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.

In early afternoon, a northbound tractor-semitrailer with horizontally mounted tubes filled with compressed hydrogen at approximately 2400 psi (166 bar) was struck by a northbound pickup truck that veered into the semitrailer's right rear axle. According to witnesses, the tractor-semitrailer then went out of control and left the roadway, coming to rest approximately 300 feet (91 meters) from the point of impact. As a result of rotational torque and impact, the end of one tube was sheared off at the bulkhead and left the tube bundle. During the process, some of the tubes, valves, piping, and fittings at the rear of the semitrailer were damaged and released hydrogen. The hydrogen ignited and burned the rear of the semitrailer. In the meantime, the pickup truck had also run off the view more

A leaking liquid hydrogen cryogenic pump shaft during the process of filling a gaseous tube delivery trailer to 2400 psi at a liquid hydrogen transfilling location caused a series of explosions and a fire. After approximately 30 minutes of filling, the operator heard a single loud explosion and then saw flames and ripples from heat generation near the ground in the hydrogen fill area. The operator quickly actuated the emergency alarm system that shut down the cryogenic pump and closed the air-actuated valves on the cryogenic pump supply line. After this shutdown, three smaller explosions were heard as well as the sound of gas releasing from a safety relief valve. The fire department was called to the scene and participated in the final shutdown of the hydrogen system as the fire was view more

An explosion occurred at a chemical plant in an analysis room containing various analyzer instruments, including a gas chromatograph supplied with hydrogen. A contract operator was performing work to install a new vent line to a benzene analyzer that was part of a group of CO2 analyzers, but separate and unrelated to the gas chromatograph. During the process of this work, a plant supervisor accompanying the contract operator doing the work had an indication of flammable gas present on a portable detector. This was in conflict with the fixed gas detector in the analysis room that was indicating that no flammable gas was present. As a precaution, the plant supervisor immediately cut off the hydrogen supply and, along with the contract operator, began the normal task of determining if view more

A refinery hydrocracker effluent pipe section ruptured and released a mixture of gases, including hydrogen, which instantly ignited on contact with the air, causing an explosion and a fire. Excessive high temperature, likely in excess of 1400°F (760°C), initiated in one of the reactor beds spread to adjacent beds and raised the temperature and pressure of the effluent piping to the point where it failed. An operator who was checking a field temperature panel at the base of the reactor and trying to diagnose the high-temperature problem was killed. A total of 46 other plant personnel were injured and 13 of these were taken to local hospitals, treated, and released. There were no reported injuries to the public.

Property damage included an 18-inch (46-centimeter) long tear in the view more

A hydrogen alarm sounded when hydrogen buildup occurred in an unmanned switching room containing backup lead acid batteries after the exhaust ventilation fans failed to start at the 1% hydrogen trigger level. Failure of the ventilation fans to vent the normal off-gassing hydrogen from the lead acid batteries resulted in the hydrogen concentration in the room increasing to 2%, which triggered the hydrogen alarm. The alarm was automatically sent to an alarm-monitoring company that alerted the local fire department as well as company personnel of the condition. The fire department was dispatched to the scene and, along with company personnel, provided secondary ventilation to lower the hydrogen concentration to normal conditions. Hydrogen leakage from lead acid batteries is normal, and view more

A pipe rupture occurred in a steam methane reformer (SMR) process that produces hydrogen and export steam. The rupture occurred in a 24-inch diameter stainless steel (SS) pipe used to allow the process gas flow to bypass the high-temperature shift converter (HTS) during start-up. When the pipe ruptured, process gas contained in process equipment located upstream and downstream of the break vented into the SMR plant yard area. The vented process gas was a mixture of hydrogen, carbon monoxide, carbon dioxide, steam, and methane at 550 psig and 650 deg F. The escaping high-pressure gas caused an energy release and subsequent fire. The fire was confined within the SMR plant, but equipment located near the pipe failure was damaged. The SMR plant distributed control system (DCS) worked view more

A previously identified generator hydrogen gas leakage into the stator cooling water system exceeded the predetermined maximum operational allowance and the nuclear plant was shut down from 100 percent power in accordance with plant operating procedures. The leak was identified by monitoring the stator water cooling system detraining tank. Following reactor shut down and generator rotor removal, a small hole was located in the collector end winding area of a slot on the top stator bar. A small particle of carbon steel (estimated to be 2 mm/0.078 inch by 0.6 mm/0.023 inch) is believed to have caused the damage. The source of the carbon steel particle was either foreign material introduced during previous generator internal work or from a phenomenon called "back-of-core burning view more

A 9,000-gallon (34,069-liter) cryogenic liquid hydrogen storage vessel, installed outdoors at a manufacturing plant in an urban area, over-pressurized and released hydrogen into the atmosphere through a safety relief device (burst disk). When the burst disk released pressure, a loud bang was heard by neighbors and reported to the local police. The police investigated and heard the sound of gaseous hydrogen escaping from the vessel's vent stack, which rose approximately 15-20 feet (4.6-6.1 meters) in the air.

Police called the local fire department. Firefighters entered the facility and told employees inside that there was an explosion on the property and they needed to evacuate. As a precautionary measure, some nearby city buildings were also evacuated and the street was view more

Within the International Space Station (ISS) oxygen generator, an increase in differential pressure across a pump supplying return water to a PEM electrolyzer fuel cell stack had persisted over a 4-month period and was approaching the shut-off limit for the system. This decrease in performance was suspected to be caused by water-borne catalyst fines containing platinum black and Teflon®* binder materials, shed by the fuel cell stack, and accumulated within the pump's inlet filter. Maintenance in the field was required.

The system had been designed for factory maintenance, and no contingency had been planned to handle field maintenance for such a circumstance. An initial assessment of hazards for the proposed filter maintenance raised the concern that opening the water line view more

An operation to increase the pressure within a hydrogen tube-trailer to 6000 psig was in progress when a burst disk failed at approximately 5200 psig and hydrogen was released. A vent line attached to the burst disk was not sufficiently anchored and bent outward violently from the thrust of the release over an approximate 4-inch moment arm, causing considerable damage to the adjacent vent system components. The operation is conducted with personnel present, but fortunately no one was in proximity when the burst disk failed.

Following the incident, the damaged portion of the tube bank, consisting of 6 tubes, was isolated by valves on the system manifold. The operation was resumed with the unaffected portion of the tube bank, possessing another 18 tubes, until a second burst disk view more