Abstract: The potential damage modes identification of 62 extended service pressure vessels in hydrocracking unit was carried out, and the correlation between pressure vessels and expected service life was classified and screened. The results show that there were 5 of the 62 pressure vessels with low correlation with the expected service life; there were 6 pressure vessels with high correlation with the expected service life, of which 3 had corrosion thinning damage. The pressure vessels were verified by strength checking, and reasonable suggestions were provided for its inspection scheme.