Increase In Internal Pressure Research Articles

Understanding post-irradiation creep behavior of M5Framatome zirconium alloy

After in reactor use, the nuclear fuel assembly of pressurized water reactors is stored in water and is eventually transported, in a dry cask, to a long-term storage facility or to a reprocessing plant. During transportation in dry environment the fuel rod temperature and internal pressure both increase. This leads to simultaneous creep deformation and annealing of the cladding tubes made of M5Framatome11M5 and M5Framatome are trademarks or registered trademarks of Framatome or its affiliates, in the USA or other countries. zirconium alloy. This study shows that post-irradiation creep, or heat treatment, leads to the recovery of the radiation induced hardening and also to the recovery of the uniform elongation because of <a>-loop annealing. On the other hand, it is shown that cladding tubes made of M5Framatome alloy exhibit low post-irradiation creep rates, especially at low applied stress. This strain rate is significantly lower than for the unirradiated material and similar to the as-irradiated material, despite the significant <a> loop annealing. The low creep rates are mainly attributed to the Nb-rich nano-precipitates that act as dispersed strengthening particles. These nano-precipitates appear under irradiation and are stable at temperatures up to 450 °C explaining their strengthening effect even after significant annealing.

Effects of external corrosion defect growth on wall pipeline under internal pressure and various defect sizes with mechano‐electrochemical interaction

AbstractThe assessment of the impact of corrosion defects on the integrity and safe operation of through‐wall pipelines is critical. In this work, a finite element‐based model was developed to study the mechano‐electrochemical (M‐E) effects of external corrosion defects on 10CrMoAl steel pipelines. The effects of parameters such as defect sizes and internal pressures on pipeline conditions are also studied. The results show that increased corrosion depth leads to stress concentration at the center of the defect. The increase in internal pressure causes local plastic deformation and anodic current density concentration at the inner edge of the defect and in the adjacent areas of the defect. M‐E interaction causes the growth of corrosion defects significantly at higher internal pressures. The corrosion defects increase with time. As the pressure increases, the failure pressure of the pipeline gradually decreases. The influence of defect depth on the corrosion rate at the defect is greater than that of defect width. With increasing in internal pressure and corrosion defect size, it will lead to more severe plastic deformation, resulting in accelerated corrosion.

Pressure monitoring and deformation analysis of a brine-filled salt cavern - A case study of Jianghan, China

Deformation stability plays a crucial role in the construction and operation of hydrocarbon storage salt caverns. Monitoring and analyzing wellhead pressure data under closed well conditions provide valuable insights into the evaluation of cavern stability. In this study, an analysis of five factors influencing internal brine pressure was conducted, which revealed that salt creep and brine thermal expansion contribute to an increase in internal brine pressure, while brine penetration, salt dissolution and cavern compressibility lead to a decrease. The atmospheric pressure, surface temperature, and earth tides are the other factors influencing wellhead pressure fluctuations. Through the analysis of wellhead pressure data from brine-filled salt cavern under closed conditions, the creep parameters of salt formations were calculated using the Norton-Hoff creep model. To further understand the behavior of brine-filled salt cavern, numerical simulations were conducted to analyze the brine temperature distribution and deformation stability. The volumetric average temperature of the brine exhibits a nonlinear increase over time, characterized by a rapid rise in the initial stage followed by a slower rate of change. Finally, the brine temperature stabilizes and converges toward the formation temperature. From deformation analysis, it was observed that the closed condition is more favorable for the maintenance of cavern stability in comparison to the open condition. The subsidence of the cavern roof is particularly sensitive and requires careful attention, especially for flat-roof salt caverns. Under closed conditions, it is crucial to control the brine pressure decrease rate and prevent excessively high brine pressure to ensure the mechanical and penetration stability of the brine-filled salt cavern. These findings provide valuable insights into the factors influencing internal brine pressure, the determination of creep parameters, the distribution of brine temperature, and the deformation stability of brine-filled salt caverns.

