Surface treatment of spiral tubes

Spiral pipe derusting and anti-corrosion process:

Derusting is an important part of the anti-corrosion process of spiral welded pipe pipelines. At present, there are many derusting methods, such as manual derusting, sand blasting and pickling and so on. Among them, manual rust removal, mechanical rust removal and painting rust removal (anti-corrosion brushing oil) are relatively common rust removal methods. The following is a brief introduction to the specific operation requirements of these three rust removal processes by welded pipe manufacturers.

1) Manual rust removal

Use scrapers and files to remove the oxide skin and casting sand on the surface of the pipes, equipment and containers, and then use a wire brush to remove the rust on the surfaces of the spiral pipes, equipment and containers, then polish them with sandpaper, and then use cotton silk to remove them. Wipe clean.

2) Mechanical descaling

First remove the oxide skin and casting sand on the surface of the pipe with a scraper and a file; then one person is in front of the rust remover, and one person is behind the rust remover, and the pipe is placed in the rust remover repeatedly to remove rust until the metal color is exposed; brush Before oiling, wipe it again with cotton silk to remove the floating ash on its surface.

3) Anti-corrosion brush oil

Pipes, equipment and container valves are generally subjected to anti-corrosion and oil brushing according to the design requirements. When there are no design requirements, the following regulations shall be followed:

1. Exposed pipes, equipment and containers must be painted with an anti-rust paint first, and then painted with two top paints before handover. If there are requirements for thermal insulation and anti-condensation, two anti-rust paints should be painted;

2. Two coats of anti-rust paint should be applied to concealed pipelines, equipment and containers. The second coat of anti-rust paint must be painted after the first coat of paint is completely dry, and the consistency of the anti-rust paint should be appropriate;

3. When the buried pipeline is used as the anti-corrosion layer, if the construction is carried out in winter, it is advisable to use rubber solvent oil or aviation gasoline to dissolve 30 A or 30 ethyl petroleum asphalt. Two kinds:

① Manual brushing: Manual brushing should be applied in layers, each layer should be reciprocated, criss-crossed, and the coating should be kept uniform without missing or falling;

② Mechanical spraying: When spraying, the sprayed paint flow should be perpendicular to the spraying surface. When the spraying surface is flat, the distance between the nozzle and the spraying surface should be 250-350mm. If the spraying surface is an arc surface, the distance between the nozzle and the spraying surface should be about 400mm. , When spraying, the movement of the nozzle should be uniform, the speed should be maintained at 10 ~ 18m/min, and the compressed air pressure used for spray painting should be 0.2 ~ 0.4MPa.

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