Event
- Event ID
- 388
- Quality
- Description
[Note HIAD validator: this an incident where a hydrogen system was affected, as effect of the initiating event, overpressure of LH2 tank with helium, but it is not a LH2 incident].
The second stage liquid hydrogen tank of the Saturn V rocket ruptured while undergoing tank pressurization tests with helium. No H2 was on board.
The tank pressure was between 22.6 and 23.5 psig at time of rupture.
Extensive damage was done to the test stand and the stage was demolished above the lower liquid oxygen tank bulk head. Considerable fragmentation of the LH2 tankage and forward skirt took place.- Event Initiating system
- Classification of the physical effects
- n.a.
- Nature of the consequences
- n.a.
- Macro-region
- North America
- Country
- United States
- Date
- -
- Component involved
- LH2 tank (stationary)
- Failure mode
- rupture, no ignition
- Initiating cause
- over-pressurisation (wrong operation)
- Root CAUSE analysis
The INITIATING CAUSE was a abnormal stress-induced material failure.
The ROOT CAUSE was caused by a wrong repair/maintenance intervention.
The pressure at which the rupture occurred was well below the design allowed pressure of 38 psig. The failure was considered to be caused by the stress induced by the poor fit of the LH2 fill-and-drain line in conjunction with the pressure applied during the test. Before the incident, a 5-inch gap had existed between the fill-and-drain line and the stage mating attachment. Hydraulic jacks were used to close the gap. Such a preload condition could have created about 28 000 to 35 000 psi hoop stress in the tank wall.
Considering the 12 000 psi stress present from the 23 psig differential pressure in the tank, the total stress in the hoop direction would be from 40 000 to 47 000 psi, well above the design value.- Root causes
- Date entry in HIAD
- 01/11/2025
Facility
- Application
- Non-road vehicles
- Sub-application
- Aerospace
- Hydrogen supply chain stage
- All components affected
LH2 rocket stage tank
- Process temperature range [C]
- cryogenic temperature (below -50°C)
- Process pressure range [MPa]
- low to medium pressure (below 2 MPa)
- Location type
- Open
- Location
- industrial area
- Operational condition
- Pre-event occurrences
Before the incident, a 5-inch gap had existed between the fill-and-drain line and the stage mating attachment. Hydraulic jacks were used to close the gap. Such a preload condition could have created about 28 000 to 35 000 psi hoop stress in the tank wall.
Emergency & Consequences
- Number of fatalities
- 0
- Number of injured persons
- 0
- Post-event summary
Extensive damage was done to the test stand and the stage was demolished above the lower liquid oxygen tank bulk head. Considerable fragmentation of the LH2 tankage and forward skirt took place.
- Emergency action
unknown, probably none
Lesson Learnt
- Lesson Learnt
For a summary of the operation of purging liquid hydrogen systems, and the preferred purging approaches, see H2TOOLS platform at https://h2tools.org/bestpractices/operating-procedures/purging#:~:text=Helium%20is%20used%20because%20at,another%20part%20of%20the%20system.
In-depth data
- Release type
- gas
- Involved substances (% vol)
- He 100%
- Release pressure [MPa]
- 0.26
- Probable IGNITION SOURCE
References
- Sources categories
- ORDIN
- Reference & weblink
Mishap no 47 in
P. L. Ordin, Review of hydrogen accidents and incidents in NASA operations, 1974, NASA TM X-71565
https://ntrs.nasa.gov/citations/19740020344Hankinson and Lowesmith, Qualitative Risk Assessment of Hydrogen Liquefaction, Storage and Transportation, FCH JU project IDEALHY, Deliverable 3.10 (2013)
confidential
(accessed October 2025)Lowesmith 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
