Research and application of high-pressure hydrogen barrier coating in high-pressure hydrogen storage and transportation

Research and application of high-pressure hydrogen barrier coating
Bao Yi and Xu Qing
Shanghai Yiyuan Energy Technology Co., Ltd
Abstract: Hydrogen embrittlement seriously affects the performance of metal materials and becomes a bottleneck restricting the efficient and safe storage and transportation of hydrogen gas. Based on the hydrogen embrittlement phenomenon in high-pressure hydrogen storage and transportation, a high-pressure hydrogen barrier coating material has been developed. Through experimental testing and practical engineering project application, the advantages of this material in solving hydrogen embrittlement problems and reducing hydrogen energy storage and transportation costs have been verified, providing a completely new solution for safe hydrogen storage and transportation.
Keywords: hydrogen embrittlement; Metal selection; Hydrogen barrier
Hydrogen energy, as an important component of clean energy, occupies a significant position in the global energy structure transformation. Hydrogen embrittlement is one of the core technical challenges faced in hydrogen energy storage and transportation, especially in high-pressure hydrogen environments where hydrogen atoms easily penetrate into metal materials, leading to embrittlement and failure. Traditional anti hydrogen embrittlement solutions rely on high cost materials such as 316L stainless steel and nickel based alloys. Although they can effectively resist hydrogen penetration in terms of performance, their high price and complex processing limit the development of hydrogen energy infrastructure. In the context of energy transition, there is an urgent demand for efficient and hydrogen resistant materials in the market. Developing a low-cost and high-performance hydrogen barrier material is expected to meet the safe and economical storage and transportation needs of hydrogen energy.
The technical challenge faced by high-pressure hydrogen gas transportation is the phenomenon of hydrogen embrittlement, which is the penetration of hydrogen atoms into the interior of metal materials, leading to material embrittlement and ultimately failure. The main reason is that hydrogen atoms diffuse in metal crystals, reducing the plasticity and toughness of the metal.
1.1 Hydrogen embrittlement mechanism and its impact
The phenomenon of hydrogen embrittlement originates from the interaction between hydrogen atoms and internal defects in metals, leading to crack propagation and material fracture (Figure 1). Experiments have shown that the diffusion coefficient of hydrogen in steel is about 1.3 × 10-8 cm ²/s. Under high pressure, hydrogen atoms diffuse into dislocations and grain boundaries in the metal lattice and accumulate at defects, resulting in a significant decrease in the fatigue strength of the material. The diffusion rate of hydrogen atoms in metals is closely related to temperature and pressure. When the pressure reaches 70 MPa, the risk of hydrogen embrittlement in ordinary low-carbon steel significantly increases, which further increases the challenges in the design and material selection of hydrogen transportation equipment.
The main impacts of hydrogen embrittlement on hydrogen energy storage and transportation processes include: (1) increased risk of material failure. In a high-pressure hydrogen environment, hydrogen atoms can penetrate into the microstructure of metal materials and interact with defects in the material, such as microcracks and grain boundaries, weakening the internal bonding strength of the material. This will increase the brittleness of the material, making it prone to cracking or damage. The increased risk of material failure poses a great challenge to the long-term stability and safety of hydrogen transmission pipelines and hydrogen storage cylinders. (2) Security issues are highlighted. During the storage and transportation of hydrogen, especially under high pressure conditions, if the material experiences hydrogen embrittlement, it may cause hydrogen leakage or even explosion, posing a serious threat to public safety. The phenomenon of hydrogen embrittlement shortens the service life of pipelines and hydrogen storage equipment, increases the risk of equipment failure and safety accidents, and limits the promotion and application of hydrogen energy. (3) Cost increase. In order to prevent hydrogen embrittlement, high cost anti hydrogen embrittlement alloy materials (such as 316L stainless steel or nickel based alloys) are usually used in the hydrogen storage and transportation process to manufacture hydrogen pipelines and hydrogen storage cylinders. Although these materials have good resistance to hydrogen embrittlement, they are expensive and increase the construction and operation costs of hydrogen energy infrastructure. Meanwhile, these materials also face technical challenges during processing and welding, further increasing the cost of equipment manufacturing and maintenance.
