Methodology of assessing individual reliability of unique structures

The paper describes the author’s methodology of quantitative reliability assessment of unique systems that are components of very expensive critical/strategic infrastructures, manufactured in very small series/batches, or even as single, unique structures. It was dubbed “theory of individual structural reliability — TISR”. With the development of the 3D digital technology and digitization that opened the door to creating digital twins in design, the share of unique products is growing non-stop in all branches of contemporary heavy industry and machine-building (rotor excavators, continuous casting plants, drilling rigs), adjacent sectors of industry (ship-building, aircraft building), and construction industry (large span bridges, super high skyscrapers, exhibition pavilions etc.). In this paper the TISR methodology is described for a class of unique and non-renewable objects using as an example a one-time-deployed-when-on-orbit robotic technological complex, designed to serve without interruption for 12–15 years in the near-space environment. The paper is a direct extract from preprint [1], revised and translated into English by its first author. The initial data needed for writing paragraphs 4 and 6 of this paper belongs to Yu. P. Pokhabov, published elsewhere, which made the description of implementing the TISR methodology in the field of unique spacecraft design up to date. The author greatly appreciates and acknowledges the provided input

PREDICTIVE MAINTENANCE OF PIPELINES WITH DIFFERENT TYPES OF DEFECTS

The paper describes a tested and proven practical methodology of predictive maintenance of pipelines with two types of defects—«loss of metal» and «pipe wall lamination», detected by the ILI technology.For the defects of the «pipe wall lamination» type the assessment of their level of danger is conducted only after they are converted to surface «loss of metal» type defects. The paper presents models on how to adequately convert the «pipe wall lamination» type of defects to the «loss of metal» type defects.A methodology is described on how to rank the defects according to their level of danger (with respect to the rupture type of failure), and how to perform the probabilistic assessment of the residual life of the inspected pipeline. The defects detected by the ILI are divided, depending on their type, size, and the level of safety factor, into three following categories: Dangerous, Potentially dangerous and Not dangerous defects. In order to account for «leak» and «rupture» types of failure, a computer based express assessment is developed of the level of severity of each defect. This defect assessment is based on graphs, which restrict the permissible sizes of defects and allow making operative decisions as to which maintenance measures should be taken, regarding each detected defect and the pipeline segment as a whole. The pipeline defects are ranked according to their potential danger, which depends on their location on the graphs. These graphs form five zones, which define the level of the defects danger.The probabilistic assessment of the residual pipeline life is performed taking into account the stochastic nature of defect growth. In order to achieve this, the maximal γ-percentile corrosion rate is defined over all detected defects. The distribution of the n detected pipeline defects is described by the two-parameter Weibull probability density function (PDF).  As the main decision parameter the gamma-percent operating time is chosen. It is characterized by 1) the safe operating time, and 2) the percentile probability that during this time the pipeline limit state will not be reached.A detailed example of implementation of the described methodology to a real product pipeline segment operating in a severe corrosion environment is given. The economical effect of the implementation is outlined

Diagnostics and reliability of pipeline systems

The book contains solutions to fundamental problems which arise due to the logic of development of specific branches of science, which are related to pipeline safety, but mainly are subordinate to the needs of pipeline transportation.          The book deploys important but not yet solved aspects of reliability and safety assurance of pipeline systems, which are vital aspects not only for the oil and gas industry and, in general, fuel and energy industries , but also to virtually all contemporary industries and technologies. The volume will be useful to specialists and experts in the field of diagnostics/ inspection, monitoring, reliability and safety of critical infrastructures. First and foremost, it will be useful to the decision making persons —operators of different types of pipelines, pipeline diagnostics/inspection vendors, and designers of in-line –inspection (ILI) tools, industrial and ecological safety specialists, as well as to researchers and graduate students

EXPERIMENTAL ASSESSMENT OF MATERIAL STRENGTH OF TWO OPERATING MAIN OIL PIPELINES

ABSTRACT The paper describes the results of a special experimental study of three types of damaged pipeline steels from two main oil pipelines that had been in operation for 15 years. The experimental study included assessments of the main static characteristics of the steels, parameters of the S-N curve, prognosis of the fatigue limits and assessment of the fracture toughness (FT) and the FT curve. Obtained results permit correct assessments of the pipelines remnant life

