High Internal Pressure Research Articles

Seismic and dynamic response characteristics of flax fiber-reinforced epoxy pipes

Dynamic and seismic response characteristics of free-spanning above-ground flax fibre-reinforced epoxy (FFRE) pipes with various diameters of 38, 60, 100, 160, and 205 mm and different fabric layers of 2, 3, and 4 (thickness of 3.4 mm–6.65 mm), and a free span of 3870 mm were investigated experimentally and numerically. The FFRE pipes were subjected to harmonic ground motions with peak ground acceleration of 0.1g, 0.2g, and 0.3g, vibration frequency of 2, 4, and 6 HZ, and a duration of 40 s, and a record from the 2011 Christchurch earthquake when the pipe was empty, half-filled or completely-filled with water to establish the effect of peak ground acceleration, vibration frequency, pipe water content, diameter and thickness on pipe displacement, acceleration, strain, and internal pressure. FFRE pipes underwent larger displacements and strains and higher transverse accelerations when the pipe was completely-filled, while the pipe underwent higher vertical acceleration and higher internal pressure when the pipe was half-filled. The pipe strain increased by up to 719% by increasing the peak ground acceleration from 0.1g to 0.3g, up to 452% by increasing the vibration frequency from 2 to 6 Hz, and up to 1358% by increasing the pipe water content from empty to completely-filled. FFRE pipes remained below their material ultimate limits, and no service or structural failure in the form of seepage or excessive deformation was detected in the pipe body, indicating great potential for using FFRE pipes as an alternative option to conventional pipes at seismic zones.

Effect of electrochemical charging on the hydrogen embrittlement susceptibility of a low-alloyed tempered martensitic steel submitted to high internal pressure

The influence of hydrogen on the mechanical behavior of a quenched and tempered 42CrMo4 steel has been evaluated by means of high internal pressure fracture tests carried out on hydrogen precharged notched cylindrical specimens. The notched cylindrical specimens were precharged for 3 h time with 1.2 mA/cm2 in two different aqueous media: 1 M H2SO4 added with 0.25 g/l As2O3 and 3.5% of NaCl solution. Hydraulic fracture tests were performed at different ramps of pressure: 7000, 220, 80, 60 and 30 MPa/h, respectively. Hydrogen damage was more marked when the acid aqueous medium (1 M H2SO4 + 0.25 g/l As2O3) was employed. In this case, a higher hydrogen concentration was introduced, leading to hydrogen decohesion micromechanisms (HEDE) near the notched region, especially when tests were performed at 60 MPa/h. Hydrogen embrittlement susceptibility is discussed in terms of the microstructural singularities and the operative fracture micromechanisms observed in each case.

Mechanical Behavior and Air Tightness of Roadway Surrounding Rock Under High Internal Pressure

Mechanical Behavior and Air Tightness of Roadway Surrounding Rock Under High Internal Pressure

Causes of High Internal Pore Pressure in a Downward-Draining MSW Landfill

Causes of High Internal Pore Pressure in a Downward-Draining MSW Landfill

Shock Wave Evaluation in Shell and Tube Heat Exchanger Tube Rupture Scenario

Abstract Shell and Tube Heat Exchangers (STHEs) are commonly used in oil and gas plants to cool or heat process fluids. A possible issue when designing such systems is represented by the tube rupture scenario, when the internal HP (high-pressure) fluid is suddenly discharged to the LP (low-pressure) fluid in the shell. Since, usually, the tube and shell sides have different design pressures, this scenario must be analyzed to assess if the safety measures are fit to protect the weakest part of the system. The time evolution of this event is characterized by different phases; in the first one, a shock wave is generated and propagated very rapidly in the system, with a time scale in the order of a few ms. The phenomenon is so rapid that pressure relief devices are not effective. This kind of wave is normally not evaluated in the majority of available publications; however, it is deemed that it is of particular relevance for large-size SHTEs, due to their significant investment cost, and hence, a methodology has been developed in this work for the purpose. The main impact of such waves is expected in the LP piping connected to the exchanger. The amplitude of the shock wave at the source location, i.e., at the ruptured tube, is calculated based on the theory of the Riemann problem, with reference to different types of HP and LP fluids. Then, the relevant propagation up to the piping entrance is studied to estimate the wave damping and the effective wave amplitude impacting it. Both validation calculations and calculations referred to new design applications and existing installations are presented, and possible mitigation measures are proposed, if any.

