Determination of Conditional Probability of Dynamic Ductile Axial Crack Arrest for Conventionally-Rolled, Lower-Toughness Linepipe Materials

Abstract

This paper presents an analytical procedure to predict the conditional probability of dynamic ductile axial crack arrest within one pipe joint length for pipeline materials operating at temperature above the brittle-to-ductile transition temperature. The analysis assumes there is an event to initiate a rupture with probability of one, so that the probability of a fracture event occurring is the probability of the rupture event (i.e., from mechanical damage) times the conditional probability of arrest within one pipe joint. The underlying deterministic model centers on the Battelle Two-Curve approach with a correction to predict the arrest length given the actual material toughness relative to the minimum arrest toughness. Past full-scale experimental results were used to develop statistical parameters that were used with the deterministic model in a Monte Carlo analysis. This model was calibrated for linepipe materials with a toughness less than 150J and a grade less than X65. Example cases are presented to demonstrate the variation of the probability of arrest with the pipeline operating conditions.