Некоторые вопросы оценки прочности, надежности и риска аварии изотермических резервуаров для хранения сжиженных газов

It is not possible to design completely reliable and flawless structures and facilities. Although precisely designed, accurately manufactured and assembled, such structures and facilities can have defects that are permissible on the condition of compliance with the established loading modes unless certain parameters are reached. The most critical issue among the threats to the safe operation of isothermal tanks to store liquefied gases is the violation of operating conditions, namely the increase in internal pressure of the gaseous phase. It is associated with the fundamental inability of a defect-free, fully serviceable thin-walled shell with a flat bottom and a conical or domed roof to withstand an emergency increase in internal gas pressure. A few accidents in isothermal tanks that occurred earlier in the world are associated with the emergency increase in internal pressure. The hazards identified when assessing the risk of accident in an isothermal tank are listed in descending order of their importance. The excess of scheduled values by structure parameters or liquefied gas storage process is prioritized as the first criticality. These are primarily the increase in internal gas pressure, then defects of structure, random impacts, etc. The algorithm for evaluating the frequency of accidental leakage in an isothermal tank remaining in operation upon the expiration of the designed lifetime is proposed.

Systematic review of the use of ultrasound for venous assessment and venous thrombosis screening in spaceflight

The validity of venous ultrasound (V-US) for the diagnosis of deep vein thrombosis (DVT) during spaceflight is unknown and difficult to establish in diagnostic accuracy and diagnostic management studies in this context. We performed a systematic review of the use of V-US in the upper-body venous system in spaceflight to identify microgravity-related changes and the effect of venous interventions to reverse them, and to assess appropriateness of spaceflight V-US with terrestrial standards. An appropriateness tool was developed following expert panel discussions and review of terrestrial diagnostic studies, including criteria relevant to crew experience, in-flight equipment, assessment sites, ultrasound modalities, and DVT diagnosis. Microgravity-related findings reported as an increase in internal jugular vein (IJV) cross-sectional area and pressure were associated with reduced, stagnant, and retrograde flow. Changes were on average responsive to venous interventions using lower body negative pressure, Bracelets, Valsalva and Mueller manoeuvres, and contralateral IJV compression. In comparison with terrestrial standards, spaceflight V-US did not meet all appropriateness criteria. In DVT studies (n = 3), a single thrombosis was reported and only ultrasound modality criterion met the standards. In the other studies (n = 15), all the criteria were appropriate except crew experience criterion, which was appropriate in only four studies. Future practice and research should account for microgravity-related changes, evaluate individual effect of venous interventions, and adopt Earth-based V-US standards.

Experimental Study on the Quantitative Relationship between the Non-contact Magnetic Signal and Detection Height of Ferromagnetic Pipelines

The non-contact magnetic detection technology has good application prospects in the detection of buried steel pipelines. However, the variation of non-contact magnetic signal and measured height is unknown. The application of the technology in pipeline burial inspection is restricted. Therefore, this article conducts non-contact magnetic signal experimental testing on full-size steel pipelines. The collection method, pipe diameter, internal pressure, measurement height, and the non-contact magnetic signal are quantitatively analyzed. And the propagation factor f G was defined to quantify the degree of influence of measurement height on the non-contact magnetic signal. The results indicate that when the measurement height increases from 0.1 m to 2.0 m, the variation amplitude of the magnetic gradient modulus obtained by the parallel acquisition method is the largest, with a change rate of - 0.35. The amplitude and linear rate of change of the propagation factor f G increase with the pipe diameter and internal pressure. The amplitude and linear rate of change of the propagation factor f G increase with the pipe diameter and internal pressure. In the range of pipe diameters from 355.6 mm to 1016 mm, the amplitude of f G variation is 0.53, and the rate of change is 0.26. Furthermore, the amplitude of f G change due to a unit increase in internal pressure is 0.022, with a corresponding rate of change of 0.0114.

Device for determination of internal pressure in beer cans by measuring the force-displacement curves

Microbiological contamination of beer is usually manifested by the production of CO2 and, hence, an increase in its concentration. The increased concentration of CO2 in a closed package leads to an increase of internal pressure, which can cause a destruction of the package and have dangerous consequences. A device for non-destructive monitoring of the internal pressure in beer cans based on measurement of force-displacement curve has been developed and characterized in this study.

