The general application of thick-walled seamless tubes must do the corresponding anti-corrosion and anti-rust treatment work. The general anti-corrosion work is divided into three processes:
1. Anti-rust treatment of pipes.
Before painting, the surface of the pipeline should be cleaned of oil, slag, rust, and zinc dust. The product quality standard is Sa2.5.
2. After the anti-rust treatment on the surface of the pipeline, apply topcoat, and the interval between them should not exceed 8 hours. When applying the topcoat, the base surface should be dry and the topcoat should be uniform, rounded and free of lumps and air bubbles. Both sides of the pipe shall not be brushed within the range of 150~250mm.
3. After the topcoat has dried and solidified, apply the paint and bundle the fiberglass cloth, and the interval between the topcoat and the paint should not exceed 24 hours.
Cracking of thick-walled seamless steel tube:
In the whole application process of thick-walled seamless steel tube, the surface sometimes encounters transverse cracks. There are many reasons for this. I will give you a detailed analysis below.
If the thick-walled seamless tube is less deformed during the entire emptying process, the inner and outer surfaces will cause additional stress in the compressive inner pull. At this time, due to the poor deformation permeability, the expansion tendency of the outer surface is greater than that of the inner layer, so the outer surface will cause additional compressive stress, and the inner surface will cause additional tensile stress. If the extra tensile stress on the inner surface has a great influence, basically the tensile stress and the extra progressive stress can be added together, which will exceed the compressive strength of the thick-walled seamless steel tube, resulting in horizontal cracking of the inner surface.
Under the corresponding structural mechanics standards, reducing various factors of plastic deformation during the production and processing of thick-walled seamless steel pipes will increase the chance of internal transverse cracks. Therefore, in the production of thick-walled seamless steel tubes, the quenching quality. It is very important to remove alkaline brittleness.
In addition to the additional radial stress, there is an additional radial stress during the entire de-lifting process. Longitudinal cracks are caused by additional radial tensile stress induced during emptying.