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Author

M. Ahammed

Other affiliations: Newcastle University
Bio: M. Ahammed is an academic researcher from University of Newcastle. The author has contributed to research in topics: Monte Carlo method & Dynamic Monte Carlo method. The author has an hindex of 13, co-authored 22 publications receiving 994 citations. Previous affiliations of M. Ahammed include Newcastle University.

Papers
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Journal ArticleDOI
TL;DR: In this paper, a probabilistic approach is adopted for the assessment of remaining life of a pressurised pipeline containing active corrosion defects, and the associated variables are represented by normal or non-normal probability distributions, relative contribution of the random variables and the sensitivity of the reliability index to the change in variance of random variables is also investigated.

192 citations

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TL;DR: A procedure is proposed in which the numerical results from a Monte Carlo reliability estimation procedure are converted to a form that will allow the basic ideas of the first order reliability method to be employed and allows sensitivity estimates of low computational cost to be made.

178 citations

Journal ArticleDOI
TL;DR: In this paper, a nonlinear limit state model for the analysis of underground pipelines, stressed both in the circumferential and the longitudinal directions, is presented, where the effects of internal fluid pressure, external soil and traffic loads, temperature and longitudinal pipe bending etc.

159 citations

Journal ArticleDOI
TL;DR: In this article, a probabilistic method for the assessment of the suitability of corroded pipelines under pressure loading is described, taking into account the uncertainties of the variables that influence suitability.

121 citations

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TL;DR: In this paper, the reliability of underground pipelines subject to externally applied loading and to corrosion, either externally or internally, or both, is estimated using probabilistic modeling of the material loss as a nonlinear function of time.
Abstract: The present paper is concerned with estimating the reliability of underground pipelines subject to externally applied loading and to corrosion, either externally or internally, or both. This affects the strength of the pipeline in resisting the applied loads so that the reliability would be expected to decrease with time. Corrosion is a phenomenon about which there is a great deal of uncertainty. One way of allowing for this is through probabilistic modeling of the material loss as a nonlinear function of time. This approach is explored in the present paper, using a nonlinear function first postulated for atmospheric corrosion. This model is incorporated into expressions for stress resulting from externally applied loading and internal pressure to provide a limit state function expressing the boundary between survival and failure of the system. The probability of system failure is then evaluated using techniques developed for structural reliability analysis.

97 citations


Cited by
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Journal ArticleDOI
TL;DR: In this paper, the main risk analysis and risk assessment methods and techniques by reviewing the scientific literature are classified into three main categories: (a) the qualitative, (b) the quantitative, and (c) the hybrid techniques (qualitative,quantitative, semi-quantitative).
Abstract: The objective of this work is to determine and study, analyze and elaborate, classify and categorize the main risk analysis and risk-assessment methods and techniques by reviewing the scientific literature. The paper consists of two parts: a) the investigation, presentation and elaboration of the main risk-assessment methodologies and b) the statistical analysis, classification, and comparative study of the corresponding scientific papers published by six representative scientific journals of Elsevier B.V. covering the decade 2000–2009. The scientific literature reviewing showed that the risk analysis and assessment techniques are classified into three main categories: (a) the qualitative, (b) the quantitative, and (c) the hybrid techniques (qualitative–quantitative, semi-quantitative). The qualitative techniques are based both on analytical estimation processes, and on the safety managers–engineers ability. According to quantitative techniques, the risk can be considered as a quantity, which can be estimated and expressed by a mathematical relation, under the help of real accidents’ data recorded in a work site. The hybrid techniques, present a great complexity due to their ad hoc character that prevents a wide spreading. The statistical analysis shows that the quantitative methods present the highest relative frequency (65.63%) while the qualitative a lower one (27.68%). Furthermore the hybrid methods remain constantly at a very low level (6.70%) during the entire processing period.

371 citations

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TL;DR: A comprehensive overview of the physical/mechanical models that have been developed to improve the understanding of the structural performance of water mains can be found in this paper, where the effect of temperature on pipe breakage is discussed from three angles.

343 citations

Journal ArticleDOI
TL;DR: A review of the literature that may assist in forming a multiscale model of corrosion in soils is presented in this article, which takes into account macro-environmental processes (rainfall, etc), soils processes (water movement, oxygen transport, etc.), processes within the oxides, and the electrochemical activity occurring at the metal surface.

300 citations

Journal ArticleDOI
TL;DR: In this paper, the authors reviewed and analyzed the current understanding of the pitting corrosion mechanism and investigated all possible factors that can cause pitting, including accurate pit depth measurements, precise strength assessment techniques, risk analysis due to pitting and the mathematical relationship of the environmental factors that causes pitting failure.
Abstract: Corrosion is a major cause of structural deterioration in marine and offshore structures. It affects the life of process equipment and pipelines, and can result in structural failure, leakage, product loss, environmental pollution and the loss of life. Pitting corrosion is regarded as one of the most hazardous forms of corrosion for marine and offshore structures. The total loss of the structure might be very small, but local rate of attack can be very large and can lead to early catastrophic failure. Pitting corrosion is a localized accelerated dissolution of metal that occurs as a result of a breakdown in the protective passive film on the metal surface. It has been studied for many years; however, the structural failure due to pit characteristics is still not fully understood. Accurate pit depth measurements, precise strength assessment techniques, risk analysis due to pitting, and the mathematical relationship of the environmental factors that causes pitting failure are also factors, which need further understanding. Hence this paper focuses on these issues. It reviews and analyses the current understanding of the pitting corrosion mechanism and investigates all possible factors that can cause pitting corrosion. Furthermore, different techniques employed by scientists and researchers to identify and model the pitting corrosion are also reviewed and analysed. Future work should involve an in-depth scientific study of the corrosion mechanism and an engineering predictive model is recommended in order to assess failure, and thereby attempt to increase the remaining life of offshore assets.

295 citations

Journal ArticleDOI
TL;DR: In this article, the reliability of pipelines with corrosion defects subjected to internal pressure using the first-order reliability method (FORM) is defined based on the results of a series of small-scale experiments and three-dimensional nonlinear finite element analysis of the burst pressure of intact and corroded pipelines.

228 citations