Is It Feasible To Use Carbon Steel Pipes for Hydrogen?

It is feasible to use carbon steel pipe for hydrogen, but attention should be paid to the permeability of hydrogen and its corrosion to carbon steel, as well as the requirements for pipe selection, design, manufacturing and installation.

Characteristics of hydrogen and its requirements for pipes

Hydrogen is a colorless and odorless gas with a density lower than that of air, and has strong permeability and diffusivity. During transportation, hydrogen can easily penetrate through tiny gaps and defects in the pipe, causing safety hazards. Therefore, for hydrogen transportation pipes, excellent sealing and anti-permeation properties are required.

In addition, hydrogen has a certain degree of corrosiveness to metals, especially under high temperature and high pressure conditions, which may cause corrosion and damage to the pipe. Therefore, the selection of pipes also needs to consider their corrosion resistance.

Material characteristics of carbon steel pipes

Carbon steel pipes are a commonly used metal pipe, including seamless steel pipe and welded steel pipe, with excellent mechanical properties and processing properties. In hydrogen transportation, carbon steel pipes can meet the needs of hydrogen transportation through reasonable material selection, design, manufacturing and installation measures.

However, it should be noted that the corrosion problem of carbon steel pipes in hydrogen environments cannot be ignored. In order to reduce the risk of corrosion, alloy steel pipes or coated steel pipes with better hydrogen corrosion resistance can be used.

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Conditions for the use of carbon steel pipes for transporting hydrogen

‌1. Pipeline material selection‌: Carbon steel pipes should be seamless steel pipes, and the inner wall should be rust-free to its original color. When welding the pipeline, carbon steel pipes should be primed with argon arc welding to prevent welding slag, rust, etc. from remaining in the pipeline‌.

2. Connection method‌: Hydrogen pipelines should be connected by welding, and other connection methods are potential sources of leakage. However, the connection with equipment and valves can be flanged or threaded, and polytetrafluoroethylene film should be used as filler when threaded. ‌

3. Valve selection‌: Ball valves and globe valves should be used for hydrogen pipeline valves. When the working pressure is greater than 0.1 MPa, gate valves are strictly prohibited. When there is alkali in the electrolytic hydrogen, the valve material cannot be copper alloy‌.

4. Anti-leakage measures: Hydrogen pipelines should avoid passing through trenches, sewers, railways and roads, etc., and casings should be installed when they should be passed through. Hydrogen pipelines must not pass through living rooms, offices, power distribution rooms, instrument rooms, stairwells and other rooms where hydrogen is not used. They should not pass through suspended ceiling technical (mezzanine) layers. Safety measures should be taken when passing through suspended ceilings and technical (mezzanine) layers.

5. Anti-static and lightning protection measures: To prevent lightning induction, leakage current and static electricity accumulation, metal pipes and metal frames, cable metal casings, and both ends of outdoor overhead hydrogen pipelines and metal pipe racks should be grounded. Metal wires should be used to cross-connect pipe flange, valves and other connections.

6. Environmental adaptability: Hydrogen pipelines should avoid passing through rooms where hydrogen is used. Cut-off valves should be installed at hydrogen entering workshops and branches of hydrogen equipment. Hydrogen equipment with open flames should also be equipped with flame arresters.

7. Safety inspection: When checking for leaks at connection points such as hydrogen equipment, pipelines and valves, neutral soapy water or a portable combustible gas detection alarm should be used. It is forbidden to use open flames for leak inspection.

In practical applications, it is also necessary to select appropriate pipe specifications and types based on the hydrogen delivery volume, pressure, temperature and other parameters. At the same time, the quality of the pipe manufacturing and installation process must also be strictly controlled to ensure the integrity and reliability of the pipe.

Summary

In summary, it is feasible to use carbon steel pipes for hydrogen, but attention should be paid to issues such as hydrogen permeability and corrosion to carbon steel. In practical applications, appropriate pipe types, specifications and manufacturing and installation methods should be selected according to the characteristics and transportation requirements of hydrogen to ensure the safety and reliability of hydrogen transportation. At the same time, with the continuous development of technology and the emergence of new materials, the choice of hydrogen transportation pipes will be more abundant and diversified in the future. For specific hydrogen transportation projects, detailed evaluation and testing should be carried out in combination with actual conditions to ensure the rationality and effectiveness of pipe selection. In addition, sufficient attention should be paid to the maintenance and inspection of the hydrogen transportation system to promptly discover and deal with potential safety hazards and ensure the long-term stable operation of hydrogen transportation.