Each installation should be evaluated based on the results of a hazard analysis considering both of these
scenarios. Separation distances as listed in documents such as NFPA 2, Hydrogen Technologies Code, are
a minimum starting point but may need to be adjusted based on analysis. Recent work by NFPA 2 has
also included overpressure criteria, but the consequences can vary depending on…

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…

Documents such as NFPA 2, Hydrogen Technologies Code, and the International Fire Code have quantity thresholds that differentiate requirements for the design of systems and enclosures. However, even the smaller quantities present a hazard under specific conditions, especially for systems that have the potential to release hydrogen into a confined or unvented space. Good engineering judgement…

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,…

Requirements for TPRD/PRD’s depend on the local regulations. Some jurisdictions require them, some do not. Others make them optional based on results of performance testing.

This is a complicated subject. Thermally activated pressure relief devices can be an important safeguard for hydrogen vessels if properly designed and installed in accordance with code requirement. Requirements vary globally and often depend on the type of vessel and its intended service (e.g. mobile or stationary). However, as with any device, TPRD’s offer both advantages and disadvantages.…

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…

Dispersion and radiation analysis should be conducted to ensure that the hydrogen cloud will not interfere with the flight path of aircraft. In addition, there may be maximum height requirements due to airport requirements depending on the location of the stack.