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.

A battery that was left on a charger over a given weekend was used to start a gasoline power generator. This battery was connected in series with another battery and the connection on the negative post was hand tightened. When an attempt was made to start the generator, the battery exploded on approximately the fifth click of the starter solenoid. No damage was done to any equipment or facilities and no one was injured.

The most probable cause of the accident was the severe overcharging of the battery (64 hours at 20 amp/hour). This charging created hydrogen, which combined with air or oxygen and an ignition source to form the explosion. One source of ignition could have been the loosely attached connection to the battery terminal. Another possible source may have been an view more

During a test run of a hybrid, fuel-cell-powered passenger ship, the on-board lead-acid batteries overheated, resulting a fire in the battery compartment. The local fire department was able to quickly put the fire out.The batteries had been replaced a few days prior from the battery supplier and were in the process of being tested for the first time on the river.The batteries are charged slowly from the fuel cell and the power is made available for cast-off and driving maneuvers.It was systematically confirmed that the fire, which was comparable to a conventional cable fire, posed no risk to the fuel cells or the hydrogen storage tanks. There was never a danger to the captain or crew, and the fire department confirmed that there was never a risk of fire spreading to the other view more

A rupture disc blew on a 20,000-gallon liquid hydrogen tank, causing the vent stack to exhaust cold gaseous hydrogen. Emergency responders were called to the scene. To stabilize the tank, the remaining hydrogen was removed from the tank except for a small volume in the heel of the tank that could not be removed manually. The tank vacuum was lost. Firemen sprayed the tank with water and directed a stream onto the fire exiting the vent stack. The water was channeled directly into the open vent stack, and the exiting residual hydrogen gas (between -423 F and -402 F) caused the water in the vent stack to freeze. The water freezing caused the vent stack to be sealed off, disabling the only exit for the cold hydrogen gas. After a time, the residual hydrogen gas in the tank warmed up, causing view more

Several parties were involved in hydrogen quality sampling when it was discovered that a hose which was being used in the collection process, connecting two sampling components, was not rated for the pressure to which it was being subjected. Upon discovery, the process was stopped, the hose was removed, and an alternate configuration of the equipment was implemented before carrying on the sampling.

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.

During maintenance on a breakaway fitting, a review of the pressure rating of the adapter fitting connecting the pipe to the breakaway found the adapter to be under rated for the design pressure. While the male straight-thread side of the "standard" fitting was rated to 7700 psig, the female compression-tube end of the same fitting was rated to only 4900 psig. The adapter was replaced with a fitting of increased wall thickness meeting the design pressure rating.

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.

A fatal accident took place at an onshore processing facility for slop water from the offshore petroleum industry.

Drilling fluids, or mud, are typically oil-water emulsions consisting of base oil (continuous phase), water (dispersed phase), and emulsifying agents. Used drilling mud, or slop, is mud enriched with water and rock cuttings from drilling --- typically 60-80% water, 10-20% emulated base oil, and 10-20% rock cuttings. The used drilling fluids are collected in slop tanks on oil platforms and later shipped to onshore facilities for further processing.

On the day of the accident, two operators were trying to remove the lid from a manhole on top of a 1600-cubic meter storage tank. However, they were not able to unscrew the rusted bolts holding the lid in place, and view more

Hydrogen was released near the ground when the vent line from a 13,000-gallon liquid hydrogen storage vessel suffered damage from unusually high winds. The toppled vent line did not shear or tear, but sustained a kink that restricted hydrogen flow and created a back pressure on the vessel relief system.

Repair efforts were hampered by the potential for cold hydrogen gas, a flammability hazard, in the work area. Shut off or redirection of the hydrogen was not possible, and variable breezes made set up of safe zones uncertain. A protocol had not been prepared for this scenario.

 

A steel tube with inner diameter of 6 mm and 10 m length was filled with radiolysis gas (stoichiometric H2-O2 mixture) at 70 bar for boiling water reactor simulations. Via a pneumatic valve, a venting line with similar cross-section and 2 m length, filled with atmospheric air, was connected.

For venting the tube, the valve was opened (fast) and an explosion occurred.

Explanation: Due to diffusion ignition in the leading shock, a flame flashed back into the pre-mixed reservoir and induced a detonation there. The tube system and involved measurement technique was destroyed. For safety reasons, the whole installation was set up in a protective container so that no person or other equipment was threatened.