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

Research and application of high-pressure hydrogen barrier coatings
Bao Yi Xu Qing
Shanghai Yiyuan Energy Technology Co., LTD

Abstract: Hydrogen embrittlement seriously affects the performance of metallic materials and has become a bottleneck restricting the efficient and safe storage and transportation of hydrogen. 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 tests and practical engineering project applications, the advantages of this material in solving the hydrogen embrittlement problem and reducing the cost of hydrogen storage and transportation have been verified, providing a brand-new solution for the safe storage and transportation of hydrogen.

Key words: Hydrogen brittleness Metal material selection Hydrogen barrier

The cracking caused by hydrogen embrittlement and the microscopic diagram of hydrogen cracks The main impacts of hydrogen embrittlement on the hydrogen energy storage and transportation process include: (1) Increased risk of material failure. In a high-pressure hydrogen environment, hydrogen atoms can penetrate into the microstructure of metallic materials and interact with defects in the materials (such as microcracks, grain boundaries, etc.), weakening the internal bonding force of the materials. This will lead to an increase in the brittleness of the material, making it prone to cracking or failure. The increased risk of failure of this material poses a significant challenge to the long-term stability and safety of hydrogen transmission pipelines and hydrogen storage cylinders. (2) Safety issues have become prominent. During the storage and transportation of hydrogen, especially under high pressure conditions, if the material undergoes hydrogen embrittlement, it may cause hydrogen leakage or even explosion, seriously threatening public safety. Hydrogen embrittlement shortens the service life of pipelines and hydrogen storage equipment, increases the risk of equipment failure and safety accidents, and restricts the promotion and application of hydrogen energy. (3) Increased costs. To prevent hydrogen embrittlement, high-cost anti-hydrogen embrittlement alloy materials (such as 316L stainless steel or nickel-based alloys) are currently commonly used in the hydrogen storage and transportation links to manufacture hydrogen transmission pipelines and hydrogen storage cylinders. Although these materials have good resistance to hydrogen embrittlement, they are expensive, which increases the construction and operation costs of hydrogen energy infrastructure. Meanwhile, these materials also face technical challenges during processing and welding, further increasing the costs of equipment manufacturing and maintenance.
1.2 Performance of different grades of pipeline steel in high-pressure hydrogen environments
In the field of hydrogen transportation, people use different grades of pipeline steel according to different application environments and cost control requirements. The following are the performance characteristics of several common pipe 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 normal environments. Disadvantage: In a high-pressure hydrogen environment, low-carbon steel has relatively poor resistance to hydrogen embrittlement. Hydrogen atoms tend to penetrate and accumulate in the metal matrix, leading to material embrittlement and cracking, especially under prolonged 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, which makes it a common material choice for medium and high-pressure hydrogen transmission pipelines. They exhibit good tensile strength and durability under normal conditions. Disadvantage: It also faces the risk of hydrogen embrittlement in a high-pressure hydrogen environment. Although a lower carbon content and specific alloy composition can enhance its resistance to hydrogen embrittlement, hydrogen embrittlement may still occur under high-pressure conditions, especially as the usage time increases. (3) High alloy steels (such as 316L stainless steel, nickel-based alloys). Advantages: High alloy steels, such as 316L stainless steel and nickel-based alloys, possess excellent corrosion resistance and hydrogen embrittlement resistance, performing exceptionally well in high-pressure hydrogen environments. Its chemical composition and microstructure can effectively resist the penetration and diffusion of hydrogen atoms, providing good safety. Disadvantages: High price, significant increase in material and processing costs, and restrictions on large-scale application. In addition, these materials are usually heavier than low-carbon steel and low-alloy steel, increasing the costs of transportation and installation.
Research and development of high-pressure hydrogen barrier coatings
To address the issue of hydrogen embrittlement, high-pressure hydrogen barrier coatings employ bio-based polymer composite materials. By coating a dense structure on the metal surface, they reduce hydrogen penetration and enhance the hydrogen resistance of traditional metal materials.
2.1 Material development process
The research and development process of coating materials combines multiple technological innovations. Researchers adopted the particle ordered arrangement technology and formed an effective hydrogen barrier through the directional arrangement of the polymer matrix. In a laboratory environment, the compactness and uniformity of the coating were repeatedly optimized, ultimately achieving the minimization of the coating thickness (approximately 30μm) while maintaining highly efficient resistance to hydrogen penetration. During the research and development stage, multiple hydrogen pressure tests (up to 70 MPa) were also conducted to verify the adhesion and fatigue resistance of the coating.
