Products

RATED WORKING PRESSURE AND MAXIMUM DEPTH OF COVER

Size In. Pressure¹ Class psi. Normal Thickness In. Laying Condition
Type 1 Trench Type 2 Trench Type 3 Trench Type 4 Trench Type 5 Trench
Minimum Depth of Cover ²- ft.
3 350 0.25 78 88 99 100§ 100§
4 350 0.25 53 61 69 85 100§
6 350 0.25 26 31 37 47 65
8 350 0.25 16 20 25 34 50
10 350 0.26 11* 15 19 28 45
12 350 0.28 10* 15 19 28 44
14 250
300
350		 0.28
0.30
0.31
 **
**
**		 11*
13
14
 15
17
19
 23
26
27
 36
42
44
16 250
300
350
 0.30
0.32
0.34
 **
**
**		 11*
13
15		 15
17
20
 24
26
28
 34
39
44
18 250
300
350
 14
17
19
 **
**
**		 10*
13
15		 14
17
19
 22
26
28
 31
36
41
20 250
300
350
 0.33
0.36
0.38
 **
**
**		 10
13
15
 14
17
19
 22
26
28
 30
35
38
24 200
250
300
350
 0.33
0.37
0.40
0.43
 **
**
**
**		 8*
11
13
15		 12
15
17
19
 17
20
24
28
 25
29
32
37
30 150
200
250
300
350
 0.34
0.38
0.42
0.45
0.49
 **
**
**
**
**		 -
8*
11
12
15		 9
12
15
16
19
 14
16
19
21
25
 22
24
27
29
33
36 150
200
250
300
350
 0.38
0.42
0.47
0.51
0.56
 **
**
**
**
**		 -
8*
10
12
15		 9
12
14
16
19
 14
15
18
20
24
 21
23
25
28
32

1 - Ductile-iron pipe is 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. (See ANSI/AWWA C150/A21.50 for design formulae.) Ductile-iron pipe for working pressures higher than 350 psi is available.
2 - An allowance for a single H-20 truck with 1.5 impact factor is included for all depths of cover.
§ - Calculated maximum depth of cover exceeds 100 ft.
* - Minimum allowable depth of cover is 3 ft.
** - For pipe 14 in. and larger, consideration should be given to the use of laying conditions other than type 1.