Metal constructions are often subject to heavy loads, therefore, in order to ensure safety, careful inspection, maintenance and effective defect removal are needed. Constructions age because of external and internal factors:
- External factors: precipitation, temperature, air mass flows, biological factors (for example, bacteria and other pests), ground pressure at negative temperature, radiation, electrical discharges.
- Internal factors: static and dynamic loading of structure, temperature, humidity, the nature of its changes, aggressive environment, various biological factors (various pests can do harm from the inside too).
Naturally, construction materials go through structural changes and wear off over time, and the reason for that is the constant flow of people, transport, etc. Usually this phenomenon is called wear and tear.