Civil Engineering Reference
In-Depth Information
TABLE 26-2. Values of the Manning Roughness Coefficient
Range
Best
Use in Design
From
Kind of Conduit
Worst
To
Closed Conduit Flow
Clean uncoated cast-iron pipe
0.011
0.015
0.013
0.015
Clean coated cast-iron pipe
0.010
0.014
0.012
0.014
Dirty or tuberculated cast-iron pipe
0.015
0.035
Riveted steel pipe
0.013
0.017
0.015
0.017
Loc-bar and welded pipe
0.010
0.013
0.012
0.013
Galvanized-iron pipe
0.012
0.017
0.015
0.017
Brass and glass pipe
0.009
0.013
Wood-stave pipe
0.010
0.014
Wood-stave pipe, small diameter
0.011
0.012
Wood-stave pipe, large diameter
0.012
0.013
Concrete pipe
0.010
0.017
Concrete pipe with rough joints
0.016
0.017
Concrete pipe, ''dry mix,'' rough forms
0.015
0.016
Concrete pipe, ''wet mix,'' steel forms
0.012
0.014
Concrete pipe, very smooth
0.011
0.012
Vitrified sewer pipe
0.010
0.017
0.013
0.015
Common clay drainage tile
0.011
0.017
0.012
0.014
Corrugated metal (2
2
⁄
3
1
⁄
2
)
0.023
0.026
Corrugated metal (3
1 and 6
1)
0.026
0.029
Corrugated metal (6
2 structural plate)
0.030
0.033
Rock, unlined
0.038
0.041
Enameled steel
0.009
0.010
Open Channel Flow
Uncoated cast-iron pipe
0.012
0.015
Coated cast-iron pipe
0.011
0.012
0.013
Commercial wrought-iron pipe, black
0.012
0.015
Commercial wrought-iron pipe, galvanized
0.013
0.017
Smooth brass and glass pipe
0.009
0.013
Smooth lockbar and welded ''OD'' pipe
0.010
0.011
0.013
Riveted and spiral steel pipe
0.013
0.015
0.017
Vitrified sewer pipe
0.010
0.017
0.013
Common clay drainage tile
0.011
0.017
0.012
0.014
Glazed brickwork
0.011
0.015
0.013
Brick in cement mortar; brick sewers
0.012
0.017
0.015
Neat cement surfaces
0.010
0.013
Cement mortar surfaces
0.011
0.015
0.013
Concrete pipe
0.012
0.016
0.015
Wood stave pipe
0.010
0.013
Plank flumes:
Planned
0.010
0.014
0.012
Unplanned
0.011
0.015
0.013
With battens
0.012
0.015
Concrete-lined channels
0.012
0.018
0.014
0.016
Cement rubble surface
0.017
0.030
Dry-rubble surface
0.025
0.035
Dressed-ashlar surface
0.013
0.017
Semicircular metal flumes, smooth
0.011
0.015
