Typical Roughness Values for Pressure Pipes

Typical pipe roughness values are shown below. These values may vary depending on the manufacturer, workmanship, age, and many other factors.

Comparative Pipe Roughness Values
Material	Manning's Coefficient n	Hazen-Williams C	Darcy-Weisbach Roughness Height
			k (mm)	k (0.001 ft.)
Asbestos cement	0.011	140	0.0015	0.005
Brass	0.011	135	0.0015	0.005
Brick	0.015	100	0.6	2
Cast-iron, new	0.012	130	0.26	0.85
Concrete:
Steel forms	0.011	140	0.18	0.6
Wooden forms	0.015	120	0.6	2
Centrifugally spun	0.013	135	0.36	1.2
Copper	0.011	135	0.0015	0.005
Corrugated metal	0.022	-	45	150
Galvanized iron	0.016	120	0.15	0.5
Glass	0.011	140	0.0015	0.005
Lead	0.011	135	0.0015	0.005
Plastic	0.009	150	0.0015	0.005
Steel
Coal-tar enamel	0.010	148	0.0048	0.016
New unlined	0.011	145	0.045	0.15
Riveted	0.019	110	0.9	3
Wood stave	0.012	120	0.18	0.6S