1. coating adhesion of coated steel pipe: the adhesion of the polyethylene coating layer is ≥30n/cm, and the adhesion of the epoxy resin coating is 1~3.
2. bending performance: no cracks will occur after bending the steel-plastic pipe with a nominal diameter not greater than 50mm, and there will be no delamination between the steel and the inner and outer plastic layers.
3. flattening performance: the steel-plastic pipe with a nominal diameter greater than 50mm and no more than 600mm is flattened, no cracks occur after flattening, and no delamination occurs between the steel and the inner and outer plastic layers.
4. hygienic requirements: the inner plastic layer of the steel-plastic pipe for transporting drinking water and hot and cold water shall meet the requirements of gb/t 17219.
5. pinhole test of coated plastic layer: use an electric spark detector to check the entire inner and outer surfaces of the steel-plastic pipe provided for the test, and there should be no electric sparks during the test.