GI Pipe for Water Supply – Advantages, Sizes & Lifespan
GI Pipe for Water Supply – Advantages, Sizes & Lifespan
GI pipes or Galvanized Iron pipes are widely used in water supply systems due to their mechanical strength, corrosion resistance, and affordability. Whether it’s for domestic use, agriculture, or urban water pipelines, GI pipe remains a preferred choice in areas where plastic pipes are not suitable or durable enough.
This article explores the complete details of GI pipe for water supply including advantages, typical sizes, coating thickness, pressure ratings, expected lifespan, and practical use cases in Indian conditions.
What is a GI Pipe?
GI pipe is made from low-carbon steel pipe that is galvanized using a layer of protective zinc coating. This zinc layer resists corrosion, making the pipe suitable for water conveyance and exposed environments. The process used is typically hot-dip galvanization, which coats the steel thoroughly and extends its life.
Advantages of Using GI Pipe in Water Supply Systems
- Corrosion Resistance: Zinc coating protects against rust formation in mild conditions.
- Strength & Rigidity: Offers higher mechanical strength compared to non-metallic pipes.
- Affordable & Widely Available: Cost-effective and easy to procure nationwide.
- Pressure Tolerance: Performs well under moderate to high water pressures.
- Long Pipe Runs: Available in lengths of up to 6 meters or more.
Applications: Rural water supply, municipal pipelines, irrigation systems, fire-fighting systems, and water transport in hilly areas.
Standard GI Pipe Sizes in Water Supply
GI pipes follow nominal bore (NB) sizing. The chart below outlines standard sizes:
| Nominal Bore (NB) | Outer Diameter (mm) | Common Use |
|---|---|---|
| 15 NB | 21.3 mm | Domestic water lines |
| 20 NB | 26.9 mm | Connection to tanks & meters |
| 25 NB | 33.7 mm | Main residential supply |
| 40 NB | 48.3 mm | Industrial water supply |
| 50 NB | 60.3 mm | High volume lines |
| 80 NB | 88.9 mm | City main connections |
Pipes are also available in Class A (Light), B (Medium), and C (Heavy) depending on wall thickness.
GI Pipe Lifespan & Durability in Water Lines
The lifespan of a GI pipe varies based on environmental exposure, water quality, and usage frequency. Typically:
- 15–20 years in moderate outdoor environments
- 10–15 years in humid or saline conditions (unless coated further)
- 5–10 years in continuous contact with acidic water
Maintenance Tip: Use anti-corrosion tape or bitumen paint for buried GI pipelines to improve lifespan.
Zinc Coating Thickness & Pressure Ratings
Hot-dip galvanized pipes conform to IS 1239 Part 1 and have the following specifications:
| Class | Wall Thickness (mm) | Pressure Rating (Kg/cm²) | Zinc Coating (g/m²) |
|---|---|---|---|
| Class A | 2.0 | 10 | 210 |
| Class B | 2.65 | 16 | 305 |
| Class C | 3.25 | 25 | 400+ |
Always choose Class B or C for high-pressure or underground water supply.
Frequently Asked Questions – GI Pipe Water Use
Is GI pipe safe for drinking water?
Yes, for short-term use. However, long exposure can cause scaling or zinc leaching. Stainless steel or copper is better for potable systems.
Can GI pipe be buried underground?Yes, but it must be coated or wrapped to prevent corrosion from soil moisture and salts.
What is the difference between GI and MS pipe?GI pipe is zinc-coated MS pipe. MS without galvanization is prone to faster corrosion.
Can GI pipes be used for hot water lines?Technically yes, but heat accelerates corrosion in GI pipes. Use stainless steel or copper for hot water systems.
What is the weight of GI pipe per meter?It depends on size and class. Example: 25 NB Class B = approx. 2.5 kg/m. See GI pipe weight chart.
Related Water Pipe Articles
- Types of Pipes for Water Supply – Full Guide
- Best Metal Pipes for Water Supply – GI, SS, Copper
- GI Pipe Weight Per Meter – Chart by Size & Class
- MS Pipe HSN Code & GST
Contact Udhhyog – GI Pipe Supplier in India
Looking for IS 1239-compliant GI pipes for water supply? Udhhyog supplies Class A/B/C GI pipes across India for domestic, municipal, and industrial water systems. We offer custom lengths, third-party testing, and mill certification.
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