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 process area alarm activated. The alarm was caused by an instrument channel located above a reaction vessel off-gas system final HEPA filter canister, which indicated 25% of the lower explosive limit (LEL) for hydrogen. Since the only source of hydrogen is from the reaction vessel during the reaction of sodium with concentrated sodium hydroxide, the immediate actions were to shutdown the reaction process and place the facility in a safe condition.

The root cause was inadequate or defective design. Had the pre-filter drains been vented to outside the building, no hydrogen could accumulate in the process area. The corrective action for this is to complete an Engineering Task Authorization (ETA) to install a sample/drain collection system with loop seals to prevent any release of view more

A temperature excursion occurred in a sealed environmental chamber during a 0°C ambient temperature test. An elevated temperature in the chamber resulted in a small fire that was confined to the environmental chamber. Visual observation indicated no damage to nearby equipment, including nearby computer cables.

A committee was assembled with the task of identifying the cause of the incident. The committee concluded that the fire was caused by failure of the heater control system for the environmental chamber. The failure of the heater control system caused the chamber temperature to eventually exceed 200°C. As the chamber temperature increased, plastic materials and electrical insulation present in the chamber started to decompose. A battery scheduled for testing was also located view more

A control room received a tank lower flammability limit (LFL) analyzer low sample flow alarm. The control room operator initiated the appropriate alarm response procedure and the facility entered limiting conditions of operation. At the time of the alarm, the facility was experiencing severe weather and the field operator was unable to investigate the alarm in the field. After the severe weather cleared, the field operator investigated the alarm and found the sample flow to be low and out-of-limits.

At the given facility, composite lower flammability limit (CLFL) monitors are used to detect the presence of hydrogen and other flammable gases in waste tank vapor spaces. Maintaining the concentration of flammable vapors in tank vapor spaces below CLFL levels maintains tank view more

While research staff were working in a lab, a staff member opened the primary valve to a 0.2" (1500 psi) hydrogen gas line connected to a manifold supplying instruments in the lab. Upon opening the valve, the hydrogen gas line failed at a fitting on the switching manifold, releasing a small amount of hydrogen gas. The staff member closed the valve immediately, then inspected the gas line and found the front ferrule (of the compression-style fitting) to be missing. There were no injuries or damage to equipment.

In the follow-on discussion with research staff, it was learned that approximately one month earlier, a similar condition (front ferrule missing from a fitting) was found while performing a modification to a similar manifold. Following a critique, management expressed view more

A deficiency was discovered in the application of a hydrogen sensor in the Rotary Mode Core Sampling (RMCS) portable exhauster. The sensor is installed in the flow stream of the exhauster designed to be used with a RMCS truck for core sampling of watch list tanks, and is part of the flammable gas detector system. During the previous week, a quarterly calibration of the sensor, per maintenance procedure, was attempted by Characterization Project Operations (CPO) technicians. Ambient temperatures during the sensor calibration were approximately 20 to 30 degrees F. Inconsistencies in calibration results and the failure of the sensor to meet the response-time calibration requirement lead to the conclusion that the unit could not reliably perform its safety function at low ambient view more

Several workers sustained minor injuries and millions of dollars worth of equipment was damaged by an explosion after a shaft blew out of a check valve. The valve failure rapidly released a large vapor cloud of hydrogen and hydrocarbon gases which subsequently ignited.Certain types of check and butterfly valves can undergo shaft-disk separation and fail catastrophically or "blow-out," causing toxic and/or flammable gas releases, fires, and vapor cloud explosions. Such failures can occur even when the valves are operated within their design limits of pressure and temperature. Most modern valve designs incorporate features that reduce or eliminate the possibility of shaft blow-out. However, older design check and butterfly valves, especially those with external appendages such view more

An operator went to purge a process tank per standard operating procedure. The operator reviewed the previous shift's purge time and determined the next required purge time. The operator found that the tank had been purged earlier than expected on the previous shift. Because the earlier purge time was not recognized, the 12-hour purge frequency was exceeded.

Background: On the previous day, during the night shift, an operator performed 12-hour hydrogen purges per the requirements of the standard operating procedure. Each of the hydrogen purges was completed within the required time limits. The operator correctly recorded the time and date that the next hydrogen purges would be required. The following morning, shift turnover was conducted. The direct and root cause of this view more

The valve stem for a funnel valve to a solution neutralization tank was found to be separated from the body of the valve. This valve is used for purging hydrogen gas from the vessel. The functional classification of this valve is safety-significant. The "as-found" condition of the affected valve prevented the valve from performing its intended design function.

The affected valve is a one-half inch polyvinyl chloride (PVC) ball valve. The valve has an extension shaft coupled to the valve body, and the valve handle is coupled to the extension shaft, allowing the valve to be operated outside the process panel cover. The valve stem is cross-drilled and the extension shaft is pinned through the stem.

With this occurrence, engineering evaluated the one-half inch PVC view more

A demolition technician noted an elevated combustible gas lower explosive limit (LEL) on a pipe that was being tested prior to cutting (No. 2 pipe). The No. 2 pipe was one of four pipes being tested. The other three pipes tested less than detectable for combustible hydrogen gas. Testing involves tapping the pipe and connecting the pipe to an Explosive Gas Detector via a tube. When an elevated LEL is identified, the pipe is allowed to vent and then retested prior to cutting. After tapping the No. 2 pipe, the work crew left the pipe open to vent and departed the area for the end of shift.

At approximately 7"45 PM on the same day, a crew was on overtime to support roofing activities. Since additional workers were available, the craft supervisor decided to re-enter the viewing view more

During inspection of a hydrogen make-up compressor, it was discovered that a 1/4” stainless steel screw and nut that mounted a temperature gauge to a stainless steel pipe was resting against the side of a schedule 160 high-pressure hydrogen pipe. Constant vibration of the process equipment had caused the bolt to rub a hole in the high-pressure suction piping, resulting in the release of make-up hydrogen. The pipe was out of sight, and the problem was identified by an employee who heard the whistling sound of escaping hydrogen. The compressor was taken offline and depressurized.