Effect Of High Pressure Hydrogen Research Articles

Evaluation of the residual fatigue lifetime of a semi-elliptical crack of a Low-Alloy steel pressure vessel under High-Pressure gaseous hydrogen

The demand for broadening fatigue crack growth behavior has increased owing to the extended use of hydrogen gas as an energy carrier, and it is known that high-pressure hydrogen has a major effect on fatigue crack growth behavior. In this study, the effect of high-pressure hydrogen on an SA-372 Grade J steel pressure vessel was analyzed using fatigue crack growth testing, fracture toughness testing, and finite element analysis. A test was performed to compare the fatigue crack growth of SA-372 Grade J steel in ambient air and 99-MPa hydrogen environments. The test results, including the identified degradation of fracture toughness and the presence of hydrogen inflection in the fatigue crack growth rate, were used in the finite element analysis to analyze the fatigue crack growth behavior under various loading and environmental conditions. The residual fatigue life was evaluated considering the morphological evolution of the crack during growth, the initial aspect ratio, and the initial crack-to-depth ratio.

Simplified Evaluation Method for Effect of High-Pressure Hydrogen On Ductility of Low Alloy Steel

Simplified Evaluation Method for Effect of High-Pressure Hydrogen On Ductility of Low Alloy Steel

A review on effect of hydrogen on rubber seals used in the high-pressure hydrogen infrastructure

Hydrogen is believed to be an important energy storage vector to fully exploit the benefit of renewable and sustainable energy. Rubber seals are widely used in high-pressure hydrogen storage system, which may cause the occurrence of fracture or deterioration behavior inside the rubber, leading to a leak of explosive hydrogen. Thus, the effect of high-pressure hydrogen on the properties of rubber seals needs to be studied. In this paper, the material properties of rubber exposed to high-pressure hydrogen are elaborated, including transport properties, chemical structure, mechanical properties, rapid gas decompression and swelling. Simultaneously the sealing performance of rubber rings under high-pressure hydrogen is also presented, consisting of static and dynamic sealing characteristics. At the end of the article, some issues are proposed to provide reference train of thought for future research, involving types of fillers and rubbers, failure modes, impact of degradation on sealing performance, key parameters and design parameters, and effects of temperature and pressure.

In Situ High Pressure Hydrogen Tribological Testing of Common Polymer Materials Used in the Hydrogen Delivery Infrastructure.

High pressure hydrogen gas is known to adversely affect metallic components of compressors, valves, hoses, and actuators. However, relatively little is known about the effects of high pressure hydrogen on the polymer sealing and barrier materials also found within these components. More study is required in order to determine the compatibility of common polymer materials found in the components of the hydrogen fuel delivery infrastructure with high pressure hydrogen. As a result, it is important to consider the changes in physical properties such as friction and wear in situ while the polymer is exposed to high pressure hydrogen. In this protocol, we present a method for testing the friction and wear properties of ethylene propylene diene monomer (EPDM) elastomer samples in a 28 MPa high pressure hydrogen environment using a custom-built in situ pin-on-flat linear reciprocating tribometer. Representative results from this testing are presented which indicate that the coefficient of friction between the EPDM sample coupon and steel counter surface is increased in high pressure hydrogen as compared to the coefficient of friction similarly measured in ambient air.

A frequency dependent embrittling effect of high pressure hydrogen in a 17-4 PH martensitic stainless steel

