Roughness Values-Hazen-Williams Equation
Commonly used roughness values for different materials are:
Hazen-Williams Roughness Coefficients (C)
Pipe Material | C |
---|---|
Asbestos Cement | 140 |
Brass | 130-140 |
Brick Sewer | 100 |
Cast iron | |
New, unlined | 130 |
10 yr. Old | 107-113 |
20 yr. Old | 89-100 |
30 yr. Old | 75-90 |
40 yr. Old | 64-83 |
Concrete or concrete lined | |
Steel forms | 140 |
Wooden forms | 120 |
Centrifugally spun | 135 |
Copper | 130-140 |
Galvanized iron | 120 |
Glass | 140 |
Lead | 130-140 |
Plastic | 140-150 |
Steel | |
Coal-tar enamel, lined | 145-150 |
New unlined | 140-150 |
Riveted | 110 |
Tin | 130 |
Vitrified clay (good condition) 110-140 | 110-140 |
Wood stave (average condition) | 120 |