(439b) Modeling Pitting Corrosion in Petroleum Storage Tank

The corrosion cost of the US oil and gas industry was $1.4 billion in 2018. It is also an environmental and safety concerns in chemical and petroleum Industries. Among different types of corrosions, pitting is the most insidious form ubiquitous in petroleum industry. It is localized to a tiny area of exposed metal surface, and the corrosion front usually propagates in the direction of gravity leading to the formation of a pit. A mathematical simulation of corrosion to bridge the gap from “post-corrosion” measurement to proactive corrosion management is needed to reduce the corrosion cost.

In this work a finite element analysis model of corrosion in a petroleum storage tank made of steel is developed to simulate the pitting corrosion using COMSOL Multiphysics®. Generally accepted reaction mechanisms along with transport and thermodynamic data obtained from literature are used. Kinetic data extracted from experimental polarization measurements by performing non-linear regression are integrated into the model. The concentration profiles, current density and electrical potential are calculated at different times. The calculated results are used to study the impacts of various parameters, such as time, corrosive species and their concentrations, conductivity of water adjacent to the surface on pit morphology and corrosion rate.