Skip to main content

BLEVE Standoff Distances

Is there a standard analysis or process for determining standoff distances for liquid hydrogen storage that covers issues beyond boiling liquid expanding vapor explosion? Are there other design considerations?

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.

Standoff Distances

Are there better standards or documented best practices for larger hydrogen storage quantities than those in NFPA 2?

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 applicable to apply contemporary engineering dispersion and radiation models to fully assess risk.
ISO TC 197 is actively developing LH2 tank standards based on recent research results in the European program described at http://preslhy.eu/. This process is usually slow because of the many nations involved and time inherently needed to reach the consensus required by the ISO standard development process.

FAQ Category
Submission Year
2024
Month
04

Equipment Spacing

How do equipment spacing and tank orientation requirements in standards such as Global Asset Protection Services 2.5.2 differ from / relate to NFPA 2?

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 deemed successful based on applied experience over the years. A risk informed approach as described within Annex E of NFPA 2 was applied to GH2 separation distances in the 2011 edition. These were further revised in 2020. Similar changes as described in Annex N of NFPA 2 were applied to LH2 distances in the 2023 edition.


These distances are based primarily on hydrogen piping releases as a function of pipe diameter and pressure. Exposures were aggregated into three groups and separation distances applied to each as applicable based on unignited vapor clouds, radiation exposure from jet fires, and overpressure. It’s important to note that many facilities have site specific issues such as large quantities, confinement, and congestion, so it may be applicable to apply contemporary engineering models to fully assess risk.
 

FAQ Category
Submission Year
2024
Month
04

High-Voltage Electrical Lines

What resources are available to better understand the challenges and risks of installing a facility near high-voltage lines? How far away should electrical classification

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 voltage overhead power transmission lines used larger distances for safety, but this was mainly due to the easement required for these lines that would exclude hydrogen (and other) systems. For safety, if a best practice was that if the failure of an uninsulated power line could touch the system, then the lines are too close. The UK has some distance criteria under ENA Technical Specification 43-8 Overhead line clearances.

FAQ Category
Submission Year
2024
Month
04
Subscribe to Site Planning
We are professional and reliable provider since we offer customers the most powerful and beautiful themes. Besides, we always catch the latest technology and adapt to follow world’s new trends to deliver the best themes to the market.

Contact info

We are the leaders in the building industries and factories. We're word wide. We never give up on the challenges.

Recent Posts