IPC04-0295 PRACTICAL METHOD OF UPDATING STOCHASTIC REMAINING LIFE OF PIPELINES USING ILI DATA

ABSTRACT The paper describes a new practical method of updating the stochastic remnant life of pipelines with defects using ILI data. The paper describes a comprehensive algorithm for assessing pipeline remnant life taking into account the stochastic results of in-line inspection (ILI). It is assumed that the pipeline segment wall has a longitudinal external crack of semi-elliptical form and is described by the J-integral. The limit state function (LSF) is described as the difference of the critical and current value of the J-integral. The latter is calculated for the current time of pipe performance and is assumed known due to monitoring of the pumping equipment. The critical crack depth is defined using the notion of fracture toughness and the J-integral approach. The algorithm contains solutions of three sequentially interconnected problems. First, the deterministic problem of fatigue crack growth (FCG) is analyzed. Then the stochastic FCG is analyzed. The probability of failure assessment algorithm is designed on the basis of the authors' version of the adaptive important sampling (AIS) procedure. The main steps of the AIS algorithm are described in detail. The samples are generated in such a way, that at all times a majority of samples belong to the fracture region. Finally, the results of the latest ILI are fused into the algorithm, providing best possible assessment of pipeline remnant life as a random variable. The remnant life update for pipeline segment with cracklike defects using ILI data takes into account three possible outcomes: defect not discovered: defect is discovered but not measured; defect is discovered and measured. This result permits solving most important problems of pipeline maintenance: prioritization of pipeline segments for repair/rehabilitation; optimization of the time between ILI; minimization of pipe operational risk. Two real cases are described of assessing the probability of fracture/leak of a pipeline section with an external crack at different periods of its performance. The described approach currently is being generalized for the case of multiple stress corrosion SC cracks

Comparative studies on assessment of corrosion rates in pipelines as semi-probabilistic and fully stochastic values

Reduction of pipeline carrying capacity and safety are often caused by corrosion and its potential damaging effects. Simple techniques which can be used to evaluate both current and the time-dependent change in the pipeline’s reliability are needed since reliability analysis is recognized as a powerful decision-making tool for risk-based design and maintenance. The prediction of future sizes of growing defects and the pipeline remaining life time are obtained by using consistent assessments of their Corrosion Rates (CRs); and these CRs may be considered as deterministic, semi-probabilistic or fully stochastic values. The idea of predicting future sizes of growing defects and corrosion rates as semi-probabilistic and fully stochastic values is considered with a comparison of the results conducted and implemented on a real life pipeline. In this contribution, a probabilistic method based on the imprecise probability approach is presented to predict the remaining life time and the failure probability of pipelines with corrosion defects by using the Monte Carlo simulation (MCS) method implemented in OpenCossan; the open source engine of COSSAN software for uncertainty quantification and risk management. The results obtained from deterministic, semi-probabilistic and probabilistic methods are compared using B31G, Modified B31G and DNV-101 pressure failure models. The proposed probabilistic method of assessment can be applied for the design of new systems as well as assessing of existing pipelines in operation.Non UBCUnreviewedThis collection contains the proceedings of ICASP12, the 12th International Conference on Applications of Statistics and Probability in Civil Engineering held in Vancouver, Canada on July 12-15, 2015. Abstracts were peer-reviewed and authors of accepted abstracts were invited to submit full papers. Also full papers were peer reviewed. The editor for this collection is Professor Terje Haukaas, Department of Civil Engineering, UBC Vancouver.Facult

Abstracts of The Second Eurasian RISK-2020 Conference and Symposium

This abstract book contains abstracts of the various research ideas presented at The Second Eurasian RISK-2020 Conference and Symposium.The RISK-2020 Conference and Symposium served as a perfect venue for practitioners, engineers, researchers, scientists, managers and decision-makers from all over the world to exchange ideas and technology about the latest innovation developments dealing with risk minimization