The loss of the inner coating will reduce the corrosion resistance of the steel pipe, steel pipe production need to strictly control the quality of the problem. The coating is mainly small diameter steel pipe, oil, embroidery, graphite, etc. are not clean, the density of the anchor pattern can not meet the requirements of the paint is not enough to cause the bond.
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The main forms are:
1. Drum is formed because the coating is not completely dry, the pipe under the sunlight insolates folded under the coating after water is heated rapidly expanding volume, bolstered internal coating.
2, The vertical fall off along the longitudinal direction of the tube is mainly uncoated light pipe in the open piled up when the rain poured into the accumulation of pipe at the bottom of the formation of the more serious rust, rust when the four steel pipe at the same time, the more serious parts of the rust is not complete, it formed along the longitudinal delamination of the body.
3, The ring drum package inside the drum package is mainly in the tube of sand blowing ash in the compressed air in the water, soot the wind straight forward, the steel pipe in the rotation, the formation of a ring of water marks,the coating also forms a ring.
4, The beginning of the end of the coating inside the end of the coating are basically in the end of the coating, because the end of the inside of the fan to the tube inside the hair, blowing the end of the tube of water, but also to prevent the air into the moisture end of steel pipe. The drum is only produced at the beginning of the coating, and not at the end of the steel pipe.
The measures to prevent falling off are:
1, The coating environment control, when the ambient humidity ≥ 90%, or body temperature below the dew point temperature below 3 ℃, should not be produced.
2, After the coating must be poured into the tube of the cooling water to clean, to ensure that the inner surface of the tube before drying.
3, Before the coating with a tube drying dehumidification device, to prevent moisture affect the quality of the coating.
4, Shot peening rust in a timely manner to clear the nozzle to prevent the nozzle blockage, while ensuring the depth of the anchor line at the same time have a certain density in order to increase the adhesion of the coating.
5, The speed of anti-corrosion can not be too fast, the process of conversion between the pipe to have a certain time interval, so that the moisture inside the tube has a natural air-drying process.
