Selection factors and application environment of anticorrosive primer for steel structure

there are clear requirements in the design blueprint, and the steel structure engineering company only needs to implement according to the design instructions.In fact, the selection of anti-corrosion primer for steel structure needs to consider five main factors, such as the surface treatment of steel structure, the environment, the type of topcoat required, the use temperature and some special corrosion conditions.The details are as follows:

Site drawing of anticorrosion and painting of steel structure

　　1Steel structure surface treatment

Different kinds of paints have different requirements for the treatment of steel structure substrate. There are strict requirements, such as zinc rich primer with sand blasting treatment above Sa2.5, epoxy iron oxide red, red lead anticorrosion, etc. which can be completely derusted, as well as rusty anti-corrosion paint which can be coated with slight rust.At the same time, the pretreatment of steel structure surface can be divided into galvanized steel structure, phosphating treatment steel structure, ordinary carbon steel bare steel and so on.Steel structure primer must be treated to a certain standard of steel structure surface, in order to have good adhesion, thus ensuring the anti-corrosion effect. Different types of steel structure primer have different requirements for the treatment, and according to the anti-corrosion requirements and different corrosion environment, the surface treatment level also changes.The requirements for rust removal grade of steel surface by primer coating shall meet the requirements in the table below.For the steel surface with corrosion grade D, spraying or throwing should be used for derusting.

Type of primer coating

Derusting grade

Strong corrosion

Medium corrosion

Weak corrosion

Phenolic resin primer

Sa2.5

St3

Asphalt primer

Sa2.5 or ST3

St3

Alkyd resin primer

Sa2.5

St3

Perchloroethylene primer

Sa2.5

–

Ethylene phosphating primer

Sa2.5

–

Epoxy asphalt primer

Sa2.5

St3

epoxy primer

Sa2.5

–

Polyurethane anticorrosive primer

Sa2.5

–

Silicone heat resistant primer

–

Sa2.5

Chlorosulfonated polyethylene primer

Sa2.5

–

Chlorinated rubber primer

Sa2.5

–

Inorganic zinc rich primer

Sa2.5

–

　　2Environment of steel structure

Before selecting anti-corrosion paint, the corrosion factors of steel structure should be fully considered. If the corrosion is slight, ordinary anti-corrosion paint can be used. For the seaside, chemical plant, bridge and other serious corrosion, or important steel structure, high-performance anti-corrosion primer should be selected.

　　3Top coat used for steel structure anticorrosion

The compatibility of anticorrosive paint and topcoat should be fully considered to avoid coating problems caused by mismatching.For example, alkyd anticorrosive paint is easy to apply, but it can not be used with two-component high-performance anti-corrosion topcoat, and epoxy zinc rich primer can not be used with alkyd enamel.

　　4Temperature of steel structure equipment

Most paints can only be used at room temperature. If it is required to be used in high temperature environment, high temperature resistant anticorrosive paint must be selected, such as inorganic zinc rich primer and silicone high temperature resistant paint.

　　5Whether there are special corrosion factors.

Strong acid, strong alkali, solvent oil, salt spray, etc., must start from the primer to strengthen the protection.In addition, the water, wet environment corrosion is serious, also need to match high-performance anti-corrosion primer, such as epoxy zinc rich primer, inorganic zinc rich primer and so on.

Application condition table of anticorrosive paint for steel structure

The rust removal standard of steel structure substrate is shown in the figure

Paint varieties

Applicable substrate

Very low substrate treatment requirements

Service temperature

Antiseptic effect

Alkyd anticorrosive paint (iron red, gray)

Bare steel, phosphatized steel structure

Thorough derusting, SA2

normal atmospheric temperature

Corrosion in general atmospheric environment

Alkyd red lead anticorrosive paint

Bare steel, phosphatized steel structure

It can be slightly rusty without loose oxide layer

normal atmospheric temperature

Corrosion in general atmospheric environment

Epoxy anticorrosive primer (iron red, gray)

Bare steel, phosphatized steel structure

Thorough derusting, SA2

Short term temperature below 200 ℃,

Long term below 100 ℃