Uneven thickness of the anti-corrosion coating on spiral steel pipe and its treatment

Spiral steel pipes are mainly used as fluid pipes and piling pipes. If the steel pipes are used for running water after they are made, they will generally be treated with anti-corrosion treatment on the inner or outer surfaces. The general anti-corrosion methods include 3pe anti-corrosion, epoxy coal tar pitch anti-corrosion, and epoxy powder anti-corrosion. Wait, because the epoxy powder dipping process is plagued by adhesion problems, the dipping of epoxy powder has not been promoted. At present, with the successful development of the special phosphating solution for the epoxy powder impregnation of Sanye, the problem of adhesion in the epoxy powder impregnation process has been overcome for the first time, and the emerging process of epoxy powder impregnation has begun to appear.

The reason for the uneven thickness of the anti-corrosion coating of the spiral steel pipe is analyzed. The uneven thickness of the coating of the 3PE spiral steel pipe is mainly manifested in the uneven thickness of the test points on each side distributed in the circumferential direction. The industry standard SY/T0413-2002 has no rules on the uniformity of thickness, it regulates the thickness value of the coating but requires that the thickness value of the coating cannot be lower than the thickness value of the point, not the average value of multiple test points.

If the thickness of the coating is not uniform during the coating process of the spiral steel pipe, the coating material will inevitably be ruined. This is because when the thickness of the coating at the thinnest part reaches the specification, the thickness of the thickest part will be greater than Apply the specified thickness. And in the case of uneven coating, it is easy to cause the coating thickness at the thinnest part of the steel pipe to fail to meet the standard. The reasons for the uneven thickness in the production process are mainly due to the uneven discharge of the material in several places and the bending of the steel pipe. An effective way to control the uneven coating of 3PE anti-corrosion pipelines is to adjust several extrusion dies to make the thickness of anti-corrosion coatings as uniform as possible in several places and to prevent unqualified steel pipes from being coated online.

Wrinkles on the surface of the coating: Extrusion of polyethylene materials and winding on steel pipes requires rolling with a silicone roller. Improper adjustments during this process may cause wrinkles on the surface of the coating. In addition, the rupture of the melt film when the polyethylene material leaves the exit to die during the extrusion process will also produce quality defects similar to wrinkles. The corresponding control methods for the cause of the wrinkles include adjusting the hardness and pressure of the rubber roller and the pressure roller. From this point of view, properly increase the extrusion amount of polyethylene to control the rupture of the melt film.