With the wide application of straight seam welded pipes, more and more people choose straight seam welded pipes(LSAW pipe or ERW pipe). The production process of straight seam welded pipe is simple, the production efficiency is high, the cost is low, and the development is rapid. It has replaced seamless pipe in more and more fields.
1. Longitudinal welded pipe rust removal and maintenance method:
Generally, the surface of straight seam welded pipe fittings is required to reach near-white level. Using this derusting grade can remove almost all scale, rust and other dirt, and the depth of the anchor pattern can reach 40~100μm, which can fully meet the adhesion requirements of the anti-corrosion layer and the steel pipe. The spray (throwing) shot derusting process can reach the near-white level with lower operating costs and stable and reliable quality. When the longitudinal welded pipe has a certain rust, it should be treated according to certain rust removal methods and methods to ensure the quality and performance of the longitudinal welded pipe, which can be used in different industries and priority areas, making important contributions and functions for the construction industry .
2. Spraying (throwing) abrasives for straight seam welded pipes:
In order to achieve the ideal rust removal effect, the abrasive should be selected according to the hardness of the surface of the longitudinal welded pipe equipment, the original rust level, the required surface roughness, and the type of coating. For single-layer epoxy, two-layer or three-layer polyethylene coating, it is easier to achieve the ideal rust removal effect by using the mixed abrasive of steel grit and steel shot. Steel shot has the effect of strengthening the steel surface, while steel grit has the effect of etching the steel surface. The mixed abrasive of steel grit and steel shot (usually the hardness of steel shot is 4050HRC and the hardness of steel grit is 5060HRC can be used on various steel surfaces, even if it is used on C-level and D-level corroded steel surfaces, the rust removal effect is also very good .
3. Derusting speed of straight seam welded pipe:
That is, the total kinetic energy E applied by the abrasive to the steel pipe per unit time and the kinetic energy E1 of the single-grain abrasive. The derusting speed of the steel pipe depends on the type of abrasive and the displacement of the abrasive. In the formula: m the spray (throwing) amount of abrasive; V the running speed of abrasive; m1 the quality of single particle abrasive. The size of m is related to the crushing rate of abrasives, which directly affects the interest of surface treatment and the cost of derusting equipment. When the equipment is fixed, m is a constant and y is a constant, so E is also a constant, but m1 changes due to abrasive crushing. Therefore, the abrasive with a lower loss rate should generally be selected, which is conducive to improving the cleaning speed and prolonging the life of the blade.
4. The particle size and proportion of abrasives for longitudinal welded pipes:
In order to obtain a better uniform cleanliness and roughness distribution, the particle size and proportion design of abrasives are very important. If the roughness is too large, the anti-corrosion layer will become thinner at the peak of the anchor pattern; at the same time, because the anchor pattern is too deep, the anti-corrosion layer will easily form bubbles during the anti-corrosion process, which will seriously affect the performance of the anti-corrosion layer.