Probability of Failure Associated with Design and Safety Factors for Intact and Corroded Pipes under Internal Pressure

Abstract

The assessment of reliability levels associated with the design and safety factors (DFs and SFs) is important for modern pipeline engineering to achieve probabilistic design using a conventional deterministic format. To this end, this paper evaluates the probabilities of failure (POFs) for different pipe configurations, corrosion defects, and DF/SFs. Two limit states are considered: the yielding of intact pipes based on Barlow’s equation and the failure of corroded pipes based on the RSTRENG model under internal pressure. The uncertainties of all the important variables are considered, including the RSTRENG model error. The POFs associated with different DF/SFs are calculated and discussed; the safety levels (e.g., safety class) of pipes based on the different DF/SFs are also determined. The DFs commonly used for the yielding of intact pipes are found to be in the highest safety class. The SFs used for corroded pipes based on the RSTRENG model are also found to be in the highest safety class for long corrosion defects but in the lowest safety class for short corrosion defects.