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 Fe_9S_8, FeCO_3, and NaCl. Calcium contain-ing 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.
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