Event
- Event ID
- 432
- Quality
- Description
- During welding of a pipe to an existing header vent system, hydrogen gas was ignited. The adjacent vessels and lines were inerted with helium and a hydrogen detection check did not indicate presence of hydrogen. The cutting was re-started and a hole was made in the header. The area was then cleared to permit a test to be conducted in a separate facility after which work on the header was continued. In striking an arc for welding, ignition of H2 gas exiting from the hole in the header resulted.
[Ordin, NASA (1974)] - Event Initiating system
- Classification of the physical effects
- Hydrogen Release and Ignition
- Nature of the consequences
- Macro-region
- North America
- Country
- United States
- Date
- -
- Main component involved?
- Venting System (Valve)
- How was it involved?
- Internal Explosion (H2-Air Mixture)
- Initiating cause
- Inadequate Or No Purge
- Root causes
- Root CAUSE analysis
- A common hydrogen vent system was used and an upstream hand-operated shut off valve was malfunctioning. Hydrogen continued to leak through that valve into the header.
IGNITION SOURCE was the welding arc.
The ROOT CAUSE can only be guessed as inadequate inspection of equipment.
Facility
- Application
- Non-Road Vehicles
- Sub-application
- Aerospace
- Hydrogen supply chain stage
- Hydrogen Storage (No additional details provided)
- All components affected
- header, vent stack
- Location type
- Unknown
- Operational condition
- Description of the facility/unit/process/substances
- WHAT IS A VENT HEADER?
A gas vent system header is a main horizontal pipe that collects gases from multiple smaller vents, such as those from appliances, storage tanks, or reactors. It is designed to safely transport these gases to a single, larger vent stack or treatment system. This central pipe consolidates emissions, allowing for more efficient control and disposal, and may also be used to direct gas to processes like a flare.
Emergency & Consequences
- Number of injured persons
- 0
- Number of fatalities
- 0
- Post-event summary
- Damage probaly only the cost of the gauge
Event Nature
- Release type
- gas
- Involved substances (% vol)
- H2 100%
- Release duration
- immediate
- Release rate
- n.a.
- Presumed ignition source
- Welding
- Ignition delay
- N
References
- Reference & weblink
Mishap no 72 in <br />
P. L. Ordin, Review of hydrogen accidents and incidents in NASA operations, 1974, NASA TM X-71565<br />
https://ntrs.nasa.gov/citations/19740020344Lowesmith et al., Safety issues of the liquefaction, storage and transportation of liquid hydrogen: An analysis of incidents and HAZIDS, Int. J. Hydrogen energy (2014) https://doi.org/10.1016/j.ijhydene.2014.08.002
Hankinson and Lowesmith, Qualitative Risk Assessment of Hydrogen Liquefaction, Storage and Transportation, FCH JU project IDEALHY, Deliverable 3.10 (2013)<br />
confidential<br />
(accessed October 2025)
JRC assessment
- Sources categories
- ORDIN