1.2 Performance of different grades of pipeline steel in high-pressure hydrogen environment
In the field of hydrogen transportation, different grades of pipeline steel are used according to different application environments and cost control requirements. The following are the performance characteristics of several common pipeline steels and their performance in high-pressure hydrogen environments:
(1) Low carbon steel. Advantages: Low carbon steel has been widely used in industrial pipelines due to its low cost and good processability and weldability. It has good toughness and ductility in conventional environments. Disadvantage: Low carbon steel has poor resistance to hydrogen embrittlement in high-pressure hydrogen environments. Hydrogen atoms are prone to penetrate and aggregate in metal matrices, leading to material embrittlement and cracking, especially under long-term high-pressure conditions. (2) Low alloy high-strength steel (such as X52, X60, X70). Advantages: It has high strength and toughness, and can withstand high pressure, making it a commonly used material choice for medium and high pressure hydrogen transmission pipelines. They exhibit good tensile strength and durability under conventional conditions. Disadvantage: There is also a risk of hydrogen embrittlement in high-pressure hydrogen environments. Although lower carbon content and specific alloy composition can enhance its resistance to hydrogen embrittlement, hydrogen embrittlement may still occur in high-pressure environments, especially with prolonged use. (3) High alloy steel (such as 316L stainless steel, nickel based alloys). Advantages: High alloy steels, such as 316L stainless steel and nickel based alloys, have excellent corrosion resistance and hydrogen embrittlement resistance, and perform well in high-pressure hydrogen environments. Its chemical composition and microstructure can effectively resist the permeation and diffusion of hydrogen atoms, providing good safety. Disadvantages: High price, significant increase in material and processing costs, and limitations on large-scale applications. In addition, these materials are usually heavier than low-carbon steel and low-alloy steel, which increases transportation and installation costs.
Research and development of high-pressure hydrogen barrier coating
To address the issue of hydrogen embrittlement, high-pressure hydrogen barrier coatings are made of biobased polymer composites. By coating a dense structure on the metal surface to reduce hydrogen permeation, the hydrogen resistance of traditional metal materials is improved.
2.1 Material development process
The research and development process of coating materials combines multiple technological innovations. The researchers used particle ordered arrangement technology to form an effective hydrogen barrier through the directional arrangement of polymer matrix. In the laboratory environment, the density and uniformity of the coating were repeatedly optimized, ultimately achieving the minimization of coating thickness (about 30 μ m) while maintaining efficient hydrogen permeation resistance. During the research and development phase, the adhesion and fatigue resistance of the coating were verified through multiple cyclic hydrogen pressure tests (up to 70 MPa).
2.2 Material Performance Testing
The experimental testing is conducted in a simulated high-pressure hydrogen environment, mainly including hydrogen permeability, adhesion, and temperature adaptability testing. The specific data is as follows:
(1) Hydrogen permeation test. Three repeated tests were conducted at 15 ℃ and 55 ℃ under a pressure of 70 MPa, and the results showed that the hydrogen permeability of the coating was 4.4 × 10-16 mol · m/(m ² · s · Pa) (15 ℃) and 2.27 × 10-15 mol · m/(m ² · s · Pa) (55 ℃), respectively. Compared with traditional 316L stainless steel 1.2 × 10-13 mol · m/(m ² · s · Pa), its hydrogen penetration resistance was improved by tens of times. (2) Adhesion test of coating. The experiment showed that under a tensile stress of 30 MPa, the adhesion between the coating and the substrate remained stable without significant peeling. (3) Temperature stability test. The coating material maintained structural integrity during high and low temperature cycling within the range of -40 ℃ to 180 ℃, without cracking or deterioration.
