PSI - Issue 16

Ihor Chudyk et al. / Procedia Structural Integrity 16 (2019) 260–264

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Ihor Chudyk et al. / StructuralIntegrity Procedia 00 (2019) 000 – 000

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An analysis of the corrosion damages on the surface of the tested pipe samples showed general uniform corrosion in the KF1 solution (Fig. 2); a slight localization is observed only along the traces of machining. However, in the KF2 medium a severe pitting corrosion was observed (Fig. 3).

Fig. 2. Corrosiion damage of the pipe samples after exposure to KF1 for 3 days at a temperature of 150 °C: general view (a) a nd view in magnification x100 (b).

Corrosion rate has a major impact on structural integrity. According to the regulative documents (NACE Standard RP0775-2005; DSTU 320.02829777.002 – 95), the allowable wall thickness deacrease should be at least 70% of the nominal one. Then the lifetime of the studied pipe with wall thickness of 9.19 mm in the KF2 environment is only 16.65 days. In this case only corrosion effect was considered. Therefore, a usage of G105 pipe for the development of wells exploited with acidic high-mineralized formation waters is economically unacceptable. However, these pipes have sufficient resistance to corrosion in medium with near-neutral pH values and can be used in wells exploited with non-acidic formation waters. Then another factors influenced on structural integrity should be considered, namely stress corrosion cracking and corrosion fatigue (Maruschak et al. (2013), Voloshyn et al. (2014)).

Fig. 3. Corrosiion damage of the pipe samples after exposure to KF2 for 3 days at a temperature of 150 °C: general view (a, c) and v iew in magnification x40 (b, d).