During an inspection, three potential safety problems were identified concerning the location of a hydrogen storage facility. The hydrogen storage facility is located on a building's roof, which is made of 30-inch-thick reinforced concrete. The following potential safety problems were identified during the inspection:

Leakage of hydrogen gas from the storage facility in proximity to the air intakes of the building's ventilation system may introduce a flammable or explosive gas mixture into the enclosure. Because the hydrogen storage facility, containing four 8,000-scf hydrogen tanks at up to 2,450 psig, is Seismic Category II, a seismic event may result in a hydrogen leak. Furthermore, the pressure relief valves in the hydrogen facility exhaust downward to within 6 inches of the roof in the vicinity of the ventilation system air intakes. It was also noted that six 8,000-scf nitrogen tanks were located in the vicinity of the building's air intakes. Nitrogen leakage and dispersion into the air intakes may lead to incapacitation of the occupants.
A detonation of a hydrogen storage tank may structurally damage and affect performance of safety-related equipment on the building's roof, such as the ventilation system intake and exhaust structure, the emergency pressurization system, and equipment in the building itself.
An explosion of the hydrogen delivery truck that provides hydrogen to the facility through a fill line located at ground level on the wall of the auxiliary building may structurally damage safety-related component cooling water pumps located inside the auxiliary building and in the vicinity of the hydrogen fill line.

Incident Date
Apr 27, 1989
  • Hydrogen Storage Equipment
  • Vessel
Damage and Injuries
Probable Cause
Contributing Factors
When Incident Discovered
Lessons Learned

The hydrogen facility does not meet industrial guidelines for facilities of this type, from the standpoint of (1) the separation distance needed between a hydrogen pipe break and the building ventilation intake to prevent buildup of a flammable or explosive gas mixture inside the enclosure, and (2) the separation distance needed to prevent damage to safety-related structures resulting from the explosion of an 8,000-scf hydrogen tank.

Safety concerns such as hydrogen leaks and storage tank detonations must be considered and used to create effective new construction designs which mitigate the consequences of such events. Existing buildings which house hydrogen storage tanks need to properly analyze all of the risks associated with the use and storage of such systems.