Q: What zinc coating thickness protects coastal H-beams?
A: Minimum 85μm zinc coating is essential for marine environments. Double-dipping ensures coverage in internal corners. Chromate passivation prevents storage corrosion. Touch-up painting maintains protection at welds.
Q: Can S235JR be used uncoated outdoors?
A: Unlike weathering steels, it lacks alloy elements for protective patina formation. Uncoated beams corrode rapidly in humid or saline environments. Protective coatings remain mandatory for exterior exposure.
Q: How does surface preparation improve coating adhesion?
A: Abrasive blasting creates microscopic anchors for coatings, quintupling adhesion strength. Uniform surface profiles prevent premature coating failure. Post-blast salt contamination must be minimized.
Q: What paint systems suit chemical plants?
A: Zinc-rich epoxy primers provide cathodic protection. Polyurethane topcoats add UV resistance. For acid exposure, glass-flake vinyl esters offer superior chemical resistance. Regular inspections ensure coating integrity.
Q: When is thermal spray aluminum preferred?
A: Ideal for high-temperature environments above 150°C where organic coatings fail. Aluminum layers self-heal through oxide formation. The process avoids distortion risks from hot-dip galvanizing.
