How to prevent rust in GI pipes?

Galvanized pipes are designed with a zinc coating that delays rusting, but once the coating is damaged or consumed, corrosion begins. Effective rust prevention requires a combination of protective strategies, correct installation, and regular maintenance.

Core Protection Methods of Galvanized Pipe Corrosion Prevention

Active Protection (Cathodic Effect)
Zinc, being more reactive than steel, corrodes first and shields the underlying metal. However, this process gradually consumes the zinc coating.

Passive Protection (Barrier Effect)
External coatings or wraps create a dense protective layer that prevents water, oxygen, and other corrosive agents from reaching the steel surface.

Key Measures for GI Pipe Rust Prevention

Proper Selection and Installation

Choose the right zinc coating thickness:

Indoor environments: ≥ 45 μm

Outdoor or humid conditions: ≥ 65–85 μm

Coastal or industrial zones: Consider alternative materials such as stainless steel or plastic-coated composite pipes.

Protect coating during installation:

Use specialized tools for cutting/threading.

Treat exposed areas (cuts, threads, scratches) with anti-corrosion coatings after installation.

Repairing Cuts and Damaged Surfaces

Clean cuts thoroughly with a brush or sandpaper.

Apply zinc-rich paint to restore sacrificial protection.

If unavailable, use an anti-rust primer (e.g., red lead, epoxy zinc yellow) followed by a topcoat.

Enhanced External Protection

Paint coatings: Apply weather-resistant paint for outdoor use.

Anti-corrosion tape: Suitable for buried pipes or hard-to-paint areas.

Use of Protective Accessories

Install plastic or rubber gaskets at supports and clamps to reduce friction and avoid galvanic corrosion.

Environmental Control & Routine Maintenance

Keep the environment dry and well-ventilated.

Avoid sharp temperature changes that may crack the coating.

Inspect pipelines annually, especially joints, cuts, and threads.

Address early signs of corrosion (white or red rust) immediately with cleaning and re-coating.

Common Misconceptions of GI Pipe Rust Prevention

Myth 1: “Galvanized pipes never rust.”
Reality: Zinc is sacrificial and will degrade. Damaged areas need maintenance.

Myth 2: “Ordinary paint works on galvanized pipes.”
Reality: Paint adhesion is poor on smooth zinc surfaces. Always use a primer before topcoating.

Myth 3: “Standard GI pipes are fine underground.”
Reality: Soil is highly corrosive. Additional protective measures are essential for buried pipes.

Read more: Construction technology of galvanized seamless pipe