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 safety research laboratory experienced two similar air-actuated ball valve failures in a 6-month period while performing hydrogen release experiments. The hydrogen release system contains a number of air-actuated ball valves which are sequenced by a Programmable Logic Controller (PLC) in order to obtain the desired release parameters. During an experimental release sequence, a PLC valve command failed to open the valve even though the PLC valve position confirm signal indicated the valve had opened. On further investigation, the valve actuator and valve stem were found to be moving correctly, but the valve was not opening. The system was depressurized and purged with nitrogen, and the valve was removed for inspection. Inspection required dismantling the valve, and in both incidents a view more

The hydrogen sensor at a hydrogen fueling station detected a slight leakage from the ground packing of the flow control valve during refueling. The refueling operation was stopped immediately. The leak was stopped by tightening the ground packing sealing screw, but it started leaking again in about a week.

The flow control valve was disassembled and inspected. Dust was found at the ground seal and the packing was distorted. Leakage was believed to be due to the dust invasion and repeated tightening of the sealing screw. The packing had been used for four years and two months without replacement.

The hydrogen fueling dispenser nozzle could not be completely disconnected from the vehicle after refueling. It was finally disconnected after trying several times. The cover of the nozzle interfered with the disconnection operation. No malfunction of the nozzle was found. It can be easily disconnected when it is withdrawn along its axis. Sometimes misalignment occurred due to the weight of the dispenser hose.

A hydrogen reformer furnace at a refinery was shutdown for maintenance to remove and cap the inlet and outlet headers of some radiant tubes that had previously developed hot spots and been isolated by externally pinching them off at the inlet. A decision was made to leave steam in the steam-generating circuit during this maintenance operation to prevent freezing. After maintenance was complete, the startup procedure required the furnace to be first heated up to 350°C (662°F) prior to introducing 4136 kPa (600 psig) steam into the radiant tubes. Just after the 4136 kPa (600 psig) startup steam was introduced into the reformer furnace inlet, the control room alarm journal reported an extreme positive pressure spike at the same time a single loud bang was reported by the operations view more

A hydrogen leak occurred at a plant's hydrogen fill station when a vendor's hydrogen fill truck trailer pulled away after filling and caught an improperly stored hydrogen fill line. The driver of the hydrogen truck trailer did not properly stow the hydrogen fill line after filling and failed to verify that the hydrogen fill line was clear of the trailer prior to departure. As the driver pulled away from the fill station, the hydrogen fill line caught on the trailer and subsequently pulled on the hydrogen fill station's ground storage tubes distribution manifold. The force of this pull bent the plant's hydrogen distribution manifold and hydrogen began leaking from a threaded connection and from the hydrogen fill line. The truck trailer driver reported hearing a view more

Hydrogen and water leakage in the main generator stator cooling water (SCW) equipment forced two separate shutdowns of a nuclear plant in a three-month period. Manufacturer weld defects on the SCW exciter end ring header are the likely cause for the hydrogen leakage.

The first nuclear plant shutdown was initiated in mid-May when an SCW leak internal to the main generator was confirmed. Events that led up to the shutdown decision started three days earlier and included an upward trend in stator coil temperatures. After two days of an elevated temperature trend, an SCW tank high-pressure alarm indicated hydrogen leakage. Per alarm response procedure, the operators vented the tank. Hydrogen leakage was determined to have increased from about 300 to 1400 ft3/day with stator water view more

On July 1, 2009, a plasma experiment was conducted to produce a small quantity of sodium borohydride from anhydrous sodium borate, methane, and hydrogen in an enclosed reaction chamber. The reactants were injected into an argon plasma flame to carry out the synthesis reaction.

After the run was completed, as per work control procedure, the experimenter removed the plasma torch from the top lid of the collection chamber and taped a piece of weighing paper over the opening so air would not get into the chamber and contaminate the product. The experimenter then installed a plastic glove bag over the top lid of the collection chamber and attached it just below the top lid using Velcro. Before final installation, the experimenter placed a screwdriver and a natural bristle paint brush view more

A hydrogen leak occurred from a 1-inch gate valve on a makeup gas line in an oil refinery gas oil hydrotreater unit. When the leak was discovered, the gas oil hydrotreater unit shutdown procedures were immediately implemented and emergency response was requested. The refinery response team along with county response teams responded, and after approximately 1/2 hour, the gas oil hydrotreater unit was fully shut down. Shutdown consisted of sufficiently depressurizing the unit and adding nitrogen to allow safe closing of the leaking 1-inch gate valve and installation of the associated missing bull plug.

During this event, the 1-inch gate valve was found to be open roughly 10% with no bull plug in the valve, allowing the hydrogen to leak to the atmosphere. In addition, a 1-inch bull view more

An instrument engineer at a hydrogen production facility was arresting the hydrogen leakage in tapping a pressure transmitter containing 131-bar hydrogen gas. The isolation valve was closed and the fittings near the pressure transmitter were loosened. The pressure dropped from 131 bar to 51 bar. The fitting was further loosened (though very little); the instrument tube slipped out of the ferrule and got pulled out of the fitting. With the sudden release of the 51-bar hydrogen, there was a loud pop (like a fire cracker) and the spark-proof tool was observed to have black spot on it. The volume of the hydrogen gas released was small, since it was in the tapping line only.

A small research sample of approximately 5 grams of aluminum hydride (alane) doped with 2-3 mol % TiCl3 contained within a glass ampoule ruptured after transit while stored in an office cabinet. The rupture was attributed to over-pressurization caused by hydrogen gas buildup within the sample over a four-month period. The glass ampoule, contained within a 0.2-inch thick cardboard shipping tube, was not a pressure-rated container. The rupture resulted in glass chards penetrating the protective cardboard shipping tube. The aluminum hydride, a fine powder, was released from the shipping tube during the pressure release. The fine aluminum powder leaked from the cabinet and set off a local smoke alarm that brought emergency responders to the scene. No personnel were present in the area when view more