Abstract: Oil temperature of No.1 and No.2 oil tanks in the Initial Station of ChangJi Oil Ppeline have been dropped year by year since the winter of 2006. Site testing results showed that the brackets of internal heat tracing coils in No.1 oil tank collapsed, dead oil layer deposited in the tank was too thick, and the heat tracing coils were covered by the dead oil layer, which led to the deterioration of heat exchange effectiveness. And the lack of assigned hot water flowrate was the main reason of oil temperature drop for No.2 oil tank. Although a relative large specific heat exchange value per rating tankage was obtained after increasing hot water flowrate, there may still existed problems in heat transfer property of coils.