Construction method of fireproof coating for steel structure

Steel structure fireproof coating is a special coating used to improve the fire resistance of steel structures, widely used in industrial plants, high-rise buildings, bridges, petrochemical facilities and other places. The construction method directly affects the fire resistance and service life of the steel structure. This article will provide a detailed introduction to the construction methods of fire-resistant coatings for steel structures, including preparation before construction, construction techniques, quality control, and precautions.

 Preparation before construction

1. Material preparation
Fireproof coating: Select suitable fireproof coatings according to design requirements to ensure compliance with national or industry standards. The commonly used fireproof coatings include two categories: expansion type and non expansion type. The specific selection should be determined according to the fire resistance limit requirements of the steel structure and the usage environment.
Diluent: Choose the appropriate diluent according to the coating manual to ensure that the coating has good workability.
Primer: Some fireproof coatings need to be coated with primer first to improve the adhesion and anti-corrosion performance of the coating.

2. Tool preparation
Spraying equipment: such as airless spraying machines, air spraying machines, etc., ensure that the equipment is clean and free of impurities.
Brushing tools: such as roller brushes, brushes, etc., used for local repairs or small-scale construction.
Mixing tools: such as electric mixers, used to evenly mix coatings.
Protective tools: such as protective clothing, masks, gloves, goggles, etc., to ensure the safety of construction personnel.

3. Base treatment
Cleaning the base surface: Remove oil stains, rust, dust and other impurities from the surface of the steel structure to ensure that the base surface is clean and dry.
Rust removal treatment: Sandblasting, shot blasting, or manual rust removal methods are used to remove rust on the surface of steel structures, achieving Sa2.5 or St3 rust removal standards.
Repair defects: Repair defects such as dents and holes on the surface of steel structures to ensure a smooth base surface.

Construction technology

1. Primer application
According to the design requirements, apply a layer of primer on the surface of the steel structure to improve the adhesion and anti-corrosion performance of the coating. The primer should be evenly applied to avoid missing or sagging.
After the primer is dried, surface inspection should be carried out to ensure that there are no defects before the construction of fireproof coating can be carried out.

2. Construction of fireproof coating
Mixing paint: Use an electric mixer to mix the fireproof paint evenly, ensuring that the paint has no sedimentation or clumping.
Spraying construction: Use airless spraying machine or air spraying machine for spraying. During spraying, the distance between the spray gun and the base surface should be kept moderate, the spraying pressure should be uniform, and the coating thickness should be consistent. The spraying sequence should be from bottom to top and from left to right to avoid missed or repeated spraying.
Brushing construction: For local repairs or small-scale construction, roller brushes or brushes can be used for brushing. When brushing, it should be evenly applied to avoid coating too thick or too thin.
Multi layer construction: According to design requirements, fireproof coatings usually require multi-layer construction. After each layer of coating is applied, the next layer should be applied only after it has completely dried. The thickness of each layer of coating should be controlled within the range required by the design.

Coating maintenance

After the completion of fireproof coating construction, appropriate maintenance should be carried out to avoid the coating being affected by external factors such as rainwater and direct sunlight. The curing time is usually 7-14 days according to the requirements of the paint manual.

3、 Quality control

1. Coating thickness control
Use a coating thickness gauge to measure the thickness of the coating, ensuring that the thickness of each layer of paint meets the design requirements. Insufficient or excessive coating thickness can affect the fire resistance effect, so the coating thickness should be strictly controlled.

2. Coating adhesion testing
Use a pull-out tester to test the adhesion of the coating, ensuring that the adhesion between the coating and the substrate meets the requirements. Coatings with insufficient adhesion are prone to detachment, which affects the fire resistance effect.

3. Appearance inspection of coating
After the construction is completed, inspect the appearance of the coating to ensure that there are no defects such as bubbles, cracks, peeling, etc. in the coating. For areas with defects, timely repairs should be carried out.

Precautions

1. Construction environment
Fireproof coating construction should be carried out under suitable environmental conditions, avoiding construction in high temperature, low temperature, humid or windy weather. The construction environment temperature should usually be controlled between 5 ℃ -35 ℃, and the relative humidity should be less than 85%.

2. Construction safety
Construction personnel should wear protective equipment to avoid direct contact of paint with skin or eyes. The construction site should maintain good ventilation to avoid the accumulation of paint volatiles.

3. Paint storage
Fireproof coatings should be stored in a cool, dry, and ventilated place, avoiding direct sunlight and high temperatures. After opening the coating, it should be used as soon as possible to avoid prolonged exposure to air.

4. Construction records
Detailed construction records should be kept during the construction process, including construction date, environmental conditions, paint batch number, coating thickness, etc., for future inspection and maintenance.

Summary

The construction method of fireproof coating for steel structures is directly related to the fireproof effect and service life of steel structures. Adequate preparation work should be done before construction, including materials, tools, and base surface treatment. During the construction process, it is necessary to strictly follow the process requirements to ensure that the coating thickness, adhesion, and appearance quality meet the design requirements. After the construction is completed, appropriate maintenance and quality testing should be carried out to ensure that the fireproof coating can play its due role. Through scientific construction methods and strict quality control, the fire resistance of steel structures can be effectively improved, ensuring the safety of buildings.