Influence of corrosion-active nonmetallic inclusions on the corrosion resistance of steel coiled tubing pipes

The influence of corrosion-active nonmetallic inclusions (CANI) on corrosion resistance of coiled tubing steels was studied in a 3% NaCl aqueous solution and model stratal water (MSW), the chemical composition of which corresponds to the water of Yabluniv oil and gas condensate field and is saturated with carbon oxide. The corrosion rate of TS-90 steel in MSW is approx. 2 times higher than that of GT-90 steel and 3 times higher in a NaCl solution. After exposure to this solution at 20 °C for 72 h uniform corrosion without pitting was observed on the GT-90 steel surface, while on HS-90 steel the pitting corrosion was observed which developed on CANI. Inclusions density is approx. 6 pcs/mm². Branched corrosion damages propagate deep into the metal from inclusions.