DEVELOPMENT OF LOADING MODELS AND ANALYSIS OF THE STRESS-STRAIN STATE OF THE MAIN GAS PIPELINE WITH COMPOSITE LININGS

The operation of sections of main gas pipelines that are on the verge of developing a design resource is associated with a number of problems in ensuring industrial safety. One of the most acute problems is the occurrence of local defects. The main material for the manufacture of main gas pipelines is steel. During the operation of the pipeline, local defects occur due to metal corrosion or mechanical damage to the gas pipe. Such concentrators with high internal pressure in the gas pipeline can lead to the destruction of the entire structure. In this case, the situation of destruction is especially critical, since it can cause a man-made disaster. To increase the shelf life of damaged sections of main pipelines in places where defects are located, banding with composite linings is used. The article contains part of a comprehensive study, which consisted in the development of methods for modeling the main gas pipeline for oil and petroleum products under seismic loads, dynamic stress-strain state under the influence of seismic loads and stress-strain state of a damaged gas pipeline reinforced with composite linings under the action of internal pressure. The technology of manufacturing linings from composite material is also described in detail. At the same time, a geometric model of the section of the main gas pipeline with composite linings was developed and an analysis of the loading of the section of the main gas pipeline in ANSYS was carried out, provided that the lining is mounted without tension on the pipeline and provided that the lining is mounted with tension, where a comparative analysis showed that the installation condition of composite linings does not significantly affect the static stress state.

An investigation of fracture modes around a spherical cavity for understanding outburst propagation mechanism

AbstractOutburst of coal and gas is a major hazard in underground coal mining where coal seam gas content/pressure is high. A cone‐shaped cavity is often observed in the coal seam after bursting, implying the likely mechanical structure being formed during outburst propagation. Although the mechanism for outburst initiation and propagation is very complex, mining‐induced fracturing and damage of the coal material is an essential component. This paper investigates the mechanical conditions that are essential to initiate fractures around a spherical cavity, a simplified form of the cone‐shaped outburst cavity. The cavity is assumed to be situated in an infinite isotropic homogeneous elastic body under internal gas pressure and far‐field hydrostatic compressive stresses as a further simplification for analytical investigation. The analytical conditions under which circumferential and radial fractures can initiate around the cavity are formulated, based on extensional strain criterion for fracture initiation. Low internal pressure on the cavity surface and high far‐field compression lead to circumferential fractures. In contrast, high internal pressure and low far‐field compression lead to radial fractures. Subsequent numerical simulations with FRACOD3D and FRACOD, the 3D and 2D in‐house fracture simulation codes, were carried out to investigate fracture patterns around a cavity and inclusion. The simulation results confirmed the analytical results, including fracture shapes and the size of fractured zone. These results provide a new angle to understand the complex mechanism of outbursts.

Numerical prediction of cavitation nuisance on hydrofoils: Combined analysis of cavity dynamics and the aggressiveness of collapsing cavitating structures

The unsteady cavitating flow past a three-dimensional twisted hydrofoil is numerically investigated by a large eddy simulation to obtain in-depth insight into the bubble dynamics near the cavitation erosion region. Macroscopic cavity evolution is captured by a multiphase flow computing frame, while the bubble oscillations in the cavitating flow are computed by solving the Gilmore bubble dynamic model, in which the driving force for the bubble movement is exported through the application of a discrete phase model. The cavitation erosion potential is then computed by a robust indicator developed based on the energy balance hypothesis. The relevance between the dynamics and the destructive essence of a cavitation bubble and the erosion intensity is thoroughly analyzed. The results show that the unsteadiness involved in the turbulent cloud cavitation is well reproduced, and the main cavitation erosion risk in the middle region of the hydrofoil is also accurately predicted comparing with the painting test results. A localized high-pressure region is identified near the rear part of the attached cavity where the mainstream encounters the primary reentrant jet flows. The peak bubble internal pressure can reach 487 MPa near the middle plane of the hydrofoil, during the stage when the surrounding liquid pressure is continuously increased. The bubbles with the smallest radius, ranging from 23.1 to 26.3 μm after compressing from their initial sizes (R0 = 100–700 μm) in the near wall region, are associated with the extremely high internal pressure, and they are responsible for the cavitation erosion damage on the hydrofoil surface.

