Mechanism of protective film formation during CO{sub 2} corrosion of carbon steel

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

OSTI ID:350201

Dugstad, A ^[1]

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1. Inst. for Energy Technology, Kjeller (Norway)

The corrosion rate of carbon steel in CO{sub 2} containing environments depends very much on the formation of protective corrosion product films. The parameters affecting film formation have been studied in a large number of flow loop experiments performed in the temperature range 20--120 C. Film formation is a complex process where the precipitation rate of iron carbonate is the main controlling factor. The precipitation rate is slow, and a high degree of supersaturation of iron carbonate in the water is necessary in order to get sufficient amount of carbonate depositing on the steel surface. The precipitation of FeCO, is facilitated by increased pH, increased temperature and by all measures which can reduce the transport of reactants and corrosion products to and from the steel surface. Periods with stagnant conditions (shut down) during the loop experiments therefore increased the protectiveness. Good protection was also obtained after periods where the steel was exposed to wet gas only. The presence of mill scale or rust from tube manufacturing and storing may also enhance the protectiveness of the corrosion film and reduce the risk for local attack. The influence of the previous exposure of the steel surface and changes in the operational parameters can be one explanation for the tendency to lower corrosion in the field compared to laboratory experiments. This is important to understand in order to make better and less conservative prediction models.

• OSTI ID: 350201
• Report Number(s): CONF-980316--
• Country of Publication: United States
• Language: English

Related Subjects

02 PETROLEUM
03 NATURAL GAS
36 MATERIALS SCIENCE
CARBON DIOXIDE
CARBON STEELS
CORROSION
CORROSION PRODUCTS
CORROSION PROTECTION
CORROSIVE EFFECTS
FIELD PRODUCTION EQUIPMENT
IRON CARBONATES
PIPELINES