Risk Of Hydrogen Embrittlement Research Articles

Comparing green hydrogen and green ammonia as energy carriers in utility-scale transport and subsurface storage

Many of the challenges associated with utility-scale hydrogen transport and storage relate to its low density, high diffusivity, and the risk of hydrogen embrittlement, motivating consideration to integrating ammonia as an energy carrier. Compared to hydrogen, ammonia is more compatible with pipeline materials and delivers energy at higher density. Ammonia is also a mature industry with a greater extent of established pipeline networks and regulations that may accelerate hydrogen transitions and penetration in energy grids. However, converting hydrogen produced by renewable-driven electrolysis into ammonia (and back to hydrogen, depending on end use) complicates logistics, and associated energy and resource demands may offset the green hydrogen's carbon neutrality. This work outlines core considerations for the use of hydrogen vs. ammonia during transport and storage operations, with an emphasis on green hydrogen or green ammonia pathways coupled to pipeline transport and underground storage. We compare tradeoffs in pipeline infrastructure and operations; subsurface storage options; and project economics. We also evaluate round-trip efficiencies (RTE) for both pathways, which indicate that hydrogen is more attractive from an energy efficiency perspective for hydrogen end-use applications due to the efficiency penalties of initial ammonia synthesis and subsequent cracking, but RTE's for ammonia transport and storage are comparable to hydrogen for direct use or ammonia-to-power systems. The tradeoffs presented in this work would need to be considered on a case-by-case basis, but indicate that selective use of ammonia as an energy-dense hydrogen carrier could support decarbonization goals in industry and hydrogen economies.

Repurposing natural gas pipelines for hydrogen: Limits and options from a case study in Germany

We investigate the challenges and options for repurposing existing natural gas pipelines for hydrogen transportation. Challenges of re-purposing are mainly related to safety and due to the risk of hydrogen embrittlement of pipeline steels and the smaller molecular size of the gas. From an economic perspective, the lower volumetric energy density of hydrogen compared to natural gas is a challenge. We investigate three pipeline repurposing options in depth: a) no modification to the pipeline but enhanced maintenance, b) use of gaseous inhibitors, and c) the pipe-in-pipe approach. The levelized costs of transportation of these options are compared for the case of the German Norddeutsche Erdgasleitung (NEL) pipeline. We find a similar cost range for all three options. This indicates that other criteria such as the sunk costs, public acceptance, and consumer requirements are likely to shape the decision making for gas pipeline repurposing.

Energization test apparatus of HTS coils cooled by liquid hydrogen and manufacture of split-type REBCO external field coil

Abstract Liquid hydrogen (LH2) is a potential coolant of high-temperature superconducting (HTS) devices. However, owing to the high flammability of hydrogen and the risk of hydrogen embrittlement in materials, studies on LH2-cooled superconducting devices are rare. We developed an LH2 test apparatus to analyze the basic characteristics of LH2 as a coolant and evaluate the energizing characteristics of LH2-cooled superconducting wires. A REBCO external field coil was designed and manufactured for conducting cooling stability tests on various HTS coils cooled by LH2. The field coil, comprising eight single pancake coils of 4 mm wide REBCO wires, with inner diameter 106 mm and outer diameter 250 mm was divided into upper and lower sections. The test coil was placed in the central space. A magnetic field perpendicular to the test coil’s wire surface was generated by running currents in opposite directions through the upper and lower sections. Each double pancake coil was securely placed in a stainless-steel housing to withstand repulsive electromagnetic forces. The manufactured field coil was cooled using LH2, energized to 150 A, and successfully generated the intended magnetic field of 1.75 T. No increase in voltage was observed in any of the double pancake coils, and there was no mechanical degradation due to electromagnetic forces. Subsequently, we initiated thermal runaway tests on various HTS coils using the manufactured field coil to assess the cooling stability of LH2-cooled HTS coils. The study will facilitate the development of explosion-proof designs and safety technologies for LH2-cooled superconducting devices and cooling systems.