Atomic Structure and Dynamics of Unusual and Wide‐Gap Phase‐Change Chalcogenides: A GeTe2 Case

Brain‐inspired computing, reconfigurable optical metamaterials, photonic tensor cores, and many other advanced applications require next‐generation phase change materials (PCMs) with better energy efficiency and a wider thermal and spectral range for reliable operations. Germanium ditelluride (GeTe2), with higher thermal stability and a larger bandgap compared to current benchmark PCMs, appears promising for THz metasurfaces and the controlled crystallization of atomically thin 2D materials. Using high‐energy X‐ray diffraction supported by first‐principles simulation, we investigate the atomic structure in semiconducting pulsed laser deposition films and metallic high‐temperature liquids. The results suggest that the structural and chemical metastability of GeTe2, leading to disproportionation into GeTe and Te, is related to high internal pressure during a semiconductor‐metal transition, presumably occurring in the supercooled melt. Similar phenomena are expected for canonical GeS2 and GeSe2 under high temperatures and pressures.This article is protected by copyright. All rights reserved.

Using J-integral analysis to predict the failure of HDPE pipes under crack face load and internal pressure

Cracks in pipes used for water transfer have been identified as a significant contributor to water loss and potential failures. To assess fracture behavior, the J-integral was computed for 3D finite element HDPE pipes (DN 355) with axial internal and external cracks (with a/ c and a/ t ratios of 0.5) subjected to a range of internal pressure (16–30 bar) and crack face load condition. Four ratios of a/ c ranging from 0.3 to 0.9 (with an increment of 0.2) were examined with the internal crack. Results indicate that under face crack loading, the external axial crack exhibits a higher J-integral intensity than the internal axial crack. J-integral values greater than 8.4 kJ/m2 were found to lead to pipe failure, with higher internal pressures (25–30 bar for external crack, and 30 bar for internal pressure). Moreover, the a/ c ratio plays a significant role in influencing the distribution of J-integral along internal crack arc length. For pipes of DN 355 size with axial cracks, internal pressure exceeding 20 bar is not recommended. These findings underscore the importance of considering J-integral values in pipe design to prevent failure.

High performance and reliable ultra-thin vapor chamber via an optimised second vacuuming and sealing process

Ultra-thin vapor chambers (UTVCs) have been widely used for cooling high-power electronics owing to their superior heat transfer properties. However, UTVCs, especially those with thicknesses below 0.4 mm, still face poor performance and unreliability problems. As a key processing technology, the second vacuuming and sealing process can significantly improve the heat transfer performance and reliability of UTVC; however, it has seldom been studied. In this study, a UTVC with a thickness of only 0.32 mm was developed, and an optimised second vacuuming and sealing process was proposed to obtain a high-performance and reliable UTVC. The UTVC, prepared via resistance welding sealing, demonstrates reliable performance, operating effectively at high temperatures (240 ℃) and internal pressures exceeding 3.3 MPa, without leakage. Optimising second vacuuming parameters effectively removes most non-condensable gas, thereby enhancing the heat transfer performance of UTVCs. UTVC proposed with the vacuuming time of 35 s, vacuuming temperature of 90 ℃, and gas collecting section length of 20 mm exhibits a thermal resistance of 1.701 W/℃ at a heat load of 3 W. This study benefits the design of a second vacuuming and sealing process for UTVC with thickness less than 0.4 mm, further promoting its industrial applications.

