Galvanized Steel Pipe
Galvanized steel pipe is a steel tube that has been coated with a layer of zinc through the hot-dip galvanizing process to protect the base metal from corrosion, widely used in exposed outdoor and wet environments.
Material
Carbon Steel. Base pipe grades include ASTM A53 Gr. B (ERW or Seamless), ASTM A106 Gr. B (Seamless), and similar grades per JIS G3442, GB/T 3091.
Model
GI Pipe, Galvanized Pipe
Size
Nominal Pipe Sizes (NPS) from 1/8 inch to 24 inches and larger. Common plumbing sizes range from 1/2″ to 8″.
Thickness
Defined by schedule (e.g., SCH 40, SCH 80). Wall thicknesses range from approximately 2 mm to over 12 mm depending on size and schedule.
Standard
ASTM A53 (Galvanized), ASTM A106 (Galv. Seamless), ASTM A123 (Zinc Coating Spec), JIS G3442, GB/T 3091.
MOQ
10 Metric Tons.
Delivery Time
Standard lead time is 4 to 8 weeks from order confirmation; common sizes are often available from stock with shorter lead times.
Long Description
Galvanized steel pipe is manufactured by first producing black steel pipe (typically seamless or ERW) and then immersing it in a bath of molten zinc. This hot-dip galvanizing process creates a metallurgically bonded zinc-iron alloy coating on both the interior and exterior surfaces. The zinc layer acts as a sacrificial anode, providing cathodic protection that prevents rust even if the coating is scratched. This pipe is characterized by its distinctive spangled surface finish and is known for its durability and extended service life in corrosive atmospheres. It serves as a primary material for conveying water and gases, as well as for structural applications where corrosion resistance is required without the need for painting. The product is available in various schedules, with threaded and coupled ends being common for plumbing applications.
Key Product Highlights
The hot-dip galvanized coating provides robust, long-term corrosion protection for both interior and exterior surfaces.
The zinc layer offers sacrificial protection, actively defending the steel even at cut edges or minor coating damage.
Galvanized pipe is readily available in standard plumbing and structural sizes with threaded ends for easy installation.
It offers a cost-effective corrosion protection solution for many applications compared to stainless steel or painted systems.
The product is suitable for a wide range of temperatures and environments, though not recommended for high-temperature steam.
Product Advantages
The standardized galvanizing process ensures consistent coating thickness and adherence to weight specifications (e.g., ASTM A123).
Minimal maintenance is required over the pipe’s lifetime due to the durable nature of the zinc coating.
Compatible with standard plumbing and construction fittings, tools, and installation practices.
Full certification includes both base pipe mechanical properties and coating quality/compliance tests.
Widely stocked in common sizes, facilitating quick procurement for maintenance, repairs, and construction projects.
Industry Application
This pipe is used for water supply lines, fire sprinkler systems, fencing and guardrails, scaffolding frames, structural supports in buildings, agricultural irrigation, compressed air lines (non-critical), and conduit for electrical wiring.
Technical Specifications
| Parameter | Unit | Galvanized ERW Pipe (e.g., ASTM A53 Gr. B) | Galvanized Seamless Pipe (e.g., ASTM A106 Gr. B) | Structural Galvanized Pipe (e.g., ASTM A500 Gr. B) | Notes |
|---|---|---|---|---|---|
| Carbon Content (C) | % | ≤ 0.30 | ≤ 0.30 | ≤ 0.26 | Base steel composition pre-galvanizing. |
| Manganese (Mn) | % | ≤ 1.20 | 0.29 – 1.06 | ≤ 1.35 | |
| Phosphorus (P) | % | ≤ 0.05 | ≤ 0.035 | ≤ 0.035 | |
| Sulfur (S) | % | ≤ 0.06 | ≤ 0.035 | ≤ 0.035 | |
| Tensile Strength | MPa | ≥ 415 | ≥ 415 | ≥ 400 | Minimum for base steel. |
| Yield Strength | MPa | ≥ 240 | ≥ 240 | ≥ 250 (Gr. B) | Minimum for base steel. |
| Elongation | % | See ASTM A53 | See ASTM A106 | ≥ 23 | |
| Hardness | HRB | N/A | N/A | ≤ 80 (Typical) | Rarely specified for galvanized pipe. |
| Outer Diameter (OD) | mm | 10.3 – 660+ | 21.3 – 850+ | 21.3 – 660+ | Broad range; structural often round, square, rectangular. |
| Wall Thickness | mm | 2.0 – 25 | 2.0 – 100+ | 1.5 – 25 | Varies by schedule and product type. |
| Length | m | Random (6m) or Threaded & Coupled (T&C) | Random (6-12m) | Random (6-12m) or Cut Length | Plumbing pipes often in fixed lengths with threads. |
| Surface Treatment | – | Hot-Dip Galvanized | Hot-Dip Galvanized | Hot-Dip Galvanized | Defining feature of the product. |
| Coating / Finish | – | Zinc Coating (Min 610 g/m² per A123) | Zinc Coating (Min 610 g/m² per A123) | Zinc Coating (Min 610 g/m² per A123) | Coating weight ensures durability. |
| Manufacturing Process | – | ERW + Hot-Dip Galvanizing | Seamless + Hot-Dip Galvanizing | ERW/Cold Formed + Hot-Dip Galvanizing | Base pipe type defines pressure capability. |
| Standard Example | – | ASTM A53 Gr. B Galvanized ERW | ASTM A106 Gr. B Galvanized | ASTM A500 Gr. B Galvanized Round | Representative specifications for different uses. |
Packaging & Surface Treatment
Pipes are bundled according to size and length. For threaded pipes, thread protectors (plastic or steel) are applied to both ends to prevent damage. Bundles are secured with steel strapping. The surface is the characteristic hot-dip galvanized zinc coating, which may have a regular spangle or minimal spangle finish. The coating is the primary treatment; no further painting is required for corrosion protection, though it can be painted for aesthetic purposes if desired.
Aliases Names
GI Pipe, Galvanized Iron Pipe, Zinc Coated Pipe, Hot-Dip Galvanized Pipe, Galvanized Conduit, Galvanized Tube.
