The Influence Of Flow’s Velocity On X-series Pipeline Steel’s Polarization Curves And Cathodic Protection

With the growing demanding for energy and the progress of science and technology, in the 21st century, the exploitation of ocean moves into the fast lane. One of the main ways to overcome the energy crisis is the exploration and exploitation of ocean energy. While, marine corrosion has been restricting the further exploration of human footsteps since the beginning of ocean energy exploitation. In order to make the ocean engineering more safe and effective in operation, human has developed lots of measures and corresponding standard for corrosion prevention.This paper adopts the method of static polarization curve, to measure and analyses the polarization curve of 4 kinds’ X pipeline steel(X65、X70、 X75、X80) in 5 different velocities of sea water (Om/s、0.25m/s、0.4m/s、0.55m、0.7m/s). At the time of getting the corrosion potential of the four kinds of steel under different velocity, We take more energy on analysing the potentials between -0.8V and -1.2V in the cathode polarization curves, to determine the effect of the flow rate to the steel’s effect of cathodic protection.The conclusion of the research have following indications:1.During the velocity range of 0-0.7m/s, with the increase of flow velocity,the series of X pipeline steel’s corrosion potential shifts to more positive potential and their’s corrosion resistance is more stronger than the static seaweater.2.1n order to make the X65、 X70、 X75、X80 getting enough protection, with the increase of flow rate, potentiostat need to enhance the voltage output value to avoid under protection. And the increase of flow rate also changed the potentiostat’s output voltage range. For this reason, we should select new range of output voltage to avoid the pipeline’s being under protection.3.With the increase of flow rate, the consumption rate of galvanic anode is increasing, meanwhile, it will make the pipeline which protected very well in static seawater to be under protection。4. The X65 is the most sensitive steel to the factor of velocity during the cathodic (sacrificial) protection process. And the X70 is the least sensitive steel to the factor of velocity during the cathodic protection process.