High-pressure Gas Environment Research Articles

Fatigue investigations of elastomers developed for high-pressure hydrogen gas environments

Hydrogen possesses many characteristics to be an ideal candidate as a more sustainable energy carrier, especially for the transport sector. For a proper optimization of this abundant resource, hydrogen needs to be compressed, and stored in high-pressure conditions, which demands improvement in technology and the development of appropriate materials. In this context, elastomeric sealing components play a critical role and they need to withstand harsh working conditions, for example, high-pressure, wide temperature range, cyclic exposure conditions, etc. In this work, eight different grades designed for this application were analyzed in terms of fatigue behavior and long-term performance. This was verified through fatigue crack growth experiments, the energy dissipation, and temperature increase during crack propagation were analyzed and correlated with micro-structural differences of materials. Furthermore, the materials were investigated at large and small deformations through uniaxial tensile tests and Dynamic Mechanical Analysis (DMA), respectively. It was found that only with the addition of a coupling agent can silica-filled NBR have properties similar to carbon black (CB) filled NBR, despite a reduction in both fatigue strength and energy dissipation. Coupling agents also involved an increase in bound rubber. Regarding CB-filled compounds, with peroxide crosslinking a reduction in fatigue strength was found, while no effect on the quantity of bound rubber was observed. Increased CB content in NBR grades led to decreased fatigue resistance and higher energy dissipation; higher bound rubber content was found as well. Also for EPDM grades, increased CB content resulted in reduced fatigue resistance. Despite an increase in energy dissipation, the content of bounded rubber was the same even with higher CB content.

In silico monitoring of non-reactive gas blistering on crystalline substrates

Blistering from gas aggregation occurs very rarely on solid substrates; however, it is commonly observed under high-pressure gas or plasma environments. This is due to the repeated aggregation process of gas molecules penetrating beneath the surface, but it has been difficult to find cases that demonstrate the dynamic mechanism on the atomic level. In this study, the dynamics of physical bombardment of argon atoms on the flat monocrystalline silicon substrate are simulated to propose an initiation principle for gas-aggregate formation. Simulations of extremely large numbers of argon atoms bombarding a limited area of single crystal silicon revealed inhomogeneous aggregation properties consistent with the experimental observations. Particularly, the results suggest that momentum transfer formed by collisions between argon trapped in the surface grooves and the argon used for bombardment is the governing factor for the aggregation behavior. The aggregated argon clusters grow in the in-plane direction while generating stress propagation in the thickness direction, ultimately causing an expansion pressure that lifts the adjacent silicon surface upwards. Our work provides a deterministic understanding of the initiation process of blister formation, which rarely occurs in physical sputtering on defect-free substrates.

Online testing of extinction method of high-pressure natural gas oil mist based on light extinction

Abstract This paper proposes a theoretical model and scheme for accurately measuring droplet concentration in high-pressure natural gas environments, aiming for precise, online measurement of lubricating oil mist. The model integrates droplet behavior, light extinction properties of the medium, and pressure, using the light extinction method. It applies the Debye Series Expansion of Mie scattering to improve the light extinction coefficient for mediums such as lubricating oil particles. Differential Optical Absorption Spectroscopy is used to calculate the extinction index of natural gas at different pressures. The study innovates by replacing the traditional parallel light path with a non-parallel path that focuses the light beam, countering beam diameter expansion due to gas pressure. Empirical testing shows the method’s accuracy in online oil mist testing under 10 MPa pressure, with less than 5% error compared to offline methods. This work paves the way for future high-pressure gas particle monitoring, particularly in the oil and natural gas sector.

Dissociative Adsorption of Hydrogen Molecules at Al2O3 Inclusions in Steels and Its Implications for Gaseous Hydrogen Embrittlement of Pipelines

