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.

In a refinery, a fire occurred at a new reactor for the vacuum distillate hydro-desulfurization unit. Internal gas (hydrogen, hydrocarbon, etc.) blew from a flange of upper piping in the reactor. It ignited producing 0.5-2 meters high flames.

The explosion and fire happened in a diesel hydro-treatment unit used to desulfurise raw diesel be means of hydrogen.The facility was expected to begin full commercial operations later in 2020.

The fire, 1 m high fire occurred in a pipe at the inlet of the hydrodesulfurisation unit of a refinery. The fire was caused by the leak of the pipe content, hydrogen and diesel fuel. According to the first elements of observation, a leak on a bolted assembly (flange) at the level of an insulation gasket of the reactor would be at the origin of the incident.The fire was detected visually and was located 25 m above the ground. The personnel was evacuated. The operator did not extinguish the flame in order not to generate a hydrogen cloud, which is highly explosive.

A diesel and gas leak (H2, H2S, CH4) occurred in a hydrodesulfurization unit (2,200 t/d). The leak location was on one of the boiler valves of the stabilization column. The released mixture (390 C / 35 bar) ignited, and due to the heat developed also other valves started leaking. The compressor was stopped and the column isolated. The fire was extinguished in 35 minutes.

Although the ARIA report (see references) does not mention it, the unit affected was very probably the oil desulfurisation unit. The release occurred following the rupture of a pipe of 250 mm in diameter. 350 kg were released to the atmosphere in 11 minutes, consisting in 80% of hydrogen, 5% of hydrogen sulfide (H2S) and 4% of water and hydrocarbons. The mixture was both toxic and flammable. H2S detector and explosimeters alarms were triggered and the operating staff cut off the supply. The cloud dispersed but the area of irreversible effects for H2S has remained within the site.

A sudden fire started in the refinery's hydrocracking unit at the hydrogen compressor of re refinery (India).

A fire started in a refinery's gas oil desulfurization unit. The purpose of this unit is to separate sulfur from hydrocarbons and to do so, the latter are raised to 340C in the presence of hydrogen and a catalyst. A gasket would be responsible for the emission of the gas that then ignited.

The leak occurred on the inlet pipe (P=21 bar, T=320C) of the diesel desulfurization reactor of a refinery. Hydrogen and diesel fuel were released in the gas phase. The hydrocarbons contaminates neighbouring fields, local residents are informed.

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.