Pub Date : 2025-10-16DOI: 10.1016/j.ijpvp.2025.105682
Gang Li , Yichao Zhu
The study of the stress corrosion cracking (SCC) behaviour of pipeline steel is of great significance for the safe operation in the oil and gas industry. However, current experimental studies, being costly in both economic and temporal terms, can only deliver data suggesting the instantaneous SCC behaviour of pipeline steel, while quantities of actual interest, such as the lifespan against SCC, cannot be measured directly. To address this issue, a semi-analytical model based on partial differential equations is developed to model the SCC kinetics for steels making oil and gas pipeline. With the effect of stress gradient on ion transportation near crack tips taken into account, the mechanism of repeated rupture of the oxide film can be mimicked. With only one parameter needing calibration, the model proposed in this study is shown to make predictions, within a few seconds on a laptop computer, over SCC indices that are difficult to experimentally measure, such as the crack incubation period under various mechanical and chemical environments. It is predicted by the model that for a 56 mm-thick API 5L X70 steel segment with a 2 mm surface scratch, it takes roughly 90 years for the scratch to become an active crack under a tensile load of 120 MPa and with an environmental pH value of 6.8 and a chloride ion concentration of 0.004 mol/L, and it takes another 30 years for SCC evolution before the final material failure.
{"title":"Full-life simulation of the stress corrosion cracking behaviour of the pipeline steel for oil and gas","authors":"Gang Li , Yichao Zhu","doi":"10.1016/j.ijpvp.2025.105682","DOIUrl":"10.1016/j.ijpvp.2025.105682","url":null,"abstract":"<div><div>The study of the stress corrosion cracking (SCC) behaviour of pipeline steel is of great significance for the safe operation in the oil and gas industry. However, current experimental studies, being costly in both economic and temporal terms, can only deliver data suggesting the instantaneous SCC behaviour of pipeline steel, while quantities of actual interest, such as the lifespan against SCC, cannot be measured directly. To address this issue, a semi-analytical model based on partial differential equations is developed to model the SCC kinetics for steels making oil and gas pipeline. With the effect of stress gradient on ion transportation near crack tips taken into account, the mechanism of repeated rupture of the oxide film can be mimicked. With only one parameter needing calibration, the model proposed in this study is shown to make predictions, within a few seconds on a laptop computer, over SCC indices that are difficult to experimentally measure, such as the crack incubation period under various mechanical and chemical environments. It is predicted by the model that for a 56 mm-thick API 5L X70 steel segment with a 2 mm surface scratch, it takes roughly 90 years for the scratch to become an active crack under a tensile load of 120 MPa and with an environmental pH value of 6.8 and a chloride ion concentration of 0.004 mol/L, and it takes another 30 years for SCC evolution before the final material failure.</div></div>","PeriodicalId":54946,"journal":{"name":"International Journal of Pressure Vessels and Piping","volume":"219 ","pages":"Article 105682"},"PeriodicalIF":3.5,"publicationDate":"2025-10-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145362499","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-10-15DOI: 10.1016/j.ijpvp.2025.105685
Haiyang Xue, Xiao Li, Jiannan Sun, Tianhang Zhang
The influence of forced alignment on the load-bearing capacity of X80 pipeline steel girth weld joints was clarified through finite element simulation.With the increase of offset distance, the peak equivalent residual stress of the weld joint increases gradually; after springback, the reduction amplitude of the peak stress of as-welded pipelines is smaller than that of stress-free pipelines.Welding residual stress reduces the load-bearing capacity of pipelines. Under the same offset, the ultimate internal pressure of stress-free pipelines is 0.430–0.750 MPa higher than that of as-welded pipelines. This difference has a significant impact on the structural integrity of high-pressure pipelines and affects the safety redundancy under extreme working conditions.As the offset distance increases, the ultimate internal pressure of pipelines decreases significantly: the ultimate internal pressure of as-welded pipelines drops from 25.585 MPa (at an offset of 0 mm) to 11.250 MPa (when the offset is ≥ 150 mm), and the impact on load-bearing capacity tends to be gentle after the offset exceeds 150 mm.This study proposes a new finite element simulation path of "welding → offset → springback". The revealed relationship between offset distance and load-bearing capacity provides theoretical support and engineering guidance for the offset control in the forced alignment construction of high-pressure X80 pipelines.
