Are you aware of the three common issues we encounter in tunnel fire-resistant coating application? Let me explain below.WeExpert personnel provide an explanation.
Tunnel fire-resistant coating projects can be quite challenging for construction workers in terms of skill proficiency. Lacking experience during the coating process can lead to various issues, such as paint peeling, insufficient thickness, and failure to meet acceptance standards. Severe problems can affect both aesthetics and project timelines. To ensure the smooth completion of construction, here are some points to be mindful of during the process.
Coating layer too thin
The purpose of applying fire-retardant coatings on steel structures is to enhance their fire resistance limit. The fire resistance performance of steel structures is closely related to the coating thickness. Different thicknesses of the same type of fire-retardant coating result in varying fire resistance limits. If the thickness of the fire-retardant coating on steel structures is not applied according to design specifications, the steel's fire resistance limit cannot meet fire safety requirements. Statistics show that issues with excessively thin coatings account for 25% of such problems. To prevent these issues, we measure the coating thickness after construction to address them.
Before construction, the tunnel fire-resistant coating and water must be mixed in a certain proportion, followed by spraying with a nozzle. As most tunnels today are high-speed tunnels, often extending for hundreds or even thousands of meters, not using spraying would severely affect the construction progress.
2. The coated surface features protuberances.
To ensure a uniform and smooth surface finish for the coating, while also meeting the required thickness, it is explicitly stated during the application of fire-resistant coatings that the coated surface should have all bosses removed to guarantee evenness. However, some contractors ignore this requirement, with some emphasizing that the steel columns should be decorated after spraying, even if there are bosses, and they accommodate their own shortcuts. Such issues account for 10% of the cases. If bosses are present, they must be removed after measurement, and the column surface must be ensured to be even and smooth before inspection; otherwise, it is deemed不合格.
After mixing the paint according to the familiar proportions, it cannot be used immediately; instead, a waiting period of 10 minutes is required to allow the slurry to fully mix. It's not advisable to mix too much paint at once, as it tends to solidify easily. If it's not used within two hours, it becomes unusable, as the paint will have solidified into a mass, leading to waste. Therefore, moderate mixing is crucial, and it greatly tests the worker's skills.
3. Incorrect selection type
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 fire-resistant limit of steel structures meets fire safety requirements, it is necessary to apply different types of fire-resistant coatings to different parts of the steel structures. Choosing the wrong type will not meet fire safety requirements, even if the coating thickness is sufficient.
The coating process cannot achieve the required thickness in one pass; typically, it requires two to three coats. It is a mistake for some construction teams to immediately apply the second coat after the first. Applying the second coat before the first is dry can easily lead to insufficient paint viscosity, causing it to peel off later. Therefore, a 24-hour interval is necessary before applying the second coat, even if the project timeline is tight.
The construction site environment is crucial, especially for tunnel fire-retardant coatings, which are mixed with water and sprayed in a mist-like form. This requires a specific environment; below 5 degrees Celsius, measures must be taken, otherwise, the paint is prone to freezing upon application.
The application of tunnel fire-resistant coatings may seem simple, but there are actually many technical issues to address. Therefore, it's better to hire a professional team for the job.
The above outlines the three common questions regarding the application of tunnel fire-resistant coatings. If you have any further inquiries, please contact our service team. Our professional technicians will be happy to explain our services. We also appreciate your support and dedication to our clients, and thank you for your continued patronage!
