Generally, anti-corrosion work is divided into three processes:
Pipe anti-rust treatment.
Before painting, oil stains, slag, rust, zinc powder, etc. on the surface of the pipeline should be removed. The product quality standard is Sa2.5.
After the anti-rust treatment on the pipe surface, the topcoat should be applied. The interval should not exceed 8 hours. When applying topcoat, the base surface should be dry, and the topcoat should be even, round, and free of lumps and bubbles. Painting is not allowed within 150~250mm on both sides of the pipe.
After the topcoat is dry and solidified, apply paint and tie the fiberglass cloth. The interval between topcoat and paint should not exceed 24 hours.
Thick-walled seamless steel pipe cracking:
Throughout the application process of thick-walled seamless steel pipes, the surface sometimes encounters transverse cracks. This incident is caused by many reasons.
If the thick-walled seamless pipe has small deformation during the entire emptying process, its inner and outer surfaces will generate additional stress during compression and internal tension. At this time, due to 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 additional tensile stress on the inner surface has a greater impact, basically the tensile stress and the additional progressive stress can be added together, which will exceed the compressive strength of the thick-walled seamless steel pipe, causing transverse cracking of the inner wall. surface.
Under the corresponding structural mechanics standards, various factors that reduce plastic deformation during the production and processing of thick-walled seamless steel pipes will increase the chance of internal transverse cracks. Therefore, when producing thick-walled seamless steel pipes, attention should be paid to quenching quality. It is very important to remove alkali brittleness.
In addition to the additional radial stress, there are also additional radial stresses during the entire lift reduction process. Longitudinal cracks are caused by additional radial tensile stresses induced during the evacuation process.
