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.

An anhydrous hydrogen fluoride (AHF) lecture bottle spontaneously exploded in a laboratory. No one was injured, but the lab was extensively damaged. The lecture bottle had split along its seam. Its cap and valve assembly were located to the immediate left.

The explosion was caused by hydrogen gas pressure build up in the cylinder. AHF comes in carbon steel cylinders as a liquefied gas under a pressure of 0.9 psi at 70 oF (i.e., the vapor pressure of the liquid). Though cylinders should be passivated with fluorine, which forms a protective coating, over time AHF may slowly react with the iron in a cylinder to form iron fluoride and hydrogen gas. The generation of hydrogen gas may produce cylinder pressures as high as several hundred psi.

Facility management confirmed that a hydrogen gas cylinder did not comply with the limiting condition for operation (LCO) for flammable gas control systems in the lab's safety requirements. Earlier erroneous calculations had shown that a release of the entire contents of the cylinder into the hood could not reach the lower flammability limit (LFL).

The facility manager determined that the LCO was applicable and immediately entered the action statement in the safety system, which required immediate termination of normal operations in the affected wing of the building. Because normal operations had already been terminated in the wing for HVAC maintenance, further efforts to terminate normal operations were not necessary. The hydrogen cylinder was removed from the hood, thus view more

A health physics technician (HPT) discovered that a scaler in an analytical laboratory was out of P-10 gas (90%Ar and 10% CH4). The HPT went to the building where auxiliary gas cylinders are stored. He located a P-10 gas cylinder and turned to search for a hand-cart. There were no hand-carts present, and the technician had to get one from another room. When he returned to the cylinder storage area, he loaded the wrong cylinder. It contained hydrogen gas instead, however, the two cylinders were next to each other and they were basically identical. The empty cylinder was then replaced by the full one and the scaler was purged for several minutes before it was used. The alpha channel worked well, however, the beta channel did not respond. An instrument technician was contacted to identify view more

DESCRIPTION: On a Friday afternoon in 2007 a traffic accident occurred at the corner of two urban streets. Two vehicles were involved. Each vehicle contained a single driver (no passengers). Vehicle 1 was a Fuel Cell Vehicle. Vehicle 2 was a conventional Toyota Camry. Vehicle 1 was traveling west, approaching an intersection with a green light, and proceeded into the intersection. Vehicle 2 was traveling north on a cross street. The driver of Vehicle 2 incorrectly perceived a green light and proceeded into the intersection. The vehicles collided in the intersection.

RESPONSE: The police were coincidentally in the area and able to respond quickly to the site. The vehicles were moved out of the intersection. Vehicle 1 (fuel cell vehicle) shut down upon impact and was pushed out of view more

A five-pound CO2 cylinder being stored in a compressed gas storage cage at a power plant failed catastrophically and became a missile. The cylinder destroyed the storage cage, then struck one of six stationary hydrogen storage cylinders used as emergency make-up for the hydrogen supply system. One of the hydrogen cylinders was broken away from its mounts and moved 10 feet from its original location. The loss of this cylinder severed the manifold tubing, creating a leak path to the atmosphere for the remaining five hydrogen cylinders. The leaking hydrogen gas apparently self-ignited, engulfing the immediate area. The site fire brigade responded and used hose lines from a distance to provide cooling until the hydrogen supply was consumed. The fire was out within seven minutes, and no off view more

An isolated vehicle hydrogen tank needed to be de-fueled, but the standard operating procedure could not be followed because the tank was inoperable and had to be manually vented with a special tool. This intentional release of hydrogen was done outside an R&D facility, but it unintentionally activated two sensors on vehicle bay gas detectors (at 20% LFL) in the adjacent indoor facility. Although each person involved in this activity was qualified to perform the work, the circumstances at the time were unusual.

The cap on a full cylinder of hydrogen was difficult to remove. A wrench was applied to turn the cap. When the cap was turned, a part of the wrench contacted the valve and opened it. Since the cap was still on the cylinder, the valve could not be closed. The area was evacuated until the cylinder had emptied.

Two scientists were changing hydrogen gas cylinders in an analytical laboratory. They were in the process of removing the cylinder cap from the new cylinder when a loud hissing noise occurred and they quickly realized that the tank was leaking. After making a quick attempt to shut off the tank, which was not possible, they left the lab and notified their supervisor.

After checking that everyone was out of the lab, the supervisor paged all staff in the vicinity to immediately evacuate to the staging area. Facility management and ES&H management were notified about the situation, and they contacted the local fire department to respond to the site in case the venting gas was ignited.

The first responders arrived quickly and spoke with facility management and the site view more

The malfunctioning of the non-return valve of the hydrogen compressor caused the pressure between the hydrogen bottle and the compressor to rise up to the maximum allowed pressure of 275 barg. As a consequence, as foreseen by the safety system, the rupture disk of the safety valve broke and the hydrogen content of the gas bottle and the pipe section involved was released on top of the building. The flame was seen for a very short period by a guard, and could have been caused by the following series of events:

Expansion of hydrogen at the end of the exhaust pipe.
Consequent mixing of hydrogen and air up to a near-stoichiometric mixture and increase of gas temperature.
Mixture ignition due to sparks from static electricity generated by gas molecule friction against view more

Forty-six hydrogen cylinders were accidentally charged with air instead of additional hydrogen during recharging operations at a synthetic liquid fuels laboratory. Cylinders were manifolded in batches of 10 or 12 to the utility compressor outside the laboratory. In normal operations, partly used cylinders containing hydrogen at a pressure of 800-900 psi were recharged to a pressure of 2000-2100 psi. Since the contaminated cylinders contained a highly explosive mixture of about 40% hydrogen and 60% air, it was decided to release the compressed gas to the atmosphere outside the building after grounding the cylinders. Two of the cylinders were successfully discharged, but an explosion occurred while the third cylinder was being discharged. Two chemical engineers were killed by the blast, view more