Galvanized Steel Pipe/ GI Tube Hot Dip Galvanized Steel Pipe

Galvanized Steel Pipe (also known as GI Tube, short for “Galvanized Iron Tube”) processed via the hot dip galvanization (HDG) method is a widely used piping and structural product. It involves immersing carbon steel pipes in a molten zinc bath (typically at 440–460°C), forming a dense, metallurgically bonded zinc-iron alloy layer and an outer pure zinc layer on the surface. This process endows the pipe with exceptional corrosion resistance, mechanical durability, and cost-effectiveness, making it suitable for plumbing, construction, infrastructure, and industrial applications. Below are its key features:

1. Superior Corrosion Resistance (Core Advantage)

• Dual Protective Layers: The hot dip galvanization process creates two critical protective layers:

• Inner zinc-iron alloy layer (50–100μm thick): Metallurgically bonded to the steel substrate, it is highly wear-resistant and resistant to chemical erosion (e.g., mild acids, alkalis, and moisture).

• Outer pure zinc layer (50–150μm thick): Acts as a sacrificial anode—zinc corrodes preferentially over steel, preventing the underlying carbon steel from rusting even if the surface is slightly scratched.

• Long Service Life: In typical environments (e.g., urban air, fresh water, or non-corrosive industrial areas), HDG steel pipes have a service life of 20–50 years (3–5 times longer than ungalvanized steel pipes). In harsh environments (e.g., coastal areas with salt spray), their lifespan is still 15–30 years with proper maintenance.

• No Post-Installation Corrosion Treatment: Unlike painted or electroplated pipes, hot dip galvanized pipes require no additional anti-corrosion coating (e.g., paint, epoxy) after installation, reducing long-term maintenance costs.

2. Excellent Mechanical Strength & Durability

• Retains Steel’s Inherent Strength: The base material is high-quality carbon steel (e.g., ASTM A53, BS EN 10255), ensuring excellent tensile strength (≥415MPa), yield strength (≥240MPa), and impact resistance. The galvanization process does not weaken the steel’s mechanical properties—HDG pipes maintain the same load-bearing capacity as ungalvanized steel pipes.

• Tough Protective Coating: The zinc-iron alloy layer is hard (Vickers hardness ≥250 HV) and adheres tightly to the steel surface, resisting scratches, dents, and abrasion during transportation, installation, and use. This durability avoids coating damage that often leads to premature rusting in other galvanization methods (e.g., electroplating).

• Temperature & Pressure Resistance: Suitable for a wide range of operating conditions:

• Temperature resistance: Can withstand -40°C to 200°C (ideal for both cold and hot water supply systems).

• Pressure bearing: Standard HDG pipes (e.g., SCH 40, SCH 80) handle working pressures of 1.0–2.5MPa, meeting the demands of residential plumbing, industrial fluid transport, and fire sprinkler systems.

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Galvanized steel pipes for structure: used for building and structural support, with strong load-bearing capacity.

Galvanized steel pipes for fluid transportation: They are used for transporting fluids such as water, natural gas, and oil, and have excellent sealing and anti-corrosion properties.