Hollow Section Gi Pipe
Product Spotlights
Galvanized steel pipe is coated with a zinc layer through hot-dip or electroplating, greatly improving corrosion resistance and service life. Common foreign grades include ASTM A53 Grade B, ASTM A795 (fire protection), BS 1387, JIS G3444 (structural), JIS G3452 (piping), and DIN 2440. One of the most frequently used search terms is GI steel pipe, which typically refers to hot-dipped galvanized pipe for low/medium pressure fluid services such as water supply, fire fighting, and gas.
Based on galvanizing method, steel pipes are mainly divided into pre-galvanized and hot-dipped types. Pre-galvanized steel pipe is made by galvanizing steel strip before tube forming, offering a thinner, smoother coating ideal for light structures like fences and scaffolding. In contrast, hot-dipped galvanized steel tube is immersed in molten zinc after tube forming, providing a thicker, more adherent coating for harsh corrosive environments. Another common keyword, galvanized steel tube, broadly covers round, square or rectangular galvanized tubes for structural support and machinery.
In construction and municipal engineering, galvanized steel pipe is widely used for fire sprinkler systems, municipal water supply networks, and outdoor cable conduits. GI steel pipe is preferred for exposed outdoor piping in Southeast Asia and the Middle East due to its weather resistance and strength. Meanwhile, galvanized steel tube is essential in agricultural greenhouses, highway guardrails, and transmission tower bracing. For projects requiring moderate pressure and easy installation, such as compressed air lines or temporary construction water lines, galvanized steel pipe remains one of the most cost-effective materials.
When selecting materials, match the grade and galvanizing method to service conditions (humidity, temperature, soil corrosion) and pressure rating. For buried pipes, choose hot-dipped galvanized pipe with additional anti-corrosion wrapping; for dry indoor environments, pre-galvanized pipe helps reduce cost. Notably, hot-dipped galvanized steel tube has a higher unit price but typically lasts 2–3 times longer than pre-galvanized pipe, making it suitable for strong-corrosion scenarios such as chemical plants and coastal projects. Regardless of which search keyword you use, always request a mill test certificate (MTC), confirm coating weight (e.g., Z275, Z450), and require hydrostatic test reports to ensure compliance with project specifications.
DN |
outer diameter |
Ordinary steel pipe |
Thickened steel pipe |
|||||
MM |
MM |
Deviation |
Thickness |
welded pipe (kg/m) |
Galvanized pipe (kg/m) |
Thickness |
welded pipe (kg/m) |
Galvanized pipe (kg/m) |
MM |
Deviation |
MM |
Deviation |
|||||
6 |
10.2 |
2.0 |
0.40 |
0.4256 |
2.5 |
|||
8 |
13.5 |
2.3 |
+12% |
0.62 |
0.64 |
2.75 |
+12% |
|
10 |
17 |
2.3 |
0.82 |
0.84 |
2.75 |
0.97 |
1.00 |
|
15 |
21.3 |
±0.5mm |
2.8 |
1.26 |
1.30 |
3.25 |
1.45 |
1.49 |
20 |
26.8 |
2.8 |
1.63 |
1.68 |
3.50 |
2.01 |
2.07 |
|
25 |
33.5 |
3.3 |
2.42 |
2.49 |
4.00 |
2.91 |
3.00 |
|
32 |
42.3 |
3.3 |
3.13 |
3.22 |
4.00 |
3.78 |
3.89 |
|
40 |
48 |
3.5 |
3.84 |
3.96 |
4.25 |
4.58 |
4.72 |
|
50 |
60 |
±1% |
3.5 |
4.88 |
5.03 |
4.50 |
6.16 |
6.34 |
65 |
75.5 |
3.8 |
6.64 |
6.84 |
4.50 |
7.88 |
8.12 |
|
80 |
88.5 |
4.0 |
8.34 |
8.59 |
4.75 |
9.81 |
10.10 |
|
100 |
114 |
4.0 |
10.85 |
11.18 |
5.00 |
13.44 |
13.84 |
|
125 |
140 |
4.5 |
15.04 |
15.49 |
5.50 |
18.24 |
18.79 |
|
150 |
165 |
4.5 |
17.81 |
18.34 |
5.50 |
21.63 |
22.28 |
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