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8750977 
Meetings & Symposia 
Case study: Pyrophoric iron reactions in refinery and petroleum industries 
Murray, I; Gauvin, R 
2017 
Interscience Communications Ltd 
2 
948-957 
English 
It is well documented that formation of pyrophoric iron sulphide from rust represents a significant fire and explosion hazard in oil and petrochemical industries. However, many conditions are required to allow growth and development of such pyrophoric iron reactions. More precisely, corrosion of steel of various refinery equipment, piping and storage tanks generates oxides and hydroxides. If the environment also contains hydrogen sulphide as a result of the addition of sulphur acting both as a binder extender and a mixture modifier, it can lead to the formation of pyrophoric iron sulphides and subsequent explosions. However, this represents only part of the problem since pyrophoric material can also create heat which has the potential to ignite residual hydrocarbons associated with the equipment containing the pyrophoric material. Fire and Explosion investigators need to understand the basic formation and oxidation processes of the iron sulphides which could be pyrophoric. This paper investigates high precision metallurgical techniques that can be applied to detect the presence of iron sulphide from rust and confirm that pyrophoric reaction was related to the cause of the disaster. Analytical methods such as high magnification electron microscopy and XRD analysis, XPS techniques and metallography, together with an evaluation of the oxide layer microstructure, are powerful tools to help Fire and Explosion investigators in their origin and cause analyses. These metallurgical techniques are presented through a case study involving the explosion of a petroleum storage tank that caused severe damage to the tank and a loss of production. A general literature review of the phenomenon of pyrophoric iron fires together with study of the general risks associated with petroleum products will be addressed in order to determine the chemistry of pyrophorics and the morphology, microstructure and composition of the oxide layers that are formed at the surface of steel equipment. Then, metallurgical analysis techniques will be applied on steel coupons collected from the fire and explosion site to demonstrate the pyrophoric species that had infiltrated the steel surface with respect to this case study. More specifically, this paper will demonstrate that high magnification and precision techniques as well as testing for the chemical liaisons allow identifying the presence of liaisons between sulphur and metal that correspond to the interaction between the iron and the sulphur forming Fe- S, thus pyrophoric oxidation.