Maximum Depths of Cover
for Minimum Pressure Classes Ductile Iron Pipe ANSI/AWWA C151/A21.51
This table tabulates the maximum depth of cover for the five types of laying conditions, along with corresponding nominal wall thickness and maximum rated working pressure, all for minimum pressure classes of ductile iron pipe. Taken from the table that follows, it is offered as a convenience for quickly checking the capabilities of minimum pressure classes of ductile iron pipe under a given set of conditions.
For the majority of internal pressure and external loading conditions, minimum pressure classes are more than adequate and possess substantial safety factors.
Size (in.) |
Pressure Class |
Thickness (in.) |
Laying Conditions Maximum Depth of Cover in Feet1 |
||||
---|---|---|---|---|---|---|---|
Type 1 | Type 2 | Type 3 | Type 4 | Type 5 | |||
4 | 350 | 0.25 | 53 | 61 | 69 | 85 | 1004 |
6 | 350 | 0.25 | 26 | 31 | 37 | 47 | 65 |
8 | 350 | 0.25 | 16 | 20 | 25 | 34 | 50 |
10 | 350 | 0.26 | 112 | 15 | 19 | 28 | 45 |
12 | 350 | 0.28 | 102 | 15 | 19 | 28 | 44 |
14 | 250 | 0.28 | see3 | 112 | 15 | 23 | 36 |
16 | 250 | 0.3 | see3 | 112 | 15 | 24 | 34 |
18 | 250 | 0.31 | see3 | 102 | 14 | 22 | 31 |
20 | 250 | 0.33 | see3 | 10 | 14 | 22 | 30 |
24 | 200 | 0.33 | see3 | 82 | 12 | 17 | 25 |
30 | 150 | 0.34 | see3 | - | 9 | 14 | 22 |
36 | 150 | 0.38 | see3 | - | 9 | 14 | 21 |
42 | 150 | 0.41 | see3 | - | 9 | 13 | 20 |
48 | 150 | 0.46 | see3 | - | 9 | 13 | 20 |
54 | 150 | 0.51 | see3 | - | 9 | 13 | 20 |
Maximum Depths of Cover for All Pressure Classes of Ductile Iron Pipe
ANSI/AWWA C151/A21.51
For other conditions not covered in these tables see AWWA C150 or consult AMERICAN for design of pipe thickness. Special thickness classes may be appropriate in such cases.
1.) An allowance for single H-20 truck with 1.5 impact factor is included for all sizes and all depths of cover.
2.) Minimum allowable depth of cover is 3’. For depths less than 3’, consult AMERICAN.
3.) Laying condition Type 1 is limited to 12" and smaller pipe. For 14" and larger pipe, laying condition Type 1 should not be used.2
4.) Calculated maximum depth of cover exceeds 100’.