Do you know the requirements for fire-retardant coatings with different fire resistance limits on steel structures, and what hazards can non-compliant fire-retardant coatings pose? Stay tuned as we bring you new knowledge to explore together.
Different types of fire-resistant coatings have varying thicknesses when applied to steel structures, and their耐火limits also differ. To ensure that the steel structure meets fire resistance requirements, it is necessary to apply different types of fire-resistant coatings to different parts of the structure. Choosing the wrong type would result in insufficient fire resistance, even if the coating thickness is adequate.
Therefore, Article 2.0.4 of the "Technical Specification for Application of Fire Retardant Coatings on Steel Structures" explicitly stipulates: For exposed steel structures indoors, lightweight roof steel structures, and steel structures with decorative requirements, when the fire resistance limit is specified to be below 1.5 hours, thin-film type fire retardant coatings for steel structures should be used; for concealed outdoor steel structures, full steel structures in high-rise buildings, and multi-story factory steel structures, when the fire resistance limit is specified to be above 1.5 hours, thick-film type fire retardant coatings for steel structures should be selected.
During the inspection of the fire-resistant coating on the steel structure of a factory building at a certain center, it was found that the building is a large single-story and two-story mixed structure. The designated fire resistance grade is Class 1, with the fire resistance limit of steel beams at 2.00 hours and steel columns at 3.00 hours.
According to the design specifications, the fire-resistant coating for the steel beams and columns in this factory should have been a thick-coating type of steel structure fire-resistant coating. However, they chose an expandable steel structure fire-resistant coating produced by a certain Materials Co., Ltd. The technical specifications, as tested by the national authority, are as follows: at a coating thickness of 5.6mm, the fire resistance limit is 1.49 hours.
To further ascertain the coating thickness of its paint, a total of 9 points were inspected. The average thickness of the fire-retardant coating on the steel beams was 0.41mm, with one point coated at 0.66mm and the thinnest point at only 0.20mm. Due to the incorrect selection of fire-retardant coating type, it was impossible to meet the design's fire resistance requirements for the steel beams and columns. Consequently, the company was instructed to select an appropriate thick-coating type of steel structure fire-retardant coating and reapply it.
Therefore, understanding the fire-resistant limit of fire-retardant coatings plays a crucial role in selecting the correct coatings for steel structure construction. It is essential to clarify this before use to avoid substandard projects that require rework, which can be costly and inefficient.