Full-scale model test for the performance of DDS prestressed composite lining with SCC-NC of high internal pressure shield tunnel

To meet the requirements of structure design for high internal pressure with large diameter tunnel and long-distance concrete pouring, a Double-layered and Double-looped Steel-strand(DDS) prestressed composite lining with Self-Compacting Concrete (SCC) and Normal Concrete (NC) was presented. A series of SCC and NC properties tests were conducted to prepare optimal DDS prestressed concrete, followed by a standing full-scale loading test to demonstrate the features of deformation and bearing capacity for the composite lining. The results showed that the DDS combined bearing structure has good bearing capacity to internal pressure, where the bearing process was divided into three stages. In the elastic stage, there was no cracks appeared and the structure began to show a tensile trend with the increase of internal pressure. The structure entered the inelastic stage when the internal pressure reached 1.1 MPa, the cracks were found to initiate. As the internal pressure was increased to 1.3 MPa, the structure entered the crack propagation stage, where the expansion of cracks in the inner lining would lead to a stress redistribution. For the internal pressure from 0 to 1.45 MPa, the average proportion of internal pressure borne by the inner lining decreases from 80 % to 70 %, while the one by the outer lining increases from 20 % to 30 %. Our findings demonstrate the mechanical behavior of the optimized bearing structures and provide guidance for the design and construction in related tunnel engineering.

Investigation into the mechano-electrochemical interaction of internal and external corrosion defects on pipe surfaces

Revealing the mechanical-electrochemical interactions (M-E) on internal and external defects in pipelines is of paramount importance for ensuring the safe operation of pipelines. The present study establishes a mechano-electrochemical multi-physics coupling model and develops a two-dimensional finite element (FE) model of internal and external defects on the pipe surface to investigate the M-E interaction of X100 steel pipe with corrosion defects on both internal and external surfaces. The results demonstrate that the M-E interaction is significantly influenced by the geometrical shape, relative position, and internal pressure of defects. Moreover, altering a single defect parameter can simultaneously impact the M-E interaction of two defects. As the depth of defects increases, the cross-sectional area between internal and external defects decreases, leading to an intensified interaction between mechanics and electromagnetics and a gradual concentration of M-E interaction at the center of defects. The magnitude of the M-E interaction exhibits a negative correlation with the length of the defect, while the presence of a long defect minimally impacts the M-E interaction on the opposing side. As the external defects gradually distance themselves from the internal defects, the M-E interaction diminishes and the concentration area of M-E interaction shifts in the opposite direction to defect migration, while stress in the non-defect region adjacent to both internal and external defects progressively intensifies. The increase in internal pressure significantly enhances the M-E interaction of internal and external defects, with the M-E interaction primarily focused on the minimum cross-sectional area of radial overlap between these defects. At low internal pressures, however, the M-E interaction becomes negligible.

Failure characteristics of buried pipelines in subsidence areas under the influence of multi-adjustable factors during coal mining: A case study of Ordos, China

Coal mining-induced ground subsidence often causes buried oil-gas pipeline failure. Insight the evolution of pipeline failure length and inflection points under the influence of adjustable factors (the distance between the panel pipe, panel width, internal pressure, and burial depth) has become increasingly essential for pipeline maintenance and operation. At present, the pipeline's failure length, failure time series, and inflection point distribution in subsidence areas are vague, which is not perfect in terms of specificity and clarity. Thus, a novel method to distinguish local failure and inflection points of pipelines is proposed by combining its moment and volume strain. Taking Panel 22102 of Ordos in western China as an example, the pipeline failure length and time series characteristics, as well as the inflection point spacing (IPS) are analyzed under the influence of adjustable factors by numerical simulation. The results show that (ⅰ) By increasing the distance between the panel pipe, and reducing the panel width, burial depth, and internal pressure, we can effectively mitigate or prevent pipe failures. For Panel 22102, the distance between the panel pipe should be less than 120 m to prevent failure. When it is unavoidable for the panel to pass underneath the pipeline, the width of the panel needs to be reduced to less than 120 m. (ⅱ) The pipeline failure length decreases by 2.9% for every 10 m reduction in the panel-to-pipeline distance. For every 10 m reduction in panel width, the pipeline failure length decreases by 5.7%. For every 0.1 m decrease in the burial depth, the pipeline failure length decreases by 2.16%. For each 1 MPa increase in internal pressure, the pipeline failure length increased by 0.48%. (ⅲ) The IPS is proportional to the panel width, burial depth, and internal pressure while exhibiting an exponential relationship with the distance between the panel and pipe. (ⅳ) The failure first spreads from the pipeline's subsidence center towards both ends, followed by spreading from both ends and the center towards inflection points simultaneously. (ⅴ) A multi-level and multi-faceted resilient management and collaborative operating pattern is established for the gas-coal integrated mining field. The research results provide scenario guidance and decision support for managers to develop adjusting measures to maintain pipelines, and also promote the coordinated mining of gas and coal resources.