Hydrogen embrittlement (HE) of steel pipelines in high-pressure gaseous environments is a potential threat to the pipeline integrity. The occurrence of gaseous HE is subjected to associative adsorption of hydrogen molecules (H2) at specific “active sites”, such as grain boundaries and dislocations on the steel surface, to generate hydrogen atoms (H). Non-metallic inclusions are another type of metallurgical defect potentially serving as “active sites” to cause the dissociative adsorption of H2. Al2O3 is a common inclusion contained in pipeline steels. In this work, the dissociative adsorption of hydrogen at the α-Al2O3(0001)/α-Fe(111) interface on the Fe011¯ plane was studied by density functional theory calculations. The impact of gas components of O2 and CH4 on the dissociative adsorption of hydrogen was determined. The occurrence of dissociative adsorption of hydrogen at the Al2O3 inclusion/Fe interface is favored under conditions relevant to pipeline operation. Thermodynamic feasibility was observed for Fe and O atoms, but not for Al atoms. H atoms can form more stable adsorption configurations on the Fe side of the interface, while it is less likely for H atoms to adsorb on the Al2O3 side. There is a greater tendency for the occurrence of dissociative adsorption of O2 and CH4 than of H2, due to the more favorable energetics of the former. In particular, the dissociative adsorption of O2 is preferential over that of CH4. The Al-terminated interface exhibits a higher H binding energy compared to the O-terminated interface, indicating a preference for hydrogen accumulation at the Al-terminated interface.

Study on laser-induced breakdown spectroscopy in high-pressure helium gas environment for deep ocean applications

Laser-induced breakdown spectroscopy (LIBS) has gained wide acceptance as an in situ detection technique for elements. However, in deep-sea applications, the sensitivity of LIBS detection will be reduced due to the high-pressure environment and the nature of water. To address the negative effects of high-pressure water, this study used the method of draining the water from the sample surface by passing high-pressure helium gas, which allowed the plasma excitation environment to be converted from high-pressure water to high-pressure gas. The available spectral signals of solid samples at 60 MPa gas pressure were obtained for the first time, and the peak intensity and spectral broadening of the spectral lines at different pressures were analyzed for comparison. We found a nonlinear decrease in the spectral intensity and a gradual increase in the spectral broadening during the pressure increase. We also investigated the effect of laser energy on the intensity and width of the spectral lines in a high-pressure helium environment and found that increasing the laser energy in a high-pressure environment enhanced the spectral intensity and that the change in laser energy almost did not affect the line width. Finally, by observing the plasma images at different pressures with different energies, this study found that the laser penetrated the high-pressure helium gas in advance and leaved a column of light in the gas, and the plasma was slowly made smaller as the ambient pressure increases. This finding explained the cause of laser energy loss and demonstrated that the LIBS signal intensity can be improved by increasing the laser energy and shortening the laser transmission distance in a high-pressure gas environment.

Dissociative adsorption of hydrogen at edge dislocation emergence on α-Fe studied by density functional theory

Pipelines provide an efficient and economical method for hydrogen transportation with a high capacity over wide ranges and long distances, contributing to accelerated realization of a full-scale hydrogen economy. However, steel pipelines are prone to hydrogen embrittlement in high-pressure gaseous environments once the generated hydrogen (H) atoms enter the steels. Dislocations are one of the most common defects contained in steels. The H atom generation and adsorption at dislocation emergences on pipeline steels have not been fully understood. This work investigated and determined the stable hydrogen adsorption configurations at the emergence of an edge dislocation on iron (Fe) (100) crystalline plane by density functional theory. The partition function was used to study the thermodynamics of dissociative adsorption of hydrogen, as well as the effects of dissociated impurity gases (i.e., oxygen, methane and water vapor) existing in the carried fluid, under pipeline operating conditions. Results demonstrate that the dislocation core is the stable site for hydrogen adsorption, followed by the sites with a tensile strain at the dislocation, although the dissociative adsorption of hydrogen can also occur at the compressive strain sites. An elevated hydrogen gas pressure and low temperature favor the hydrogen adsorption. The three impurity gases can have dissociative adsorption occur at the edge dislocation. Moreover, their adsorptions are more thermodynamically favorable than hydrogen. Oxygen has the most stable adsorption configuration, followed by water vapor and then methane. Pre-adsorbed O-containing gases (i.e., oxygen and water vapor) compete with the hydrogen adsorption and decrease the stability of the hydrogen adsorption configuration. The competing effect of the impurity gases with hydrogen adsorption occurs only when they adsorb at the compressive sites of the dislocation. When the impurity gases pre-adsorb at the tensile strain sites of the dislocation, they have little influence on hydrogen adsorption.

