When making the
anti-corrosion spiral steel pipe (SSAW), the inner and outer surfaces of the spiral steel pipe need to be sandblasted first, and then the inner wall is coated with primer, after the primer is dried, the intermediate paint is applied, and the intermediate paint is dried before applying the topcoat. After the inner wall is finished, the anti-corrosion layer treatment of the outer wall is carried out, and the production method is the same as that of the internal anti-corrosion.
Internal and external precision welding of spiral steel pipe → flat chamfering of pipe end → ray and ultrasonic testing → hydraulic test → internal and external shot blasting and rust removal → intermediate frequency heating → internal epoxy powder coating → external 3PE coating extrusion winding, the anti-corrosion steel pipe is completed.
The production process steps of the outer anti-corrosion layer of the spiral steel pipe are as follows:
The surface of the steel pipe should be pretreated according to the specified cleaning method to remove rust, grease, dust, paint, moisture and other contaminants.
1. After the surface pretreatment of the steel pipe is qualified, apply the primer as soon as possible. The primer should be applied evenly, with no leakage, no bubbles, and no coagulation. The dry film thickness should not be less than 25μm.
2. Leave 100~150mm at both ends of the steel pipe without primer, and apply a topcoat before curing after the primer is dry.
3. After hard drying and before curing, apply two coats of topcoat, and then wind the glass cloth. The glass cloth should be taut, the surface should be flat, without wrinkles and bulges, the width of the pressing edge should be 20~25mm, and the overlapping length of the cloth head should be 100~150mm.
4. After the glass cloth is wound, apply the third topcoat. The amount of paint is required to be full, and all the meshes of the glass cloth should be filled with paint.
5. After the third topcoat is dry, apply the fourth topcoat. A glass cloth soaked in topcoat can also be used for wrapping in place of a second topcoat.
6. After the glass cloth and the third topcoat are dry, apply the fourth topcoat, and immediately wrap two layers of glass cloth, apply the fifth topcoat, or wrap two layers of glass cloth soaked with topcoat. Once dry, apply a final top coat.
7. The applied anti-corrosion layer should be left to solidify naturally.
Matters needing attention in the production process of anti-corrosion spiral steel pipe:
1. The steel pipe must be derusted on the inner and outer surfaces. Chemical derusting, manual derusting and equipment derusting can be used, and the grade reaches Sa2.
2. Avoid water or moisture on the surface of the steel pipe, and any dirt should be removed in time.
3. Apply primer when the surface of the steel pipe is dry.
4. After coating the anti-corrosion layer, let it dry before loading and shipping.
