Straight seam steel pipe is a welded steel pipe with the weld seam parallel to the longitudinal direction of the steel pipe. The production process of straight seam welded pipe is simple, the production efficiency is high, the cost is low, and the development is fast. The strength of the spiral welded pipe is generally higher than that of the straight seam welded pipe. However, compared with the same length of straight seam pipe, the length of the weld is increased by 30~100%, and the production speed is lower.
Straight seam steel pipes include straight seam submerged arc welded steel pipes (LSAW) and straight seam electric resistance welded pipes (ERW).
Rust removal and maintenance of straight seam welded pipes:
It is generally required that the surface of the straight seam welded pipe fittings reach nearly white level (Sa2.5). Practice has proved that the construction process of epoxy, vinyl, phenolic and other anti-corrosion coatings commonly used in straight seam welded pipe fittings.With this rust removal grade, almost all oxide scale, rust and other dirt can be removed, and the anchor pattern depth reaches 40~100μm, which fully meets the adhesion requirements of the anti-corrosion layer and the steel pipe.The spray (throwing) rust removal process can achieve near-white technical conditions with low operating costs and stable and reliable quality.When a certain rust occurs on the straight seam welded pipe, it should be treated according to certain rust removal methods and methods to ensure the quality and performance of the straight seam welded pipe, which can be used in different industries and priority areas, and make an important contribution to the construction industry.
Spray (throwing) abrasive for straight seam welded pipe:
In order to achieve the ideal rust removal effect, the abrasive should be selected according to the hardness of the surface of the straight seam welded pipe equipment, the original rust level, the required surface roughness, the type of coating, etc.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 the surface of grade C and D rusted steel, the rust removal effect is also very good .
Derusting speed of straight seam welded pipe:
That is, the total kinetic energy E of the abrasive applied to the steel pipe per unit time and the kinetic energy of the single particle abrasive E1 The rust removal speed of the steel pipe depends on the type of abrasive and the displacement of the abrasive. In the formula: m abrasive spray (throwing) amount; V abrasive running speed; m1 single particle abrasive quality. The size of m is related to the abrasive crushing rate, and the size of the crushing rate directly affects the interest of surface treatment operations and the cost of rust removal equipment. When the equipment is fixed, m is a constant, y is a constant, so E is also a constant, but due to the broken abrasive, m1 changes,Therefore, abrasives with lower loss rate should generally be selected, which is beneficial to improve cleaning speed and long blade life.
The particle size and ratio of the abrasive for the straight seam welded pipe:
In order to obtain better uniform cleanliness and roughness distribution, the particle size and ratio design of abrasive are very important. If the roughness is too large, it is easy to cause the anti-corrosion layer to become thinner at the peak of the anchor pattern; at the same time, because the anchor pattern is too deep, the anti-corrosion layer is easy to form bubbles during the anti-corrosion process, which seriously affects the performance of the anti-corrosion layer.
Straight seam steel pipes include straight seam submerged arc welded steel pipes (LSAW) and straight seam electric resistance welded pipes (ERW).
Rust removal and maintenance of straight seam welded pipes:
It is generally required that the surface of the straight seam welded pipe fittings reach nearly white level (Sa2.5). Practice has proved that the construction process of epoxy, vinyl, phenolic and other anti-corrosion coatings commonly used in straight seam welded pipe fittings.With this rust removal grade, almost all oxide scale, rust and other dirt can be removed, and the anchor pattern depth reaches 40~100μm, which fully meets the adhesion requirements of the anti-corrosion layer and the steel pipe.The spray (throwing) rust removal process can achieve near-white technical conditions with low operating costs and stable and reliable quality.When a certain rust occurs on the straight seam welded pipe, it should be treated according to certain rust removal methods and methods to ensure the quality and performance of the straight seam welded pipe, which can be used in different industries and priority areas, and make an important contribution to the construction industry.
Spray (throwing) abrasive for straight seam welded pipe:
In order to achieve the ideal rust removal effect, the abrasive should be selected according to the hardness of the surface of the straight seam welded pipe equipment, the original rust level, the required surface roughness, the type of coating, etc.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 the surface of grade C and D rusted steel, the rust removal effect is also very good .
Derusting speed of straight seam welded pipe:
That is, the total kinetic energy E of the abrasive applied to the steel pipe per unit time and the kinetic energy of the single particle abrasive E1 The rust removal speed of the steel pipe depends on the type of abrasive and the displacement of the abrasive. In the formula: m abrasive spray (throwing) amount; V abrasive running speed; m1 single particle abrasive quality. The size of m is related to the abrasive crushing rate, and the size of the crushing rate directly affects the interest of surface treatment operations and the cost of rust removal equipment. When the equipment is fixed, m is a constant, y is a constant, so E is also a constant, but due to the broken abrasive, m1 changes,Therefore, abrasives with lower loss rate should generally be selected, which is beneficial to improve cleaning speed and long blade life.
The particle size and ratio of the abrasive for the straight seam welded pipe:
In order to obtain better uniform cleanliness and roughness distribution, the particle size and ratio design of abrasive are very important. If the roughness is too large, it is easy to cause the anti-corrosion layer to become thinner at the peak of the anchor pattern; at the same time, because the anchor pattern is too deep, the anti-corrosion layer is easy to form bubbles during the anti-corrosion process, which seriously affects the performance of the anti-corrosion layer.
