Five processes in the construction of epoxy coal tar anti-corrosion steel pipes

Five processes in the construction of epoxy coal tar steel pipes.

One Primer and topcoat before wrapping with fiberglass

1. The construction of epoxy coal tar paint adopts brushing method according to the site conditions.

2. After the rust removal of the steel is inspected and qualified, the primer and topcoat shall be applied. When painting, the welding position of the steel assembly shall be left as much as possible, with a reserved length of about 150mm, to avoid difficulty in cleaning the root during welding and affecting the welding quality.

3. For steel surfaces with a high degree of pit dust (>2mm), putty should be mixed to level it up.

4. Mix the epoxy coal tar paint thoroughly and let it mature for 15-30 minutes, then use it up within 4 hours.

5. After the steel sandblasting is qualified, the primer should be applied immediately. Therefore, attention should be paid to the influence of dust on the painting, and the painting should be carried out as far away from the sandblasting area as possible or the sandblasting construction should be suspended.

If the interval between paint reapplication is too long, the paint surface needs to be roughened with sandpaper or grinding wheel before applying the final coat of paint.

7. Apply a coat of topcoat after the primer surface dries and before curing, and apply a fine coat of topcoat after the topcoat dries and before curing. During construction, the process flow is often continuous, so special attention needs to be paid to the painting interval time to protect the painting interval between small and large painting intervals. During on-site construction, the interval time for coating should be determined based on the performance of the coating and weather conditions.

8. The operation of epoxy coal tar paint should be carried out in accordance with the material instructions and specifications provided with the goods.

9. The painting construction tools should be clean, and the cleaning and post-treatment during use should be appropriate.

10. When painting, the layers should be criss crossed and each layer should be repeated. The time interval for painting should meet the technical requirements of the coating, and the thickness of the paint film should comply with the design requirements. During the drying process of the paint film, the surrounding environment should be kept clean to prevent the surface of the paint film from being contaminated.

II Wrap glass fiber

1. The winding of fiberglass should be carried out immediately after the application of high-quality topcoat. Wrap 3 layers of fiberglass as required.

2. When winding fiberglass, it is required to overlap the edge by 15-25mm and the joint by 100-150mm during edge pressing.

If there are bubbles when wrapping the cloth, use a small knife to cut it open, then squeeze out the air inside the bubbles and smooth the surface.

4. The winding of the entire glass fiber should have a uniform and smooth surface.

III Topcoat coating with epoxy coal tar, stable performance steel pipe

After wrapping the fiberglass, immediately apply the topcoat. Apply two coats of topcoat after wrapping the fabric.

2. When applying the topcoat, it is necessary to ensure that the coating is fully covered and that there are no omissions or pinholes.

3. The coating protects the glass fiber by fully covering and impregnating it.

4 Drying and maintenance

After the stable performance is completed, let it stand and dry on its own for at least 8 hours without moving, so that it is not exposed to rain or water. It can only be transported after it is dry.

Five Repair and patching of performance stability layer

During transportation and installation, there may be damage to the performance stability layer. After installation and acceptance, it is necessary to repair the performance stability layer.

During the repair process, rust stains on the surface of the steel should be removed using a grinding machine or manually, with a rust removal grade of St3 or higher.

2. The performance stable layer used for repairing and patching should be consistent with the adjacent performance stable layer. The connection between the new performance stable layer and the old performance stable layer is stepped, and the interface must be overlapped. The overlap should be kept at least 50mm or more.

3. Due to its small and complex size, the repair site is difficult to operate, and inspection personnel are prone to negligence. Construction personnel should pay special attention to consciously protecting the quality.