The explosion characteristics of the insulating oil under unconfined conditions and its damage assessment

With the application of ultra-high voltage (UHV) technology, a substantial amount of energy released from an internal arc fault in the transformer leads to the instantaneous decomposition of insulating oil into various flammable gases. This results in a rapid increase in internal pressure, making it highly probable for the transformer casing to rupture. Consequently, the insulating oil and its decomposition products disperse in the air, which in the presence of an ignition source, can trigger an explosive accident. To reveal the explosion characteristics of insulating oil, experiments and simulations are conducted under unconfined conditions. Besides, a quantitative explosion risk assessment is conducted. The results indicate that, at 20 ms, a high temperature and strong turbulence region appears at about 0.9 m from the center of the cloud and 0.7 m in height, and the combustible cloud is initiated near the region. The safety distances for humans free from the hazard of shock waves are 11.79 m, 13.74 m, and 21.63 m with the amount of insulating oil of 10 L, 15 L, and 20 L, respectively, and the safety distances for humans free from the hazard of thermal radiation are 21.2 m, 26.4 m, and 29.2 m respectively.

Effect of hydrogen embrittlement on the safety assessment of low-strength hydrogen transmission pipeline

Currently, no systematic approach exists for the safety assessment method of hydrogen transmission low-strength pipeline, it is necessary to study the effect of hydrogen embrittlement (HE) on the method of failure assessment diagram (FAD) for the defective pipe. The hydrogen charging experiments of tensile and Charpy impact specimens for the L245 pipe steel were carried out with charging time of 0, 30, 90, and 120 h, and then the tensile and Charpy impact tests were immediately conducted. The HE indexes of tensile and Charpy impact properties were presented to quantitatively analyze the effect of HE under tensile and impact deformation processes. Subsequently, the FAD method coupled with the effect of HE was investigated to analyze the difference in the safety assessment method between hydrogen and non-hydrogen environments. Finally, the fracture morphology of tensile and Charpy impact specimens was observed to analyze the responses of microscopic fracture modes between hydrogen and non-hydrogen environments. The results show that the effect of HE on the tensile properties of the base material is more sensitive than that of the weld joint. The FAC with the effect of HE for safety assessment of defective pipes shrinks by reducing the safe zone. The decrease ratio of safety factors affected by HE presents an increasing tendency as the increase of crack depth while showing a decreasing tendency as the increase of internal pressure.

Parameter design of the compressed air energy storage salt cavern in highly impure rock salt formations

Compressed air energy storage (CAES) salt caverns are suitable for large-scale and long-time storage of compressed air in support of electrical energy production and are an important component for realizing renewable energy systems. In this paper, the use of sediment voids in highly impure rock salt formations for CAES is proposed. The interaction between the insoluble sediment and the cavern wall is analyzed. A geomechanical model is established to optimize the design parameters of CAES salt caverns. The simulation results show that as the cavern height increases, the displacement decreases in the bottom sediment region and increases in the waist. As the internal air pressure increases, the safety factor increases, while the volume shrinkage and displacement decrease. The plastic zone and the strength utilization rate decrease, and the safety factor increases with increasing pillar width. Based on the above results, the long cylindrical cavern is recommended to have a height in the range of 260–280 m and a diameter of 80 m. The minimum internal air pressure is 10–12 MPa, and the maximum internal air pressure is 16–18 MPa. The pillar widths between caverns are approximately 2.0–2.5 times the cavern diameter. In this study, for a single cavern with a diameter of 80 m and a height of 260–280 m, the upper free volume (excluding sediment) and the lower sediment filled volume of a single cavern are approximately 4.6–5.0 × 105 m3 and 7.2–7.8 × 105 m3, respectively. The sediment voids used for storing compressed air increase by at least approximately 3.6 × 105 m3, which is approximately 0.8 times the upper free cavern volume. The results show that the CAES salt cavern in highly impure rock salt is feasible and has great potential.

