Rust removal method and grade division of steel structure

   

A large amount of steel will be needed in the steel structure engineering design, but if the steel used in the construction is rusty, the service life will be shortened greatly. It is also a challenge to personal safety. The collapse of houses is not uncommon, and it has been paid more and more attention in recent years. Today we will share some derusting methods with you!

Pickling to Remove Rust

Immersing the steel components to be painted in an acid tank, and use acid to remove oil and rust on the surface of the components. The pickling process is also efficient and the rust removal is more thorough. But after pickling, the components must be washed with hot or clean water. If there is residual acid, the rust of the components will be more severe.

Manual Derusting

Some relatively simple tools, such as scrapers, grinding wheels, emery cloths, wire brushes, etc., are manually used to remove rust on steel components. This method has low work efficiency, poor working conditions, and incomplete rust removal.

Sandblasting

It uses the pressure of compressed air to continuously impact the surface of steel components with quartz sand or iron sand to clean up the rust, oil, and other debris on the surface of the steel, then exposing the true color of the metal steel. This method has high efficiency and thorough rust removal, which is a relatively advanced rust removal process.

 

Picture- iron sand

How to divide the corrosion grade of steel structure?

Grade A: The steel surface is completely covered with an oxide scale and almost no rust.

Grade B: The surface of the steel that has been rusted and part of the oxide scale has peeled off.

Grade C: Steel surface with a small amount of pitting corrosion, and the oxide scale can be scraped off due to corrosion.

Grade D: The oxide scale has been completely peeled off due to corrosion and pitting corrosion has generally occurred on the steel surface

Construction

Method

 Characteristics of Applicable Coatings Product Facility Advantages & Disadvantages
Drying Speed Viscosity Type
Brushing Slow Low plasticity Oil paint

Phenolic paint

Alkyd paint etc.

 General components and buildings, various equipment pipes, etc. Various brushes Low investment, simple construction method, suitable for coating of various shapes and sizes;

The disadvantage is poor decoration and low construction efficiency
Manual Roll Coating Slow Low plasticity Oil paint

Phenolic paint

Alkyd paint etc.

 General large plane components and management, etc. Roller Low investment, simple construction method, suitable for painting large areas; the disadvantages are the same as brushing method
Dip Coating Proper dryness, good leveling, moderate drying speed Good thixotropy Various synthetic resin coatings Small parts, equipment and mechanical parts Dipping tank, centrifugal and vacuum equipment Less equipment investment, simple construction method, less paint loss, suitable for constructing complex components;

The disadvantage is that the leveling is not very good, there is sagging, pollution, and the solvent is volatile
Air Spraying Fast evaporating and moderate drying Low viscosity Various nitrocellulose paint, rubber paint, architectural vinyl paint, polyurethane paint, etc. Various large components and equipment and pipelines Spray gun, air compressor, oil-water separator, etc. The equipment investment is small, the construction method is more complicated, and the construction efficiency is higher than the painting method;

The disadvantage is that the consumption dose is large, the pollution phenomenon is easy to cause fire.
Mist Spraying Paint with high boiling point solvent High non-volatile content, thixotropic Prototype coatings and high non-volatile coatings Various large steel structures, bridges, pipelines, vehicles and ships, etc. High pressure airless spray gun, air compressor, etc. The equipment investment is large, the construction method is more complicated, the efficiency is higher than the air spray method, and the thick coating can be obtained;

The disadvantage is that part of the paint is also lost, and the decoration is poor.
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