Steam cracking requires specifically extreme conditions such as a special furnace called pyrolysis furnace. Also, the time of reaction is very important; it is limited to several tenths of a second, to reduce the formation of heavy aromatic products and coke. The pressure should be low, around 2-3 bar abs. to prevent hydrocarbon species from combining among themselves to from hydrocarbon and coke. The figure below is a representation of the pyrolysis of hydrocarbons: