Types and selection of oil casing pipe coatings

Oil casing pipe coatings are mainly used to prevent corrosion, reduce friction, and extend service life. Common pipe coating types include:

1. Epoxy coating (FBE, Fusion Bonded Epoxy)

Features: A dense protective layer is formed by electrostatic spraying and high-temperature curing, which is resistant to chemical corrosion and has strong adhesion.
Application: Widely used in acidic environments (such as those containing H₂S, CO₂) and seawater corrosion environments.

2. Polyethylene/polypropylene coating (2PE/3PE)

2PE coating: bottom layer epoxy resin + outer layer polyethylene, resistant to mechanical damage.
3PE coating: Add an intermediate bonding layer to further improve impact resistance and corrosion resistance.
Applicable scenarios: highly corrosive soil or submarine pipelines.

3. Polyurethane coating
Advantages: Excellent wear resistance, suitable for dynamic friction environments (such as frequent drilling).
Use: casing couplings or easily worn parts.

4. Zinc coating (galvanized or thermally sprayed zinc)
Function: sacrificial anode protection, delaying electrochemical corrosion of steel.
Limitation: short protection period when used alone, often combined with other coatings.

5. Ceramic coating
Features: extremely high temperature resistance and wear resistance, but high cost and brittleness.
Application: high temperature and high pressure wells (such as geothermal or deep wells).

6. Composite coating system
For example: epoxy primer + polyurethane topcoat, combining the advantages of different materials.

7. Special functional coating
Anti-scaling coating: reduce mineral deposition (such as fluoropolymers).
Insulating coating: used for galvanic corrosion protection.

Selection factors:
Environment: acidic (select FBE), seawater (3PE), high temperature (ceramic).
Cost: epoxy resin is economical, ceramic coating is expensive.
Construction conditions: compatibility is required for on-site patching.

Notes:
1. The coating needs to pass API, ISO and other standard tests (such as salt spray resistance and cathodic stripping resistance).
2. Avoid mechanical damage during transportation and installation.
3. Different coatings can be used in combination (such as galvanizing + epoxy) to cope with complex working conditions. The actual selection needs to be combined with the specific environment and engineering requirements of the oil well.

Read more: Types of drilling casing pipe or Casing pipe vs Drill pipe