The effects of hydrogen on tensile and fatigue-life properties of 17-4PH H1150 steel have been investigated by using a smooth, round-bar specimen for tensile tests and circumferentially-notched specimen for fatigue-life tests. The specimens were precharged by an exposure to 35-100 MPa hydrogen gas at 270°C for 200 h. For the 100 MPa hydrogen exposure, the steel showed a significant degradation in ductility loss, translated by a relative reduction in area, RRA, of 0.31. The fatigue-life test of the present notch specimen (stress concentration factor of 6.6) reflects the fatigue crack growth (FCG) for long cracks. The fatigue limit of the non-charged and H-charged notched specimens, defined by the threshold of non-propagation for long cracks, was not affected by hydrogen. At a higher stress amplitude, the H-charged specimen showed a significant FCG acceleration ratio compared to the non-charged specimen. Although, an upper bound of the FCG acceleration seemed to exist, this ratio was approximately 100. The fracture surface of the H-charged specimen was covered with quasi-cleavage (QC) at a lower stress amplitude and with a mixture of QC and intergranular (IG) facets at higher stress amplitudes. It has been suggested that a cycle-dependent crack growth accompanied by QC occurs at a lower stress amplitude, whereas a mixture of cycle-dependent crack growth (accompanied by QC) and time-dependent crack growth (accompanied by IG) occurs otherwise. This mixture justifies the 100 times FCG acceleration ratio in spite of the existence of the upper bound.

An in situ tribometer for measuring friction and wear of polymers in a high pressure hydrogen environment.

High pressure hydrogen effects on the friction and wear of polymers are of importance to myriad applications. Of special concern are those used in the infrastructure for hydrogen vehicle refueling stations, including compressor sliding seals, valves, and actuators. While much is known about potentially damaging embrittlement effects of hydrogen on metals, relatively little is known about the effects of high pressure hydrogen on polymers. However, based on the limited results that are published in the literature, polymers also apparently exhibit compatibility issues with hydrogen. An additional study is needed to elucidate these effects to avoid incompatibilities either through design or material selection. As part of this effort, we present here in situ high pressure hydrogen studies of the friction and wear on example polymers. To this end, we have built and demonstrated a custom-built pin-on-flat linear reciprocating tribometer and demonstrated its use with in situ studies of friction and wear behavior of nitrile butadiene rubber polymer samples in 28 MPa hydrogen. Tribology results indicate that friction and wear is increased in high pressure hydrogen as compared both with values measured in high pressure argon and ambient air conditions.

Effect of high pressure hydrogen on the mechanical characteristics of single carbon fiber

In this study, carbon fiber was exposed to a pressure of 7MPa for 24h in high pressure chamber. The tensile test for carbon fiber was conducted to estimate the effect on the high pressure hydrogen in the atmosphere. To determine the tensile strength and Weibull modulus, approximately thirty carbon fiber samples were measured in all cases, and carbon fiber exposed to high pressure argon was evaluated to verify only the effect of hydrogen. Additionally, carbon fiber samples were annealed at 1950°C for 1h for a comparison with normal carbon fiber and then tested under identical conditions. The results showed that the tensile strength scatter of normal carbon fiber exposed to hydrogen was relatively wider and the Weibull modulus was decreased. Moreover, the tensile strength of the annealed carbon fiber exposed to hydrogen was increased, and these samples indicated a complex Weibull modulus because the hydrogen stored in the carbon fiber influenced the mechanical characteristic.

高圧水素曝露によるゴム材料の高次構造変化の振動分光学的検討

高圧水素曝露によるゴム材料の高次構造変化の振動分光学的検討

The effect of high pressure hydrogen on the creep fracture of notched ferritic-steel components

In order to study hydrogen attack under near-service conditions, an experimental technique for examining the multiaxial behaviour of model-sized tubular components was modified to allow exposure to high pressure hydrogen gas, at a temperature in the creep range for the material chosen. Components with both axial and circumferential internal notches were loaded using the internal pressure of hydrogen, at a temperature of 600°C. The material under study was a low-alloy ferritic steel, 2 1 4 Cr–Mo, used widely in pressure vessels and piping in the petro-refinery industry, where high pressure hydrogen is encountered. Analysis of the results takes the form of metallographic investigation, correlation of rupture life with base-line data, and characterisation of damage evolution. The distribution of inter-granular voids and cavities observed by S.E.M. confirms the stress-assisted nature of hydrogen-induced degradation. The hydrogen attack caused a dramatic change in the multiaxial creep deformation mechanism from von Mises control to maximum principal stress, a factor very important in the design of plant components. The effect of this change on the reference-stress calculations for both notch types is examined in terms of the stress rupture time correlation with base-line data. C* values are compared with standard data for the material. Factors incorporated in the method of C* calculation, such as the reference stress equations and Norton constants, which may influence the value of the results are considered.

