Unusual refinery boiler tube failures due to corrosion by sulfuric acid induced by steam leaks

Conference · Thu Dec 31 04:00:00 EST 1998

OSTI ID:352627

Lopez-Lopez, D; Wong-Moreno, A ^[1]

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1. Instituto de Investigaciones Electricas, Cuernavaca (Mexico)

Corrosion by sulfuric acid in boilers is a low probability event because gas temperature and metal temperature of boiler tubes are high enough to avoid the condensation of sulfuric acid from flue gases. This degradation mechanism is frequently considered as an important cause of air preheaters materials degradation, where flue gases are cooled by heat transfer to the combustion air. Corrosion is associated to the presence of sulfuric acid, which condensates if metal temperature (or gas temperature) is below of the acid dew point. In economizer tubes, sulfuric acid corrosion is an unlikely event because flue gas and tube temperatures are normally over the acid dewpoint. In this paper, the failure analysis of generator tubes (similar to the economizer of bigger boilers) of two small oil-fired subcritical boilers is reported. It is concluded that sulfuric acid corrosion was the cause of the failure. The sulfuric acid condensation was due to the contact of flue gases containing SO{sub 3} with water-steam spray coming from leaks at the interface of rolled tube to the drum. Considering the information gathered from these two cases studied, an analysis of this failure mechanism is presented including a description of the thermodynamics condition of water leaking from the drum, and an analysis of the factors favoring it.

• OSTI ID: 352627
• Report Number(s): CONF-980316--
• Country of Publication: United States
• Language: English

Related Subjects

02 PETROLEUM
36 MATERIALS SCIENCE
BOILERS
CARBON STEELS
CORROSIVE EFFECTS
DEW POINT
FAILURE MODE ANALYSIS
FUEL OILS
PETROLEUM REFINERIES
STEAM
SULFURIC ACID