A hydrogen leak occurred on the hydrogen line of a hydro-desulfurization unit, followed by ignition . The failure was located on a supply manifold of the unit at a support beam. The unit was shut down.The accident was caused by external corrosion which had developed at a support point, under the pipe insulation. A regular thinning of the piping was observed over a length of 450 mm on the lower semi-circumference. The maximum thickness loss was 6.5 mm. The mechanical analysis concluded that the operating pressure was sufficient to cause this initial failure in the weakened area.

The truck was carrying 25 m3 of liquid hydrogen and was parked in the parking lot of a road restaurant. The hydrogen escaped through the safety devices of the tank and then dispersed (the weather was wet and there is fog). Technicians from the charter company degassed the tank until the leak stopped, then escorted the truck to a technical centre. A crack in the inner tank causing a pressure build-up could be the cause of the accident.

Hydrogen leaked from an analyser and ignited .On-site staff isolate the leak. As the leak was very quickly isolated, the amount of hydrogen released was negligible. Event no. 35501 of the French database ARIA (accessed December 2020) https://www.aria.developpement-durable.gouv.fr/accident/35501/

Since the release could not be stopped by intervening at the leaking point, the fire brigade decided to vent the whole content of the pallet (246 m3) by gradually opening the valves and by keeping the rack cool. The rack of the bottles was empty after four hours and the rescue operation ends at noon after the cylinder rack has been checked by an expert from the gas supply company. The residents returned to their homes and the plant's activity restarted one hour later.

The station was storing 6,000 litres of liquid hydrogen in ten tanks. Rescue services were alerted and the station's activity is interrupted. The leak was stopped by closing the valves. According to the H2Tools report (see references), a vehicle fill had depleted the high-pressure hydrogen inventory. Consequently, the compressor turned on to refill the storage by compressing 4 bar (60 psig) hydrogen from a liquid hydrogen tank up to the 380 bar (5500 psig) compressed storage tank. After running about 2 hours, a crankshaft bearing started to fail.

The release occurred on a pipeline inside a steam cracking unit located between two hydrogenation units. The gaseous mixture transported through this line (2" diameter, 30 bar, 40C) was composed of 95% hydrogen, 4% methane and 1% nitrogen. The line was located in a rack within the cold sector, at a height of 6 m. The personnel shut down the steam cracker and isolated the sector and the units cuts were sent to the flare system.

Employees were trying to open the manhole cover (600 mm diameter) of a hydrofluoric acid tank with a grinder, when an explosion occurred. The explosion was probably caused by the presence of hydrogen formed by the acid attack of the metal.

The sodium chlorate production unit had restarted after a maintenance shutdown phase. The mercury cells had been under nitrogen flushing since the beginning of the shutdown to avoid the presence of oxygen (prevention of the risk of explosion of the oxygen/hydrogen mixture). Although the ARIA report (see references) does not mention it, the shutdown probably had been caused by a hydrogen leak signal. Around mid-day a new hydrogen leak was detected on the nozzle of a cell collector which had just been repaired.

The syngas leak (hydrogen + methane) occurred at exit of the ammonia production reactor and led to an explosion followed by a fire.The start point of the sequence of events was the syngas at the reactor outlet reaching an abnormal pressure of 150 bar and a temperature of 300C. This caused a flange seal to move, causing the gases to leak. The accident caused a pressure waves and fire observed on the installations over a distance of 450 metres.

A truck driver carrying compressed gas cylinders loaded on pallets stopped on the emergency stop lane of a highway after a tyre burst. The gases transported were: 120 m of oxygen, 24 acetylene cylinders, 106.80 m of hydrogen, 120 m of nitrogen, and 3.6 m of B20 balloon gas. Seeing smoke from an axle, the driver of the vehicle uncoupled and moved the tractor away and warned the emergency services. Firemen were called to stop the fire: they extinguished the fire kept cooled the gas bottles and extinguished the fire two and a half hours later.