Detection of hydrogen release

Event

Event ID: 401
Quality: 3
Description: During a filling at a hydrogen refuelling station, the station was shut down due to a gas detection. The leak was extremely small and difficult to locate but the gas was directed upwards towards the gas sensor which shut down the station. The safety equipment performed well as it should and safely shutdown the station. The tiny leak was located about 8 cm from the end fitting in the middle of the hose.
Discovered during inspection.
Event Initiating system: Hydrogen system initiating event
Classification of the physical effects: Unignited Hydrogen Release
Nature of the consequences: leak no ignition
Macro-region: Europe
Country: Norway
Date: 03/12/2012
Component involved: dispenser (hose)
Failure mode: leak, no ignition
Initiating cause: material degradation (generic)
Root CAUSE analysis: It is suspected that the hose failure was due to an extreme temperature swing. It was the first really cold weather we had experienced being between -15 and -18c. The hose was sent back to the manufacturer for testing and no leak was found which was very interesting. The cause was never officially determined but the problem was resolved.
Root causes: Material/ manufacturing error
Environment
Date entry in HIAD: 01/01/2017

Number of fatalities: 0
Number of injured persons: 0
Emergency action: All safety equipment operated as designed and shut the system down.

Lesson Learnt: All safety equipment operated as designed and shut the system down. In fact, if it were not for the hydrogen released, this could be classified as near-miss. Hoses are consumable parts; they damage quickly because they experience frequent pressure cycles characterised by very high pressures differences and temperature gradients. Moreover, they are also subjected to external mechanical stress such as bending and twisting during the filling.