First results of non-evaporable getter pump studies for the application in the EAST tokamak

Enhanced particle exhaust is pivotal in optimizing fuel recycling and bolstering plasma performance within fusion reactors. Non-Evaporable Getter (NEG) pumps, renowned for their robust high-temperature tolerance, high pumping speeds and large adsorption capabilities, emerge as highly promising candidates for augmenting the particle exhaust efficiency of tokamaks. Rigorous evaluations have been undertaken to ascertain their pumping efficacy within a vacuum testing setup and the EAST tokamak environment. Experimental data have consistently demonstrated that NEG pumps maintain stable operation across a broad temperature range, from ambient conditions to 200 °C, with a notable direct correlation observed between the pumping speed and the ambient temperature. Their performance surpasses that of conventional cryopumps, especially at D2 gas pressures exceeding 0.1 Pa. Additionally, the application of nitrogen passivation has been validated as an effective method to modulate the pumping speed and to mitigate the risk of hydrogen embrittlement and oxygen and carbon contaminations. Despite exposure to the extreme operational demands, including 30 h of plasma exposure, and lithium processing, atmospheric conditions, and water leaks, the NEG pumps preserved approximately 70 % of their initial pumping capacity. These results underscore the compatibility of NEG pumps with the challenging environments of plasma operations, positioning them as a viable and promising solution for particle exhaust in the next-generation fusion reactors.

Influence of the Al Content on the Electrochemical Behavior of Zn-Al Cold-Sprayed Coatings in the Context of the Deep Geological Disposal of Radioactive Waste

For high-level radioactive waste, the French National Radioactive Waste Management Agency is currently developing a 500 m deep geological disposal facility called Cigéo. Carbon steel containers will be used to contain the wastes in the specific conditions of the disposal. The use of a sacrificial coating was studied as an additional protection for the containers against corrosion. A previous work had shown the possibility to use Zn-Al coatings in this specific medium. To optimize the coatings’ performance, the cold-spraying process was considered instead of the previously used wire arc spraying because it can increase the cohesion between the particles in the coating. Moreover, three aluminum contents, i.e., 5, 15 and 25 wt.%, were considered. The characterization of the obtained coatings revealed a strongly heterogeneous composition for the lower Al content (5 wt.%), with local Al contents from 1.3 wt.% Al to 44.5 wt.% Al. The corrosion study was carried out in a specific solution mimicking the pore solution of the surrounding cementitious material designed for disposal at a temperature of 50 °C. First, the polarization curves acquired with coated steel electrodes revealed the pseudo-passive behavior of the 25 wt.% Al coating, while for the other compositions, the coating remained active. Moreover, the higher aluminum content (25 wt.%) induced an important decrease in potential, with a possible risk of hydrogen embrittlement for the protected steel. Secondly, the sacrificial properties were investigated through 6 months of experiments using coated electrodes with cross-like defects and coated electrodes coupled with bare steel electrodes. Whatever the composition of the coating, the protection was maintained, with the 15 wt.% Al coating giving the best performance.

A comparison study of constant current and square wave current in the bidirectional electromigration rehabilitation on chloride-contaminated concrete

The objective of this study is to reduce the hydrogen embrittlement risk of rebar caused by the continuous constant current (CC) in the bidirectional electromigration rehabilitation (BIEM). Three types of square wave current (SWC) were applied in the BIEM treatment on a Cl--contaminated concrete, in the saturated calcium hydroxide containing 1 mol/L triethylenetetramine (TETA). The sample experienced the BIEM with a constant current density of 3 A/m2 was chosen as the control sample with the same electricity consumption. After 4 cycles of treatment, the concentration profiles of Cl- and TETA were measured in the protective layer. The corrosion current densities of the rebar were analyzed by various electrochemical tests. The stress-strain curve of the rehabilitated rebar was tested, and its hydrogen embrittlement risk was estimated. The results suggested that the SWC more effectively removed Cl- and migrated TETA than the CC did, with the same electricity consumption and treatment duration. The rebar experienced the former BIEM exhibited a higher fracture energy ratio and a lower corrosion rate than the one experienced the latter treatment. In general, the SWC was more effective and lower hydrogen embrittlement risk than CC in the BIEM rehabilitation treatment.