{"title":"The influence of forced alignment on the bearing capacity of welded joints in X80 pipeline steel","authors":"Haiyang Xue, Xiao Li, Jiannan Sun, Tianhang Zhang","doi":"10.1016/j.ijpvp.2025.105685","DOIUrl":"10.1016/j.ijpvp.2025.105685","url":null,"abstract":"<div><div>The influence of forced alignment on the load-bearing capacity of X80 pipeline steel girth weld joints was clarified through finite element simulation.With the increase of offset distance, the peak equivalent residual stress of the weld joint increases gradually; after springback, the reduction amplitude of the peak stress of as-welded pipelines is smaller than that of stress-free pipelines.Welding residual stress reduces the load-bearing capacity of pipelines. Under the same offset, the ultimate internal pressure of stress-free pipelines is 0.430–0.750 MPa higher than that of as-welded pipelines. This difference has a significant impact on the structural integrity of high-pressure pipelines and affects the safety redundancy under extreme working conditions.As the offset distance increases, the ultimate internal pressure of pipelines decreases significantly: the ultimate internal pressure of as-welded pipelines drops from 25.585 MPa (at an offset of 0 mm) to 11.250 MPa (when the offset is ≥ 150 mm), and the impact on load-bearing capacity tends to be gentle after the offset exceeds 150 mm.This study proposes a new finite element simulation path of \"welding → offset → springback\". The revealed relationship between offset distance and load-bearing capacity provides theoretical support and engineering guidance for the offset control in the forced alignment construction of high-pressure X80 pipelines.</div></div>","PeriodicalId":54946,"journal":{"name":"International Journal of Pressure Vessels and Piping","volume":"219 ","pages":"Article 105685"},"PeriodicalIF":3.5,"publicationDate":"2025-10-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145324823","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This study presents a simplified evaluation of extremely low-cycle fatigue crack growth beyond small-scale yielding conditions using the reference stress method. Japan, a country frequently affected by earthquakes, faces critical challenges in ensuring the structural integrity of nuclear power plants under the excessive loads caused by large-scale seismic events. To address these challenges, the FDF Subcommittee (Phases I to III) was established under the Atomic Energy Research Committee of the Japan Welding Engineering Society. As part of its work, the FDF Subcommittee developed a guideline for evaluating crack growth using the reference stress method. This study consolidates the findings of the FDF Subcommittee. To validate the guideline, extremely low-cycle fatigue tests were conducted on a carbon steel pipe with a circumferential crack subjected to four-point bending, resulting in a through-wall life of a few hundred cycles. The crack growth behavior observed in the fatigue tests was analyzed in accordance with the guideline, which predicts crack length and depth based on the J-integral evaluated using the reference stress method, without resorting to elasto-plastic analysis. On average, the analysis consistently predicted through-wall lives approximately 33 % longer than those obtained in the tests. Despite this discrepancy, the simplicity of the reference stress method, which eliminates the need for finite element analysis, makes the guideline highly valuable from an engineering perspective. Furthermore, the experimental findings provided critical insights into the limitations of the reference stress method.
