The event occurred in an atmospheric pressure tank storing effluents. The plant was in the production phase. The head of the overfill prevention valve located at the top of the tank was thrown a distance of 77 m. The tanks shell was deformed (curved downward) but not leaking. Employees noted a noise similar to the opening of a valve, and a low-pressure alarm in the tank appeared in the control room, despite the fact that the level and temperature were normal.

Two workers were asked to change the piping and support of a feed line into an intermediate storage vessel for hydrochloric acid. The explosion occurred when they opened the gas line and started grinding on the support, The flame propagated back into the tank, causing a second explosion inside. The explosion was caused by the unexpected presence of a considerable amount of hydrogen in the tank. According tot the eMARS and ARIA report (see references) , the hydrogen was formed in a reaction of metal powder traces and the hydrochloric acid, and must have accumulated over a period of two months.

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.

In a plant producing calcium carbide (CaO + 3C -> CaC2 + CO), a dust collector clogged, probably due to the failure of the cleaning device (nitrogen nozzles) which allowed the dust to build a plug.During the procedure of introducing a poker through an inspection hatch at the lower level, a small explosion occurs and a large amount of dust is ejected through the vent. The cloud containing carbon monoxide and hydrogen ignited. The fire spread to the electrical cables supplying the equipment.

In a graphite purification workshop, the cooling circuit of an electric furnace leaks, the water decomposes in contact with materials heated to a temperature of 1,800C; the gas mixture (hydrogen, air...) explodes. The carbon contained in the furnace is dispersed and ignites.

A deflagration occurred inside the tank at the start of grinding operations. The tank had contained sulfuric acid. All preparatory procedures had been properly carried out: neutralisation of residual sludge with carbonate, measurement of oxygen and inflammable gases at various points. The explosion was due to the ignition of approximately 100 g of hydrogen in a dead zone of the tank, which had not been checked with detectors. The hydrogen had been produced by the corrosion of the iron of the tank by the sulfuric acid. The consequences were one dead and 2 severely injured.

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 fire broke out on a worm ("vis sans fin") supplying a conveyor of aluminum. The ignition of the powder on the ground was caused by the flame cutting operation on the worm shell which generated scales. The incandescent Al dust has been then swept by the wind spread to the atomisation tunnels, the sewers and a lost well. The dust and hydrogen formed upon contact with water caused four violent explosions. The fire spread to a stock of Al powder stored in bags and drums.

(WARNING, UNCLEAR IF H2 WAS INVOLVED)The explosion occurred in a chemical reactor tank of a plant (SEVESO low level) manufacturing products for medical imaging. According to the investigation, the reaction casing the explosion concerned only the gas phase, at the dome of the reactor, consisting of oxygen (due to degassing), and a flammable gas a mixture. The investigation has proposed two alternatives:1. The reaction between di-chloromethane (CH2Cl2) and oxygen stated by a electrostatic charge. 2.

In a chemical plant (SEVESO), corrosion on the water side of a cooling exchanger caused water to enter the sulfuric acid and attack the steel in the tank. This reaction produced hydrogen that accumulated in the dome of the tank and caused the explosion.The explosion causes the cover of a 99.2% sulfuric acid tank to open partially. The tank was filled to 300 t of its total 1500 t capacity. The cover opened along the circumference of the tank at the dome / shell fitting. The POI (internal emergency plan) was started.