A leak occurred at a of a liquid withdrawal valve of a liquid hydrogen storage tank. The hydrogen escaped at the flange between the valve body and the upper part of the valve (flange with tongue and groove). 40 kg of hydrogen were lost.The accidental release was due to the use of bolts different from those prescribed. By using the wrong ones (old bolts), the bolt material was able to flow at the specified tighteningtorque. This meant that there was insufficient tightening torque, which led to a leak.

The event occurred at the hydrogenation unit of a pharamceutical company. 145 kg of hydrogen were released the atmosphere at the gas circulation pump, due to a maintenance error . A specialist company (third-party company), had replaced the cylinder head of pump, but during assembly they did not re-isntalled the prescribed temperature sleeve for the thermometer (the temperature sleeve is the pressure-bearing element).

The accidental hydrogen release occurred when testing the storage system connected to a PEM electrolyzer. The leak test consisted in filling the storage with hydrogen at step-wise increase of pressure. After the step at 3 bar (0.3 MPa), which did not reveal any leak, the storage was pressurised up to 5 bar (0.5 MPa). At that moment a hissing sound occurred from the storage at the outside of the building indicating a leak.

The incident involves a gas booster provided by a manufacturer. This device is used in the experimental platform of the project to raise the pressure in pipelines from 60 to 80 barg (from 6 to 8 MPa), allowing the gas to flow in a close loop. After 5 weeks of operation, a critical gas leakage through the vent port was detected.At the moment of the incident, the compressor was working with a mixture of hydrogen and methane (H2/CH4 blend 20/80 %v/%v). The booster was sent to the manufacturer for inspection and reparation. Severe damage in the seals of the vent port was found.

A truck-trailer carrying compressed hydrogen cylinders stopped on an autobahn and reported a hydrogen leaking from the cylinders. The highway was immediately closed in both directions. When the fire brigade arrived, the truck had stopped on a hard shoulder, and the driver had al-ready left his vehicle. A pipe was reported to be leaking hydrogen. Fire-fighters closed a valve on the affexted cylinder group to stop the leak.

A fire broke out on a transformer transforming 225,000 V into 15,000 V in a metallurgical plant. This transformer supplies electrical power the site and to a neighbouring factory. In the following three hours, staff brought the fire under control with CO2 extinguishers, the internal emergency plan was activated, and the firefighters ventilated the premises and took readings of the flames using a thermal camera. Meanwhile, however, the shutdown of the electrical installation caused the stop of the operation of an electrolysis unit using zinc sulphate.

This near miss occurred at the at an airport's hydrogen refilling station. Around 4:30 a.m., the hydrogen detector of the station was triggered and a sound and light alarm were activated. The hydrogen filling station was up in safe mode and the hydrogen storage system isolated. The connection pipes were purged via the vent and the power supply cut off. An on-call technician from the company in charge of managing the station arrived at 6:15 a.m., confirmed that the installation has been made safe and stopped the alarm. The leak was located on the compressors filter.

This near miss occurred at an airport's hydrogen refilling station. At 7:35, a hydrogen leak was detected by hearing whistles in the near of a pipe. The operators warned the airport firefighters ten minutes later. Upon their arrival, the firefighters set up a security perimeter of 150 m around the installation. The station is located on the border between the public space and the private space and was surrounded by a fence with a gate accessible only by a code unknown to the emergency services.

This near miss occurred at a depot site with 20 fuel cell buses are operated by a local bus company. A hissing sound was heard coming from a hydrogen tank at the refuelling facility, and the local fire department was alerted.After roughly two hours, the fire brigade managed to close the main hydrogen supply, temporarily solving the problem, and local buses were able to resume their service, but were not able refill their H2 cylinders.

Early in the morning of (3:00 AM), the personnel on one of the companies on site reported a potential pipeline leak just south of the valve station. The potential leak was discovered due to bubbling water in the ditch. No visible hydrocarbon sheen was noted, indicating a probable non-hydrocarbon gas leak. Later in the morning, the personnel tested their area gas pipelines and determined that their company was not the source of the leak. Later on the same day, another company tested their pipelines and determined that their hydrogen pipeline was the source of the leak.