Production Process of FRP (Fiberglass Reinforced Plastic) Wrapped Anti-corrosion Steel Pipe

FRP wrapped anti-corrosion steel pipe is a composite anti-corrosion pipeline product widely used in buried sewage treatment, chemical engineering, marine engineering, and soil corrosion environments. It combines the high mechanical strength of the steel pipe with the excellent chemical resistance, impact resistance, and long-term stability of fiberglass reinforced plastic (FRP), forming a robust protective barrier against external corrosive factors. The production process of the FRP wrapping layer directly determines the anti-corrosion performance and service life of the finished pipe, which is crucial when choosing a reliable supplier.

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 surface contaminants using high-pressure cleaning agents. 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 primer, the FRP layer, and the steel pipe substrate.

2.Primer and Intermediate Coating Application

After pretreatment, a special adhesive primer is applied to the pipe surface. The primer forms a strong bonding bridge between the steel pipe and the subsequent FRP layer, preventing delamination and improving the overall adhesion and corrosion resistance of the composite structure. Depending on the project requirements, an intermediate coating may also be applied to further enhance the bonding and anti-corrosion performance.

3.Mechanical FRP Wrapping Process

The core step of the production process is the mechanical wrapping of the FRP layer. The steel pipe is rotated at a constant speed while being fed through the winding machine. Continuous glass fiber roving or mat is impregnated with resin (such as unsaturated polyester resin, epoxy resin, or vinyl ester resin) and wound tightly around the pipe surface. The winding tension, angle, and resin content are precisely controlled to ensure uniform coverage, consistent thickness, and maximum density of the FRP layer. The number of layers and thickness are determined by the specific anti-corrosion and mechanical requirements of the project.

4.Curing and Solidification

After the FRP layer is fully applied, the pipe enters the curing process. Depending on the resin type, the pipe is cured at room temperature or in a controlled-temperature oven to complete the cross-linking reaction of the resin. This ensures the FRP layer forms a rigid, dense, and fully bonded structure with excellent mechanical strength, impact resistance, and chemical resistance. Proper curing is critical to prevent defects such as delamination, blistering, or incomplete bonding.

5. Finishing and Quality Inspection

After curing, the pipe ends are trimmed and polished to remove excess resin and glass fiber burrs. Protective caps are installed to prevent damage to the FRP layer during transportation and installation. 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, FRP wrapped anti-corrosion steel pipe provides a reliable, long-lasting anti-corrosion solution for pipeline projects in highly corrosive environments worldwide.