The problem of mechanochemical corrosion of a vertically standing or hanging elastic tube under its own weight is considered. The influence of a local smooth reduction in the initial thickness of the tube (up to 12.5%) on its durability and manifestation of the mechanochemical effect is studied. The numerical analysis revealed that despite the fact that the presence of a defect reduces the service life of the tube, it only slightly intensifies the mechanochemical effect compared to the same initially perfect tube; therefore, for relatively short, both initially perfect and defective tubes this effect can be ignored. For relatively short tubes, a permissible initial thinning of the tube wall can be taken into account by consideration of the same initially perfect tube with the ultimate residual thickness increased by the depth of the defect. However, for long tubes this approach gives a slightly overstated durability. The effect of the initial thickness of the tube was also investigated.