Table 4. Calculated Flow Velocities and Friction Values 
Velocity (ft/sec) of Flow for Pipe 
Concrete Discharge of Inside Diameter Shown: 
Rate (cu yd/hr) 
60 
50 
40 
30 
NOTE: The theoretical frictional shear stress between the flowing 
concrete and the pipewall that is required to balance the 
net downward force due to gravity is 0.037 psi of pipe 
interior surface area for a 3.0-in. ID pipe, 0.044 psi for 
a 3.5-in. ID pipe, and 0.050 psi for a 4.0-in. ID pipe. 
30 
