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 Panel considers two approaches to be acceptable.
Regarding the concept of introducing hydrogen gas into natural gas pipelines, this is indeed a hot topic and there are recent quantitative treatments of fatigue crack growth driven by pressure cycling and potentially accelerated by hydrogen. Some analysis has shown that it can be acceptable to operate natural gas pipelines with a hydrogen blend. However, this is highly dependent…
Hydrogen cylinders contain pure hydrogen unless they are specifically manufactured for and marked as a mixture. The purity grade is usually between 99.5% and 99.9999%. The balance is typically inert gases (such as nitrogen) with just ppm levels of other contaminants, but this can vary depending upon the production source. When emptied, the residual is still the same purity of hydrogen, just at…
It is possible to store large quantities of gaseous hydrogen above ground, but it will likely require a large footprint due to its relatively low density even at high pressure. Also, if the quantity equals or exceeds 10,000 lb., the facility will need to comply with OSHA 1910.119 process safety management requirements if located in the US. Similar regulations exist in Europe and Asia that…
This production rate of hydrogen of about 96 kg/h is quite significant, which depending upon the application might require a significant amount of storage. There will be a need to determine how many kg the project wants to store from this production rate in order to determine how much hydrogen ground storage is needed. Since the project is in Europe, look for pressure vessel manufacturers that…
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.
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…
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…
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…
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