The natural life of equipment is mainly determined by the physical wear and tear of equipment. With the extension of equipment service time, the equipment is aging and the maintenance cost is increasing gradually, forming a vicious use stage, that is, an economically unreasonable use stage. Therefore, the natural life of equipment can not be used as an estimation basis for equipment renewal.
Technical life
The technical life is mainly determined by the intangible wear and tear of equipment, which is generally shorter than the natural life. The faster the scientific and technological progress, the shorter the technical life.
Economic life
The economic life of equipment is determined by the increase of equipment maintenance cost and the decrease of use value.