A Study Of The Corrosion Inhibitors For Floating Roof Tank In Natural Seawater

Water is usually used to test the water pressure when tanks of oil reserve base are repaired in the offshore areas. However, due to the limited fresh water resources, It is an effective means to solve the problem of the lack of fresh water with seawater pressure test. However, the internal surface of a tank submerged in the seawater will be corroded in the process of pressure test.Therefore, it is a premise of studying and taking effective protective measures to ensure tank overhaul with the seawater pressure test.In which, adding corrosion inhibitor is a better anti-corrosion methods.The Inhibition effect of the one-component,product inhibitor, multi-component corrosion inhibitor was studied by the methods of polarization curve with No. 2 steel for the substrate, it has selected the main components of inhibitors, and prescriptions have been optimized by orthogonal experimental.In this way, four kinds of high effect corrosion inhibitor was obtained. The inhibition effect of prescriptions have been verified by the methods of weight loss. The results of weight loss indicated that prescription 1 and 3 have excellent protective effect for all seven kinds of steels at 25℃, and inhibition efficiency is above 95%. Inhibition efficiency of prescription 2 and 4 is above 80%.In considering the cost, harm of emission and inhibition effect, prescription 3 is used ultimately. The results of weight loss further indicated that the corrosion rate increased gradually with the increasing temperature within the range of temperature studied. The linear fit of variation of blank corrosion rate with temperature has good correlation. Inhibition efficiency of prescription 3 is above 96% in the range of 10-35℃.The results of weight loss indicated that inhibition efficiency of prescription 3 is above 90% for different steel.Corrosion rate of weight loss in the field has similar result with simulation experiment in the laboratory,the accuracy of simulation experiment has been verified.It also found that corrosion products adhere to the surface after field experiments without inhibitor,general corrosion has taken place in the surface, and no pitting. A layer of light blue film formed in the surface with prescription 3,and no pitting.The observations of bulk tank indicated that tank top, bottom, all parts of the wall have been well protected in the field.