Determination of the pressure and composition of wet gas fluid inclusions: An in situ Raman spectroscopic approach

Carbonaceous fluid within mineral-hosted inclusions provides important information for carbon cycle in deep Earth. In addition to CH4 and CO2, heavy hydrocarbons (e.g., C2H6 and C3H8) are frequently observed in carbonaceous fluid inclusions (i.e, wet gas inclusions with C1/∑Ci < 0.95). However, determination of the composition of such complex volatiles is difficult based on traditional microthermometric measurements. Here we carried out experimental calibrations on Raman spectroscopic measurements of the pressure (P) and composition of the CH4 ± C2H6 ± C3H8 ± H2S system at room temperature and 0.1–130 MPa. We confirmed that the C–H symmetric stretching vibration band of CH4 [ν1(CH4), ∼2917 cm−1] shifted to lower wavenumber with rising pressure, thus the P-ν1(CH4) relationship could be applied to calculate the pressure of wet gas. It should be noted that the presence of C2+ and/or H2S will shift the [ν1(CH4)] to lower wavenumber at constant pressure (with the order of C3H8 ≥ H2S > C2H6). Obviously, the P-ν1(CH4) relationship derived from pure CH4 system could not be simply applied to wet gas inclusion, otherwise the pressure would be overestimated. To avoid the overlap of the C–H vibrations of CH4, C2H6 and C3H8, the peak areas and peak heights of the overtone vibration of CH4 [2ν4(CH4), ∼2580 cm−1], C–C symmetric stretching vibrations of C2H6 [ν3(C2H6), ∼995 cm−1] and C3H8 [ν8(C3H8), ∼868 cm−1], and S–H symmetric stretching vibration of H2S [ν1(H2S), ∼2612 cm−1] were fitted using Gaussian + Lorentz functions. The obtained peak areas and peak heights were then used to calculate the Raman quantification factors (F factor and G factor, respectively) of C2H6, C3H8 and H2S relative to CH4, respectively. Both the F factor and G factor increased with rising pressure, whereas the FC2H6, FC3H8 and GH2S kept nearly constant at ∼5.69, 6.39 and 153.8, respectively in high pressure gas mixtures (e.g., >30 MPa). Therefore, for inclusions with higher internal pressure, the molar ratio of CH4, C2H6, C3H8 and H2S could be determined by the aforementioned F and G factors. This method was applied to the calcite-hosted single-phase gas inclusions in the Upper Permian Changxing Formation carbonate reservoir from the eastern Sichuan Basin (South China). Our results indicated that the trapping pressure would be obviously overestimated if the presence of heavy hydrocarbons was not taken into account.

Selection of Suitable Pipe Material for New Water Distribution Network Using Analytic Hierarchy Process – A Case Study of Athivilai Village of India

This study was made to design a new water distribution network for the Athivilai village of Tamilnadu, India. The associated problems of the village are improper water supply for growing water requirements during the summer season. The cost, service life, and material type play an important role when designing a new network. In this study, the suitable pipe material is chosen by using Analytical Hierarchy Process. The criteria selected for Analytic Hierarchy Process include Cost, Service life, Ease of maintenance, Corrosion, Leakage, and Internal pressure. The results show that the Ductile Iron pipe ranks top position followed by High Density Polyethylene, Polyvinyl Chloride, and Galvanized iron. After selecting the pipe material, the design of water distribution network is done in EPANET 2.0 software. The results show that the diameter of pipes ranges from 40 mm to 250 mm. Since the corrosion of smaller diameter Ductile Iron pipes are faster, the High Density Polyethylene pipe which acquires the second rank can be used for diameters smaller than 80 mm. For pipes with a diameter greater than 80 mm, Ductile Iron pipes are used. Furthermore, since a continuous system of supply is designed, the pressure rises above 60 m during non peak hours which indicates that the pipes are constantly subjected to internal pressure. Both the selected pipes can withstand high internal pressure which confirms the results obtained by the Analytic hierarchy process are suitable.

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.

