The most common question contractors and plumbers ask. Both GI and MS are iron-based pipes — but they behave very differently. Here's a complete, practical comparison to help you choose right.
Between these two, GI is usually considered where corrosion protection is required; MS is commonly chosen for fabrication and dry structural service. The final pipe, class, coating and joint system must match the project design.
GI pipe is steel pipe protected by a zinc coating; plain MS pipe has no galvanised barrier. The coating improves corrosion resistance, but neither material has one guaranteed lifespan: water chemistry, soil, coating damage, fabrication, lining and maintenance all matter.
| Property | GI Pipe | MS Pipe |
|---|---|---|
| Full Name | Galvanized Iron Pipe | Mild Steel Pipe (ERW) |
| Coating | Zinc galvanized inside and outside | No coating — bare steel |
| Rust Resistance | Better while the zinc coating remains intact | Needs a suitable coating or lining in corrosive service |
| Best Use | Water supply lines, plumbing | Structural, fabrication, industrial gas |
| Potable-water use | Use only where the exact product and project specification permit it | Requires an approved material, lining and water-system design |
| Weldability | Zinc fumes — ventilate well | Easy to weld |
| Weight | Slightly heavier (zinc coating) | Lighter for same size |
| Price (1" B Class) | ~₹650/pc (10ft) | ~₹163/mtr |
| Underground service | Life depends on soil, moisture, coating/lining, joints, cathodic protection where required and maintenance | |
| Standard | IS:1239 | IS:1239 |
| Common Brands | Tata & Jindal | Jindal Star & Tata |
Exposed water services, tank connections and other lines where the plumbing specification calls for galvanised steel. For concealed domestic hot and cold water, compare current approved polymer systems too.
Buried steel needs an engineered corrosion-protection system. Galvanising may help, but soil conditions, wrapping/coating, drainage and inspection determine suitability.
Agricultural installations where mechanical strength is important and the selected coating, joints and water chemistry are compatible with the service.
Factory water or compressed-air services where the process designer specifies GI. Temperature, pressure, corrosion allowance and joint ratings must all be checked.
Use only the pipe material, schedule, fittings and listing approved by the fire-system designer and applicable code; requirements vary by system.
Gas piping is safety-critical. Use the material, class, joining method and installer required by the gas provider and applicable code.
Compound gates, window grills, balcony railings — all fabricated from MS because it welds easily and can be painted.
Scaffolding on construction sites is almost always MS pipe — it's stronger in tension and compression, and cheaper than GI.
Industrial gas lines carrying dry gases (no moisture) — LPG distribution mains, nitrogen lines, compressed dry air.
Industrial shelving, furniture frames, greenhouse structures — MS is preferred when the finished item will be painted or powder-coated.
Exhibition stalls, temporary sheds, event stages — where the pipe is not a permanent installation and rust over time doesn't matter.
Hollow structural sections (HSS) for building columns and beams — MS hollow pipe is widely used in pre-engineered buildings.
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