Abstract: Corrosion of Hastelloy C-276 tube bundle of the first preheater for tail gas catalytic combustion in a petrochemical PTA plant occurred in the range of 100 to 300 mm at the tube bundle inlet after 13 years of operation. And the same corrosion phenomenon occurred again after only three and a half months of operation after replacing the tube bundle of the heat exchanger of the same material. Aiming at the above problems, the behavior of high corrosion rate of C-276 tube bundles at inlet end was studied by comparing such factors as operation time, operating conditions and changes in medium composition combining with the analysis of corrosion morphology of heat exchanger tubes, energy spectrum analysis of corrosion products and the results of velocity boundary layer analysis in the flow inlet area of heat exchanger tubes, the corrosion mechanism was determined and it was concluded that the increase of water content in the tail gas was the key factor to corrosion failure. Meanwhile, the corresponding protection suggestions were proposed according to the analysis results.

Key words: PTA plant, Hastelloy, C-276, pipe bundle, corrosion failure, tail gas