Double pipes can be used in certain circumstances to reduce the likelihood of external leaks and increase
the likelihood of detection by monitoring the space between the two pipes. Vacuum jacketed piping is
double walled and is used in liquid hydrogen service to provide insulation. While not equipped with gas
detection in the annular space, loss of vacuum is used to indicate an…
The primary safety standards for applicable to this piping in the U.S. are ASME B31.3, B31.12, and NFPA 2. The editions used should be those adopted by the local jurisdiction. Design of an LH2 piping system should always be conducted and reviewed by engineers experienced in cryogenic piping design. The equipment should also be installed per NFPA 2 and NFPA 55. IT is recommended that the piping…
The conversion is based on the condition as determined from a variety of non-destructive techniques which are commonly used for pipeline mechanical integrity programs. Existing natural gas pipelines are frequently evaluated for conversion to hydrogen, hydrogen-natural gas blend, and other fluid services.
The conversion can be done safely if handled with the proper expertise and…
Hydrogen has been transported safely through pipelines for over 50 years. There are dozens of pipeline networks in safe operation globally, with several individual networks that approach up to 1000 miles.
Significant testing and some demonstration projects are underway to ensure safety. Some of the aspects under investigation include compatibility of the pipe and other materials,…
Acceptability of materials is highly dependent on the specific application. Applied stress levels, exposure to contaminants, the operating temperature, the partial pressure, and number and magnitude of material stress cycles are some of the factors that affect material selection. Guidance is provided within documents such as ISO 11114, Gas cylinders - Compatibility of cylinder and valve…
Because cast irons are relatively brittle materials, they should generally be avoided in industrial and
transmission pipeline applications. In low pressure applications like residential distribution piping
systems, the use of cast irons is probably acceptable.
Hydrogen affects the mechanical properties of most materials. For example, hydrogen reduces the
fracture toughness and increases the fatigue crack growth rate in steels. There is a significant amount of
research, analytical work, and codes and standards development being undertaken to improve our
understanding of how these materials can be utilized in pipelines. The results of the…
Several organizations published a paper together on this topic in 2017 (see attached). Based on comparisons with tests and CFD simulations, the following conclusions were drawn:
At least three of the ASME B31 piping codes are logical choices:
Considerations for code selection include:
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