Page 270 - Pipelines and Risers

Remaining Strength of Corroded Pipes 243

The design equation for corroded pipelines, based on the new criteria is given by:
L2
For --<50
Dt
l-xA
1 -(1+O.6275XL -0.003375X~~1'2XA
(14.41)
1
.-x x x >o
t- ,-
Y
L*
>
For - 50
Dt
1 1-x,
; XflowXt -xp20 (14.42)
1-(0.032XL+3.3)-'XA

The limit state function is
L2
For - < 50
Dt
- 1
g(x) =-xMxflowxt
Y
1-x,
(14.43)
*1- (1+0.6275XL -0.003375Xt]112XA
-X,

L2
For ->50
Dt
- 1
g(x) =- xMxflow xt
Y
1- x, (14.44)
.I- (0.032XL +3.3)-'XA -X,

14.5.3 Uncertainty
Bias for Criteria, XM
Model uncertainty XI, is introduced for the criteria to account for modeling and methodology
uncertainties. It reflects a general confidence in the design criteria for a real life in-situ
scenario.