Evaluation of Hydrogen Embrittlement Risk of Long-Term Operated Gas Pipelines Made of 10G2BT Steel

Evaluation of Hydrogen Embrittlement Risk of Long-Term Operated Gas Pipelines Made of 10G2BT Steel

Hydrogen-induced cracking of X70 steel affected by sulfate-reducing bacteria and cathodic potential: experiment and density functional theory study

Submarine pipeline are often exposed to the risk of hydrogen embrittlement from the dual action of marine sulfate-reducing bacteria (SRB) and cathodic protection (CP). In this work, hydrogen permeation test, slow strain rate tensile (SSRT) experiments, and density functional theory (DFT) were used to explain the hydrogen embrittlement (HE) mechanism of subsea pipeline steel under the action of SRB and CP. When the applied CP potential is increased from −850 mV to −1200 mV, the hydrogen seepage current increases 1.8 times. And the tensile specimens pre-charged with hydrogen exhibit significant hydrogen embrittlement behavior. DFT calculations show that the increased concentration of hydrogen atoms on the material surface decreases the diffusion potential barrier, leading to a larger hydrogen seepage current. In addition, the aggregation of hydrogen atoms in the steel weakens the chemical bonds between Fe atoms, leading to hydrogen embrittlement.

Comparative Assessment of Environment‐Assisted Cracking Susceptibility of Different Grade API 5L Steels in CO2, CO2/H2S, and H2S Environments

The risk of hydrogen embrittlement (HE) and stress corrosion cracking (SCC) is a strong concern for material selection in the oil and gas sector. The presence of H2S enhances hydrogen charging, which can increase hydrogen embrittlement (HE) susceptibility. There are knowledge gaps about HE in the environment saturated with pure carbon dioxide (CO2) and with CO2 containing H2S. CO2 has a strong impact on corrosion rate as well, enhancing cathodic reactions. CO2 might also have a direct contribution to hydrogen charging and cracking mechanisms. This study addresses the assessment of hydrogen permeation and HE of X65 and X80 steels in CO2 and/or H2S environments. The performance of both steel grades is investigated, supported by experimental approach. The results indicate that the loss of mechanical resistance is due to hydrogen uptake and diffusion as well as the anodic dissolution, especially in Solution B. It is observed that X80 steel used in this work is more susceptible to cracking than X65 steel even in pure CO2. It is concluded that the advantage of using a higher‐mechanical‐resistant steel, X80 can be suppressed by HE effects.

Research on the dynamic characteristics of natural gas pipeline network with hydrogen injection considering line-pack influence

Hydrogen energy has the advantages of renewable, clean and high energy density, which is considered as the most potential secondary energy in the 21st century. But transportation is a major constraint on development of hydrogen. A possible solution is to inject hydrogen into natural gas network for transport. Due to the obvious differences in the properties of natural gas and hydrogen, it is necessary to establish natural gas pipeline model with hydrogen injection to explore the influence of hydrogen on pipeline. The line-pack of natural gas network can improve the flexibility of the system to deal with uncertainties, and the line-pack has a significant impact on the dynamic characteristics of the natural gas network under the change of external conditions. When hydrogen is injected into the natural gas network, the line-pack is affected by both pressure and hydrogen mixture ratio, and the line-pack influence on the dynamic characteristics of the network is more complicated. In this paper, a natural pipe network with hydrogen injection is established based on the finite difference method, and simulation is carried out under different situations to explore the influence of different line-pack on the dynamic characteristics of the natural gas network. The results show that the response speed of hydrogen mixture ratio is faster under the condition of low line-pack, which is conducive to reducing the risk of hydrogen embrittlement when the hydrogen mixture ratio surges for a short time. However, the pressure loss caused by the increase of flow can be reduced in the high line-pack state.

