Hazen Williams C: design_fire_protection_steel
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 |
|---|---|---|---|---|---|---|
| design_fire_protection_steel | design_value | 130 | 100 | 120 | 120 | C=120 per NFPA 13 for dry or preaction steel pipe systems; conservative for fire demand calculations; use C=100 for heavily corroded dry systems |
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