{"title":"Extremely low-cycle fatigue crack growth evaluation of carbon steel pipe with circumferential surface crack by reference stress method","authors":"Masahiro Takanashi , Kiminobu Hojo , Masao Itatani , Motoki Nakane , Kenji Yashirodai , Yukio Takahashi , Hiroshi Okada","doi":"10.1016/j.ijpvp.2025.105684","DOIUrl":"10.1016/j.ijpvp.2025.105684","url":null,"abstract":"<div><div>This study presents a simplified evaluation of extremely low-cycle fatigue crack growth beyond small-scale yielding conditions using the reference stress method. Japan, a country frequently affected by earthquakes, faces critical challenges in ensuring the structural integrity of nuclear power plants under the excessive loads caused by large-scale seismic events. To address these challenges, the FDF Subcommittee (Phases I to III) was established under the Atomic Energy Research Committee of the Japan Welding Engineering Society. As part of its work, the FDF Subcommittee developed a guideline for evaluating crack growth using the reference stress method. This study consolidates the findings of the FDF Subcommittee. To validate the guideline, extremely low-cycle fatigue tests were conducted on a carbon steel pipe with a circumferential crack subjected to four-point bending, resulting in a through-wall life of a few hundred cycles. The crack growth behavior observed in the fatigue tests was analyzed in accordance with the guideline, which predicts crack length and depth based on the J-integral evaluated using the reference stress method, without resorting to elasto-plastic analysis. On average, the analysis consistently predicted through-wall lives approximately 33 % longer than those obtained in the tests. Despite this discrepancy, the simplicity of the reference stress method, which eliminates the need for finite element analysis, makes the guideline highly valuable from an engineering perspective. Furthermore, the experimental findings provided critical insights into the limitations of the reference stress method.</div></div>","PeriodicalId":54946,"journal":{"name":"International Journal of Pressure Vessels and Piping","volume":"219 ","pages":"Article 105684"},"PeriodicalIF":3.5,"publicationDate":"2025-10-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145416529","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-10-12DOI: 10.1016/j.ijpvp.2025.105683
Yihua Li, Xiaoting Gu
CO2 readily corrodes the inner wall of pipe bends during transport, significantly affecting the safe operation of the pipeline. Presently, the majority of research solely examines the corrosion of bends by a singular mechanism, neglecting the effects of various physical field interactions. In practical working situations, bends induce many mechanical stress actions and electrochemical responses, potentially resulting in a more complex scenario. Consequently, for the X80 pipeline, a mechanical-electrical coupling corrosion model for CO2 transport bends was developed to examine the corrosion behaviour of CO2 on the bend under various physical fields, including velocity and pressure fields. The sensitivity of parameters such as inlet flow rate, bending angle, and radius of curvature was analysed, culminating in the establishment of a corrosion prediction model. The findings indicate that corrosion in the bend section exceeds that in the straight section, with internal corrosion in the bend being greater than external corrosion. As the inlet flow rate increases, the corrosion rate accelerates, but the acceleration rate diminishes after reaching 2 m/s. Additionally, as the radius of curvature and bending angle increase, the corrosion rate progressively decreases, slowing after reaching 2D and 70°, respectively; therefore, it is recommended to select a pipe with a curvature radius greater than 2D. On-site workers may also determine suitable bend parameters according to pertinent contour maps. The study's results can enhance the optimisation of CO2 transport process parameters and bend selection, hence improving safety performance and extending the service life of the bends.
{"title":"Simulation of CO2 corrosion and prediction model for corrosion rate based on mechanical-electrical interaction in pipe bends","authors":"Yihua Li, Xiaoting Gu","doi":"10.1016/j.ijpvp.2025.105683","DOIUrl":"10.1016/j.ijpvp.2025.105683","url":null,"abstract":"<div><div>CO<sub>2</sub> readily corrodes the inner wall of pipe bends during transport, significantly affecting the safe operation of the pipeline. Presently, the majority of research solely examines the corrosion of bends by a singular mechanism, neglecting the effects of various physical field interactions. In practical working situations, bends induce many mechanical stress actions and electrochemical responses, potentially resulting in a more complex scenario. Consequently, for the X80 pipeline, a mechanical-electrical coupling corrosion model for CO<sub>2</sub> transport bends was developed to examine the corrosion behaviour of CO<sub>2</sub> on the bend under various physical fields, including velocity and pressure fields. The sensitivity of parameters such as inlet flow rate, bending angle, and radius of curvature was analysed, culminating in the establishment of a corrosion prediction model. The findings indicate that corrosion in the bend section exceeds that in the straight section, with internal corrosion in the bend being greater than external corrosion. As the inlet flow rate increases, the corrosion rate accelerates, but the acceleration rate diminishes after reaching 2 m/s. Additionally, as the radius of curvature and bending angle increase, the corrosion rate progressively decreases, slowing after reaching 2D and 70°, respectively; therefore, it is recommended to select a pipe with a curvature radius greater than 2D. On-site workers may also determine suitable bend parameters according to pertinent contour maps. The study's results can enhance the optimisation of CO<sub>2</sub> transport process parameters and bend selection, hence improving safety performance and extending the service life of the bends.</div></div>","PeriodicalId":54946,"journal":{"name":"International Journal of Pressure Vessels and Piping","volume":"219 ","pages":"Article 105683"},"PeriodicalIF":3.5,"publicationDate":"2025-10-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145324824","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-10-11DOI: 10.1016/j.ijpvp.2025.105679
