Reliability-based Inspection Planning Research Articles

Practical Approach for Reliability-Based Inspection Planning of Jacket Platforms Using Bayesian Networks

AbstractThis study aims to present a probabilistic framework for inspection, maintenance, and repair planning of jacket platforms based on the Bayesian probabilistic networks. To this end, consider...

Reliability-Based Inspection Planning of 20 MW Offshore Wind Turbine Jacket

Reliability-Based Inspection Planning of 20 MW Offshore Wind Turbine Jacket

Reliability based inspection planning using fracture mechanics based fatigue evaluations for ship structural details

Survey and inspection of ship structures is essential in order to monitor the integrity of the hull. With increasing ship size, the number of details susceptible to fatigue damage may be significant. Also as the ship nears the end of its design life, more effective inspections are required to ascertain the structural health of the ship. Reliability based inspection techniques are a possible way for ensuring the effectiveness of the surveys. In the present work, the applications of fracture mechanics based fatigue crack evaluations have been demonstrated to prepare reliability based inspection plans for a Very Large Crude Carrier (VLCC). Probabilistic considerations have been applied taking into account the uncertainty in various parameters related to the loads, materials as well as the parameters of fatigue crack growth. Scheme for updating of reliability of a given ship structural detail has been presented which employs Bayesian approach. Effect of utilization of various inspection techniques has been demonstrated. Various cases such as no-detection of crack, detection of crack with & without repair have been considered. Finally, the results have been also compared with the reliabilities in the current practice of fixed periodical inspections. The paper demonstrates that reliability based inspections are a feasible technique for integrity management of ship structural details while maintaining a practicable work schedule.

A study on reliability-based inspection planning – Application to deck plate thickness measurement of aging tankers

In order to conduct a timely and effective inspection to avoid the ultimate failure of deck plate, a reliability-based procedure for inspection planning is introduced. A review of the uncertainties in deriving the capacity of deck plate and through life degradation effects on tanker structural integrity is given. Using the Latin Hypercube sampling method to perform the Monte Carlo Simulation, the time-variant failure probabilities of deck plate are computed, then compared with target values. Based on the comparison, the time for thickness measurement of deck plate is predicted. A total of 1080 cases for nine sample tankers are analyzed to illustrate the procedure, including sensitivity and parametric studies. This paper is a sequel to the preceding paper [6], where a semi-probabilistic approach is presented to assess the time-variant ultimate strength of aging tanker’s deck plate considering corrosion wastage.

Safety and inspection planning of older installations

A basic assumption often made in risk- and reliability-based inspection planning is that a Bayesian approach can be used. This implies that probabilities of failure can be updated in a consistent way when new information (from inspections and repairs) becomes available. The Bayesian approach and a no-crack detection assumption imply that the inspection time intervals usually become longer and longer with time. For ageing platforms several small cracks should be expected to be observed according to the bath-tub curve development often assumed – implying an increased risk for crack initiation (and coalescence of small cracks) and increased crack growth. This should imply shorter inspection time intervals for ageing structures. Different approaches for updating inspection plans for older installations are proposed. The most promising method consists of increasing the rate of crack initiations at the end of the expected lifetime – corresponding to a bath-tub hazard rate effect. The approach illustrated is for welded steel details in platforms. Systems effects are considered, including the use of dependence between inspection and failure events in different components for inspection planning.

Reliability-Based Inspection of Corroded Ship-Type FPSO Hulls

This paper proposes a time-variant probabilistic corrosion model derived from a database with 157 thickness measurement records of 140 tankers. Incorporating the corrosion model in a time-dependent reliability method and referring to a required limit of safety level, a reliability-based inspection planning is proposed for ship-type floating production, storage, and offloading units (FPSOs) based on corrosion renewal criteria that account simultaneously for thickness reduction, hull girder ultimate strength, stiffened panel buckling strength, and plate ultimate strength

Reliability based inspection planning of offshore structures

This paper presents a series of studies on the development and application of reliability based inspection planning techniques for offshore structures including fixed and floating platforms and jack-up drilling rigs. The general methodology is presented which broadly applies to all three types of offshore structure and differences between the characteristics of the various structures which need to be reflected in the detailed methodology are highlighted in the paper. The need for using these techniques is discussed together with the benefits achieved from their application. Case studies are presented to demonstrate the application and benefits of these techniques and important trends are highlighted through the results of parametric sensitivity studies. Furthermore, areas where more work is required to advance these applications further are also identified and discussed.