Vibration analysis of radial tire using the 3D rotating hyperelastic composite REF based on ANCF

In order to analyze the influence of tread structure and rotating angular speed on the vibration characteristics of radial tire, a 3D rotating hyperelastic composite REF (3D-RHCREF) model is proposed. Different form uniform cylindrical tread in other REF models, the tread is simplified as a hyperelastic composite revolving shell, whose discretization and parameterization are achieved by using three-order segmented Bézier curve and complete-gradient ANCF space curved trapezoid element. In the proposed 3D-RHCREF, the generalized inertial force with the centrifugal force and Coriolis force are obtained by introducing a rotation matrix into the framework of ANCF. Based on Kirchhoff-Love theory and hyperelastic constitutive relation, the generalized hyperelastic force of composite tread is derived and the compensation of initial generalized hyperelastic force is proposed. According to the D'Alembert principle, the nonlinear dynamic differential equations are established, then the modal equations are derived on the basis of the equilibrium position. By comparing with the FEM model of radial tire, the validity of the proposed model and calculation method is verified. The 3D-RHCREF is used to analyze the influences of internal pressure, tread pressure sharing ratio, belt structure and rotating angle speed on the vibration characteristics of radial tire. The vibration frequency will increase with the increase of internal pressure and the decrease of tread pressure sharing ratio; different belt structures of tread will cause changes in vibration frequency; the radial vibration frequency will be split into two traveling wave frequencies in two directions with the increase of rotating angular speed, and the circumferential/lateral vibration frequencies will almost only increase slightly with the increase of rotating angular speed.

Experimental Investigation on Near-Field Acoustic Propagation Characteristics of Leakage Detection in Submarine Pipelines

The leakage of subsea oil and gas pipelines can have adverse impacts on production progress and the ecological environment. Investigating the sound source and near-field sound propagation of pipeline leaks is essential for understanding the acoustic characteristics of and variations in these leaks. Such understanding is significant for the accurate detection and location of small leaks in pipelines. In this study, we designed an experimental system to study the characteristics of leakage sound signals. We introduced the formation mechanism of leakage sound sources and reviewed corresponding theoretical research. The leakage sound signal’s characteristic frequency range was determined to be between 1 kHz and 2 kHz. We examined the effects of pipeline pressure, leakage aperture, and detection distance on the acoustic signal characteristics. The results show that as internal pipe pressure increases, the leakage sound signal intensity first increases and then decreases. As the leakage aperture increases, the intensity of the leakage sound signal increases. Within a short distance, the intensity remains consistent regardless of detection distance. The results of this experimental study can guide the acoustic internal detection of pipelines. This study has practical significance in the timely detection of small leaks in pipelines and preventing leakage accidents from occurring.

Flow–solid coupling analysis of underground reinforced concrete forked pipe enclosing rock and structure

The stability of the surrounding rock for the construction excavation and the reinforcement of the lining structure during operation in the water-rich area is a difficult problem for the design of high-head underground turnout pipes. Firstly, according to the mechanism of excavation load release and surrounding rock damage evolution, the seepage effect of excavation in the construction of the forked caves is coupled to the surrounding rock stress damage, and an iterative method of numerical simulation of the coupled mutual feedback effect of excavation surrounding rock stress and seepage is proposed. Then, based on the cracking characteristics of the high internal water pressure reinforced concrete turnpike lining, a numerical analysis method of the coupling interaction between lining cracking and internal water seepage is proposed by coupling internal water seepage to stress damage in the lining by cracking the forked pipe structure. Applying the aforementioned method to a forked pipe project, the results show that: during the construction period, there is a significant increase in the damage zone, stress, and displacement of the rock around the cavern after considering the coupled iterations; during the operation period, with the increase in internal water pressure, the lining structure accelerates cracking due to the external infiltration of internal water; after the internal water is applied, the surrounding rock bears the main internal water pressure and the reinforcement bears only part of the circumferential force. The method provides theoretical support for the analysis and calculation of the reinforcement of similar underground high-pressure tunnels for rock support and lining structures and has certain theoretical and engineering significance.