Georg Veile , Jürgen Rudolph , Nina Grözinger , Martin Herzig , Michael Grimm , Stefan Weihe
{"title":"Corrigendum to “Improving fatigue testing of AISI 304L stainless steel in high temperature water regarding their complex hardening and softening material behaviour” [Int. J. Pres. Ves. Pip. Volume 218 Part B (2025) 105612]","authors":"Georg Veile , Jürgen Rudolph , Nina Grözinger , Martin Herzig , Michael Grimm , Stefan Weihe","doi":"10.1016/j.ijpvp.2025.105679","DOIUrl":"10.1016/j.ijpvp.2025.105679","url":null,"abstract":"","PeriodicalId":54946,"journal":{"name":"International Journal of Pressure Vessels and Piping","volume":"219 ","pages":"Article 105679"},"PeriodicalIF":3.5,"publicationDate":"2025-10-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145747328","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Grade 91 steel is widely used in the power plants for high-temperature applications. The tested specimens were fabricated from base metal and welded portions of Grade 91 steel for conducting tensile and creep tests in the temperature range of 575–675 °C and the stress range of 60–220 MPa, respectively. Understanding the creep deformation behaviour of Grade 91 steel up to rupture at different applied stresses is essential for ensuring reliable creep life and safe operation of the structural components of the power plants. The rupture times were obtained from 15 h to 5208 h for the samples of BM and WM. The stress dependence of minimum creep rate and rupture time is followed the Norton power law and the stress exponents were found in the range of 4.6–19.3 for the temperature range of 575–675 °C. The strain-hardening exponent is also substantially increased at 625 °C during tensile behaviour, which presence of MX precipitates. The higher stress exponent resulted at 575 °C and 625 °C, is mainly due to interaction of dislocations with the precipitates and grain boundaries. Furthermore, threshold stress analysis is performed for the base metal and weld joints to find the operating mechanism of creep. By considering threshold stresses, the true stress exponents are found to be approximately 4.6 and 5.1 within the temperature range of 575–675 °C, confirmed as dislocation climb is the rate-controlling mechanism of creep. The minimum creep rate and rupture time data followed Monkman-Grant relationship. The selected samples were taken for characterization using optical microscopy and scanning electron microscopy. The elemental compositions of the precipitates were analyzed using energy dispersive X-ray spectroscopy. This study gives an understanding of the role of microstructure on creep rupture behaviour of Grade 91 steel in the base metal and weld joints.
{"title":"Creep deformation behaviour of Grade 91 steel and its weld joints: A comparative study","authors":"Sumit Kumar Mohanty , Swarnalata Behera , Chandan Pandey , Krishna Guguloth","doi":"10.1016/j.ijpvp.2025.105678","DOIUrl":"10.1016/j.ijpvp.2025.105678","url":null,"abstract":"<div><div>Grade 91 steel is widely used in the power plants for high-temperature applications. The tested specimens were fabricated from base metal and welded portions of Grade 91 steel for conducting tensile and creep tests in the temperature range of 575–675 °C and the stress range of 60–220 MPa, respectively. Understanding the creep deformation behaviour of Grade 91 steel up to rupture at different applied stresses is essential for ensuring reliable creep life and safe operation of the structural components of the power plants. The rupture times were obtained from 15 h to 5208 h for the samples of BM and WM. The stress dependence of minimum creep rate and rupture time is followed the Norton power law and the stress exponents were found in the range of 4.6–19.3 for the temperature range of 575–675 °C. The strain-hardening exponent is also substantially increased at 625 °C during tensile behaviour, which presence of MX precipitates. The higher stress exponent resulted at 575 °C and 625 °C, is mainly due to interaction of dislocations with the precipitates and grain boundaries. Furthermore, threshold stress analysis is performed for the base metal and weld joints to find the operating mechanism of creep. By considering threshold stresses, the true stress exponents are found to be approximately 4.6 and 5.1 within the temperature range of 575–675 °C, confirmed as dislocation climb is the rate-controlling mechanism of creep. The minimum creep rate and rupture time data followed Monkman-Grant relationship. The selected samples were taken for characterization using optical microscopy and scanning electron microscopy. The elemental compositions of the precipitates were analyzed using energy dispersive X-ray spectroscopy. This study gives an understanding of the role of microstructure on creep rupture behaviour of Grade 91 steel in the base metal and weld joints.</div></div>","PeriodicalId":54946,"journal":{"name":"International Journal of Pressure Vessels and Piping","volume":"219 ","pages":"Article 105678"},"PeriodicalIF":3.5,"publicationDate":"2025-10-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145324822","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-10-10DOI: 10.1016/j.ijpvp.2025.105676
