What Are The Common Types Of Coatings Used On Steel Pipes?

• Features

Formed by immersing steel pipes in molten zinc, the zinc layer tightly bonds with steel surface.
Low production cost, easy processing and wide availability.
Zinc has sacrificial anti-corrosion effect: it corrodes first to protect the steel substrate.

• Pros

Good anti-rust performance for normal atmospheric environment.
High mechanical hardness, not easy to scratch during handling and installation.

• Cons

Poor resistance to acid, alkali and corrosive soil; not suitable for long-term burial in harsh ground.
Not recommended for high-temperature pipelines and drinking water pipes with strict hygiene standards.

• Application

Building water pipes, scaffolding pipes, fire protection pipes, outdoor overhead pipelines, general drainage systems.

• Features

Epoxy powder fused and cured on steel pipe surface, forming a dense hard coating.

• Pros

Ultra-strong adhesion, not easy to peel off.
Outstanding resistance to chemicals, high temperature and abrasion.
Thin but compact coating, no influence on pipe connection.

• Cons

Brittle, easy to crack under severe impact or bending.
Higher cost; construction requires strict process control.

• Application

Oil & gas gathering pipelines, high-temperature industrial process pipes, chemical medium delivery pipes, pipe fittings and elbows.

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• Features

Composite structure: epoxy primer + adhesive layer + outer PE layer, the most mature external anti-corrosion coating for long-distance pipelines.

• Pros

Top-level comprehensive anti-corrosion performance, excellent resistance to soil corrosion, moisture and mechanical damage.
Strong adhesion, long service life .
Resist wear, bending and external pressure.

• Cons

Higher cost than single-layer PE and galvanized coating.
Complicated production process.

• Application

Long-distance buried oil pipelines, natural gas transmission pipelines, cross-regional large-scale water conveyance pipelines.

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• Features

Thermoplastic polyethylene material, usually green, black or blue in appearance.
Smooth coating surface, excellent waterproof and anti-corrosion ability.

• Pros

Low friction coefficient, good flow medium performance.
Flexible, impact-resistant, suitable for buried pipelines.
Moderate price, widely used in municipal projects.

• Cons

Poor high-temperature resistance; coating may soften under long-term high temperature.
Weak resistance to strong chemical solvents.

• Application

Municipal water supply pipes, farmland irrigation pipes, general buried sewage pipes (the so-called green coated steel pipe mostly uses this coating).

• Features

Coating material is epoxy resin, applied via spraying, rolling or electrostatic powder coating and thermally cured.Forms a dense, non-porous and rigid film tightly bonded to the steel surface.

• Pros

It delivers outstanding chemical and corrosion resistance with strong adhesion. It prevents scale and bacteria growth, featuring long service life and good compatibility with various pipe connections.

• Cons

The coating is brittle and vulnerable to cracking under heavy impact. It has poor UV resistance and cannot endure prolonged sunlight, and its cost is higher than galvanized and single-layer PE pipes.

• Applications

It is widely used for potable water pipelines, sewage and chemical medium delivery pipes. It also serves oil & gas lines, marine pipelines and underground fire protection systems.

• Features

Concrete is cast onto the pipe exterior to form a thick, rigid outer shell. Steel mesh is often added inside the concrete for reinforcement.

• Pros

It offers superior resistance to external pressure, impact and abrasion. The heavy weight keeps pipes stable underwater or in deep burial.

• Cons

The pipe becomes heavy and bulky, raising transport and installation costs. The concrete layer may crack under bending or strong vibration.

• Applications

Mainly used for subsea pipelines, river-crossing pipelines and large buried pipelines in deep water or soft soil areas.