What materials should be used for gaseous hydrogen piping and tubing?

The use of 300 series stainless steel for piping and tubing of gaseous hydrogen is favored due to its excellent strength, resistance to corrosion, and durability under high pressures, which are critical factors for handling gaseous hydrogen. Hydrogen has a small molecular size that can cause embrittlement in certain metals, but 300 series stainless steel has a relatively good tolerance to hydrogen embrittlement, making it a reliable choice for such applications. Additionally, this type of stainless steel maintains integrity and performance over a wide range of temperatures, further enhancing its suitability for transporting gaseous hydrogen.

Other materials listed, such as aluminum alloys, while lightweight and corrosion-resistant, can be more susceptible to hydrogen embrittlement under certain conditions. Plastic composites may not provide the necessary pressure ratings and chemical resistance when exposed to hydrogen. Copper alloys, on the other hand, are generally not recommended due to their susceptibility to hydrogen embrittlement and potential for corrosion in hydrogen service. Thus, the properties of 300 series stainless steel make it the preferred choice for ensuring safe and efficient handling of gaseous hydrogen.