Haiyue Pang , Qu Liu , Zhipeng Cai , Kejian Li
This study investigates the failure of an Inconel 783 alloy bolt that fractured during service in a medium-pressure control valve of an ultra-supercritical power unit. The failure mechanism was analyzed through fractographic observation, metallographic examination, and finite element analysis. The results indicate that the bolt failed via sudden fracture initiated by fatigue crack propagation. The failure process involved three stages: (1) fatigue crack initiation and growth from a surface scratch to a depth of approximately 1 mm; (2) subsequent crack extension dominated by stress-accelerated grain boundary oxidation (SAGBO); and (3) final fracture when the crack reached a critical length of about 15 mm. Two primary contributing factors were identified. First, improper heat treatment during manufacturing resulted in an insufficient precipitation of secondary β phase along the grain boundaries, which significantly reduced the material's resistance to SAGBO. Second, a pronounced negative creep phenomenon was observed, which was attributed to the incomplete precipitation of the γ′ strengthening phase in the as-received material. This negative creep led to an abnormal increase in the actual service stress by approximately 22.3 %, further accelerating both fatigue crack initiation and SAGBO-driven crack growth. This work provides a technical reference for the failure prevention of Inconel 783 bolts under high-temperature and high-stress service conditions.
{"title":"Failure investigation of the inconel 783 alloy bolt used in an ultra-supercritical power plant","authors":"Haiyue Pang , Qu Liu , Zhipeng Cai , Kejian Li","doi":"10.1016/j.ijpvp.2025.105676","DOIUrl":"10.1016/j.ijpvp.2025.105676","url":null,"abstract":"<div><div>This study investigates the failure of an Inconel 783 alloy bolt that fractured during service in a medium-pressure control valve of an ultra-supercritical power unit. The failure mechanism was analyzed through fractographic observation, metallographic examination, and finite element analysis. The results indicate that the bolt failed via sudden fracture initiated by fatigue crack propagation. The failure process involved three stages: (1) fatigue crack initiation and growth from a surface scratch to a depth of approximately 1 mm; (2) subsequent crack extension dominated by stress-accelerated grain boundary oxidation (SAGBO); and (3) final fracture when the crack reached a critical length of about 15 mm. Two primary contributing factors were identified. First, improper heat treatment during manufacturing resulted in an insufficient precipitation of secondary β phase along the grain boundaries, which significantly reduced the material's resistance to SAGBO. Second, a pronounced negative creep phenomenon was observed, which was attributed to the incomplete precipitation of the γ′ strengthening phase in the as-received material. This negative creep led to an abnormal increase in the actual service stress by approximately 22.3 %, further accelerating both fatigue crack initiation and SAGBO-driven crack growth. This work provides a technical reference for the failure prevention of Inconel 783 bolts under high-temperature and high-stress service conditions.</div></div>","PeriodicalId":54946,"journal":{"name":"International Journal of Pressure Vessels and Piping","volume":"219 ","pages":"Article 105676"},"PeriodicalIF":3.5,"publicationDate":"2025-10-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145289780","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-10-10DOI: 10.1016/j.ijpvp.2025.105681
Benard Kipsang , Behzad Vasheghani Farahani , Krzysztof Wacławiak , Wim De Waele
Considering the complex stresses in power boiler piping and the oblique orientation of cracks, mixed mode I/III loading plays a significant role in crack propagation during service. This research investigates the fracture characteristics of 14MoV6-3 power plant steel under mixed mode I/III loading. Experimental techniques are implemented using the 3D full-field Digital Image correlation (DIC) tool to measure the Crack Tip Opening Displacement (CTOD) in quasi-static loading conditions. Single Edge Notch Tension (SENT) specimens are used to assess tilted notches' effect on their tearing resistance. Three different notch angles 00, 22.50, and 45° are assessed. The contribution of mode III CTOD to crack opening is quantified. In all cases, it can be inferred that the fracture toughness under mixed mode I/III loading is slightly higher than under mode I loading. Numerically, the problem is solved using the finite element method, FEM, formulation extended to the fracture mechanics theory in which J-Integral is acquired and compared to the experimental solution, a good agreement was verified. The mode-I Stress Intensity Factor (SIF) is calculated from the DIC data using the overdeterministic algorithm to obtain an alternative solution and assess the experimental campaign's robustness. Therefore, a comprehensive comparison is drawn amongst all acquired results. Furthermore, the fracture resistance (R-curves) of the different notch angles is experimentally evaluated.
