Study Of Tank Bottom Corrosion Behavior Upon Bituminous Sands

The corrosion beneath the tank floor is usually very severe, and corrosion on tank floor built on tarsands is rarely studied. This paper mainly studies the effect of water content, oxygen-concentration cellcorrosion and stray current corrosion on this kind of corrosion. After analyzing the tar sands layer andcorrosion cause and type, a set of experiment facility is designed and built based on relative research. In theexperiment, tar sands corrosion in dry situation and in distilled water and tap water is studied bypolarization curve and EIS. And analysis on components of underground water, rain and atmosphere isgiven to get the simulation corrosive water for test. Polarization behavior is also studied1) when there is athin layer of water between the tank floor and tar sand and2) when there is local water puddle.This paper also calculates the oxygen concentration distribution beneath the tank floor by usingformula of oxygen concentration-corrosion potential, and gets the law of potential distribution when anodicequilibrium potential, polarization slope and exchange current density are given.Simulation is offered about tank stray current corrosion when there is impressed current cathodicprotection on nearby pipelines using BEASY software, to get the influence of stray current on tank floorcorrosion. In the simulation, this paper also studies the effect of tar sand resistivity, soil resistivity, relativelocation of pipeline and tank, tank diameter, auxiliary anode current and stray current in two pipelinesystem on tank floor corrosion.A experiment is specially conducted for electrified railway stray current corrosion, to study the effectof distance and current in electrified railway on tank floor potential distribution. In the last,This paper compares the potential size when there is tar sands below and that when soil below,analyzing the effect of tar sands on stray current interference.