Hydrogen sulfide,often present in sulfur-bearing crude tankers,can react with iron to form various sulfides like ferrous sulfide,ironic sulfide and ferrous disulfide,the tendency of which react with oxygen in air to form potentially explosive mixtures.

The formation of iron sulfides in low-temperature location of oil refinery equipment was analyzed,and the spontaneous combustion tendency of each iron sulfide formed was investigated in different way.

This paper is aimed at introducing the authors' research of the spontaneous combustion characteristics of iron sulfides as a result of the reactions of hydrogen sulfide to the different degrees of humidity of the iron oxide black, iron oxide red and the iron hydroxide.

The oxidation heat of the iron sulfides is regarded as the main cause of tank fire.

Self-ignition accident by sour oil tank was analyzed,and the major reason was found to be thermal oxidation of iron sulfides generated from reaction of rust with hydrogen sulfide.

iron sulphides were synthesized mainly by way of gas-solid reaction ofmetallic iron or iron-nickel alloys with the mixture of H,S and H,.

Fe2O3,Fe(OH)3 and Fe3O4 formed by the corrosion of the inner wall of oil tank were further reacted with wet hydrogen sulphide at room temperature without the presence of oxygen to form iron sulphides,and the heat release from the oxidation of iron sulphides was the main cause of the spontaneous burning of oil tank storing sufur containing oil products.