51314-4267-Mechanisms of Localized Corrosion Due to the Co-Presence of Silica Sand Deposit and Imidazoline Base

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Product Number: 51314-4267-SG

ISBN: 4267 2014 CP

Author: Jin Huang

Publication Date: 2014

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Mechanisms of localized corrosion due to the co-presence of silica sand deposit and imidazoline based corrosion inhibitorJin Huang1 Bruce Brown and Srdjan NesicInstitute for Corrosion and Multiphase Technology342 west State StreetAthens OH 45701USAABSTRACTCorrosion experiments were conducted on API 5L X65 mild steel specimens in inhibited 1 wt% NaCl aqueous solutions saturated by CO2 at pH 5.0 and 25°C. Individual silica grains and crystals were placed on the steel samples both prior to and after corrosion inhibitor addition to study the potential localized corrosion due to the presence of the silica particles. An imidazoline based corrosion inhibitor was able to inhibit the surface average corrosion rate by 90% however localized corrosion in the form of pitting was observed right underneath each silica sand particle regardless weather the corrosion inhibitor was added prior to sand deposition or after sand deposition. The pitting penetration rate was measured using a profilometer and was found to be 10 times larger than the inhibited general corrosion rate. It was concluded that localized corrosion initiated immediately underneath each sand grain as the inhibitor preferentially adsorbed on the silica surface and left the steel beneath it unprotected. This led to formation of galvanic cells and caused accelerated localized corrosion at those locations.Key words: CO2 corrosion silica deposit mild steel pitting localized corrosion mechanisms1. This author is currently with Brine Chemistry Solutions LLC 8285 El Rio Street Suite 100 Houston TX 77054