Introduction to the anti-corrosion of the inner wall of large-diameter steel pipes and preparations
First, introduction to the anti-corrosion of the inner wall of large-diameter steel pipes:
1. Before processing, all steel pipes should first be rust-free on the steel plate on one side of the inner wall of the large-diameter steel pipe, until the metal reveals the metallic luster (whitening). It should meet the sa2.5 level standard required in GB8923-88 "S...
First, introduction to the anti-corrosion of the inner wall of large-diameter steel pipes:
1. Before processing, all steel pipes should first be rust-free on the steel plate on one side of the inner wall of the large-diameter steel pipe, until the metal reveals the metallic luster (whitening). It should meet the sa2.5 level standard required in GB8923-88 "Surface rust level and rust removal level of steel before painting".
2. The steel after rust removal should be processed immediately (to prevent secondary rust). After processing, use a clean rag to wipe off the residual rust powder on the inner wall of the steel pipe (if secondary rust is found, perform secondary rust removal to ensure painting), and promptly use GZ-2 gray new polymer anti-corrosion coating (thick paste type) to brush two coats as primer, and use sky blue paint to brush two coats of topcoat, so that the total thickness of the paint film reaches 250-300μm on both bottoms and sides.
3. Primer should be applied before steel pipe fittings leave the factory, and topcoat should be applied before steel pipe installation. No paint should be applied within 200mm at both ends of all steel pipe fittings (at the installation weld), and the paint should be applied after the steel pipe fittings are installed.
4. When applying primer, only a brush is needed, and spraying is not allowed. Topcoat can be applied by spraying.
5. The painting site should have ventilation conditions to prevent the metal surface from getting wet. The site is prohibited from having bad weather such as strong winds, flying dust, and scorching sun exposure (such as high temperatures>70℃, or too low <+5℃ rainy days, etc.). Painting is not allowed. It is best to paint at 10℃-25℃ and relative humidity below 70%.
Second. Construction preparation before welding large-diameter steel pipes:
1. Organize relevant operators, familiarize themselves with construction drawings and regulations, formulate welding processes, and prepare welding operation instructions.
2. Welders should be trained in corresponding projects and have operation qualifications for corresponding projects.
3. Check whether the roundness and misalignment of the steel pipes arriving meet the relevant technical requirements.
4. Check whether there are defects such as scars, cracks, and severe rust on the surface of the steel pipe sections.
5. Before installing large-diameter steel pipes, the steel pipe sections should be measured and numbered one by one, and it is advisable to select steel pipe sections with small differences in steel pipe diameters for welding.
