The paper compares two analytical solutions for the equal-rate mechanochemical corrosion of an elastic spherical shells subjected to internal and external pressure. Results based on the G. Lame’s formulas for a pressurized thick hollow sphere and on the thin-walled spherical shell model are analyzed when applied to relatively thin shells. The rates of corrosion at the inner and outer surfaces are supposed to be proportional to the maximum principal stress at the surface involved.