Performance Evaluation Of Iron-base Sacrificial Anodes And Its Application In Offshore Engineering

The electrochemical properties and performance selection of several kinds of iron-base materials as sacrificial anode for cathodic protection of 12Cr steel structure in offshore engineering were studied in this article .The research about the sacrificial anode property is carried out on the basis of related national and international standards. The results indicated that at different current density and experimental temperature, the material C had better performances in regards with most negative open-circuit potential, steady closed-circuit potential, larger electrical capacity and highest current efficiency, among the several types of iron-base anodes materials. In addition, for those iron-base anodes materials, the characteristics such as uniform corrosion morphology, the easily separated corrosion products were able to meet the requirements of sacrificial anode material for cathodic protection. Therefore, the anode material C, for its excellent performance, was finally selected as the sacrificial anode for protecting 12Cr steel tubes in offshore engineering.Polarization curve test also has been made on the selected anode material C and 12Cr steel materials. The result indicates the difference in corrosion potential of 12Cr steel and sacrificial anode material C was higher, the polarization of 12Cr steel was strong, while the polarization of sacrificial anode C is weak, this demonstrates that it is feasible to protect 12Cr steel tube with sacrificial anode C in laboratory.The simulating test has been made on the actual protection potential of 12Cr steel structure under the cathodic protection of iron-base anode C. The result indicates that in the real sea, material C could perform effective protection to 12Cr steel structure quickly and made it reached the required protected potential.An experiment about aluminothermic welding to anode cable has been done and the evaluation of welding process has been given. It shows that the firm extent of welding-point, the hardness of weld heat influence area and the depth of Cu-osmosis all meet the designing demand. The research also provides the related weld procedure and anode cast procedure of 12Cr steel tubes according to the demand.The article made a cathodic protection design on 12Cr tubes in PY30-1 tube shelf based on its parameters obtained from the experiments mentioned above.