Structural Analysis and Optimization of Urban Gas Pressure Regulator Based on Thermo-Hydro-Mechanical Coupling

As a core component in the gas transmission process, the internal wall surface of a gas pressure regulator is prone to failure due to long-term exposure to a high-pressure gas environment, resulting in poor reliability of the regulator. Thus, a thermo-hydro-mechanical coupling model for the FL gas pressure regulator is established in this paper, and the thermo-hydro-mechanical coupling results are verified by engineering data. The effect of valve opening on the parameters (temperature, deformation, and stress) of the gas pressure regulator is studied in detail through simulation. The results show that the stress is greater at the sleeve, valve bore, and outlet valve seat wall under the opening of 20% of the regulator. Finally, the response surface method is used to optimize the regulator to obtain a good fit and high predictive ability of the response surface equation. The optimal parameters for the gas pressure regulator are as follows: the wall thickness of the sleeve is 7.25 mm, the diameter of the valve bore is 25 mm, and the wall thickness of the outlet seat is 31.05 mm. The maximum equivalent stress with this combination of parameters is 135.62 MPa.

Evaluating a natural gas pipeline steel for blended hydrogen service

An X70 natural gas pipeline steel that is being considered for blended natural gas/hydrogen gas service was evaluated in a high-pressure hydrogen gas environment. Fracture toughness testing and fatigue crack growth rate testing were conducted according to ASTM standards and the results are presented in the context of ASME B31.12 qualification. While a reduction in fracture toughness was observed, the fracture toughness and fatigue behavior were within acceptable bounds for hydrogen service.

Crystal growth of Sr2IrxRu1−xO4 for [formula omitted

We describe the synthesis of crystalline Sr2IrxRu1−xO4 via a floating zone growth technique. We find that the use of a high pressure gas environment (70 bar mixed O2 and Ar) greatly decreases the volatility and loss of the IrO2 and RuO2 reactants. The resultant gram-sized samples are more uniform in composition than comparable flux-grown crystals.

Synthesis of titanium dioxide nanoparticle by means of discharge plasma over an aqueous solution under high-pressure gas environment

In this study, the utilization of an electric field generated by the high voltage discharge plasma over a liquid water surface containing glycine compound to synthesize titanium dioxide (TiO2) nanoparticles was demonstrated. The experiments were conducted in a batch-type system with applied voltages ranging from 18.6 − 23.4 kV under various pressurized gases at room temperature. The results indicated that the applied voltages, applied pulse numbers, and pulsed repetition rates had a significant influence on the decomposition reaction of glycine compounds and titanium rod electrode erosion. The ultraviolet − visible (UV − vis) spectra showed that titanium dioxide nanoparticles could be observed in each solution product, and most of them were brookite-type structures. According to the HRTEM images, TiC was also produced as a nanoparticle product. Based on the experimental results, this process is applicable and could result in advanced metal-based nanoparticle synthesis technology.

Pulsed Discharge Plasma in High-Pressure Environment for Water Pollutant Degradation and Nanoparticle Synthesis

The application of high-voltage discharge plasma for water pollutant decomposition and the synthesis of nanoparticles under a high-pressure argon gas environment (~4 MPa) was demonstrated. The experiments were carried out in a batch-type system at room temperature with a pulsed DC power supply (15.4 to 18.6 kV) as a discharge plasma source. The results showed that the electrode materials, the pulsed repetition rates, the applied number of pulses, and the applied voltages had a significant effect on the degradation reactions of organic compounds. Furthermore, carbon solid materials from glycine decomposition were generated during the high-voltage discharge plasma treatment under high-pressure conditions, while Raman spectra and the HRTEM images indicated that titanium dioxide with a brookite structure and titanium carbide nanoparticles were also formed under these conditions. It was concluded that this process is applicable in practice and may lead to advanced organic compound decomposition and metal-based nanoparticle synthesis technologies.

Effect of δ-ferrite on susceptibility to hydrogen embrittlement of 304 austenitic stainless steel in high-pressure hydrogen atmosphere

Purpose The purpose of this paper is to demonstrate the effect of δ-ferrite on the susceptibility to hydrogen embrittlement of type 304 stainless steel in hydrogen gas environment. Design/methodology/approach The mechanical properties of as-received and solution-treated specimens were investigated by the test of tensile and fatigue crack growth (FCG) in 5 MPa argon and hydrogen. Findings The presence of δ-ferrite reduced the relative elongation and the relative reduction area (H2/Ar) of 304 stainless steel, indicating that δ-ferrite increased the susceptibility of hydrogen embrittlement in 304 stainless steel. Moreover, δ-ferrite promoted the fatigue crack initiation and propagation at the interface between δ-ferrite and austenite. The FCG tests were used to investigate the effect of δ-ferrite on the FCG rate in hydrogen gas environment, and it was found that δ-ferrite accelerated the FCG rate, which was attributed to rapid diffusion and accumulation of hydrogen around the fatigue crack tip through δ-ferrite in high-pressure hydrogen gas environment. Originality/value The dependence of the susceptibility to hydrogen embrittlement on δ-ferrite was first investigated in type 304 steel in hydrogen environment with high pressures, which provided the basis for the design and development of a high strength, hydrogen embrittle-resistant austenitic stainless steel.

