The vessel affected by the incident was a gas storage used for the desulfurisation process. The desulfurization gas had high hydrogen content. The vessels had cracks in the upper transverse fillet welds at the gas inlet which caused low stress brittle fractures. The cracks had been found during the maintenance, but not fixed. This eventually caused a gas release. Approximately 2.5 hours after that a leak was detected and reported, a first explosion occurred.

While filling a 9 litre gas cylinder with pressurised hydrogen in the hydrogen storage area, a blast occurred which destroyed the low pressure gauge, followed by a jet fire which damaged the surface of the cylinder.The cylinder to be filled, including pressure gauge and control system, had been provided by a third party. Its nominal pressure was 35 MPa, however the maximal pressure of this filling would have been much lower, less than 20 MPa, corresponding to the maximal pressure of the bulk storage available.

During the shipments of incinerator bottom ash, flammable gasses including hydrogen generated and caused two explosions. The first explosion was in the forecastle store and the second in the cargo hold.The vessel was loaded with a cargo of 2333 tonnes of unprocessed incinerator bottom ash. The chief engineer, who was inside the forecastle store at the time, suffered second degree burns and was airlifted to a nearby hospital.

This incident occurred in a unit processing vegetable oils and fats. A fire-brigade from the involved town was at the scene in a few minutes and was assisted by the Fire Department of a bigger city. Approximately one hour later the fire was extinguished. An employee of a contractor was injured when he fell from a scaffold, and two truck drivers were examined as outpatients. The results of the internal investigation is not publicly available.

The hydrogen buffer tanks that exploded were part of an experimental facility experimenting generation of renewable hydrogen from a water electrolyzer coupled to solar panels.The three hydrogen tanks (40 m3 capacity each at pressures of 1,2 MPa one of them and 0,7 MPa the two others) were receiving the hydrogen produced by the electrolyzer. Firefighters said all three tanks were destroyed in the explosion; there was no fire, but the explosion was strong enough to send debris being scattered in an area well over 3,000 square meters.

Explosion in a fine organic chemical plant (Seveso classified )The event occurred during the cleaning of a reactor. At the completion of a batch manufacturing of a soft reducing agent, an operator was rinsing the 3000-litre reactor first with a solvent and then with a water jet . Noticing a smoke release, they informed their team leader, who opened the manhole of the reactor. This action caused a flash type explosion at the reactor entrance. According to the ARIA report (see references), the rinsing water reacted with sodium hydride (NaH) residues on the reactor walls to form hydrogen.

The fire broke out in the acid etching tank of the ferric chloride manufacturing unit of a SEVESO-classified chemical plant. In this tank, the attack reaction of the iron metal with hydrochloric acid in solution is carried out, which results in ferrous chloride and hydrogen. The hydrogen generated is swept away by a large supply air fan to maintain the gaseous sky of the tank below the LFL. A few days after the accident, the operator opened and analysed the tank to determine the origin of the fire.

The event occurred in a university research building dedicated to the study of the take-off of space launchers . An operator gave the alarm during the hydrogen pressure pre-setting phase. he had seen on the video surveillance screen a flame at a pressure regulator on the line located on the walkway above the test hall.

The accident occurred during the night during the production of a silicon oil- and additive-based waterproofing agent. A junior technician (hired 6 months back), recently assigned to this post, was left without supervision to manage a process modified very recently and executed only for the second time. In the process, the order of addition of reactants was not specified. The technician loaded first 800 kg of oil into the tank at first floor, started heating the reactor, and descended to the ground floor to pump the reagent.

The event early on a Saturday morning, when the plant was thus practically empty. Nevertheless, the chronology of the accident can be reconstructed from the testimonies of the few operators who were present at the time:Phase 1: Gas leak - Loud whistling from the hydrogen storage facility could be heard , lasting 20 to 40 seconds.Phase 2: Explosion - The released hydrogen cloud ignites. A very bright, red-orange fireball measuring 15 to 20 m in diameter was visible for 3 minutes. Witnesses in a common room, located 100 m away from the pit, felt the shock wave and the heat from the blast.