Comparative Study on Rate of Flow Accelerated Corrosion (FAC) of API 5L X-52-65-70 Steels in a Brine added with H₂S at 60°C by Using a Rotating Cylinder Electrode (RCE)

摘要

This work focuses on how important the hydrodynamic conditions are on the corrosion rates occurringin steel type API 5L grades such as X52, X65 and X70 when are exposed to synthetic brines with andwithout H2S at 60C. Experiments were conducted using a rotating cylindrical electrode (RCE) underhydrodynamic flow conditions over a rotation range from 0 to 6500 rpm (3.744 m/s). It was found outthat the rotation rate affects the electrochemical process that takes place on the steel surface since itincreases the corrosion rate when the rotational rate is increased. The effect of H2S presence on thesteel caused substantial corrosion rates as a function of flow rate. Under the presence of H2S, thecorrosion products were composed mainly of iron oxides, one sulphate (mikasaite) and some sulfur asthe mackinawite, which was non-adherent and breaks out easily. The steel API 5L X-70 exhibited thebest performance under the presence of H2S at 60C with respect to the corrosion rate by yielding thelower corrosion values.