Hazen Williams C: ductile_iron_unlined
Hazen-Williams roughness coefficients (C values) for pressure pipe hydraulic calculations. Covers new and aged pipe materials: ductile iron (cement-lined/unlined), cast iron at 0/5/10/20/30/40 years, carbon steel (new/corroded/lined), copper, brass, PVC, HDPE, CPVC, FRP, concrete, asbestos cement, galvanized steel, stainless steel, lead, vitrified clay. Includes AWWA M31 and NFPA 13 design C values. C value ranges (min/typical/max) and recommended design values are provided.
| pipe material | pipe condition | c value max (dimensionless) | c value min (dimensionless) | c value typical (dimensionless) | design c value (dimensionless) | notes |
|---|---|---|---|---|---|---|
| ductile_iron_unlined | 10_years | 120 | 100 | 110 | 105 | Significant tuberculation in typical water; C drops ~2/yr unlined; use cement-lined for new construction |
| ductile_iron_unlined | 20_years | 110 | 80 | 95 | 90 | Heavy tuberculation expected; must be pigged/relined or replaced; unacceptable for fire protection flow |
| ductile_iron_unlined | new | 140 | 120 | 130 | 120 | Unlined DIP corrodes/tuberculates rapidly in most water systems; rarely used for potable water; C drops quickly with age |
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