{"title":"Investigation of mixed mode I/III fracture of 14MoV6-3 power plant steel using 3D-digital image correlation","authors":"Benard Kipsang , Behzad Vasheghani Farahani , Krzysztof Wacławiak , Wim De Waele","doi":"10.1016/j.ijpvp.2025.105681","DOIUrl":"10.1016/j.ijpvp.2025.105681","url":null,"abstract":"<div><div>Considering the complex stresses in power boiler piping and the oblique orientation of cracks, mixed mode I/III loading plays a significant role in crack propagation during service. This research investigates the fracture characteristics of 14MoV6-3 power plant steel under mixed mode I/III loading. Experimental techniques are implemented using the 3D full-field Digital Image correlation (DIC) tool to measure the Crack Tip Opening Displacement (CTOD) in quasi-static loading conditions. Single Edge Notch Tension (SENT) specimens are used to assess tilted notches' effect on their tearing resistance. Three different notch angles 0<sup>0</sup>, 22.5<sup>0</sup>, and 45° are assessed. The contribution of mode III CTOD to crack opening is quantified. In all cases, it can be inferred that the fracture toughness under mixed mode I/III loading is slightly higher than under mode I loading. Numerically, the problem is solved using the finite element method, FEM, formulation extended to the fracture mechanics theory in which J-Integral is acquired and compared to the experimental solution, a good agreement was verified. The mode-I Stress Intensity Factor (SIF) is calculated from the DIC data using the overdeterministic algorithm to obtain an alternative solution and assess the experimental campaign's robustness. Therefore, a comprehensive comparison is drawn amongst all acquired results. Furthermore, the fracture resistance (R-curves) of the different notch angles is experimentally evaluated.</div></div>","PeriodicalId":54946,"journal":{"name":"International Journal of Pressure Vessels and Piping","volume":"219 ","pages":"Article 105681"},"PeriodicalIF":3.5,"publicationDate":"2025-10-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145324833","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-10-09DOI: 10.1016/j.ijpvp.2025.105680
Chengbo Wang , Xumin Guo , Longfei Chi , Guoxiong An , Tianyu Zhao
The dynamic research of hydraulic pipelines has received widespread attention. The pipelines laid outside the aero-engine inevitably have assembly deviations, which may affect the vibration state of the pipelines. However, fluid-coupled modes analysis of pipelines considering installation deviations is very limited. Given this situation, this paper proposes a hydraulic pipeline dynamic model considering installation deviation based on Timoshenko beam theory and the incremental analysis method. The equivalence of the fluid is achieved through the addition of the stiffness matrix and damping matrix, and the installation deviation is characterized by the initial displacement matrix. A fluid-coupled modal analysis of the hydraulic pipeline with installation deviations is conducted based on the established model. The accuracy of the pipeline model is validated through literature and modal experiments on pipelines with installation deviations. The natural frequencies of the L pipeline under the combined effects of flow velocity, pressure, and installation deviations are analyzed. The results show that the natural frequency of hydraulic pipelines with installation deviation decreases with the increase of fluid velocity and pressure, and this change dominates, while the impact of installation deviation on the natural frequency of hydraulic pipelines is relatively weak. Axial installation deviations have a more pronounced effect on L-shaped pipelines compared to lateral deviations. Specifically, as the axial tensile installation deviation increases, the natural frequency of the pipeline also rises, and this law changes with the change of boundary conditions. This study can provide potential technical support and theoretical guidance for pipeline dynamics analysis and fault diagnosis with installation deviation in engineering.
