Reliability estimates of the inspection requirements for tubular welded joints
- Southwest Research Inst., San Antonio, TX (United States). Dept. of Materials and Mechanics
A simple model is described to relate the structural reliability to the inspection interval and the inspection sensitivity for tubular joints used in the construction of fixed offshore structures. This model is based on a fracture mechanics analysis of the tubular joints. The starting point in the model is the distribution of initial defects present in the tubular joints after fabrication. Full-scale fatigue test results on tubular joints are combined with a fracture mechanics model in order to estimate the distribution of initial defect sizes. This initial defect distribution is assumed to grow in service under the action of fatigue loading and environment. A probabilistic fracture mechanics model, incorporating a random crack growth rate, is used to calculate the distribution of defects after any number of cycles in service. The associated probability of failure is calculated from the probability of the calculated defect distribution exceeding a known distribution of critical crack sizes. This failure probability is modified by inspection with an associated inspection reliability, an interval between inspections, and by the defect distribution introduced due to repair. The model is then exercised on a simple tubular joint geometry in order to demonstrate the applicability of the proposed approach.
- OSTI ID:
- 55802
- Report Number(s):
- CONF-940230--; ISBN 0-7918-1265-0
- Country of Publication:
- United States
- Language:
- English
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