Maximum Depths of Cover
for Minimum Pressure Classes of Ductile Iron Pipe
ANSI/AWWA C151/A21.51
Size (in.) |
Pressure Class |
Thickness (in.) |
Laying Conditions Maximum Depth of Cover in Feet1 |
||||
---|---|---|---|---|---|---|---|
Type 1 | Type 2 | Type 3 | Type 4 | Type 5 | |||
14 | 250 | 0.28 | see3 | 112 | 15 | 23 | 36 |
16 | 250 | 0.30 | 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 |
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.
Maximum Depths of Cover
for All Pressure Classes of Ductile Iron Pipe
ANSI/AWWA C151/A21.51
This table lists maximum depths of cover for the five types of laying conditions for all standard pressure classes; also tabulated are the corresponding nominal wall thickness and maximum rated working pressure. (Note: Although not listed in the following table, ductile iron pipe for working pressures higher than 350 psi is available. Consult AMERICAN regarding specific conditions involved.)
Size (in.) |
Pressure Class psi4 |
Nominal Thickness (in.) |
Laying Conditions Maximum Depth of Cover in Feet5 |
||||
---|---|---|---|---|---|---|---|
Type 1 | Type 2 | Type 3 | Type 4 | Type 5 | |||
14 | 250 | 0.28 | see8 | 116 | 15 | 23 | 36 |
14 | 300 | 0.30 | see8 | 13 | 17 | 26 | 42 |
14 | 350 | 0.31 | see8 | 14 | 19 | 27 | 44 |
16 | 250 | 0.31 | see8 | 116 | 15 | 24 | 34 |
16 | 300 | 0.32 | see8 | 13 | 17 | 26 | 39 |
16 | 350 | 0.34 | see8 | 15 | 20 | 28 | 44 |
18 | 250 | 0.31 | see8 | 106 | 14 | 22 | 31 |
18 | 300 | 0.34 | see8 | 13 | 17 | 26 | 36 |
18 | 350 | 0.36 | see8 | 15 | 19 | 28 | 41 |
20 | 250 | 0.33 | see8 | 10 | 14 | 22 | 30 |
20 | 300 | 0.36 | see8 | 13 | 17 | 26 | 35 |
20 | 350 | 0.38 | see8 | 15 | 19 | 28 | 38 |
24 | 200 | 0.33 | see8 | 86 | 12 | 17 | 25 |
24 | 250 | 0.37 | see8 | 11 | 15 | 20 | 29 |
24 | 300 | 0.40 | see8 | 13 | 17 | 24 | 32 |
24 | 350 | 0.43 | see8 | 15 | 19 | 28 | 37 |
30 | 150 | 0.34 | see8 | - | 9 | 14 | 22 |
30 | 200 | 0.38 | see8 | 87 | 12 | 16 | 24 |
30 | 250 | 0.42 | see8 | 11 | 15 | 19 | 27 |
30 | 300 | 0.45 | see8 | 12 | 16 | 21 | 29 |
30 | 350 | 0.49 | see8 | 15 | 19 | 25 | 33 |
36 | 150 | 0.38 | see8 | - | 9 | 14 | 21 |
36 | 200 | 0.42 | see8 | 87 | 12 | 15 | 23 |
36 | 250 | 0.47 | see8 | 10 | 14 | 18 | 25 |
36 | 300 | 0.51 | see8 | 12 | 16 | 20 | 28 |
36 | 350 | 0.56 | see8 | 15 | 19 | 24 | 32 |
4.) These pipes are adequate for the rated working pressure indicated for each nominal size plus a surge allowance of 100 psi. Calculations are based on a 2.0 safety factor times the sum of working pressure and 100 psi surge allowance. Ductile iron pipe for working pressures higher than 350 psi is available.
5.) An allowance for a single H-20 truck with 1.5 impact factor is included for all sizes and all depths of cover.
6.) Minimum allowable depth of cover is 3’. For depths less than 3’, consult AMERICAN.
7.) Calculated maximum depth of cover exceeds 100’.
8.) Laying condition Type 1 is limited to 12" and smaller pipe. For 14" and larger pipe, laying condition Type 1 should not be used.
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.