1.What zinc coating is recommended for ordinary drying workshops?
Applicable Scenario: Mechanical assembly plants, electronic component plants, and storage plants (free from acid and alkali, high humidity, and dust accumulation).
Recommended zinc coating thickness: 120-180g/m2 on both sides (corresponding to a zinc coating thickness of 17-25μm, a medium-weight zinc coating).
Core Logic:
These plants require only basic rust protection-in an environment free of corrosion-accelerating agents (such as Cl⁻ and SO₂), a pure zinc coating (Z-type) of 120-180g/m2 can protect against trace amounts of moisture and dust in the air through the "sacrificial anode effect." Combined with the relatively stable environment within the plant (no strong UV rays, minimal rain), the coating can achieve a service life of 15-20 years.
Additionally, this zinc coating offers optimal workability, meeting the bending and punching requirements of common plant components (such as wall purlins, lightweight support steel frames, and ceiling keels). It is also cost-effective and suitable for large-scale applications. Typical components: wall/roof color-coated board substrate, light purlins, ceiling keels, and equipment guardrails.
2.What zinc coating thickness is recommended for high humidity/dust workshops?
Applicable Scenarios: Food processing plants (such as slaughterhouses and aquaculture facilities), textile plants, and ceramic/building materials plants (high dust and humidity).
Recommended zinc coating thickness: 180-275g/㎡ on both sides (corresponding to a zinc coating thickness of 25-38μm for heavy-duty applications).
Core Logic:
High humidity (relative humidity ≥85%) accelerates electrochemical corrosion of the zinc coating. Dust accumulation (such as flour and ceramic powder) absorbs moisture, forming "localized corrosion cells" and accelerating localized zinc corrosion.
A zinc coating of 180-275g/㎡ (pure zinc or alloyed zinc (ZF)) provides a more robust "protective reserve" and slows down localized corrosion. For components that require frequent cleaning (such as food processing plant walls), alloyed zinc (ZF) is recommended-its harder and more wear-resistant surface is less susceptible to damage from friction during cleaning.
Typical components: Wall/roof load-bearing purlins, equipment supports (such as drying equipment supports), and floor drain covers.
3.What is the recommended zinc coating thickness for mild chemical/acid-base plants?
Applicable Scenarios: Pharmaceutical plants (weakly acidic and alkaline environments), electroplating workshops (peripheral areas), and fertilizer warehouses (no direct leakage).
Recommended zinc coating thickness: 275-350g/㎡ on both sides (corresponding to a zinc coating thickness of 38-49μm, for a heavy-duty zinc coating).
Core Logic:
Low-concentration acidic and alkaline vapors in the environment (such as organic acids in pharmaceuticals and trace amounts of chromic acid mist in electroplating workshops) can damage the "white rust protective film" on the zinc surface (ZnO and Zn(OH)₂ are easily soluble in acids and alkalis), leading to continuous corrosion of the exposed zinc layer.
A thick zinc coating of 275-350g/㎡ can extend the "sacrificial anode cycle" and should be combined with a corrosion-resistant organic coating (such as polyvinylidene fluoride (PVDF) or epoxy resin coating) to achieve dual protection (zinc + coating) and prevent direct contact between the zinc layer and acid and alkali.
Processing Note: Thick pure zinc coatings are prone to cracking during bending. It is recommended to use a "soft substrate" (such as Preheating (60-80°C) to minimize processing damage.
Typical components: load-bearing steel frames on factory exterior walls, protective fences around acid and alkali equipment, and ventilation ducts (parts not in direct contact with acids and alkalis).
4.What zinc coating thickness is recommended for heavily corroded workshops?
Applicable Scenarios: Chemical production workshops (such as chlor-alkali and sulfuric acid production), marine chemical plants (near salt spray), and metallurgical plants (high-temperature, high-sulfur environments).
Recommended zinc coating thickness: ≥350g/㎡ on both sides (corresponding to a zinc coating thickness of ≥49μm, or alternatively, zinc-aluminum-magnesium coating).
Core Logic:
Highly corrosive environments (such as high concentrations of Cl⁻, SO₂, and high-temperature flue gases) rapidly degrade conventional zinc coatings. Even a 300g/㎡ zinc coating can fail within 3-5 years.
If cold-rolled galvanized steel is used, a super-heavy-duty pure zinc coating of ≥350g/㎡ is required, and must be combined with a high-temperature-resistant and high-corrosion-resistant coating (such as a fluorocarbon coating and primer). A more preferred option is zinc-aluminum-magnesium coating (ZM) (containing 10%-12% Al and 1%-3% Mg). Its corrosion resistance is 3-5 times that of conventional zinc coating, extending its service life to 25-30 years in highly corrosive environments. The weldability is superior to that of thick pure zinc coatings.
Typical components include the main load-bearing steel frame of the plant (not directly exposed to high temperatures), exhaust gas treatment system piping supports, and outdoor equipment platforms.
5.What is the logic behind zinc coating selection for cold-rolled galvanized steel in industrial plants?
Final zinc coating thickness = plant corrosion level (core) + component function (auxiliary) + service life (target)
Normal dry plant: 120-180g/m2 (pure zinc coating, low-cost for large areas);
High humidity/dust plant: 180-275g/m2 (pure zinc coating or alloyed zinc coating, alloying preferred for wear resistance);
Mildly chemical plant: 275-350g/m2 (extra-heavy-load pure zinc coating + anti-corrosion coating);
Severely corrosive plant: ≥350g/m2 (standard galvanized coating (coating required) or zinc-aluminum-magnesium coating (preferred).