Nanostructure of calcium phosphate films synthesized by pulsed laser deposition under 1 Torr: Effect of wavelength and laser energy

In this study, we investigated aspects about the nanostructure of calcium phosphate films formed by pulsed laser deposition under a high-pressure gas (argon) environment (1 Torr) that are not addressed in the literature by using infrared and green laser sources. The plume generated from an ablated hydroxyapatite target was deposited directly over transmission electron microscopy (TEM) grids during 120 s to allow for the use of TEM techniques to investigate the morphology, composition and structure of deposited films from the micron to the nanoscale. The films were found to comprise five different calcium phosphate structures: (1) unstructured amorphous thin film formed by the deposition of ions and molecules over the substrate, (2) dense nanoparticles (<20 nm) formed over the substrate, (3) low Ca/P ratio spherical particles (<400 nm) formed on the way to the substrate, (4) rich Ca/P ratio ring-shaped particles (>400 nm) ejected from the target and (5) crystalline particles (~500 nm) removed from the target. Although all samples presented these five structures, the morphology, abundance and size population were all different. This work opens a window to elucidate the complex mechanism underlying calcium phosphate film deposition and growth by pulsed laser deposition.

Achieving Ultrahigh Output Energy Density of Triboelectric Nanogenerators in High-Pressure Gas Environment.

Through years of development, the triboelectric nanogenerator (TENG) has been demonstrated as a burgeoning efficient energy harvester. Plenty of efforts have been devoted to further improving the electric output performance through material/surface optimization, ion implantation or the external electric circuit. However, all these methods cannot break through the fundamental limitation brought by the inevitable electrical breakdown effect, and thus the output energy density is restricted. Here, a method for enhancing the threshold output energy density of TENGs is proposed by suppressing the breakdown effects in the high‐pressure gas environment. With that, the output energy density of the contact‐separation mode TENG can be increased by over 25 times in 10 atm than that in the atmosphere, and that of the freestanding sliding TENG can also achieve over 5 times increase in 6 atm. This research demonstrates the excellent suppression effect of the electric breakdown brought by the high‐pressure gas environment, which may provide a practical and effective technological route to promote the output performance of TENGs.

A coupled cohesive modeling approach for predicting fractures in low alloy steel under high-pressure hydrogen gas

Hydrogen-induced fractures usually occur in low alloy steel under the influences of stress concentration and high-pressure hydrogen gas. The purpose of this study was to predict the hydrogen-induced fracture behavior of low alloy steel under a high-pressure hydrogen gas environment. The hydrogen-sensitive cohesive model was used for the prediction of crack propagation, which took into account the influence of high-pressure hydrogen gas. The coupling model between hydrogen diffusion and plastic deformation was also applied by using UMAT and UMATHT subroutines. Disk pressure tests were performed on 4130X steel with different hydrogen pressure rise rates to demonstrate the coupled cohesive modeling approach. The hydrogen-induced fracture behaviors of the 4130X steel disk predicted by the proposed approach showed good agreement with experimental results. Numerical results indicated that hydrogen accumulated at the anchorage of the disk and reduced the maximum cohesive stress with the enhancement of localized plastic deformation. Therefore, the crack growth rate of the disk increased under a high-pressure hydrogen gas environment with relatively low maximum cohesive stress and low fracture energy.

Quasi-Newtonian Environmental Scanning Electron Microscopy (QN-ESEM) for Monitoring Material Dynamics in High-Pressure Gaseous Environments.

