The problem of uneven thickness of anti-corrosion coating of spiral steel pipe and its treatment method

Spiral steel pipes are mainly used as fluid pipes and piling pipes. After the steel pipes are made, if they are used for running water, they will generally be treated with anti-corrosion on the inner or outer surface. The general anti-corrosion includes 3pe anti-corrosion, epoxy coal tar anti-corrosion, epoxy powder anti-corrosion, And so on, because the epoxy powder dipping process is plagued by adhesion problems, the dipping of epoxy powder has never been promoted. At present, with the successful development of the special phosphating solution for epoxy powder dip molding of Sanye, it has overcome the adhesion problem of the epoxy powder dip molding process for the first time, and the emerging process of epoxy powder dip molding 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 3PE spiral steel pipe coating mainly reflects the uneven thickness of the test points on each side scattered in the circumferential direction. The industry standard SY/T0413-2002 has no rules for the uniformity of thickness, which 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 coating thickness is not uniform during the coating process of the spiral steel pipe, it will inevitably lead to the waste of the coating material. This is because when the coating thickness at the thinnest part is guaranteed to reach the specification, the thickness of the thick part will be larger than The thickness of the coating specification. Moreover, in the case of uneven coating, it is easy to form a situation where the thickness of the coating at the thinnest part of the steel pipe does not meet the specification. The reasons for the uneven thickness in the production process are mainly due to the unevenness of the material in several places and the twists and turns of the steel pipe. The effective way to control the uneven coating of 3PE anti-corrosion pipes is to adjust several extrusion dies to make the thickness of the anti-corrosion coating in several places as uniform as possible, and the unqualified steel pipes are not coated on the line.

Wrinkles on the surface of the coating: The extrusion and winding of the polyethylene material onto the steel pipe require the rolling of a silicone roller. Improper adjustment during this process may cause wrinkles on the surface of the coating. In addition, the cracking of the melt film when the polyethylene material is released from the exit die during the extrusion process will also produce quality defects similar to wrinkles. The corresponding control methods for the causes of wrinkles include adjusting the hardness and pressure of the rubber roller and the pressure roller. From this point of view, the extrusion amount of polyethylene is appropriately added to control the rupture of the melted film.