Analysis on aeroelastic stability of rectangular-planed air-supported membrane structures

This research investigates aeroelastic stability of rectangular-planed air-supported membrane structures subjected to wind actions. By employing potential theory to tackle air flows, the relations between extra aerodynamic forces and structural motions are resolved through the utilization of the boundary element method and the finite element method, capturing the complexities associated with structural geometries and wind pressure distributions. By combining these extra aerodynamic forces with structural dynamic equilibrium equations, critical instability wind velocities for various structural vibration modes are derived. The simulation results are validated through aeroelastic wind tunnel tests, demonstrating a close alignment between the numerical findings and experimental observations in terms of the critical wind velocity and the corresponding instability mode. Additionally, the study analyzes influences of structural geometric configurations, internal pressures, and membrane tensile stiffness on the critical instability wind velocities and corresponding instability modes. It is observed that lower aspect ratios, smaller structural spans, higher internal pressures, and greater membrane tensile stiffness can increase the critical instability wind velocity, corresponding to variations in critical instability mode shapes. Results obtained from this research are expected to provide guidance for the development of wind-resistant designs for air-supported membrane structures.

Study on forming process of equal wall thickness metal spiral pipe by single screw pump

To solve the problems of poor high temperature resistance of conventional screw pump stator and difficult machining of screw pump stator with equal wall thickness, this paper created a finite element model of equal wall thickness metal spiral pipe for single screw sump with 42CrMo based on tube hydroforming (THF). In this paper, the forming effects of different processes were evaluated by analysing the average pitch, wall thickness thinning rate and inner contour accuracy. Due to the particularity of design section and irregular plastic flow of material, the wall thickness of internal high pressure forming decreases seriously; on the other hand, because the diameter of the designed section is relatively large, the minimum ratio of D2 to Dmin is 1.12, which shows that wrinkles appear in external high pressure forming. As a result, based on the problems of internal and external high pressure forming, a coupling forming process was proposed. The results show that different parameters of coupling forming have little effect on the average pitch of metal spiral tube, and its maximum deviation is 1.08%; while thickness reduction ratio is proportional to initial diameter and thickness. Besides, when the liquid pressure is 350 MPa, the diameter is 60 mm and the wall thickness is 7.5 mm, the contour matching degree is higher; but the material accumulation and wrinkling will happen when the pipe diameter greater than 60 mm.

Mathematical modeling and optimization of pasteurization for the internal pressure and physical quality of canned beer

Globally, beer is the most popular alcoholic beverage. To accomplish microbial stabilization and extend the shelf life of beer, it is typically subjected to in-package pasteurization using a tunnel pasteurizer. However, high internal pressure can cause can bulging during pasteurization, leading to significant product loss. In this study, an empirical mathematical model was constructed to describe the effects of can thickness (0.245–0.270 mm), fill volume (320–338 mL), carbon dioxide content (5.70–6.10 g/L), and pasteurization temperature (59–66 °C) on the internal pressure inside canned beer. A laboratory-scale pasteurization setup was used to pasteurize samples based on the worst-case scenario of commercial pasteurization. The mathematical model (R2 = 0.90) showed that all parameters significantly influenced the internal pressure of pasteurized canned beer (p < 0.05). Additionally, the physical, chemical, and biological properties of pasteurized canned beer were assessed. All values fell within an acceptable range of industrial standards. A simplified 2nd-order polynomial equation (R2 = 0.90) was created and verified for industrial use. The data are well represented by the simplified model, which suggests that it could be used for optimization of product- and process parameters to reduce the occurrence of can bulging in commercial pasteurization of canned beer.

Quantifying turgor pressure in budding and fission yeasts based upon osmotic properties

