Corrosion-control Technique of Carbon Steel Seawater Cooling Apparatus

摘要

Internal surfaces of carbon steel cooling tubes of 14, 16 and 19 mm ID were protected by a new kind of corrosion-control technique. The basic study was conducted on tubes containing stagnant and flowing seawater. Through monitoring the protection potential and current of internal surfaces of cooling tubes, the changes of the protection potential of internal tube surfaces, the changes of the protection potential and current vs time and the effects of the diameter of tubes and the flow rate of seawater on the protection potential of internal tube surfaces were studied. The mean protection current density of internal tube surfaces for 11 months was about 0.4mA/m~2. After 11 months, the protection potential at the remote end of cooling tubes from the anode was-940mV(vs Ag/AgCl reference electrode). The results show that the protection distance of internal surfaces of cooling tubes (19mm ID) has been increased to above 3 m from the former 0.3 m (from the single end). After simulated experiment for one year, the observation showed that the cooling tubes was just as the same as that before the experiment and there was not corrosion occurred inside tubes.