Small LH2 leak during transfer

Event

Event ID: 66
Quality: 3
Description: The driver of a liquid hydrogen tanker noticed a small plume at the rear while traveling on a highway. He pulled over and found that the manual vent valve had opened due to vibration. The valve was tightened and no further incident occurred during the rest of the trip. The vent valve was thoroughly inspected upon arrival back at the base terminal, but no problem could be found.
Event Initiating system: Hydrogen System Initiating Event
Classification of the physical effects: Unignited Hydrogen Release
Nature of the consequences: Leak No Ignition (No additional details provided)
Macro-region: North America
Country: United States
Date: 10/02/1990
Main component involved?: Flange (Bolts)
How was it involved?: Leak & Formation Of A Flammable H2-Air Mixture
Initiating cause: Loss Of Tightness (Road Vibrations)
Root causes: System Design Error
Root CAUSE analysis: INITIAL CAUSE was the opening the manual vent valve due to vibration.
The ROOT CAUSE was probably a design which did not took into account the whole range of mechanical solicitations which the pressure control system of the tanker could experiment when travelling.

Application: Hydrogen Transport And Distribution
Sub-application: LH2 tanker
Hydrogen supply chain stage: Hydrogen Transfer (No additional details provided)
All components affected: vent valve
Location type: Open
Operational condition: Normal

Lesson Learnt: This incident is very similar to other, such as the HIAD_070, which attributed to road vibrations the opening of the vapour return valve.

Reference & weblink: Event incident ID I-1990040021 of the PHMSA database (Pipeline and Hazardous Materials Safety Administration, 1996),<br />
https://portal.phmsa.dot.gov/analytics/saw.dll?Portalpages<br />
(accessed September 2024)