Previous versions of NFPA 55 listed overhead power lines within the separation distance tables with no voltage distinction. The separation distances were 15 ft for GH2 and 25 ft for LH2 for all overhead electrical lines. The current edition of NFPA 2 includes these in overhead utilities; the distance for GH2 and LH2 will vary with pressure and diameter of the hydrogen piping. In practice, high…

The Global Asset Protection Services (GAPS) standard was written 20 years ago for property loss prevention at crowded chemical plants and is intended for existing and new oil and chemical facilities to limit explosion over-pressure and fire exposure damage; thus, the purpose is different than NFPA 2. NFPA distances were based on studies from the 1960s as well as qualitative factors that were…

There is technically no upper limit for GH2 storage listed within the separation distance tables within Chapter 7 of NFPA 2. For LH2, there is a 75000-gallon upper limit for the LH2 storage separation distance tables within Chapter 8 for LH2. 
It’s important to note that many facilities have site specific issues such as large quantities, confinement, and congestion, so it may be…

These distances are based primarily on hydrogen piping releases and resultant vapor clouds and jet flames based on pipe diameter and pressure. It’s important to note that many facilities have issues such as confinement and congestion, so it may be applicable to apply contemporary engineering models to assess risk.

The Panel considers two approaches to be acceptable. 

1. Stainless steel (corrosion resistant) lines embedded in concrete. This keeps the piping out of direct contact with the earth and provides a degree of physical protection from activities such as digging. 
2. Lines enclosed within a PVC sleeve. The PVC sleeve would usually be directly buried but could also be…

The HSP is not familiar with this particular fitting or its potential application in H2 service but can offer engineering judgment. Many similar compression-type swaged fittings are used in H2 service. These fittings must be used within the manufacturer recommendations for pressure, temperature, and fluid service. Deformation is also introduced into stainless steel tubing in other ways, such…

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…