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

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 pipe is made, if it is used for water drainage, it will generally be treated with anti-corrosion treatment 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 epoxy powder dipping has never been promoted. At present, with the successful development of the special phosphating solution for epoxy powder dipping of Sanya Coconut, the adhesion problem of the epoxy powder dipping process has been overcome for the first time, and the emerging process of epoxy powder dipping has begun to appear.

Analyze the reasons for the uneven thickness of the anti-corrosion coating of the spiral steel pipe. The uneven thickness of the 3PE spiral steel pipe 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 on the uniformity of thickness. It regulates the thickness of the coating, but it is required that the thickness of the coating cannot be lower than the thickness of the point, rather than the average value of multiple test points.

If the coating thickness of the spiral steel tube coating is not uniform, it will inevitably cause the waste of the coating material. This is because when the thickness of the coating at the thinnest part reaches 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, the thickness of the coating at the thinnest part of the steel pipe is simply not up to the standard. The reasons for the uneven thickness during the production process are mainly uneven materials in several places and twists and turns of the steel pipe. A useful way to control the uneven coating of 3PE anti-corrosion pipelines is to adjust several extrusion dies to make the thickness of the anti-corrosion coating at several places as uniform as possible, and the unqualified steel pipes are not coated on the line.

Coating surface wrinkles: Polyethylene materials are extruded and wound onto steel pipes and require silicone rollers. Improper adjustments in this process may cause wrinkles to be extruded on the coating surface. In addition, when the polyethylene material is extruded from the exit die, the melt film will also have 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 amount of extrusion of polyethylene is appropriately added to control the melt film break.