A review of hydrogen embrittlement in gas transmission pipeline steels

Abstract Hydrogen transport by blending hydrogen into natural gas transmission pipelines and by pure-hydrogen pipelines is a prospective mode of energy transmission during the transition to renewables. The risk of hydrogen embrittlement (HE) in pipeline steels must first be quantified to ensure safe pipeline operation. This review provides an overview of HE in pipeline steels. Most pipeline steels have reduced ductility when exposed to hydrogen partial pressures of 100 bar and above. Higher-strength pipeline steels (X80 and X100) have been found to undergo HE at ∼50 bar hydrogen. Hydrogen-induced subcritical crack growth in pipeline steels has not been reported in the literature. There are few articles on HE in pipeline welds, with some indications that the weld is more susceptible to HE, and some indications that it is less. The relationship between hydrogen pressure and absorbed hydrogen concentration has not been evaluated. Gaps in knowledge are identified in the conclusions.

Application of laboratory and on field techniques to determine the risk of hydrogen embrittlement in gaseous hydrogen and relative mixtures transport and storage

The European Green Deal aims to achieve the climate neutrality in Europe by 2050; furthermore, an intermediate target fixes a first reduction of greenhouse gas emissions by minimum 55% within 2030, with reference to 1990 levels. In these contexts, and in particular in hard-to-abate processes as steelmaking, hydrogen could be a key instrument to achieve the above-mentioned sustainability targets. It can be produced from renewables and does not produce direct CO2 emission when used. On the other side, one of the main issues related to hydrogen use is the fact that it involves a certain risk linked to potential susceptibility of steels to hydrogen embrittlement phenomenon that could also lead to catastrophic failures. Suitable materials should be used in these applications by performing a prior evaluation of material susceptibility. The characterization consists in determining the behaviour of materials when exposed to hydrogen atmosphere, in order to determine a hydrogen threshold value for failure. To approach this theme, a first experimental was carried out on steels typically applied in oil and gas industry. Experimental included hydrogen diffusivity, solubility and mechanical tests. Moreover, electrochemical charging was compared to gaseous charging, confirming the first methodology is much more severe and thus not very significant for high-pressure gas applications. Furthermore, a continuous monitoring technique for hydrogen embrittlement risk assessment is under development. The methodology is based on high-resolution gas sensors used to measure the hydrogen flux permeating through the metal wall of transport and storage components. Relative signal can be correlated with the material susceptibility to hydrogen embrittlement in order to assess related failure risk. The device was tried on a pressure vessel containing pure hydrogen to assess the system’s sensitivity.

An optimized microchannel Ta target for high-current accelerator-driven neutron sources

An optimized neutron producing tantalum target with an optimized internal microchannel cooling was developed for a 70 MeV proton beam with a peak current of 100 mA, a duty cycle of 1.43% and an average power of 100 kW on a target surface area of 100 cm 2. In this work a target with microchannel cooling structure is described which matches with the proton’s energy to minimize hydrogen implantation and to produce energy deposition with optimum homogeneity inside the target to minimize the thermal stresses. For the purpose of getting an optimal target design, the investigations of energy deposition, proton fluence, the spatial distribution of (p, n) reactions and the spatial distribution of stopping protons of the target with different microchannel geometries were performed with the particle transport code FLUKA. The resulting design produces a homogeneous proton fluence and energy deposition without hot spots. Furthermore, only 4.4% of the impinging protons accumulate in the metal target, which significantly decreases the risk of hydrogen embrittlement and blistering.

Application of line pipe and hot induction bends in hydrogen gas

For the upcoming hydrogen economy, transport pipelines for hydrogen gas and gas mixtures of hydrogen and natural gas are one of the important components. For the application of steel in hydrogen gas it is necessary to handle the risk of hydrogen embrittlement by adapting the right knowledge. Compared to existing hydrogen pipelines, which are safely running since decades, higher gas pressures and steel strength levels are in discussion. For a safe operation and limited resource consumption it is necessary to clarify the product requirements. The semi-finished products medium and large line pipes and bends are regarded over the production chain: pre-material, hot rolled strip, welded pipes, and induction bent pipes. The interaction of hydrogen with steel is investigated since decades. For hydrogen gas, the surface reaction with steel is considerably reduced compared to other corrosion reactions i.e. with sour gas. This results in a much lower amount of introduced hydrogen atoms within the material. Results of lab trials of different materials after storage in pressured hydrogen gas will be shown to clarify this point. Furthermore, results of tests of applicability of commonly used flow coats in hydrogen atmosphere are shown. For a possible failure scenario of a hydrogen transport line the investigations must be focused on local effects of hydrogen enrichment in conjunction with mechanical loads. There are different laboratory tests possible to evaluate these material reactions. They are shown and discussed in the view of the following aspects: product qualification, further product and specification development and suitable approval tests.

