Severe pitting corrosion occurred in a horizontal steel pipeline used to transport multiphase fluid, including water, oil, and natural gas, after 2 months of service. The pitting corrosion rate was up to 42 mm/year. Chemical analysis, X-ray diffractometry, and EDAX showed that the corrosion products mainly consisted of Fe9S8, FeCO3, and NaCl. Calcium containing inclusions were also found in the matrix of the steel, which may accelerate corrosion. The early failure was attributed to the high proportion of water, the slow flow velocity, and the use of unqualified material. The following conclusions were made: 1) The relatively low pH value, high salinity, and high bacterial content made very corrosive in the pipeline which failed prematurely. 2) The stratified fluid and high water cut contributed to rapid perforation at the bottom of the pipeline. 3) The presence of complex calcium containing inclusions in the steel may have accelerated localised corrosion. 4) The combined use of a corrosion inhibitor and bactericide can control the corrosion to a satisfactory extent.
Pitting corrosion of steel pipeline in oil-water-gas multiphase flow system
Lochkorrosion an Stahlrohrleitungen in mehrphasigen Öl-Wasser-Gas-Strömungssystemen
British Corrosion Journal ; 35 , 1 ; 73-74
2000
2 Seiten, 2 Bilder, 2 Tabellen, 4 Quellen
Article (Journal)
English
unlegierter Stahl , Rohrleitung , Erdölfernleitung , Erdöl , Öltransport , Erdgas , Mehrphasenströmung , Korrosionsgeschwindigkeit , Korrosionsprodukt , Fließeigenschaft , Morphologie (Körper) , Einschluss , Sulfid , Carbonat , Lochfraßkorrosion , Gewichtsverminderung , Röntgenstrahlbeugung , chemische Zusammensetzung
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