Hydrogen Explosion on the Hydrogen Storage Facility of a Pharmaceutical Plant
The event early on a Saturday morning, when the plant was thus practically empty. Nevertheless, the chronology of the accident can be reconstructed from the testimonies of the few operators who were present at the time:Phase 1: Gas leak - Loud whistling from the hydrogen storage facility could be heard , lasting 20 to 40 seconds.Phase 2: Explosion - The released hydrogen cloud ignites. A very bright, red-orange fireball measuring 15 to 20 m in diameter was visible for 3 minutes. Witnesses in a common room, located 100 m away from the pit, felt the shock wave and the heat from the blast. The hydrogen in the associated tanks also burned completely.
Event Date
October 1, 1988
Record Quality Indicator
Region / Country
Event Initiating System
Classification of the Physical Effects
Nature of the Consequences
Causes
Cause Comments
The immediate cause of the event was the sudden mechanical failure of the storage cylinder due to hydrogen embrittlement. The root cause is probably to be found in operation and organization dimensions, but the company had recycled the cylinder without any documentation of its previous history. Possibility of embrittlement and the fatigue stress due to pressure cycling had not been taken into account. Thus also lack of a properly performed risk assessment.
Facility Information
Application Type
Application
Specific Application Supply Chain Stage
Components Involved
gaseous hydrogen storage, steel cylinder
Storage/Process Medium
Location Type
Location description
Industrial Area
Pre-event Summary
The affected tank had been recycled, but the previous operative history was unknown.
Currency
Lessons Learned
Lessons Learned
Several factors contributed to the hydrogen embrittlement of the steel in this accident:A) The pressure contributing to the hydrogen sorption phenomenon on the surface of the steel;B) The purity of the hydrogen gases used could even be a determining factor that triggers the hydrogen embrittlement phenomenon. The gas used on the site had a very low oxygen content (0.5 ppm) which can aggravate the hydrogen embrittlement phenomenon. Oxygen helps inhibit this phenomenon;C) The level of stress of the cylinder's casing against its support structure, the cylinder being used as an accumulator;D) The mechanical performance characteristics of the cylinder's steel;E) The lack of information related to the previous operative history (age, cycles numbers, pressure ranges) of the tank.F) The operating conditions for a pressure vessel, particularly when used as an buffer tank, should be designed and assessed considering fatigue phenomena.
Event Nature
Emergency Action
The fire brigade was called, and the unit was shut down via an emergency stop switch. Upon their arrival they saw that approximately 2/3 of the pit was on fire; and a flame front ranging from 3 and 4 m in height.The pit was flooded with foam. and the hydrogen line supplying the storage facility isolated.
Release Type
Release Substance
Hydrogen Release Concentration (%)
100.00
Release Amount (kg)
12.00
Release Pressure (bar)
150.00
Ignition Source
Ignition Delay (s)
20
Detonation
No
Deflagration
No
High Pressure Explosion
No
High Voltage Explosion
No
Flame Type
Source Category
References
References
Detailed investigation report