Galvanized (GI) Pipe Manufacturers in India

Hot-dip pipe is dipped into molten zinc after it is made, so zinc covers the inside, outside and weld area. Pre-galvanized pipe uses zinc-coated coil, so the coating is usually thinner. Avon Steel's GI pipes are hot-dip galvanized in our own plant.

In practice this matters at the weld seam and the cut ends. A pre-galvanized pipe is formed and welded after the coil is coated, so the seam area has little or no zinc and needs touch-up. A hot-dip pipe is coated after welding, so the seam, bore and outer surface are all protected.

IS 1239 (Part 1) groups pipes into three classes by wall thickness for the same nominal bore. Light is Class A (thinnest wall), Medium is Class B and Heavy is Class C (thickest wall). A heavier class has a thicker wall, weighs more and can handle higher pressure and rougher handling.

• Light (A): low-pressure and non-critical uses such as fencing, light frames and temporary structures.
• Medium (B): the most commonly specified class, used for plumbing, general engineering and moderate-pressure water lines.
• Heavy (C): higher pressure, fire-fighting, steam and industrial lines.

On site, the classes are often identified by a painted colour band: yellow for light, blue for medium and red for heavy.

IS 1239 (Part 1):2004 covers mild steel tubes for water, gas, steam and air lines, in plain and galvanized form, up to 150 mm nominal bore. It corresponds to BS 1387:1985 and EN 10255. For larger diameters, IS 3589 applies. The zinc coating on galvanized tubes is covered by IS 4736 (hot-dip zinc coatings on steel tubes). Structural galvanized tubes are covered by IS 1161, and scaffolding tubes by BS EN 39.

Avon Steel's GI pipes are made to IS 1239 (Part 1):2004 under a BIS licence.

A well-made hot-dip galvanized pipe commonly lasts several decades. Trade sources quote about 25 to 30 years in polluted urban or coastal air, and 40 to 50 years or more in cleaner rural settings, with some indoor lines lasting longer. Actual life depends on the zinc coating thickness and uniformity, water chemistry (acidic or soft water and high chloride speed up corrosion), temperature, flow velocity, and whether the pipe is buried or exposed.

Because zinc corrodes in preference to steel, even a scratched coating keeps protecting the pipe until the zinc nearby is used up.

IS 1239 requires tubes to pass a hydraulic test at about 5 MPa (roughly 50 kgf/cm²). This is a factory test pressure, not the working pressure. The safe working pressure is lower and depends on the class (heavy is higher than medium, and medium higher than light), the pipe size, the operating temperature, and the joints and fittings used, since threaded joints reduce the allowable pressure.

For fire-fighting, high-pressure or steam lines, please share your design pressure and we will recommend the class. Always follow the pressure rating required by your system designer.

Start with the nominal bore (NB) your design or plumber specifies; this is the size used for ordering, and the outside diameter is larger than the NB figure (for example 1 inch NB has an OD of 33.7 mm). Then choose the class and length:

• Flow and size: pick the NB that carries the required flow at an acceptable velocity.
• Class: light for low-load uses, medium for general water and plumbing, heavy for higher pressure or tougher service.
• Application and standard: water lines (IS 1239 / IS 3589), structural (IS 1161), irrigation casing (IS 4270).
• Joints: threaded, grooved or welded; thicker walls suit threading better.

If you are unsure, send us the application, working pressure and length, and our team will suggest a size and class. See the sizes-in-inches table above for NB to OD matching.

• Steel cost: hot-rolled coil prices move with the market.
• Size and class: a bigger bore or thicker class means more steel per metre.
• Zinc coating: zinc is priced separately and a heavier coating costs more.
• Quantity and length: bulk orders and standard lengths price better than small or special-length orders.
• End finish: plain, bevelled, threaded or socketed ends.
• Certificates, testing and freight: third-party inspection, test certificates and delivery distance.
• Taxes: GST is charged as applicable.

Pipes are usually priced per kg or per tonne; send us your size, class and quantity for a written quote.

Yes. We manufacture in Ludhiana, Punjab, and supply dealers, contractors and project buyers in Punjab, across India and to export markets. Share your delivery location with your enquiry and we will confirm freight and transit time.

Minimum order quantity and dispatch time depend on size, class and the current production plan. Send your requirement and we will confirm the quantity and delivery date in your written quote.

Yes. We supply a manufacturer's test certificate for each lot covering chemical and mechanical properties, hydraulic test and zinc coating checks, as per IS 1239. Third-party inspection can be arranged on request.

Pipes made under a BIS licence also carry the ISI mark, and Avon Steel is ISO 9001:2015 certified.

GI pipe is ordered by nominal bore (NB), and the inch size is the nominal figure, not the real outside diameter. Our standard sizes run from 1/2 inch (15 NB, OD 21.3 mm) to 10 inch (250 NB, OD 273.1 mm). Common ones are 1/2 inch (15 NB), 3/4 inch (20 NB), 1 inch (25 NB), 1-1/2 inch (40 NB), 2 inch (50 NB), 3 inch (80 NB), 4 inch (100 NB) and 6 inch (150 NB). The full table is given above.