How to Evaluate Whether a Ductile Iron Pipe Is of High Quality?

1. The material of the ductile iron pipe shall be ductile iron with a ferritic matrix, and the structure shall contain a certain amount of spherical graphite.

2. The water pressure test result, tensile strength, and elongation shall comply with the provisions of GB/T 13295-2013.

3. The surface hardness shall not exceed 230 HBW (Brinell Hardness Value).

4. No defects that hinder use are allowed on the inner and outer surfaces.

5. The inner surface of the cast iron pipe shall be lined with cement mortar; some pipes shall be provided with an epoxy sealant layer on the cement mortar lining, and the outer surface shall be coated with zinc-sprayed asphalt. Before coating, the inner and outer surfaces shall be smooth and free of rust, iron flakes, and other impurities; after coating, the inner and outer surfaces shall also be smooth, and the coating shall be uniform and firmly adhered, without abnormalities due to temperature changes (hot or cold) in the climate. For pipes only lined with cement mortar, the roughness coefficient shall be less than 0.013; for pipes with cement mortar lining plus epoxy sealant layer, the roughness coefficient shall be less than 0.008. The thickness of the sprayed metallic zinc shall not be less than 130 g/m² (Note: The original text "130g/m7" is considered a typo and has been corrected to "130g/m²" in accordance with industry standards), and the zinc content of the metallic zinc shall be at least 99.95%.

6. An insertion mark shall be sprayed on the outer surface of the spigot with white paint, and the spraying requirements shall be in accordance with GB/T 13295-2013.

7. Each socket of the ductile iron pipe and each pipe fitting shall be equipped with a matching rubber ring, and a spare rubber ring shall be provided at 1% of the total number of rubber rings. The cost of the spare rubber rings shall be included in the total bid price.

8. The pipes shall be delivered from the factory with pre-applied cement mortar lining, epoxy coating (for relevant pipes), and asphalt coating on the outer wall. The inner cement lining shall comply with ISO 4179, the outer asphalt coating shall comply with ISO 8179, and the inner epoxy coating shall comply with ISO 16132-2004.

9. The inspection items, inspection methods, and inspection rules shall be carried out in accordance with GB/T 13295-2013.