I. Classification by Galvanizing Process
Hot-Dip Galvanized Steel Pipe
Process: Submerged in molten zinc (≈450°C), forming a thick zinc layer (50–80μm).
Features: Superior corrosion resistance, long lifespan (20–30 years), higher cost.
Applications:
Construction: Outdoor water supply/drainage, fire sprinkler systems, structural supports.
Municipal: Water transmission, low-pressure gas delivery, streetlight poles.
Industrial: Chemical plant pipelines, greenhouse frameworks.
Electro-Galvanized Steel Pipe (Cold Galvanized)
Process: Electroplating a thin zinc layer (5–15μm).
Features: Smooth surface, weaker corrosion resistance (5–10 years), lower cost.
Applications:
Indoor electrical conduits, furniture frames, temporary structures.
II. Classification by Pipe Type
Galvanized Welded Steel Pipe
Process: Steel sheet welded and then galvanized (common sizes: DN15–DN200).
Applications:
Low-pressure fluid transport (water, gas, heating).
Scaffolding (e.g., "scaffold tubes" with couplers).
Galvanized Seamless Steel Pipe
Process: Seamless pipe hot-dipped in zinc, high pressure-rated.
Applications:
High-pressure systems: Oil/petrochemical pipelines.
Machinery: Hydraulic cylinders, bearing sleeves.
Galvanized Square/Rectangular Tube
Features: Aesthetic, easy to install.
Applications:
Architectural decoration (guardrails, door/window frames).
Exhibition stands, shelving, subway ventilation ducts.
Galvanized Spiral Welded Pipe
Process: Spiral-welded large-diameter pipes (DN300+).
Applications:
Municipal drainage, oil/gas transmission.
Bridge/wharf piling.
III. Classification by Application
Galvanized Pipes for Low-Pressure Fluids (GB/T 3091)
Transport water, gas, or air in buildings.
Fire Protection Galvanized Pipes
Used in sprinkler systems, hydrant pipelines (pressure-rated).
Electrical Conduit Pipes (e.g., JDG/KBG)
Thin-wall electro-galvanized pipes for cable protection.
Structural Galvanized Pipes (GB/T 13793)
Steel structures, curtain wall frameworks.
IV. Key Notes
Corrosion Resistance: Hot-dip for humid/outdoor use; electro-galvanized for dry interiors.
Restrictions:
Not for high-pressure gas (requires seamless pipes).
Avoid direct drinking water (zinc leaching risk; use stainless steel).
Joining Methods: Threaded (screwed), flanged, or grooved couplings with leak-proof seals.