Indoor non-expandive steel structure fire retardant coating


Non-expanding steel structure fire retardant coating
3.1 Preparation requirements
3.1.1 Non-expanding steel structure fire retardant coating can be constructed by spraying, troweling, etc. Before construction, please choose an appropriate construction method and dry and solidify under normal natural conditions.
3.1.2 For non-expandive steel structure fire retardant coatings, the bottom layer should be used in combination with epoxy zinc-rich primer.
3.1.3 Before construction, cover and protect parts and other objects that do not need to be sprayed.
4. Construction work process

5. Construction work steps
5.1 Steel structure surface treatment
5.1.1 Use a grinder or hand tools to polish the steel structure surface, use cotton cloth or a clean brown brush to wipe off dust, and use cleaning agents to clean oil stains.
5.1.2 The joints of the welding parts should be treated with emphasis. Use a steel shovel, scraper, steel brush or grinder to remove welding debris, oxide scale and rust. The rust removal level should meet the St2 level standard.
5.1.3 The treated steel structure base layer should be painted with primer within 4 hours. When the steel structure is stored in the factory, it should not exceed 16 hours. When the relative air humidity is greater than 75%, the interval should be shortened.
5.1.4 Anti-rust primer construction can only be carried out after passing the acceptance inspection.
5.2 Anti-rust primer application
5.2.1 Before painting, the treated surface should be cleaned to remove dust and debris. The anti-rust primer can be applied only after passing the inspection.
5.2.2 The construction temperature and humidity should be in accordance with the instructions. In case of rain, fog, strong wind, etc., outdoor construction is not allowed, and protective measures should be taken in the constructed parts.
5.2.3 Epoxy zinc-rich primer is a two-component paint. The mixing ratio is 10:1. Stir component A thoroughly and add component B and continue stirring until uniform. The aging period is 20 minutes (20℃) and the pot life is 4 hours (20℃). According to the on-site viscosity requirements, Appropriately add 0-20% special diluent for dilution. After the first coat of anti-rust primer is dry, the next coat can be applied.
5.2.4 All painted parts must not be missed. The coating surface should be smooth and flat, consistent in color, and visually free from pinholes, bubbling, sagging, cracking, damage and other defects.
5.2.5 The total dry film thickness of the coating is 60-90 μm. A paint film thickness gauge must be used to check whether the thickness of each paint film meets the design requirements.
5.3 Quality inspection
5.3.1 Appearance inspection: The coating should be smooth and flat, consistent in color, and free of defects such as pinholes, blistering, sagging, cracking and damage.
5.3.2 Primer thickness inspection: Use a magnetic thickness gauge to check. The primer thickness is required to be uniform, and the primer thickness and number of layers should meet the design requirements.
5.3.3 Use the finger touch method to determine whether the coating is surface dry, and use the blade method to determine whether the coating is dry. The fire retardant coating can be constructed only after the primer is completely dry.
5.4 Fire retardant coating construction
5.4.1 Construction can only be carried out after the rust removal and anti-rust treatment on the surface of the steel structure meets the requirements and dust and other debris are removed.
5.4.2 Spraying, troweling and other construction methods can be used. It is recommended that large-area structures such as steel beams and steel columns use spraying, and small-area structures such as channel steel and tie rods use troweling. If spraying is used, a self-weighted spray gun can be used. The diameter of the spray gun nozzle is 6-10mm, the working pressure of the air pump is 0.4-0.8Mpa, and the vertical distance between the spray gun and the surface of the substrate to be sprayed is 300-500mm.
