Structural steel has a significant weakness—it is prone to corrosion. An incomplete estimate indicates that the economic loss in China due to corrosion exceeds 40 billion RMB annually. Out of the 90 million tons of steel produced each year, approximately 30% is consumed by various forms of corrosion. An incomplete estimate suggests that the reference lifespan for structurally maintained steel structures is generally: 70 years for production buildings, 50 years for corroded production buildings, and 80 years for non-production buildings. In contrast, reinforced concrete structures (including frame structures, shear wall structures, cylinder structures, frame-shear wall structures, etc.) have a lifespan of 50 years for production buildings, 35 years for corroded production buildings, and 60 years for non-production buildings. This highlights the importance of regular maintenance and care for steel structures after installation.
However, recent surveys have found that some users of steel structures are unaware that maintenance and care are required for them. This has led to severe corrosion, often undetected by users, resulting in numerous safety hazards for steel structure products, reducing their safety in use, and even affecting their normal operational functions. It is recommended that design units not only specify the coating requirements for steel structures in their design instructions but also propose maintenance and care requirements based on their usage. The design instructions should consider environmental factors during the use of steel structures, as well as their usage time and lifespan, before determining the type of paint and film thickness to ensure the lifespan of the steel structure. Additionally, the timing and methods of maintenance and care should be established to ensure the extension of the steel structure's service life.
Case 1: Observations reveal that the rust on steel structures typically grows at an exponential rate each year. The first year presents patchy rust spots, which then develop into rust blisters. By the second year, after the blisters burst, the steel begins to corrode deeply under the influence of external media, and the coating starts to peel off, carrying iron oxide with it. The table below lists the annual corrosion conditions of a steel structure factory building that, due to incomplete rust removal and lack of anti-corrosion maintenance and care over a 10-year period, suffered severe damage.
Protect structural steel, extend service life
It is essential to maintain the cleanliness and dryness of the steel structure surface. Regular cleaning should be performed on areas prone to accumulating dust, such as the base of steel columns and joints.
2. Regularly remove rust spots and apply a coating of metal or non-metallic material.
3. Regular fire treatment is conducted; when the steel's heat resistance point reaches between 430-540°C, its tear resistance and toughness sharply decline.