Experimental investigation on the hydrogen embrittlement characteristics and mechanism of natural gas-hydrogen transportation pipeline steels

Hydrogen blended with natural gas is one of the best ways for large-scale hydrogen transportation; however, pipeline steels exploited for transferring natural gas have the risk of hydrogen embrittlement. Therefore, the hydrogen damage mechanism and resistance property of different steel pipelines should be carefully examined to select suitable materials for the task mentioned above. The common X42, X52, X70, and AISI 1020 are taken into account as research objects. Their mechanical properties and hydrogen absorption properties in a hydrogen environment are investigated to explore further factors affecting the hydrogen embrittlement of material. Dynamic slow strain rate tensile test results show that these materials exhibit varying hydrogen embrittlement sensitivity in a hydrogen environment. AISI 1020 has the highest hydrogen embrittlement susceptibility, then X70, and X42 presents the lowest one. Generally, hydrogen embrittlement behaviours are strengthened by increasing the current density. As the current density grows, the fracture mode of pipeline steels transforms from the ductile fracture to the quasi-cleavage fracture and finally turns into the cleavage fracture. The hydrogen embrittlement fracture of the tensile specimen results from the action of the HEDE and HELP in various zones. TDS test results indicates that the content of C and Mn significantly influence on the hydrogen solubility in metal materials.

Effects of Al-Si coating structures on bendability and resistance to hydrogen embrittlement in 1.5-GPa-grade hot-press-forming steel

Hot-press-forming (HPF) steels have attracted great attention as automotive reinforcement parts, but are exposed to the potential risk of hydrogen embrittlement (HE) because H introduced easily during HPF processes is hardly de-trapped through the solidified coating. In particular, H seriously deteriorates bendability, which is one of the main properties to be considered. In this study, the Al-Si coating structures were modified to improve H emission by increasing H diffusivity. The effects of coating structures on bendability and H desorption were investigated by interrupted bending tests, H-permeation tests, and thermal desorption analyses according to elapsed time after H-charging. Immersion in an Al-10%Si bath and the subsequent HPF process (930 °C for 6 min) produced a 33 μm-thick multiple coating structure composed of Fe2Al5, FeAl, and ferrite layers. On the other hand, the reduced Al-Si adhesion amount from the dip bath and the increased time and temperature (950 °C for 30 min) produced a 30 µm-thick body-centered-cubic (BCC)-based coating structure composed of FeAl and ferrite layers. The BCC-based crystal structure, reduced Al content in the FeAl layer, and coarsened ferrite grains effectively enhanced H diffusivity and suppressed H-induced degradation. Moreover, the softened FeAl and thick ferrite layers improved bendability by allowing the large strain accommodation of bending deformation. Thus, this work proposes an optimal Al-Si coating design that enhances both bendability and resistance to H-induced degradation for secure HPF steel applications.

Hydrogen Entry into Steel Under Corrosion Products

Hydrogen entry into high-strength steel after local sodium chloride predeposition and during exposure to humid air was studied using scanning Kelvin probe. Two regions with different pH, potential, and red rust composition were formed on the corroding side of the specimen. Hydrogen permeating through the specimen was detected over the region with the net cathodic character, which was linked to oxygen reduction taking place on top and within the red rust layer whereas anodic dissolution progressed inside the rust covered pits creating conditions favorable for formation of hydrogen ions. No measurable hydrogen entry was detected in the area covered with an apparently homogeneous layer of corrosion products and corroding uniformly. The finding that corrosion pits were the main source of atomic hydrogen implies that the susceptibility of high-strength steels to pitting corrosion is an important parameter for evaluation of the risk of hydrogen embrittlement under atmospheric conditions.

