Anti-corrosion Pipe Coating

Published:2025-09-04 | Last Updated: 2025-09-04    Views: 127

I. Why are anti-corrosion coatings needed for pipelines?

During the transportation of oil, natural gas, water, and chemical media, pipelines are exposed to humid, soil, electrochemical corrosion, and chemical erosion environments for long periods of time, causing metals to gradually rust and even perforate. In order to extend the service life of pipelines, ensure transportation safety, and reduce maintenance costs, it is necessary to apply anti-corrosion coatings to the surface of pipelines.

II. Common Types of Corrosion-Resistant Pipe Coatings

(1) Fusion-bonded Epoxy Powder Coating (FBE)

Process:

Steel pipes that have undergone sandblasting rust removal (Sa 2.5 grade) are heated to approximately 220°C, then coated with epoxy powder. The powder melts and cures at high temperatures to form a dense coating.

Features:  

Excellent adhesion and corrosion resistance  

Resistant to chemical corrosion and cathodic delamination  

Temperature range generally -20°C to +80°C  

Uniform coating thickness and high construction efficiency  

Applications:  

Oil and natural gas long-distance pipelines  

Drinking water transmission pipelines  

External corrosion protection for highly corrosive industrial pipelines

(2) Three-layer polyethylene coating (3PE)  

Process:  

First layer: Spray epoxy powder (FBE) as a primer to enhance adhesion to the steel pipe  

Second layer: Apply special adhesive (AD)

Third layer: Extruded high-density polyethylene (PE) protective layer for mechanical protection  

Features:  

Excellent corrosion resistance and mechanical protection performance  

Impact-resistant, wear-resistant, and resistant to humid heat  

Long service life, up to 30 years or more  

Strong construction adaptability, suitable for large-diameter pipelines  

Applications:  

Buried oil and gas long-distance transmission pipelines  

Water transmission pipelines in highly corrosive soil environments

(3) Double-layer polyethylene coating (2PE)  

Process:  

First layer: Spray epoxy powder or liquid epoxy as the base layer  

Second layer: Extruded polyethylene protective layer  

(Compared to 3PE, the adhesive layer is omitted)

Features:  

Simple process, lower cost  

Good corrosion resistance, but slightly lower peel resistance than 3PE  

High mechanical strength and impact resistance  

Applications:  

Medium- and short-distance water and oil pipelines  

Buried pipelines in general corrosion environments

(4) Polyurethane coating

Process:

Apply two-component or single-component polyurethane materials to the pipe surface via spraying, brushing, or other methods to form a highly flexible coating.

Features:

Excellent flexibility, wear resistance, and impact resistance

Superior waterproof performance, adaptable to structural deformation

Good adhesion to various substrates such as metal and concrete

Applications:

Marine engineering pipelines

Chemical storage tanks and piping

Pipeline outer walls in high-wear conditions

(5) Epoxy coal tar coating

Process:

Mix epoxy resin with coal tar and fillers, add a curing agent, and apply to the pipe surface to form a thick film coating.

Features:

Good water resistance, resistant to soil corrosion

Low cost, simple construction

Poor environmental performance, use restricted in some areas

Applications:

Buried water supply pipes

General industrial water pipelines

Temporary or economical anti-corrosion projects

III. Corrosion-resistant coating comparison table

IV. Common standards for anti-corrosion pipe coatings

V. Main inspection items for anti-corrosion coatings

VI. How to Select Corrosion-Resistant Pipeline Coatings

(1) Select Based on the Conveyed Medium

1) Water or Neutral Liquids

Options: FBE, 2PE, 3PE, cement mortar lining

Features: Corrosion-resistant, hygienic, cost-effective

2) Petroleum, Natural Gas, or Oil Products

Options: FBE, 3PE, 2PE

Features: Chemical corrosion resistance, resistance to cathodic剥离

3) Acidic, alkaline, or chemical liquids

Options: Double-layer FBE, polyurethane, liquid epoxy

Features: Strong corrosion resistance, material selection depends on medium concentration

(2) Select based on environmental conditions

1) Buried long-distance pipelines

Recommended: 3PE, FBE double-layer  

Reason: Impact resistance, moisture and heat resistance, good mechanical protection  

2) Underwater or marine environments  

Recommended: Polyurethane coating, 3PE  

Reason: Abrasion resistance, seawater corrosion resistance, good flexibility  

3) Outdoor pipelines or high-temperature environments  

Recommended: FBE high-temperature type, liquid epoxy, polyurethane  

Reason: High-temperature resistance, UV resistance, strong adhesion