What is Lessons Learned?

What is H2LL?

This database is supported by the U.S. Department of Energy. The safety event records have been contributed by a variety of global sources, including industrial, government and academic facilities.

H2LL is a database-driven website intended to facilitate the sharing of lessons learned and other relevant information gained from actual experiences using and working with hydrogen. The database also serves as a voluntary reporting tool for capturing records of events involving either hydrogen or hydrogen-related technologies.

The focus of the database is on characterization of hydrogen-related incidents and near-misses, and ensuing lessons learned from those events. All identifying information, including names of companies or organizations, locations, and the like, is removed to ensure confidentiality and to encourage the unconstrained future reporting of events as they occur.

The intended audience for this website is anyone who is involved in any aspect of hydrogen use. The existing safety event records are mainly focused on laboratory settings that offer valuable insights into the safe use of hydrogen in energy applications and R&D. It is hoped that users will come to this website both to learn valuable lessons from the experiences of others as well as to share information from their own experiences. Improved safety awareness benefits all.

Development of the database has been primarily supported by the U.S. Department of Energy. While every effort is made to verify the accuracy of information contained herein, no guarantee is expressed or implied with respect to the completeness, causal attribution, or suggested remedial measures for avoiding future events of a similar nature. The contents of this database are presented for informational purposes only. Design of any energy system should always be developed in close consultation with safety experts familiar with the particulars of the specific application.

We encourage you to browse through the safety event records on the website and send us your comments and suggestions. We will continue to add new records as they become available.

How does H2LL work?

If you have an incident you would like to include in the H2LL database, please click the "Submit an Incident" button at the top of the page. You will be asked for a wide range of information on your incident. Please enter as much of the information as possible. In order to protect your and your employer's identities, information that may distinguish an incident (your contact information, your company's name, the location of the incident, etc.) will not be displayed in the incident reports on H2LL.

Lessons Learned Corner

Visit the Lessons Learned Corner Archives.

Key themes from the H2Incidents database will be presented in the Lessons Learned Corner. Safety event records will be highlighted to illustrate the relevant lessons learned. Please let us know what you think and what themes you would like to see highlighted in this safety knowledge corner. You can find all the previous topics in the archives.

Incident Synopsis
While a hot air dryer was being used to free a coupling in a hydrogen cryostat (an apparatus used to maintain constant low temperatures), a flash fire occurred. The H2 cryostat was being dismantled.

Causes
The temperature at the center of the cryostat was sufficiently low to liquefy air. The prescribed requirements for purging and bringing the cryostat to room temperature were circumvented. The H2 - air mixture was formed and ignition was assumed to be a spark from an open filament of the dryer.

Incident Synopsis
While attempting to replace a rupture disk in a liquid H2 vessel, H2 gas was released and ignited. In fighting the fire, liquid N2 was sprayed onto a second liquid H2 vessel located nearby. This resulted in cracking of the outer mild steel vacuum jacket. The loss of the vacuum caused a rapid increase in pressure and rupture of the burst disk of the second vessel. H2 boiled off and was burned in the fire.

Cause
The rupture disk was being replaced with a load of liquid H2 in the vessel and no separating inerting gas. The H2-air mixture was probably ignited by static discharges. Rupture of the second vessel burst disk was caused by the low-temperature exposure of the mild steel vacuum jacket.

Incident Synopsis
During pressure testing of a H2 tank for investigation of quick-release manhole cover, the tank burst at a pressure between 60-67 psig. Flow regulators indicated peak pressure of 67 psig.

Cause
The tank was over pressurized. A mistake was made in interpreting the blueprint, believing the tank was designed to withstand 150 psig, yet the actual design limit was 50.7 psig.

Incident Synopsis

A hydrogen compressor had been shut down for repairs and was being put back into service when an explosion occurred, resulting in property damage. The compressor was equipped with interchangeable intake and outlet valves.

Cause

The discharge valve was installed in the intake valve position, causing the cylinder head to blow off and release H2 to the atmosphere. The ignition source was not indicated.

Incident Synopsis
A H2 air explosion occurred near a H2 compressor, located outside. Gaseous H2 had been released from a vent stack when a relief valve was actuated. The source of ignition was not known, but considerable damage was inflicted onto the system by the ensuing fire and explosion. Following the explosion, the shut-off valves were closed and the system was vented.

Cause
Two relief valves were located in the 3,000 psig system downstream of a 5,000/3,000 regulator. The relief valves were sized to handle substantially different flows. (One was designed for another program.) The relief valve was believed to have opened when the pressure setting was being increased from 2,700 to 2,900 psig. The accuracy of the 5,000 psig gauge used to control the dome of the 5 view more

Incident Synopsis
A technician was welding a cable suspended over a stainless steel H2 instrument line. During the welding process, two holes were accidentally burned through the hydrogen tubing. The operator heard a hissing sound and closed the valve, but the hydrogen had already ignited and it burned his hand while he was feeling for a leak.

Cause
A short during welding caused the pinholes in the tubing containing the gaseous H2.

NaAlH4 powder mixed with hexane was placed in two metal trays and dried by placement in a glove box antechamber under vacuum. After several days, the trays were moved into the glove box main chamber. As the powder in one of the trays was being transferred to a container involving scraping of a metal sieve and metal milling balls with a metal spatula, a portion of the powder in the tray spontaneously reacted rapidly, creating a pressure pulse which cracked the window at the back of the glove box. No injuries occurred, and the glove box window was resealed using tape within one to two minutes.

Incident Synopsis

A hydrogen explosion occurred in an emergency battery container used to transfer fuel elements. The container had five emergency power batteries. Damage was incurred by the explosion.

Cause

The H2 concentration in the container increased because the battery charger had been left on charge. In addition, the container was placed in an un-ventilated airlock. Ignition of the H2-air mixture was believed to be caused by the relays and micro switches activated when the airlock door was opened.

Incident SynopsisDuring shipping preparation operations, out-gassed hydrogen/oxygen from a recently discharged silver/zinc battery in a hermetically sealed drum was ignited. Ignition was caused by a spark generated by the scraping of the battery against the side of the drum. An explosion occurred, blowing the lid from the drum, charring desiccant bags within the drum, and causing other damage.CauseThe cause of the incident was inadequate handling/transporting/storage techniques. The battery was placed in the drum too soon after discharge.

Incident Synopsis
At an offsite liquid H2 fill station, a liquid hydrogen trailer hit a gaseous H2 purge shut off valve handle. Tubing attached to the purge valve was bent on both ends but did not leak.

Cause
The driver was not sufficiently careful in approaching the liquid H2 system fill point.