5.4.3 Construction of the first layer of fire-retardant coating: Primer must be applied before spraying and applying non-expandive steel structure fire-retardant coating (priming should be carried out by spraying, so that hollowing is less likely to occur. If spraying is not allowed on site, you can use The surface of the fire-retardant coating applied by the roller coating method should be roughened, and the bottom of the steel structure should not be exposed, which is beneficial to the bonding with the next layer of fire-retardant coating). The preparation ratio of the base material is non-expanding steel structure fire retardant coating: 707 emulsion: water = 1:0.25:0.8~1 (100 kg of powder is added with 25 kg of 707 emulsion, and the amount of water can be increased or decreased appropriately according to construction needs). Stirring method: First add water to the mixer, then add the measured 707 emulsion to the mixer, the stirring time is about 2 to 3 minutes; then add the non-expandable steel structure fire retardant coating, stir until uniform (10-15 minutes), time It should not be too long (note: the water consumption can be adjusted appropriately to suit the construction). The base material should be sprayed with a portable spray gun or applied with a paint roller. The thickness should be 1.5 to 2.0 mm. It should not be too thin or too thick. The bottom layer should be basically uniform and there should be no exposed surface of the steel structure. The mixed paint should be used up within 2 hours each time, and the next manual application can be carried out after 24 hours (after it is completely solidified and hardened).
5.4.4 Construction of the second to nth layer of fire-retardant coating: The preparation ratio of the coating is non-expanding steel structure fire-retardant coating: water = about 1:1. Stir at low speed until uniform (10-15 minutes). It should not be too late. long, mix well. The construction of the second layer and above of fire retardant coating can be carried out by spraying or troweling. The second layer of fire-retardant coating should be constructed when the first layer of fire-retardant coating is 70-80% dry (about 24 hours later); if the drying time of the first layer is too long, water should be sprayed appropriately before the second layer of construction. The construction thickness of each layer can be 8~10mm until the fire protection design thickness is reached. The interval between two applications is 24 hours, which should not be too long or too short. The mixture stirred each time should be used up within 2 hours. During inter-layer construction, the surface of the fire-retardant coating should not be smooth but can be made into a rough surface, which is beneficial to the bonding of the upper and lower layers.
5.4.5 When the temperature is high in summer or the coating interval is too long, water spraying maintenance should be carried out to prevent the coating from cracking, peeling and powdering due to water loss; once the package is opened, it should be used in time. If the coating is found to be damp or crusty, blocks and shall not be used; Construction environment: During construction and within 24 hours after construction, the ambient temperature should not be lower than 5°C. Like all cement mortars, it will suffer freezing damage before solidification. However, under extremely dry and hot conditions, necessary maintenance conditions should be created to prevent the coating from losing water too quickly (such as sunshade and water spray measures, etc.) 5.4.6
When the thickness of the coating is equal to or greater than 20mm, after the second application, When applying intumescent steel structure fire retardant coating (coating thickness is about 8-10mm), it is necessary to tie glass fiber mesh cloth. The specifications should be wire diameter φ0.5mm-φ1.5mm and mesh opening 10mmx10mm; the corners of the coating can be made Right angle or arc shape with radius 10mm. According to the actual conditions of different specifications of the on-site steel structure, cut the mesh cloth into a reasonable length. When hanging the mesh, pay attention to the pressing of the inner and outer corners of the steel structure. Do not make it too high. There should be a gap between the glass fiber mesh cloth and the steel structure. Leave a gap of about 8mm-10mm, and the overlap length of the mesh cloth is 50-100mm. Just press the cut fiberglass mesh cloth flatly on the slurry.
5.4.7 When constructing the skirt and the top of the steel structure, a 30º-45º bevel should be made with the fire-retardant coating. After the coating is dry, the top of the bevel must be sealed with outdoor sealant. (The method is shown in the figure below


5.4.8 The constructor should bring a thickness gauge to detect the coating thickness and ensure that the coating thickness meets the design requirements.
5.4.9 When the coating reaches the design required thickness, the last coating should be smoothed to ensure a uniform and smooth surface.
5.5 Quality inspection
5.5.1 Use visual method to check whether the color of the paint is consistent with the selected sample.
5.5.2 Use a thickness gauge to measure different points (not less than 5 points per square meter) to check whether the coating thickness meets the design requirements.
5.5.3 Whether the coating has any leakage, powder loss, obvious cracks, etc. If there are any individual cracks, they should be repaired immediately.
5.5.4 Use a 0.75-1kg hammer to lightly tap the coating to check its strength, etc., and use a 1m flat ruler to check the flatness of the surface.
5.6 Maintenance
5.6.1 After the construction of the fire-retardant coating is completed, measures should be taken to prevent rain, vibration, and sun exposure.
