what the ASME B31.12 think about the use of hydrogen in 304L pipelines

ASME B31.12 is the American Society of Mechanical Engineers' code for the design and construction of hydrogen pipelines. While I can't access specific or proprietary content from ASME, I can provide a general overview of the considerations around using 304L stainless steel for hydrogen service based on existing knowledge up to my last update. 304L stainless steel is known for its good corrosion resistance and is often used in various piping applications. However, when it comes to hydrogen service, several factors must be considered: 1. **Hydrogen Embrittlement**: Stainless steels, including 304L, may experience hydrogen embrittlement, which can lead to reduced ductility and toughness, increasing the risk of cracking under certain conditions. 2. **Service Conditions**: The suitability of 304L for hydrogen service can depend on the specific temperature, pressure, and concentration of hydrogen. Elevated temperatures can exacerbate issues related to embrittlement. 3. **Leakage and Permeation**: Hydrogen is a small molecule that can permeate through many materials, including metals. This characteristic can lead to safety concerns and affect the integrity of the pipeline. 4. **Material Selection**: ASME B31.12 provides guidance on material selection for hydrogen piping systems. It may recommend specific grades or types of materials better suited for hydrogen service that can resist the effects of hydrogen, particularly at high pressures. 5. **Welding and Fabrication**: The welding procedures and methods used to join 304L pipes can also impact their suitability for hydrogen applications. Special consideration might be needed to mitigate the risk of cracking during fabrication and in service. In conclusion, while ASME B31.12 allows for the use of certain materials in hydrogen pipelines, including stainless steel, it emphasizes careful evaluation of the potential risks, including those related to hydrogen embrittlement and permeation. Consulting the full ASME B31.12 code and related standards for detailed requirements and recommendations is crucial when designing a hydrogen pipeline system.