Analytical method for deformation and stress calculation of bell-and-spigot joints in PVC-U pipes

The stable operation of water supply pipelines relies significantly on the structural safety of pipe joints. A novel analytical pipe joint structural calculation method based on the Novozhilov thin shell theory was proposed to calculate the deformation and stress of bell-and-spigot joints in unplasticized polyvinyl chloride (PVC-U) pipes under internal pressure. An equivalent stress index was established to investigate and evaluate the safety performance of pipe joints. The effects of various factors, including spigot insertion depth, the clearance between the bell and spigot, internal pressure, and different pipe nominal outside diameter (DN) and nominal pressure (PN) series, on the maximum equivalent stress of pipe joints, were thoroughly analyzed. The results indicate that the maximum equivalent stress under nominal pressure is located on the inner surface of the bell and consistently exceeds the design stress. The influence of spigot insertion depth on the maximum equivalent stress is minimal. However, as the clearance value between the bell and spigot decreases and the internal pressure increases, the maximum equivalent stress increases significantly. Pipes with smaller DN and PN series result in a higher maximum equivalent stress at the joint. The analytical method indicates that increasing pipe thickness and reinforcing the bell with continuous carbon fiber filament winding are two potentially effective methods to enhance the mechanical performance of the joint and reduce the maximum equivalent stress. This study's findings offer valuable theoretical support for designing and selecting joints in PVC-U pipelines.

Acoustic frequency analysis of the vibrational resonant frequencies of Special Nuclear Material containment

The increase of the resonant frequencies of a Magnox containment package that have been detected by an electromagnetic acoustic transducer and a microphone, are the result of an increase in internal pressure of the package. Therefore, it is possible to infer an internal pressure measurement of the Magnox package by measuring the shift of different resonant frequencies. A model of the Magnox package has been constructed to predict the acoustic vibrational resonant frequencies of the package wall and the corresponding mode shapes. Laser Doppler vibrometer measurements of the Magnox package wall have confirmed the presence of the predicted mode shapes and the resonant frequencies at which they occur have been reasonably estimated by the model.

Detection of the internal pressure in beer cans by measuring the force-displacement curves

Microbiological contamination of beer is manifested in many cases by the production of CO2 and an increase in its concentration. An increase in the concentration of CO2 in a closed package leads to an increase in internal pressure, which can cause the destruction of the package with dangerous consequences. This case study aimed to verify the applicability of force-displacement measurement for non-destructive monitoring of the internal pressure in beer cans.

Contact mechanical behavior and leakage prediction of metal lenticular gaskets in bolt flange joints of ultrahigh pressure pipelines

Metal lenticular gaskets have been widely applied in the bolt flange joints of high and ultrahigh pressure pipelines due to their semi-self-tightening sealing properties. However, research on the leakage prediction of the metal lenticular gaskets is still lacking, which limits their further optimal design and sealing performance improvement. In this paper, an elastoplastic contact mechanics analysis of a metal lenticular gasket used in the bolted flange joint of ultra-high pressure polyethylene pipelines was firstly carried out. The analytical formulas of contact stress and contact width were derived and compared with corresponding numerical results. Then, based on the surface topography measurement, a leakage model was established, in which the pipe surface was simplified to a smooth rigid flat surface, and the gasket surface was simplified to an equivalent rough surface composed of identical wedges. Finally, an analytical leakage prediction formula for the metal lenticular gasket was proposed. In addition, the effects of influence factors on leakage rate were discussed. It is shown that the analytical formulas can accurately calculate the contact stress and contact width in elastoplastic contact. The leakage rate increases with the decrease of the bolt load and the increase of internal pressure. For the ultrahigh pressure pipeline with internal pressure of 200 MPa, the minimum bolt load should be ensured to be higher than 120 kN in order to meet the T5 tightness level. In addition, the initial contact diameter is basically proportional to the leakage rate, while the change of gasket inclination angle has little effect on the leakage rate. Therefore, the contact diameter can be designed to be as small as possible within a reasonable range. This work can provide a theoretical basis for the sealing optimal design of metal lenticular gaskets.