5.6.2 After the product is formed, the coating can be sprayed with water or other maintenance measures can be used to maintain the product where conditions permit.
5.7 Precautions for coating construction
5.7.1 During construction in northern areas with large climate and temperature differences, steel components must be treated with metal mesh. Fire retardant coatings in coastal humid areas should be protected.
5.7.2 It is not suitable for the construction of this product when the ambient temperature is lower than 5℃ in winter; it is not suitable for the construction of this product when the surface temperature of the substrate to be constructed is higher than 50℃ in summer.
5.7.3 During construction in the rainy season, rainproof measures should be taken for the newly completed fire retardant coating.
5.7.4 It is not suitable to operate when the wind speed is greater than 5m/s, or when it rains or there is condensation on the surface of the components.
5.7.5 Pay attention to the coating thickness of the first layer of construction.
5.7.6 When the fire retardant coating construction needs to be interrupted or the coating needs to be repaired due to some reasons, the coating should leave a 30-40° slope as the joint surface for the next continued construction or repair. Before construction and repair, the slope should be cleaned and moistened to ensure that the new and old surfaces are well combined.
5.7.7 Non-expandive steel structure fire-retardant coatings must be protected from rain and moisture during transportation and storage. They must not be used when the fire-retardant coatings solidify and agglomerate.
5.7.8 After each construction, the equipment and tools used should be cleaned with clean water in time.
5.7.9 If there is a graded intersection operation during construction, safety should be paid attention to.
6. Quality control measures and quality assurance system
6.1 Construction management process
The entire steel structure fire-retardant coating project should be subject to full-process quality management, and the quality management system should include:
A. Preparation work;
B. Technical disclosure;
C. Spraying and plastering of fire-retardant coatings Combination;
D. Quality assessment;
E. Data compilation.
6.2 Specific requirements for quality
6.2.1 The appearance and color must be consistent and comply with design and contract requirements.
6.2.2 The thickness of the fire retardant coating shall meet the specified requirements.
6.2.3 There are no cracks on the coating surface.
6.2.4 The surface is smooth, without obvious depressions, firmly bonded, and free of powdering, looseness and floating slurry.
6.2.5 Product test reports are complete.
6.3 Quality assurance measures
6.3.1 Set up full-time quality inspectors to be responsible for testing and quality control.
6.3.2 During construction, product instructions must be carefully read and the construction plan must be implemented.
6.3.3 Strictly conduct opening inspection to check product model, variety and color.
6.3.4 Strict self-inspection, check and test at any time, and keep records.
6.3.5 Special personnel must be responsible for the preparation and stirring of paint.
6.3.6 Fill in the construction records in detail, including ambient temperature, humidity and construction conditions.
6.3.7 Cooperate with Party A of the project to obtain quality visas.
6.4 Quality Inspection
6.4.1 Thickness: Use a thickness gauge to detect the thickness.
6.4.2 Color: Check visually, follow the design and compare with the color card or sample.
6.4.3 Cracks: Visual inspection or measurement with steel ruler, refer to standard CECS24-90.
6.4.4 Adhesion: Use a 0.5-1kg hammer to lightly tap the coating surface without falling off.
6.4.5 Coating appearance: visual inspection.
6.5 Quality control measures
6.5.1 Organize on-site quality inspection personnel and relevant construction management personnel to hold special quality management meetings to study relevant quality documents and quality standards and formulate quality management systems.
6.5.2 Strict self-inspection and control can only exceed the standard, not lower the standard. Take the initiative to invite the project supervisor to conduct on-site inspection in a timely manner.
6.5.3 Before painting, the model, name, and color of the product should be checked, and the manufacturing date and product certificate should be checked at the same time. The proportioning and stirring of the paint must be operated by a dedicated person, and monitoring records must be filed.
6.5.4 When a quality accident is discovered, the specific cause must be analyzed, a quality accident investigation report must be filled in, corrective suggestions must be made, and repairs must be made in a timely manner.
6.5.5 The project quality inspector shall report the project construction quality status to the project manager at any time and fill in quality records to reflect the project construction quality status in detail.