1.What are the core scenarios where coatings need to be maintained or replaced?
Physical damage to the coating, coating failure caused by environmental corrosion, and natural loss of coating due to aging
2.What are the reasons why the coating needs maintenance or replacement?
Causes of physical damage to the coating: Mechanical damage (impact, friction, installation bumps) causes the zinc layer to fall off, exposing the steel substrate. The processing process (such as welding, bending) destroys the integrity of the coating, and the zinc layer at the welding point evaporates due to high temperature to form a gap.
Environmental corrosion causes coating failure: High humidity/industrial pollution area: sulfur dioxide and chloride react with the zinc layer to form white powdery "zinc rust", and the zinc layer becomes thinner after continuous corrosion.
Seaside/salt spray environment: chloride ions penetrate the zinc layer, accelerating the electrochemical corrosion of the steel matrix, and the life of the zinc layer is shortened to 5-8 years (normal outdoor is 15-20 years). ◦ Contact with acidic and alkaline media: such as acidic mist in chemical workshops and contact with agricultural fertilizers, the zinc layer is quickly corroded
3.What are the maintenance measures to delay coating loss?
Annual cleaning: Use a high-pressure water gun to wash away salt/dust on the surface → Reduce electrochemical corrosion.
Dry area coating enhancement: In areas prone to water accumulation such as eaves and equipment bases → Apply polyurethane topcoat (water resistance).
Galvanic corrosion isolation: When in contact with stainless steel/copper → Add nylon gaskets or insulating glue to block the current.
4.What are the strategies for controlling maintenance costs?
Preventive maintenance: Check the integrity of the zinc layer regularly (once a year), and repair early damage (such as white rust) with zinc paste in time to avoid the development of red rust (repair cost increases 5 times).
Environmental adaptation selection: Hot-dip galvanizing (zinc layer 100-150μm) is preferred for seaside projects, which reduces maintenance costs by 50% compared with electroplating galvanizing; industrial pollution areas are equipped with coating protection to reduce the frequency of later maintenance.
Life cycle optimization: For long-term projects of more than 20 years, a thick zinc layer (such as hot-dip galvanizing 85μm) is selected in the early stage. Although the initial cost is 10%-15% higher, the full-cycle maintenance cost is reduced by 40%.
5.What is the maintenance vs. replacement decision process?
Detect zinc layer thickness: Use a magnetic thickness gauge to measure. Maintenance is required if the thickness is below the threshold (e.g. <50μm); Evaluate corrosion level: When red rust appears or the base rust is >0.5mm, replace the component first;
Cost comparison: When the maintenance cost is >30% of the price of the new component, it is more economical to replace it directly.