2.3 Performance advantages of coating materials
The high-pressure hydrogen barrier coating is based on advanced bio based polymer composite material technology, which constructs an efficient hydrogen barrier by arranging particles in an orderly manner on the surface of the substrate. Compared to other materials of the same type, this coating material exhibits excellent resistance to hydrogen embrittlement, temperature adaptation range (-40 ℃~180 ℃), and adhesion (over 30 MPa). Coating materials are not only suitable for hydrogen transmission pipelines, but also for various storage and transportation equipment such as high-pressure hydrogen storage cylinders and hydrogen doped natural gas pipelines. Wide temperature adaptability and durability can provide reliable solutions for hydrogen energy storage and transportation in different scenarios.
Traditional anti hydrogen embrittlement materials such as 316L stainless steel and nickel based alloys are expensive. By applying high-pressure hydrogen barrier coatings to ordinary low-alloy steel, the overall cost is significantly reduced. Comprehensive analysis shows that using coated ordinary steel reduces equipment material costs by about 65% compared to using 316L stainless steel, which has significant economic benefits for large-scale hydrogen transportation equipment. In addition to reducing raw material costs, the high durability and fatigue resistance of the coating significantly extend the service life of hydrogen delivery equipment, reducing equipment maintenance and replacement costs. Experimental data shows that coating materials can extend the service life of equipment by 5-10 years, greatly reducing the long-term operating costs of equipment. In addition, due to the excellent adhesion and corrosion resistance of the coating, the maintenance cycle of the equipment can be extended from every 3 years to every 5-7 years, further reducing maintenance and downtime costs during operation.
Analysis of Application Effectiveness
(1) PetroChina Baoshiwei Baoji Steel Pipe Co., Ltd. Project
PetroChina Baoshi Wei Baoji Steel Pipe Company selected X70 grade steel and coated it with high-pressure hydrogen barrier coating in its long-distance hydrogen pipeline project. The project involves a 25 kilometer long pure hydrogen transmission pipeline with a pressure rating of 10 MPa. The application of coatings improves the resistance of pipelines to hydrogen embrittlement, reduces crack propagation caused by hydrogen permeation, and lowers the overall project cost. Compared to the traditional solution using 316L stainless steel, the cost has been reduced by about 60%. (2) The high-pressure hydrogen storage cylinder project of Guangzhou OPR Hydrogen Energy Technology Co., Ltd. adopts Type III hydrogen storage cylinders with high-pressure hydrogen barrier coating on the inner wall, which are used for high-pressure hydrogen storage at 70 MPa. The coating application of this project not only significantly improved the hydrogen permeation resistance of the hydrogen storage bottle, but also achieved a cost savings of about 40% through coating technology. Compared with stainless steel hydrogen storage cylinders, the coating material extends the service life of the cylinder by 5 years and reduces the risk of hydrogen leakage. (3) The hydrogen pipeline project of Xi'an Changqing Oilfield Design Institute has been coated with high-pressure hydrogen barrier coating material, effectively enhancing the pipeline's resistance to hydrogen embrittlement and ensuring the safety and efficiency of hydrogen transportation.
4 Conclusion
The problem of hydrogen embrittlement is the main bottleneck that restricts the safety and economy of hydrogen storage and transportation equipment. Although traditional hydrogen resistant materials such as 316L stainless steel and nickel based alloys have good resistance to hydrogen embrittlement, their high prices greatly increase the construction cost of hydrogen storage and transportation systems. High pressure hydrogen barrier coating materials can be applied to ordinary steel, effectively preventing the penetration of hydrogen atoms, significantly improving the hydrogen embrittlement resistance of ordinary steel, and reducing material costs. The high-pressure hydrogen barrier coating material coated with pure hydrogen transport pipelines is expected to be widely used in large-scale hydrogen storage and transportation, providing an economically feasible solution for the construction of hydrogen energy infrastructure.
Author Profile:
Bao Yi, born in 1999, holds a bachelor's degree and is a technical engineer. She mainly engages in research on the application of polymer materials engineering. Contact information: 17501605667, shtyb-raymond@steeltube-cn.com .
Source: Pipeline Protection, Issue 5, 2024 (Total Issue 78)