There are multiple requirements for the surface treatment of galvanized steel pipes, as follows:

1. Cleanliness: The surface of the steel pipe should be removed from impurities such as oil, dust, oxide scale, and welding slag to ensure that the galvanized layer is closely combined with the surface of the steel pipe.
2. Surface quality: There should be no defects such as rust spots, burrs, dents, and scratches on the outer surface. If the depth of the defect exceeds 25% of the coating thickness and the localized area exceeds 5% of the coating surface area, the defect should be repaired and maintained before galvanizing is completed.
3. Coating thickness: The thickness of the galvanized layer should comply with national standards, generally 5-15μm. The minimum average value of the galvanized layer on the outer surface shall not be less than 5 μm, and the minimum local value shall not be less than 4 μm.
4. Uniformity of galvanized layer: The galvanized layer should be evenly covered on the surface of the steel pipe, and defects such as missing plating, heavy plating, and bulges should not occur.
5. Adhesion of the galvanized layer: The galvanized layer should have good adhesion and should not peel or fall off.
6. Corrosion resistance: The galvanized layer should have good corrosion resistance and be able to maintain stable performance in different environments.
7. Welding seam treatment: The welding seam should be smooth, free of welding slag, and treated with rust prevention.