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Gas transmission pipeline system was designed very
conservativelydue to the server losses of lives and properties
after fracture failure.In order to evaluate the conservatism of
safety margins of a pipeline system, the well-developed modern
engineering reliability analyses wereused instead of traditional
statistics methodology.The objective of thisstudy was to have a
quantitative reliability analysis of transmission pipeline
system by using probabilistic fracture mechanics approachwhere
ductile pipe fracture mechanics models were developed. Two
probabilistic fracture mechanics models for(1)leak and
(2)leakand break failures had been developed respectively; the
reliability ofgas transmission pipeline system was estimated by
Monte Carlo Simulationmethod First-Order-Second-Moment method.
The results showed that both MCS method and FOSM method couldbe
applied satisfactorily ,and also showed the inappropriateness by
a traditional statistic's analysis for a scarce data.Sensitivity
analyses were processed to show that the major
uncertaintyresided on defect size,and the most influential
failure mode on reliabilitywas leak that indicated the key
strategy on failure prevention.To the conclusion,a raise of
design factor of stress ratio to 0.6 will still maintain the
pipe integrity in a conservative condition.
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