The color of cast iron pipes is usually related to their use, anti-corrosion treatment or industry standards. Different countries and industries may have specific requirements for colors to ensure safety, corrosion resistance or easy identification. The following is a detailed classification:
1. General meaning of DINSEN SML Pipe color
·Black/dark gray / Original cast iron or asphalt / anti-corrosion coating Drainage, sewage, municipal pipelines
·Red / Fire pipes, high temperature resistance or special markings / Fire system, high pressure water supply
·Green / Drinking water pipes, environmentally friendly coatings (such as epoxy resin) / Tap water, food grade water supply
·Blue / Industrial water, compressed air / Factory, compressed air system
·Yellow / Gas pipelines (less cast iron, mostly steel pipes) / Gas transmission (some areas still use cast iron)
·Silver / Galvanized anti-rust treatment / Outdoor, humid environment, high corrosion resistance requirements
2. Special requirements for cast iron pipe colors in domestic and foreign markets
(1) Chinese market (GB standard)
Drainage Cast Iron Pipes: usually black (asphalt anti-corrosion) or original iron gray, partially coated with epoxy resin (green).
Water Supply Cast Iron Pipe: Ordinary cast iron pipe: black or red (for fire protection).
Ductile Iron Pipe (DN80-DN2600): outer wall sprayed with zinc + asphalt (black), inner lining with cement or epoxy resin (gray/green).
Fire Protection Pipe: red coating, in line with the fire protection specification of GB 50261-2017.
Gas Pipe: yellow (but modern gas pipes are mostly made of PE or steel pipes, and cast iron is rarely used).
(2) US market (AWWA/ANSI Standard)
AWWA C151 (ductile iron pipe):
Outer wall: usually black (asphalt coating) or silver (galvanized).
Inner lining: cement mortar (gray) or epoxy resin (green/blue).
Fire Protection Pipe (NFPA standard): red logo, some require the words “FIRE SERVICE” to be printed.
Drinking Water Pipe (NSF/ANSI 61 certification): the inner lining must meet the sanitary standards, there is no mandatory requirement for the outer wall color, but green or blue logo is often used.
(3) European market (EN standard)
EN 545/EN 598 (ductile iron pipe):
External Anticorrosion: zinc + asphalt (black) or polyurethane (green).
Inner Lining: cement mortar or epoxy resin, no strict color regulations, but must comply with drinking water standards (such as KTW certification).
Fire Pipe: red (some countries require printing “FEUER” or “FIRE”).
Industrial Pipe: may be blue (compressed air) or yellow (gas, but cast iron pipes have been gradually replaced).
(4) Japanese market (JIS standard)
JIS G5526 (ductile iron pipe): The outer wall is usually black (asphalt) or galvanized (silver), and the inner lining is cement or resin.
Fire pipe: red painting, some require printing “fire fighting”.
Drinking water pipe: green or blue lining, in line with JHPA standard.
3. The influence of the color of special anti-corrosion coatings
Epoxy resin coating: usually green or blue, used for high anti-corrosion requirements (such as seawater, chemical industry).
Polyurethane coating: may be green, black or yellow, with strong weather resistance.
Zinc + asphalt coating: black outer wall, suitable for buried pipes.
4. Summary: How to choose the color of cast iron pipes?
Select by use:
Drainage/sewage → black/gray
Drinking water → green/blue
Firefighting → red
Industry → by medium identification (such as yellow gas, blue compressed air)
Select by standard:
China (GB) → black (drainage), red (firefighting), green (drinking water)
Europe and the United States (AWWA/EN) → black (external anti-corrosion), green/blue (lining)
Japan (JIS) → black (outer wall), red (firefighting)
If you still don’t know how to choose, please contact DINSEN
Post time: Mar-26-2025