Construction before welding of large-diameter steel pipes and anti-corrosion treatment of the inner wall of the pipe
Construction preparation before welding of large diameter steel pipe:
1. Organize relevant operators, be familiar with construction drawings and specifications, formulate welding procedures, and prepare welding operation instructions.
2. Welders should be trained in corresponding items and have operating qualification certificates for corresponding items.
3. Check whether the roundness and the amount of misalignment of the delivered steel pipe meet the relevant technical requirements.
4. Check the surface of the metal pipe section for defects such as scars, cracks, and serious corrosion.
5. Before installing large-diameter steel pipes, the pipe joints should be measured and numbered one by one, and pipe joints with small diameter differences should be selected for butt welding.
6. Welding in windy, rainy, and snowy weather. Wind-proof, rain-proof, and snow-proof sheds are provided.
7. Make the welder clarify requirements and welding measures before welding.
Anti-corrosion of the inner wall of large-diameter steel pipe:
1. Before processing all steel pipes, the steel plate on the inner wall of the large-diameter steel pipe should be de-rusted, and the metal should be exposed to the metal luster (whitening).
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 tube (if secondary rust is found, perform a secondary rust removal to ensure painting), and use GZ-2 gray new polymer in time Two coats of anticorrosive paint (heavy build type) are used as primers, and two coats of sky blue paint are used for the topcoat, and the total thickness of the paint film reaches 250-300μm on both sides.
3. The primer should be finished before the pipe fittings leave the factory, and the topcoat should be painted before the pipeline is installed. All pipe ends (installation welds) should not be painted within 200mm. Paint after the pipe fittings are installed.
4. When applying the primer, only a brush is required, and the spray method is not allowed. The spray method can be used for the topcoat.
V. Ventilation conditions for the painted site to prevent wet metal surfaces, strong winds, dusty, hot sun, and other bad weather on the site, (such as high temperature> 70 ℃, or low temperature <+5 ℃ rainy days, etc.) Painting work is not allowed. The painting should be carried out at 10℃-25℃ and relative humidity below 70%.