example, a decrease in the initial axial tension (clamping force) and repeated external forces in the direction perpendicular to the axis. A Junker-type loosening test used to evaluate the performance of various types of locking devices in a short period of time has been established. In such a test, it is possible to compare the loosening performance characteristics of various bolted joints and locking devices. However, it has not been possible to absolutely determine the period of time that they can maintain their initial locking performance. This paper presents a method of estimating the absolute locking performance of bolted joints. The absolute evaluation of self-loosening is indispensable for the prediction of the lifetime of locking devices (parts and methods) in actual machines. From the results of our experimental study, we found a strong linear correlation on logarithmic coordinates between the decreases in axial tension (measured/initial axial tension) and the number of operations (or working time or mileage) since the last tightening. The loosening phenomenon of bolted joints can be observed as the tendency of the initial or residual axial tension to decrease. By utilizing the regression formula at logarithmic coordinates, we show an estimation method for residual axial tension to answer various questions such as “How much of the axial tension remains after tens of thousands of hours (operations)?” Therefore, it is possible to determine to what extent can the bolted joints of long-life machines and plant equipment in medium-to-long-term use be considered to loosening failure. Finally, we describe the judgement criterion for loosening. We examine evaluation criteria such as “Is the residual axial tension sufficient for the prevention of loosening failure?” The limit surface pressure is examined as the upper limit axial tension. As the lower limit axial tension, the allowable value of the external transverse force is examined.
{"title":"Evaluation for Residual Lifetime and Remaining Axial Tension to Loosening Failure on Bolted Joints Used in Long-Life Machine and Plant Equipment","authors":"Soichi Hareyama, K. Manabe, Satoshi Kobayashi","doi":"10.1115/pvp2022-80082","DOIUrl":"https://doi.org/10.1115/pvp2022-80082","url":null,"abstract":"\u0000 The bolted joints used in mechanical structures loosen owing to, for example, a decrease in the initial axial tension (clamping force) and repeated external forces in the direction perpendicular to the axis. A Junker-type loosening test used to evaluate the performance of various types of locking devices in a short period of time has been established. In such a test, it is possible to compare the loosening performance characteristics of various bolted joints and locking devices. However, it has not been possible to absolutely determine the period of time that they can maintain their initial locking performance. This paper presents a method of estimating the absolute locking performance of bolted joints. The absolute evaluation of self-loosening is indispensable for the prediction of the lifetime of locking devices (parts and methods) in actual machines. From the results of our experimental study, we found a strong linear correlation on logarithmic coordinates between the decreases in axial tension (measured/initial axial tension) and the number of operations (or working time or mileage) since the last tightening. The loosening phenomenon of bolted joints can be observed as the tendency of the initial or residual axial tension to decrease. By utilizing the regression formula at logarithmic coordinates, we show an estimation method for residual axial tension to answer various questions such as “How much of the axial tension remains after tens of thousands of hours (operations)?” Therefore, it is possible to determine to what extent can the bolted joints of long-life machines and plant equipment in medium-to-long-term use be considered to loosening failure. Finally, we describe the judgement criterion for loosening. We examine evaluation criteria such as “Is the residual axial tension sufficient for the prevention of loosening failure?” The limit surface pressure is examined as the upper limit axial tension. As the lower limit axial tension, the allowable value of the external transverse force is examined.","PeriodicalId":23700,"journal":{"name":"Volume 2: Computer Technology and Bolted Joints; Design and Analysis","volume":"152 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-07-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79603185","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}
Matthias Müller, O. Bernhardi, J. Denecke, H. Schildberg, J. Schmidt
Explosions of premixed gases with DDT, the transition from deflagration to detonation, are a risk in the process industry with potentially catastrophic consequences. Robust and simple design methods are required for industrial use. Such a simplified design method based on finite element analysis is proposed to model the dynamic behavior of pipes loaded by gas explosions of premixed gases including DDT. First, it is reviewed how the pressure load of the gas explosion and the resulting material behavior has been modeled in previous publications. The analytical equations are then extended for describing the pressure load as a function of time and location by considering the leading compression wave as it affects the pressure load of the overdriven detonation. The extended analytical equations are parameterized using Chapman-Jouguet conditions and experimental results from publications for both static equivalent pressure and the location of the DDT. To describe the plastic material behavior at high strain rates, the well-known Johnson-Cook plasticity model is used. The material parameters of the model are derived from simple experiments, which are available in an industrial environment. The comparison of a finite element simulation with experimental data shows that the concept of equivalent static pressure can be extended to an FEM analysis, which in the future will allow the sizing of complete pipe systems including tees, bends and flanges while considering plastic deformation.
{"title":"Analysis of Plastic Deformation of Pipes Due to Deflagration to Detonation Transition Using Static Equivalent Pressure","authors":"Matthias Müller, O. Bernhardi, J. Denecke, H. Schildberg, J. Schmidt","doi":"10.1115/pvp2022-84790","DOIUrl":"https://doi.org/10.1115/pvp2022-84790","url":null,"abstract":"\u0000 Explosions of premixed gases with DDT, the transition from deflagration to detonation, are a risk in the process industry with potentially catastrophic consequences. Robust and simple design methods are required for industrial use. Such a simplified design method based on finite element analysis is proposed to model the dynamic behavior of pipes loaded by gas explosions of premixed gases including DDT.\u0000 First, it is reviewed how the pressure load of the gas explosion and the resulting material behavior has been modeled in previous publications. The analytical equations are then extended for describing the pressure load as a function of time and location by considering the leading compression wave as it affects the pressure load of the overdriven detonation. The extended analytical equations are parameterized using Chapman-Jouguet conditions and experimental results from publications for both static equivalent pressure and the location of the DDT. To describe the plastic material behavior at high strain rates, the well-known Johnson-Cook plasticity model is used. The material parameters of the model are derived from simple experiments, which are available in an industrial environment. The comparison of a finite element simulation with experimental data shows that the concept of equivalent static pressure can be extended to an FEM analysis, which in the future will allow the sizing of complete pipe systems including tees, bends and flanges while considering plastic deformation.","PeriodicalId":23700,"journal":{"name":"Volume 2: Computer Technology and Bolted Joints; Design and Analysis","volume":"140 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-07-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77559396","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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