2.2 Material Performance Testing
The experimental tests were conducted in a simulated high-pressure hydrogen environment, mainly including hydrogen permeability, adhesion and temperature adaptability tests. The specific data is as follows
Hydrogen permeation test. Three repeated tests were conducted at 15℃, 55℃ and 70 MPa pressure respectively. The results showed that the hydrogen permeability of the coating was 4.4×10-16 mol·m/(m²·s·Pa) at 15℃ and 2.27×10-15 mol·m/(m²·s·Pa) at 55℃. Compared with the traditional 316L stainless steel at 1.2×10-13 mol·m/(m²·s·Pa), its resistance to hydrogen permeation has been improved by tens of times. (2) Adhesion test of the coating. Tests show that under a tensile stress of 30 MPa, the adhesion between the coating and the substrate remains stable, and no obvious peeling occurs. (3) Temperature stability test. The coating was carried out within the range of -40℃ to 180℃. During the high and low temperature cycles, the structural integrity of the coating material was maintained without any cracking or deterioration.
2.3 Performance Advantages of Coating Materials
The high-pressure hydrogen barrier coating, based on advanced bio-based polymer composite material technology, constructs an efficient hydrogen barrier on the substrate surface through the orderly arrangement of particles. Compared with other similar materials, this coating material performs outstandingly in terms of hydrogen embrittlement resistance, temperature adaptability range (-40℃ to 180℃), and adhesion (over 30 MPa). The coating material is not only suitable for hydrogen transmission pipelines, but also can be applied to various storage and transportation equipment such as high-pressure hydrogen storage cylinders and hydrogen-blended natural gas pipelines. Its wide temperature adaptability and durability can provide reliable solutions for hydrogen storage and transportation in various 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 common low-alloy steels, the overall cost has been significantly reduced. Comprehensive analysis shows that compared with 316L stainless steel, the use of coated ordinary steel reduces the material cost of equipment by approximately 65%, which has significant economic benefits for large-scale hydrogen transportation equipment. In addition to the reduction in raw material costs, the high durability and fatigue resistance of the coating have significantly extended the service life of hydrogen delivery equipment, reducing equipment maintenance and replacement costs. Experimental data show that coating materials can extend the service life of equipment by 5 to 10 years, significantly reducing the long-term operating costs of the equipment. In addition, due to the coating's excellent adhesion and corrosion resistance, the maintenance cycle of the equipment can be extended from every three years to every five to seven years, further reducing the maintenance and downtime costs during operation.
3. Analysis of Application Effects
The project of petrochina Baoshiwei Baoji Steel Pipe Co., LTD
In its long-distance hydrogen pipeline project, petrochina Baoshiwei Baoji Steel Pipe Company selected X70 grade steel and coated it with a high-pressure hydrogen barrier coating. This project involves a 25-kilometer-long pure hydrogen transmission pipeline with a pressure rating of 10 MPa. The application of the coating enhances the hydrogen embrittlement resistance of the pipeline, reduces the crack propagation problem caused by hydrogen permeation, and lowers the total project cost. Compared with the traditional solution using 316L stainless steel, the cost has been reduced by approximately 60%. (2) In the high-pressure hydrogen storage cylinder project of Guangzhou OPR Hydrogen Energy Technology Co., LTD., Type III hydrogen storage cylinders were adopted, with the inner walls coated with high-pressure hydrogen barrier coatings, which were applied to the storage of high-pressure hydrogen at 70 MPa. The application of the coating in this project not only significantly enhanced the anti-hydrogen permeation performance of the hydrogen storage bottles, but also achieved a cost savings of approximately 40% through the coating technology. Compared with stainless steel hydrogen storage cylinders, the coating material extends the service life of the gas cylinders by five years and reduces the risk of hydrogen leakage. (3) In the hydrogen pipeline project of Xi 'an Changqing Oilfield Design Institute, high-pressure hydrogen barrier coating materials were applied, effectively enhancing the pipeline's resistance to hydrogen embrittlement and ensuring the safety and efficiency of hydrogen transportation.
4 Conclusion
Hydrogen embrittlement is the main bottleneck restricting 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 hydrogen embrittlement resistance, 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. By effectively preventing the penetration of hydrogen atoms, they significantly enhance the hydrogen embrittlement resistance of ordinary steel and reduce material costs. High-pressure hydrogen barrier coating materials for pure hydrogen delivery pipelines are expected to be widely applied in large-scale hydrogen storage and transportation, providing an economically feasible solution for the construction of hydrogen energy infrastructure.

Author's Profile
Bao Yi, born in 1999, holds a bachelor's degree and is a technical engineer. He mainly engages in research on the engineering application of polymer materials. Contact: 17501605667, shtyb-raymond@steeltube-cn.com.

Source: Pipeline Protection, Issue 5, 2024 (Total Issue 78)