Surface Treatment Methods for Spiral Pipes

Introduction to Rust Removal and Anti-Corrosion Processes
Rust removal is a crucial step in pipeline anti-corrosion treatment. Currently, there are various rust removal methods, including manual derusting, sandblasting, acid pickling, and more. Among them, manual derusting, mechanical derusting, and coating-based rust removal (anti-corrosion painting) are the most common methods. Below, Ruineng Anti-Corrosion Equipment provides a brief introduction to the specific operational requirements for these three rust removal processes.

1. Manual Derusting
Use scrapers and files to remove scale and casting sand from the surface of pipelines, equipment, and containers.

Then, use a wire brush to eliminate loose rust.

Polish the surface with sandpaper.

Finally, wipe the surface clean with cotton yarn.

2. Mechanical Derusting
First, remove scale and casting sand from the pipeline surface using scrapers and files.

One operator stands in front of the derusting machine, while another stands behind it, feeding the pipeline through the machine repeatedly until the bare metal surface is exposed.

Before painting, wipe the surface again with cotton yarn to remove dust and loose particles.

3. Anti-Corrosion Painting
Pipelines, equipment, containers, and valves are generally painted according to design specifications. If no specific requirements are provided, the following standards apply:

① Exposed Pipelines, Equipment & Containers
Apply one coat of primer first.

Before project handover, apply two topcoats.

If insulation or condensation protection is required, apply two coats of primer.

② Concealed Pipelines, Equipment & Containers
Apply two coats of primer.

The second coat should only be applied after the first has fully dried.

The primer’s viscosity must be appropriate for proper adhesion.

③ Buried Pipelines (Winter Construction Considerations)
For winter construction, dissolve No. 30A or 30B petroleum asphalt using rubber solvent oil or aviation gasoline at a weight ratio of 1:2 (asphalt:gasoline).

Painting Methods:
① Manual Brushing

Apply paint in layers with overlapping strokes (horizontal and vertical) to ensure even coverage.

Avoid missed spots or dripping.

② Mechanical Spraying

The spray gun should be perpendicular to the surface.

Flat surfaces:Maintain a distance of 250–350 mm between the nozzle and surface.

Curved surfaces:Keep a distance of ~400 mm.

Move the nozzle evenly at a speed of 10–18 m/min.

Use compressed air at a pressure of 0.2–0.4 MPa.http://www.hnftsteels.com

This process ensures effective rust removal and long-lasting anti-corrosion protection for pipelines and related equipment.