Environmental scanning electron microscopy (ESEM) is a powerful technique that enables imaging of diverse specimens (e.g., biomaterials, chemical materials, nanomaterials) in a hydrated or native state while simultaneously maintaining micro‐to‐nanoscale resolution. However, it is difficult to achieve high signal‐to‐noise and artifact‐free secondary electron images in a high‐pressure gaseous environment due to the intensive electron‐gas collisions. In addition, nanotextured substrates can mask the signal from a weakly scattering sample. These drawbacks limit the study of material dynamics under extreme conditions and correspondingly our understanding in many fields. In this work, an imaging framework called Quasi‐Newtonian ESEM is proposed, which introduces the concepts of quasi‐force and quasi‐work by referencing the scattering force in light–matter interactions, to break these barriers without any hardware changes. It is shown that quasi‐force is a more fundamental quantity that has a more significant connection with the sample morphology than intensity in the strongly scattering regime. Experimental and theoretical studies on the dynamics of droplet condensation in a high‐pressure environment (up to 2500 Pa) successfully demonstrate the effectiveness and robustness of the framework and that the overwhelmed signal of interest in ESEM images can be reconstructed through information stored in the time domain, i.e., frames captured at different moments.

Prospects of Hardening of Steels and Alloys in a High-Pressure Gas Environment

The paper discusses the application potential of quenching in high-pressure nitrogen with respect to mediumand high-alloy steels, as well as precipitation-hardening alloys. A procedure for predicting the structure and properties of steels and alloys after quenching is proposed. It is shown that gas quenching provides a high level of mechanical properties while maintaining the geometry of the precision products due to elimination of surface oxidation.

High voltage insulation and gas absorption of polymers in high pressure argon and xenon gases

High pressure gas time projection chambers (HPGTPCs) are made with a variety of materials, many of which still await proper characterization in high pressure noble gas environments. As HPGTPCs increase in size toward ton-scale detectors, assemblies become larger and more complex, creating a need for detailed understanding of how structural supports and high voltage insulators behave. This includes identification of materials with predictable mechanical properties and without surface charge accumulation that may lead to field deformation or sparking. This paper explores the mechanical and electrical effects of high pressure gas environments on insulating polymers PTFE, HDPE, PEEK, POM and UHMW in argon and xenon, including studying gas absorption, swelling and high voltage insulation strength.

Corrosion-resistant systems of formate packer fluid for G3/N80/TP110SS pipes at high temperature, high pressure and high H2S/CO2 ratios.

A series of corrosion problems caused by high-temperature, high-pressure and high-acid gas environments has been an issue in oil and gas production for a long time. During the development of a high-acid gas field, the petroleum pipe is subjected to many aspects of corrosion, and the corrosion mechanism is complicated by the condition of the coexistence of H2S/CO2. Based on the study of the corrosion problem associated with the formate packer fluid in Southwest China, three kinds of steels were studied for corrosion prevention in the alloy G3/N80 steel/TP110SS steel. The study shows that the corrosion rate of the formate packer fluid is low, but corrosion is severe in environments characterized by high temperatures, high pressures and high-acid gas contents. Based on the consideration of cost and the difficulty of realization, an anti-corrosion system was constructed based on the existing packer fluid, mainly through the introduction of a variety of anti-corrosion additives. Through the selection of various additives and corrosion experiments, a corrosion protection system of formate packer fluid was developed. Corrosion tests show that the corrosion rate of the system must be less than 0.076 mm yr−1 to achieve the purpose of corrosion protection. The formate packer fluid with corrosion protection can meet the needs of the current application.

Ti:Pt:Au:Ni thin-film CVD diamond sensor ability for charged particle detection

This work demonstrates the development of diamond sensors with reliable contacts using a new metallization formula, which can operate under high-pressure gas environment. The metallization was created using thin film layers of titanium, platinum, gold and nickel deposited on a single crystal electronic grade CVD diamond chip. The contacts were 2 mm in diameter with thickness of 50/5/20/150 nm of Ti:Pt:Au:Ni. The optimum operating voltage of the sensor was determined from the current-voltage measurements. The sensor was calibrated with 239Pu and 241Am alpha radiation sources at 300 V. The energy resolution of the Ti:Pt:Au:Ni diamond sensor was determined to be 7.6% at 5.2 MeV of 239Pu and 2.2% at 5.48 MeV of 241Am. The high-pressure gas loading environment under which this sensor was used is discussed. Specifically, experimental observations are described using hydrogen loading of nickel as a means of initiating low energy nuclear reactions. No neutrons, electrons, ions or other ionizing radiations were observed in these experiments.