Page 245 - Buried Pipe Design

Design of Pressure Pipes 219

Mean Stress (MPa)
0 6.9 13.8 20.7 27.6 34.5 41.4 48.3
4000 27.6
Vinson
3500 24.1
Positive/Negative Line USU
3000 20.7
Stress Amplitude (psi) 2500 1.E+4 Burst Line 17.2 Stress Amplitude (MPa)

Cycles to failure
13.8
2000
1500
10.3
1000 5.E+4 2.E+4 6.9
2.E+5 1.E+5
1.E+6 5.E+5
500 3.5
10.E+6 3.E+6
40.E+6
0 0
0 1000 2000 3000 4000 5000 6000 7000
Mean stress (psi)
Figure 4.16 Curves predicted by Eq. (4.19) over entire domain.

Stress Amplitude – psi (MPa)
3000 (20.7) 2000 (13.8) 1500 (10.3) 1000 (6.89) 700 (4.83) 500 (3.45) 300 (2.07) 200 (1.38) 150 (1.03) 100 (0.69) 50 (0.34) 20 (0.14)

3000 20.7
Vinson
2500 USU 17.2
Positive/Negative line 13.8
Mean Stress (psi) 1500 10.3 Mean Stress (MPa)
2000

1000 Design
space
500 3.45
2000 psi limit
0 0
10 3 10 4 10 5 10 6 10 7 10 8 10 9
Number of Cycles
Figure 4.17 Plot of the number of cycles to failure vs. mean stress with design space shown
shaded.