Page 300 - Buried Pipe Design

Rigid Pipe Products 271

p 0.8P o
P o 187.5 lb/in 2

3 P o p
W W o
P
o
W 1111
W
o
[ (P P) /P] 1/3 [ (P 0.8P) /P] 1/3
o
o
o
o
o
1900 lb/ft
The pipe must be designed or selected for 187.5 lb/in internal pres-
2
sure and an external load of 1900 lb/ft, each acting independently. The
rated strength as determined by the manufacturer includes a safety
factor of 1.2. Thus, the transient capacity is considered to be 1.2 times
the design capacity for lined-cylinder pipe.
1.2 P o 1.2 187.5 225 lb/in 2
1.2 W o 1.2 1900 2280 lb/in 2

Case I (no surge):

3 225 150
Max. load 2280 1581 lb/ft
225
Safe live load 1581 1111 470 lb/ft

Case II (no live load):

3 225 p
1111 2280
225
or
1111
3
p 225 1 199 lb/in 2
2280
Safe surge pressure 199 150 49 lb/in 2

Embedded-cylinder pipe
Try
W o 1900 lb/ft