Walled cells, such as plants, fungi, and bacteria cells, possess a high internal hydrostatic pressure, termed turgor pressure, that drives volume growth and contributes to cell shape determination. Rigorous measurement of turgor pressure, however, remains challenging, and reliable quantitative measurements, even in budding yeast are still lacking. Here, we present a simple and robust experimental approach to access turgor pressure in yeasts based upon the determination of isotonic concentration using protoplasts as osmometers. We propose three methods to identify the isotonic condition – three-dimensional cell volume, cytoplasmic fluorophore intensity, and mobility of a cytGEMs nano-rheology probe – that all yield consistent values. Our results provide turgor pressure estimates of 1.0 ± 0.1 MPa for Schizosaccharomyces pombe, 0.49 ± 0.01 MPa for Schizosaccharomyces japonicus, 0.5 ± 0.1 MPa for Saccharomyces cerevisiae W303a and 0.31 ± 0.03 MPa for Saccharomyces cerevisiae BY4741. Large differences in turgor pressure and nano-rheology measurements between the Saccharomyces cerevisiae strains demonstrate how fundamental biophysical parameters can vary even among wild-type strains of the same species. These side-by-side measurements of turgor pressure in multiple yeast species provide critical values for quantitative studies on cellular mechanics and comparative evolution.

Accelerated Degradation Test on Electric Scroll Compressor Using Controlled Continuous Liquid Slugging

Refrigerant-based electric scroll compressors are known for their reliability, efficiency, and quiet operation. They are often used in heat pump systems due to their ability to efficiently handle varying levels of load conditions, both for heating and cooling modes of operation. As electric compressors are considered the heart of the heat pump system, being able to determine degradation of compressors prior to failure is of paramount importance for the health of this system. Typical failures for electric scroll compressors range from electrical faults, refrigerant leaks, to mechanical failures and overheating. Specifically, one of the primary failure modes for an electric scroll compressor is mechanical damage due to the high stress effects of refrigerant liquid slugging. These stresses are due to excessively high internal pressures exhibited on the compressor scrolls, which are generated by compressing liquid refrigerant at the suction side of the compressor. This paper provides a new testing methodology that introduces liquid slugging at various degrees of refrigerant quality to degrade a compressor to near the end of useful life. Furthermore, this test aims to determine specific operating conditions and signals that can indicate early compressor degradation. This fault injection configuration consists of a modified heat pump system with the addition of two low pressure heat exchangers added in parallel (with respective electronically controlled expansion valve for each heat exchanger) used to control the refrigerant quality during compressor operations. For a given refrigerant quality, the heat pump system was operated at a fixed compressor performance conditions to sustain liquid slugging for a fixed duration. Afterwards, refrigerant was controlled to be pure vapor at the compressor suction side and the compressor was controlled at several different performance conditions (i.e., fixed compressor suction superheat temperature and compressor pressure ratios, at various compressor speeds), so as to duplicate conditions known to us from the compressor component data sheet for an ideal electric scroll compressor. Through these tests, the results show that the severity of scroll failures depend heavily on the refrigerant quality and the amount of liquid slugging exposure time. Furthermore, symptoms of compressor degradation are detected using the following signals: i) temperature and pressure at the compressor suction side, ii) temperature and pressure at the compressor discharge side, and iii) electric compressor speed and power consumption. To further aid in determining the compressor degradation ground truth, complete compressor teardown was performed to identify sections within the compressor that exhibited significant amounts of wear as compared to a stock compressor.

Underground storage tank blowout analysis: Stability prediction using an artificial neural network

Most geotechnical stability research is linked to “active” failures, in which soil instability occurs due to soil self-weight and external surcharge applications. In contrast, research on passive failure is not common, as it is predominately caused by external loads that act against the soil self-weight. An earlier active trapdoor stability investigation using the Terzaghi's three stability factor approach was shown to be a feasible method for evaluating cohesive-frictional soil stability. Therefore, this technical note aims to expand “active” trapdoor research to assess drained circular trapdoor passive stability (blowout condition) in cohesive-frictional soil under axisymmetric conditions. Using numerical finite element limit analysis (FELA) simulations, soil cohesion, surcharge, and soil unit weight effects are considered using three stability factors (Fc, Fs, and Fγ), which are all associated with the cover-depth ratio and soil internal friction angle. Both upper-bound (UB) and lower-bound (LB) results are presented in design charts and tables, and the large dataset is further studied using an artificial neural network (ANN) as a predictive model to produce accurate design equations. The proposed passive trapdoor problem under axisymmetric conditions is significant when considering soil blowout stability owing to faulty underground storage tanks or pipelines with high internal pressures.