Coating Structure of TPEP Anti-Corrosion Steel Pipes

Coating Structure of TPEP Anti-Corrosion Steel Pipes

TPEP (Two-layer Polyethylene and Epoxy) anti-corrosion steel pipes utilize a composite coating system that combines the chemical resistance of fusion bonded epoxy (FBE) with the mechanical durability of polyethylene (PE). This dual-layer structure forms an integrated protective barrier that ensures long-term performance in harsh environments, such as underground municipal pipelines or oil and gas transmission systems.

1. Steel Substrate (Base Pipe)

The core of the TPEP pipe is a high-strength seamless or spiral welded steel pipe, which provides structural integrity and pressure resistance. Prior to coating, the steel surface is:

• Shot-blasted to near-white metal finish (Sa2.5 or higher)

• Cleaned and preheated to ensure strong coating adhesion

2. Inner Layer: Fusion Bonded Epoxy (FBE)

Thickness: typically 80–150 microns
Function:

• Provides a dense, crosslinked barrier to prevent corrosion

• Chemically bonds to the steel surface

• Resists water, salts, acids, and other corrosive agents

Characteristics:

• High dielectric strength

• Strong adhesion to steel

• Excellent resistance to cathodic disbondment

3. Middle Adhesive Layer (Modified Polyolefin Primer)

Thickness: usually 170–250 microns
Function:

• Serves as a bonding agent between the epoxy and polyethylene layers

• Maintains flexibility and prevents delamination

Characteristics:

• Strong chemical compatibility with both layers

• Enhances peel strength and coating stability under stress

4. Outer Layer: Polyethylene (PE)

Thickness: typically 1.8–3.0 mm
Function:

• Provides mechanical protection against soil stress, impact, and abrasion

• Shields the epoxy layer from UV exposure, chemicals, and physical damage

Characteristics:

• High impact resistance

• Durable and weatherproof

• Long-term protection in underground environments

Layer Summary

• Steel Substrate – Structural support

• Fusion Bonded Epoxy (FBE) – Internal corrosion resistance

• Adhesive Layer – Composite bonding strength

• Polyethylene Outer Layer – External mechanical protection

Conclusion

The TPEP coating structure integrates chemical shielding and mechanical durability in a multi-layer system. This design ensures that the steel pipe can withstand internal corrosion, external damage, and long-term environmental exposure, making TPEP-coated steel pipes a highly reliable choice for demanding infrastructure applications.