Hydrogen Embrittlement and Hydrogen Trapping Behaviour in Advanced High Strength Steels

Modern advanced high strength steels (AHSS) for the automotive sector often contain retained austenite which promotes remarkable combinations of strength and ductility. These high strength steels may however be subject to a risk of hydrogen embrittlement. For the current contribution, hydrogen trapping and embrittlement behaviour were investigated in AHSS compositions having different levels of retained austenite. Hydrogen permeation tests revealed that hydrogen diffusion was slower for increased levels of retained austenite, being controlled most likely by reversible trapping at austenite-matrix interfaces. External hydrogen embrittlement tests via step loading also revealed that resistance to hydrogen was lower for increased levels of retained austenite. It was suggested that during step loading the hydrogen accumulated at austenite-matrix interfaces, leading to cracking when the applied stress was high enough.

Minimising the risk of hydrogen embrittlement (HE) and hydrogen assisted stress cracking (HASC) within steel lifting products used in the marine environment

Hydrogen embrittlement (HE) and hydrogen assisted stress cracking (HASC) are processes that detrimentally affect certain steels. These processes are understood and well documented. In recent years there has been an accumulation of product failures involving steel lifting components in the offshore industry. These failures have individually been investigated and confirmed as the result of HE and HASC. There continues to be an assumption that steel lifting components that comply with international standards are suitable for use offshore; however, the corrosive environment and effects of dynamic load amplification on lifting components in the offshore environment significantly increase their susceptibility to HE and HASC. Our intention is to provide the offshore industry with technical guidance on the correct material selection in steel lifting components, over and above the requirements of international standards, to mitigate the risk of failure caused by HE and HASC. The definition of toughness in metallurgy and lifting is the ability of the material to absorb energy and to plastically ‘deform’ without fracturing. Our research highlights that a high-grade steel’s hardness and toughness is critical.

(Invited) Corrosion Behavior and Hydrogen Permeation of Steel Materials Under Wet-Dry Cyclic Environment

Higher strength steels have been required from the viewpoint of safety and energy saving in the fields of transportation equipment and infrastructure. However, it is known that the higher the strength of steels, the higher the risk of hydrogen embrittlement. It has been reported that hydrogen embrittlement occurs even in atmospheric corrosive environment, and solving the problem of hydrogen embrittlement will be the key to the future hydrogen energy society. For that purpose, it is necessary to clarify the hydrogen embrittlement behavior due to atmospheric corrosion. We focused on surface potential measurement as a technique to visualize permeated hydrogen. The purpose of this study is to clarify the hydrogen permeation behavior of steel materials under atmospheric corrosive environment.A 50 x 50 x 0.5t mm of pure iron plate was used as the sample. After grinding both surfaces of samples and degreasing with ethanol, nickel plating was applied to the hydrogen detective side of the sample. Hydrogen penetration was accelerated by a wet-dry cyclic corrosion test using a droplet of 0.5 M NaCl solution. The distilled water was added after second cycles to avoid the accumulation of NaCl. The potential of the hydrogen detective surface was measured with time in the drying process by surface potential device. The surface potential probe is set on the XY stage and the surface potential distribution can be obtained by scanning the probe. In this study, the surface potential of the copper plate in contact with the sample was adjusted at 0V as the reference potential.Although the corrosion occurred on the surface in the drying process after dropping the NaCl solution, no surface potential change was observed on the hydrogen detective side of the sample in that process. The surface potential started to change in a part of the surface of the sample immediately after the droplet was completely dried, and after 1hour, the size and shape of the potential changed area became almost the same as those of the corrosion products. No corrosion occurred on the hydrogen detective side of samples during the surface potential measurement, indicating that the surface potential change is attributed to the atomic hydrogen penetrated through the samples. The surface potential changed area gradually disappeared, and almost no potential change was observed on the surface after 72 hours. The change in surface potential after the second cycle of wet and dry cyclic corrosion test showed the same tendency as in the first cycle, and a potential distribution close to the shape of corrosion products was observed.