Minnesota Concrete Pipe Association
Manhole Sizing

Minimum Circumferential Clearances Required

Manhole Sizing - Plan view
REINFORCED CONCRETE PIPE
PIPE SIZE WALL B WALL C
O.D. O.D.
12" 16" 18"
15" 19 1/2" 21"
18" 23" 24 1/2"
21" 26 1/2" 28"
24" 30" 31 1/2"
27" 33 1/2" 35"
30" 37" 38 1/2"
33" 40 1/2" 42"
36" 44" 45 1/2"
42" 51" 52 1/2"
48" 58" 59 1/2"
54" 65" 66 1/2"
60" 72" 73 1/2"
66" 79" 80 1/2"
72" 86" 87 1/2"
78" 93" 94 1/2"
84" 100" 101 1/2"
90" 107" -
96" 114" -
102" 121" -
108" 128" -
120" 142" -
Vertical Clearances Required
MAX. PIPE SIZE OF RCP
MANHOLE DIA. FROM STRAIGHT THRU TO 135 ANGLE IF 90 ANGLE IF 180 ANGLE
48" 24" RCP 18" RCP 24" RCP
60" 33" RCP 27" RCP 33" RCP
72" 36" RCP 33" RCP 36" RCP
84" 48" RCP 36" RCP 48" RCP
96" 54" RCP 42" RCP 54" RCP
Chart to be used to determine manhole sizing.

producers@mnconcpipe.org
2005 Minnesota Concrete Pipe Association