Effect of high-pressure hydrogen on crack growth in carbon steel

The effect of high-pressure hydrogen and temperature on crack growth was studied in wedge-opening-load (WOL) samples of a low-carbon steel. At temperatures above 280 ‡C, a hydrogen pressure of 3 ksi gave an increasing amount of acceleration in crack growth. These conditions approached but were below that needed to give hydrogen attack (HA) in the surrounding matrix. The value ofda/dt increases exponentially with temperature, andQ is roughly equal to that for grain boundary diffusion. The growth is absent atK1 = 0 but varies little withK1 above 15 MPa√m. The value ofda/dt increases steadily with hydrogen pressure in the range of 3 to 21 MPa.

SPECIMEN SIZE DEPENDENCE OF LOW FREQUENCY FATIGUE TESTS IN HIGH‐PRESSURE HYDROGEN

Abstract— Fatigue data required for estimates of cracked component lifetimes are conventionally obtained by cyclic loading of specimens manufactured to a specific geometry. Crack growth in the specimen results in an increase in the stress intensity factor range and crack growth curves are calculated from the variation of crack length with time. An environmental fatigue study of the effect of high pressure hydrogen on the low cycle fatigue of a medium strength steel has shown that, due to effects of elapsed time in the environment and effects of specimen size, in certain circumstances this procedure may not yield geometry‐independent results which can be applied with confidence to cracked components. It is concluded that to obtain useful crack growth data in cases where fracture is influenced by diffusion or other strongly time dependent processes might require a modified approach to fracture mechanics testing procedures.

Pure Hydrocarbon Reforming Reactions with Platinum Type Petroleum Reforming Catalysts (Part 2)

Though many studies have been made on reforming of naphtha and pure hydrocarbons over Pt-Cl-Al2O3 type catalysts, very few of them report indetails on extensive reaction conditions for reforming of paraffinic hydrocarbons. We studied the details of n-Heptane Reforming Reactions and the effect of high pressure hydrogen in the reforming reaction. Reforming experiments were carried out with a micro-reactor, which was packed with catalyst of 0.605 to 1.007g and directly connected with a gaschromatograph. Reaction temperature: 500, 520, 540°C, total pressure: 10.7, 20.3, 35.0, 44.5atm, Liquid Hourly Space Velocity: 2.43-17.76vol/vol•hr and hydrogen to feed supply mole ratios: 5, 10, 15.Nine kinds of aromatics and naphthenes (by cyclization), six kinds of heptane-isomers (by isomerization), and thirteen kinds of paraffinic hydrocarbons from methane to hexanes (by hydrocracking) were analyzed. The total conversion of n-heptane increases with the rise in temperature, total pressure and the contact time.The conversion of n-heptane to cyclic-compounds generally increases in proportion to the rise in temperature, total pressure and the contact time, the maximum value of cyclization conversion being indicated at the total pressure of 35 to 40 atmospheres. Though the conversion of n-heptane to heptane-isomers is influenced complicately by each factor of reaction conditions, the variable ranges of the conversion are divided to three classes of Before Max. Values, Max. Values and After Max. Values. The operating conditions indicating max. values in isomerization-conversion transfer to lower temperatures and the shorter contact time in proportion to the rise in total pressure, but at the total pressure of 10atm and lower no max. values are indicated. The conversion of n-heptane to the lower paraffinic hydrocarbons increases in proportion to the rise in temperature, total pressure and the contact time. Rates of conversion of n-heptane to methane through hexanes are: (QC3H8≈QC4H10>QC5H12≈QC2H6>QC6H14_??_QCH4). Therefore, hydrocracking reaction of n-heptane takes place mainly on the acidic-active-sites of catalyst. The conversion of each reaction in n-heptane reforming generally increases in proportion to the rise in the total pressure before max. values.