1.How to choose suitable galvanized channel steel in high humidity and humid environment?
Use hot-dip galvanized channel steel (coating thickness ≥ 85μm), and add passivation treatment (such as chromate passivation or chromium-free passivation) on the surface to improve moisture resistance.
Use an overhead bracket during installation, keep a distance of ≥100mm from the wall/ground, and reserve ventilation holes (such as opening a 20mm diameter air hole every 2 meters).
Upgraded protection: For long-term immersion in a humid environment (such as aquarium brackets), galvanizing + epoxy powder coating (thickness ≥300μm) can be used to form a moisture-proof barrier.
2.How to choose suitable galvanized channel steel for coastal and salt spray corrosion environments?
Zinc-aluminum-magnesium coated channel steel (Zn-Al-Mg) is preferred. The aluminum and magnesium elements in the coating can form a dense oxide film, and the salt spray resistance life is 3-5 times that of ordinary galvanizing (such as 100μm thickness salt spray resistance test > 3000 hours).
If hot-dip galvanizing is used, the coating thickness needs to be increased to 100-120μm, and a fluorocarbon paint sealing layer (thickness ≥ 50μm) is used to block the penetration of chloride ions.
Structural optimization: Avoid using the installation method with the groove facing up, and change the bolt connection to stainless steel countersunk bolts + insulating gaskets to reduce crevice corrosion.
3.How to choose suitable galvanized channel steel in industrial corrosive environment (acid, alkali, chemical pollution)?
Mildly corrosive environment (pH=4-10):
Hot-dip galvanizing + epoxy resin coating (thickness ≥200μm), resistant to medium concentration acid and alkali corrosion (such as 10% sulfuric acid, 20% sodium hydroxide).
Severely corrosive environment (pH＜4 or＞12):
Use galvanizing + nickel-phosphorus alloy coating (thickness ≥50μm), and then line the surface with polyethylene (PE) or polyvinyl chloride (PVC) sheet to form an isolation layer.
Extreme scenarios (such as strong acid storage tank brackets) can directly use galvanized channel steel wrapped with glass fiber reinforced plastic (FRP), and the corrosion resistance is close to that of stainless steel.
4.How to choose suitable galvanized channel steel in high temperature environment?
Medium temperature environment (60-200℃): Use thermal spraying zinc-aluminum alloy coating (Al content 15%-20%), the temperature resistance is improved to 300℃, and an aluminum oxide protective film is formed at high temperature.
Reserve thermal expansion gap during installation (such as setting a 10mm expansion joint every 5 meters) to avoid cracking of the coating due to thermal expansion and contraction.
High temperature environment (＞200℃): Use galvanized channel steel + high temperature resistant coating (such as silicone resin paint, temperature resistance above 400℃), or directly use aluminum-infiltrated channel steel (aluminum-iron alloy layer temperature resistance up to 600℃).
5.How to choose suitable galvanized channel steel for underground and buried environments?
Conventional soil (pH=6-8): Hot-dip galvanizing layer thickness ≥100μm, wrapped with polyethylene anti-corrosion tape to form a double barrier of mechanical protection + electrochemical protection.
Strongly corrosive soil (acidic red soil, saline-alkali soil): Use zinc-aluminum-chromium plated channel steel (Dacromet process), combined with impressed current cathodic protection (such as buried zinc alloy sacrificial anode), and increase the anode density when the soil resistivity is ＞50Ω・m.