Author(s)

M. Purcar, J. Deconinck1, B. Van den Bossche, L. Bortels & P. J. Stehouwer

Abstract

An advanced three-dimensional Boundary Element Method (BEM) approach is used to quantify the influence and mitigation of a steel reinforced concrete foundation on the cathodic protection (CP) level of a neighbouring buried tank. Due to the fact that the reinforced concrete is connected to the CP system, this concrete structure attracts a substantial fraction of the current that is injected by far field anodes. As a consequence, the tank wall that is facing the foundation, is under protected (tank/soil potential -600 to –700 mV vs. Cu/CuSO4), while the opposite tank wall (facing the far field) is well protected (-1200 mV vs. Cu/CuSO4). These simulations are in agreement with the measurements. Rather than remediate this situation by an expensive trial and error approach, Gasunie preferred to cooperate with ElSyCa and to simulate first the effects of various possible solutions they had in mind. These simulations predict a significant improvement of the tank wall protection level by about 200 mV at the foundation side when insulating screens are placed between the tank and the foundation (depending on size and position of the screens) while the far field side is hardly influenced. As the solver is fully integrated in the SolidWorks CAD environment, any modification of the dimensions of the entire configuration (e.g. the screens), the surface mesh characteristics (determining the computational accuracy), and the physico-chemical input parameters (polarisation characteristics, soil conductivity, etc.) can be established in a fast and easy manner. Keywords: cathodic protection systems, advanced software packages, advanced BEM.

Keywords

cathodic protection systems, advanced software packages, advanced BEM.