Production Process of Epoxy Coal Tar Pitch Anti-corrosion Steel Pipe

Epoxy coal tar pitch anti-corrosion steel pipe is a widely used anti-corrosion pipeline product for buried water supply, sewage treatment, municipal engineering, and petrochemical projects. It combines the high mechanical strength of carbon steel pipe with the excellent water resistance, chemical resistance, and soil corrosion resistance of epoxy coal tar pitch coating, forming a tough, impermeable protective layer. The anti-corrosion coating is critical to the service life of the pipeline, which is crucial when choosing a reliable supplier. The production process of epoxy coal tar pitch coating directly determines the anti-corrosion performance and long-term stability of the finished pipe.

1.Steel Pipe Surface Pretreatment

The first and most critical step in the production process is the surface preparation of the steel pipe. The pipe is first degreased to remove oil, grease, and other contaminants. Then, it undergoes shot blasting or sandblasting to eliminate rust, scale, welding slag, and debris, achieving a near-white metal finish (typically Sa2.5 standard) with controlled surface roughness. This step is essential to ensure strong mechanical adhesion between the coating and the steel pipe substrate, preventing delamination and blistering.

2.Primer Application

After pretreatment, the steel pipe surface is cleaned and dried. A special epoxy coal tar pitch primer is applied evenly to the pipe surface. The primer penetrates the rough surface, forming a strong bonding bridge between the steel pipe and the subsequent topcoat. It also provides initial corrosion protection, preventing the cleaned surface from re-oxidizing before the main coating is applied.

3.Coating Application (Multi-Layer System)

The core step of the process is the application of the epoxy coal tar pitch coating, which is typically applied in a multi-layer system (such as two-oil, three-oil two-cloth, or five-oil three-cloth):

4.Curing and Drying

After the final coating is applied, the pipe enters the curing process. Depending on the coating type, the pipe is cured at room temperature or under controlled conditions to allow the epoxy coal tar pitch to fully cross-link and harden. Proper curing is critical to developing the coating’s full chemical resistance, water resistance, and adhesion properties. It prevents defects such as soft spots, blistering, or poor interlayer adhesion.

5.Finishing and Quality Inspection

After curing, the pipe ends are trimmed, and any excess coating is removed. Protective caps are installed to prevent damage to the coating during transportation. Every finished pipe undergoes comprehensive quality control before delivery:

Only pipes that pass all inspections are marked with specifications, batch numbers, and certification marks, then packaged for delivery. With mature production technology and strict quality control, epoxy coal tar pitch anti-corrosion steel pipe provides a reliable, cost-effective anti-corrosion solution for buried pipeline projects worldwide.