Explosion in the Storage of a Hrs
A major leak (estimated between 1.5 and 3 kg) of hydrogen from high-pressure storage, resulted in a detonation, from hydrogen a refuelling station.Causes were two untightened bolts securing the gasket between the high-pressure tank and the pipeline. Gasket held for over 2 years against 900 bar pressure before eventually giving way due to fatigue induced by pressure oscillations during refuelling.Specific tank was the one closest to the ground; after breaching the high-pressure gasket, hydrogen quickly broke through the low-pressure gasket and rapidly leaked to atmosphere, forming and explosive cloud.The untightened bolts were blamed on faulty assembly by manufacturer NEL, who took responsibility. They enacted new procedures, similar to the aviation industry, to ensure such a mistake would not occur again.Damage to surrounding buildings (65 m away) indicate that a detonation occurred. The HRS was by a busy roundabout at the outskirts of Oslo on a day when Norwegians were driving home from holidays.Two car drivers were checked in at hospitals after their airbags opened due to the shockwave, but there were no direct damages to people; injuries were light.Neighbourhood was alarmed by the loudness of the blast, which was heard in a large area; one dog panicked and jumped from a balcony at the fourth floor of a neighbouring building.NEL shut down immediately all similar plants worldwide pending inspection on bolts. Station operator Uno-X has after 10 months not yet reopened their hydrogen stations, and may have been permanently swayed against the technology.
Event Date
June 10, 2019
Record Quality Indicator
Region / Country
Event Initiating System
Classification of the Physical Effects
Nature of the Consequences
Cause Comments
Immediate cause for the release were two not properly tightened.Root cause was Human error during assembly. The two bolts were screwed in place by hand, but not tightened.Unexpectedly, pressurization did not cause gasket to fail immediately, which made the system pass inspection. Gasket held against 900 bars for over 2 years before eventually failing to fatigue.Monitoring system was not programed to detect leaks by monitoring abnormal pressure loss in high-pressure tank.
Facility Information
Application Type
Application
Specific Application Supply Chain Stage
Components Involved
Hydrogen stationary storage, hydrogen refueling station
Storage/Process Medium
Location Type
Location description
Inhabited Area
Pre-event Summary
Refueling station in the open. Storage confined by fence. No roof present.Event occurred shortly after a refueling, as the compressor started refilling the high-pressure tank.The increase in pressure caused an uncompressed gasket to fail after 2,5 years of operation.For a short time during the event, the leak could have been detected by an abnormal pressure loss in the high-pressure sensor, but this had not been implemented as a trigger to an alarm.
Currency
Lessons Learned
Lessons Learned
The system passed inspection, but was not safe. The gasket was far more resilient than assumed, and hid a faulty assembly for over 2 years.High-pressure components need to follow precise procedures for assembly, with double witnesses.Manufacturer of the storage system enacted strict protocols for assembly with double-witness (as in aviation industry).A more robust design of the outer perimeter of the refuelling station would shield members of the public from projectiles would presumably be a good start.
Event Nature
Emergency Action
17:30 Hydrogen leaked from tank and ignited 17:37 First emergency responders on the scene17:40 Nel receives first report of the incident 17:41 E18 and E16 closed 17:47 Security zone of 500 meters established19:28 Robot used to cool down site 20:14 E18 in Sandvika is open for traffic20:14 Fire department confirms fire under control
Emergency Evaluation
Estimation is up to 3 kg of hydrogen leaked over few seconds. Fire continued on station equipment.
Release Type
Release Substance
Hydrogen Release Concentration (%)
100.00
Release Amount (kg)
3.00
Release Pressure (bar)
900.00
Ignition Source
Detonation
No
Deflagration
No
High Pressure Explosion
No
High Voltage Explosion
No
Flame Type
Source Category
References
References
FC Bulletin, July 2019
Manufacturer report statement (Published: 27 June, 2019; Updated: 29 June, 2019) https://nelhydrogen.com/status-and-qa-regarding-the-kjorbo-incident/ (accessed June 2020)
FCBulletin June 2019