Abstract: Corrosion is the destructive attack of a metal and its properties by chemical or electrochemical reaction with its environment. The importance of corrosion studies is threefold includes conservation, improved safety and economic losses. The structural deterioration of all metallic mains is due to the external corrosion which is included by environmental and operation conditions. It is necessary to remember that the choice of material depends on many factors, including corrosion resistance, cost, fabricability, strength. Complete corrosion resistance is almost all media can be achieved by the use of glass, but it is not practical. The corrosion resistance of the material is the most important properties in most engineering applications. In this investigation, FWTPET process has been carried to achieve high-quality leak-proof joints. SA 213 tube and SA 387 tube plate are dissimilar material joined using by FWTPET process of interference fit with backing block. Polarization study and AC impedance spectra have been used to investigate the corrosion parameters of the material system immersed in well water in the absence and presence of the inhibitor Sodium Potassium Tartrate (SPT) and the result shows the increase of corrosion resistance in the materials.