Abstract: Corrosion products from various locations of refining units were collected and natural oxidation experiments were arranged to study the oxidation and spontaneous combustion behaviors of these corrosion products. Results show that the existence of elemental sulfur could promote the oxidation of corrosion products and even speeds up the process of spontaneous combustion, which threatens the refinery security, thus sulfur recovery units should be the main object to be concerned. Water could inhibit the spontaneous combustion of corrosion products by absorbing heat, reducing temperature and isolating oxygen in some ways. But if the content of ferrous sulfide in the corrosion products is high enough, spontaneous combustion may happen as well. Corrosion products collected from the top of refining units are more dangerous than those from the bottom since containing less water.

Key words: refining unit, corrosion products, natural oxidation, spontaneous combustion