Galvanized Steel Pipe Manufacturing Process for Greenhouse Structures

Galvanized steel pipes are one of the most widely used structural materials in modern greenhouses.
They offer excellent corrosion resistance, high strength, strong weather durability, and a long service life — making them the key supporting components of greenhouse structures.

Raw Material Selection

• Steel Strip Material:High-quality low-carbon steel (Q195, Q235, or Q355) with good weldability and plasticity.
• Surface Requirements:The surface of the strip must be smooth, free of cracks, rust, and other defects.
• Thickness Range: Generally between 1.5 mm and 3.0 mm, depending on the greenhouse span and design requirements.
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Production Process Flow

Steel Coil Uncoiling → Leveling → Forming → High-Frequency Welding → Inner & Outer Seam Treatment → Sizing & Straightening → Cutting → Hot-Dip or Cold Galvanizing → Inspection → Packing

Detailed Process

• Uncoiling & Leveling
  Steel coils are placed on the uncoiler and leveled to remove internal stress, ensuring stable forming quality.
• Forming & Welding
  The leveled steel strip is gradually rolled into round or square pipes through rollers.
  High-frequency induction welding (HF welding) ensures smooth and firm welds with no burrs.
• Weld Seam Treatment
  The inner and outer weld seams are trimmed to remove excess welding material, ensuring a smooth internal surface to prevent rust or water accumulation.
• Sizing & Straightening
  Pipes are precisely shaped to ensure dimensional accuracy within ±0.5 mm and a straight, even appearance.
• Cutting
  Pipes are cut to specified lengths, typically 6 m or 8 m, depending on customer requirements.
• Galvanizing Process
  Two methods are commonly used:

— Hot-Dip Galvanizing:
Pipes are immersed in molten zinc at about 450 °C, forming a strong alloy bonding layer.
Zinc layer thickness ≥ 60–80 μm, service life: 15–25 years.

— Cold (Electro) Galvanizing:
A uniform zinc coating is applied through electroplating.
Zinc layer thickness 10–20 μm, more economical, suitable for cost-effective greenhouse projects.

• Inspection & Packaging
  Inspection items include surface quality, dimensions, zinc layer thickness, adhesion, and weld strength.
  Pipes are bundled or wrapped with anti-rust film for convenient transportation and handling.

Key Features

• Superior corrosion resistance — Zinc coating protects against oxidation and moisture.
  • High structural strength — Excellent toughness, capable of withstanding wind and snow loads.
  • Long service life — Hot-dip galvanized pipes can last over 20 years outdoors.
  • Easy installation — Suitable for welding, bolted, or insert-type connections.

Application Fields

• Smart greenhouses, flower houses, vegetable nurseries, and eco-restaurants
• Livestock sheds, shading structures, and rainwater collection shelters

High-quality galvanized steel pipes form the foundation of a strong and durable greenhouse.
Through scientific manufacturing processes and strict quality control, each pipe ensures superior strength, corrosion resistance, and longevity — providing reliable support for modern agricultural greenhouses.