Crude oil, during the extraction phase, is always rich in light hydrocarbons and often in sulphured hydrogen. Methane does not get wasted, but is collected in pipes to be depurated and distributed.
These applications are usually carried out in the sea and on earth installations. Platforms, perforation systems, oil pipelines terminals, refineries, oil pipelines and transport both during exploration and production, stock tanks, silos, tunnels, and tanks are all at high risk of explosion, H2S and lack of oxygen. Leaks close to valves, flanges, welding works, tanks cleaning and repair process, can be dangerous. Rust on big steel structures indicates a reduction of oxygen, if in limited spaces without aeration possibilities.
Flammable gases: naturally there are gases or vapours deriving from the regular activity of the system. Their presence due to any type of breakdown or accidental leak puts this place among the most dangerous.
Sulphured hydrogen (H2S): it is present in great quantity since it is a product of the decomposition of crude oil.
Lack of oxygen (O2): it can be caused in closed places by the presence of other gases or by the reduced or worsened aeration conditions.
Inflammable gases: in smaller concentration even than LEL with regard to the volume they explode in presence of a minimum flash source resulting in often serious consequences for people and things.
H2S: colourless gas stands out for its characteristic smell of rotten eggs. A low-concentration exposure causes eye and throat irritation, cough, acceleration of breathing and fluid formation in the respiratory ways. High concentrations kill the olfactory nerve so making impossible to smell its disgusting odour, and may cause unconsciousness in few minutes.
O2: both excess and lack of oxygen may cause important diseases, sometimes death.