{"title":"Effect of installation deviation on the natural characteristics of hydraulic L-shaped pipelines: Simulation and experimental study","authors":"Chengbo Wang , Xumin Guo , Longfei Chi , Guoxiong An , Tianyu Zhao","doi":"10.1016/j.ijpvp.2025.105680","DOIUrl":"10.1016/j.ijpvp.2025.105680","url":null,"abstract":"<div><div>The dynamic research of hydraulic pipelines has received widespread attention. The pipelines laid outside the aero-engine inevitably have assembly deviations, which may affect the vibration state of the pipelines. However, fluid-coupled modes analysis of pipelines considering installation deviations is very limited. Given this situation, this paper proposes a hydraulic pipeline dynamic model considering installation deviation based on Timoshenko beam theory and the incremental analysis method. The equivalence of the fluid is achieved through the addition of the stiffness matrix and damping matrix, and the installation deviation is characterized by the initial displacement matrix. A fluid-coupled modal analysis of the hydraulic pipeline with installation deviations is conducted based on the established model. The accuracy of the pipeline model is validated through literature and modal experiments on pipelines with installation deviations. The natural frequencies of the L pipeline under the combined effects of flow velocity, pressure, and installation deviations are analyzed. The results show that the natural frequency of hydraulic pipelines with installation deviation decreases with the increase of fluid velocity and pressure, and this change dominates, while the impact of installation deviation on the natural frequency of hydraulic pipelines is relatively weak. Axial installation deviations have a more pronounced effect on L-shaped pipelines compared to lateral deviations. Specifically, as the axial tensile installation deviation increases, the natural frequency of the pipeline also rises, and this law changes with the change of boundary conditions. This study can provide potential technical support and theoretical guidance for pipeline dynamics analysis and fault diagnosis with installation deviation in engineering.</div></div>","PeriodicalId":54946,"journal":{"name":"International Journal of Pressure Vessels and Piping","volume":"219 ","pages":"Article 105680"},"PeriodicalIF":3.5,"publicationDate":"2025-10-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145266997","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-10-08DOI: 10.1016/j.ijpvp.2025.105670
Gopal Ji Rai, Suhrit Mula, Gautam Agarwal
Increasing energy consumption brings significant challenges, including increased greenhouse gas emissions and rising costs. To overcome these issues, Advanced Ultrasupercritical (AUSC) thermal power plants are proposed to operate at high steam temperatures (983 K) and pressures (310 bar). To meet this demand, materials should be able to withstand the harsh environments during service life. Considering cost-effectiveness, cast Superni 625, an Indian equivalent of Inconel 625, is proposed for high-temperature applications, whereas 304H austenitic stainless steel is recommended for moderately high temperatures. Joining these two alloys, thus, assumes importance, and integrity of the dissimilar welds at high service temperatures becomes critical. In this work, 304H ASS and Superni 625 alloy were welded using ERNiCrMo-3, a Mo-rich filler metal, by multi-pass gas tungsten arc welding (GTAW). Macro & microstructural analyses demonstrated the formation of a sound joint. The weld metal (WM) predominantly comprised an austenite phase, exhibiting distributions of Mo and Ti/Nb carbides within interdendritic areas. The micro-hardness assessment indicated the highest hardness at the filling area of the weld metal, whereas 304H base metal is the weakest zone. Tensile tests at 923 K on transverse specimens of the welded plates revealed failure within the 304H base metal, indicating superior weld metal tensile strength. Furthermore, tensile tests at 923 K on longitudinal specimens revealed the weld metal strength to be higher than either of the base metals. The higher strength of the weld metal than the Superni 625 base metal at high temperature is attributed to the absence of Laves phase in the weld metal and a more pronounced PLC effect. In addition, at high temperature, the strength of the heat-affected zone near the 304H base metal side was found to be higher than the 304H base metal, which is attributed to dynamic strain aging in the heat-affected zone. The V-notch Charpy impact toughness of the weld metal was found to be significantly higher (79.7 ± 4.04 J) than the acceptable value (47 J) as per the existing standard (EN ISO 3580:2017). Fractography showed dimples at room temperature that elongated with increased temperature. At 923 K, the fracture mode was primarily mixed, exhibiting dimples from micro-voids coalescence alongside faceted features. Through extensive weld metal characterization, it is concluded that the chosen welding method for dissimilar welding was performed successfully, which has applications at high temperatures, including AUSC.
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