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Inspection sampling of pitting corrosion


Khalifa, M and Khan, FI and Haddara, M, Inspection sampling of pitting corrosion, Insight: Non-Destructive Testing and Condition Monitoring, 55, (6) pp. 290-296. ISSN 1354-2575 (2013) [Refereed Article]

Copyright Statement

Copyright 2013 British Institute of Non-Destructive Testing

DOI: doi:10.1784/insi.2012.55.6.290


The objective of this paper is to estimate the sample size required to assess the maximum pit size over an entire asset that is subject to pitting corrosion.

The Bayesian updating approach and the extreme value method are integrated into a single proposed framework to estimate the sample size. The extreme value method is used to predict the maximum pit size by extrapolating the inspected area (sample) to the entire asset's area. The Bayesian updating approach is used to update prior information obtained from the previous inspection once newly obtained information is available from the current inspection.

The estimated sample size ensures that the predicted maximum pit size over the entire asset is within an acceptable margin of error at a specified confidence level.

Using the proposed framework, two closed-form formulae are developed for calculating the sample size required to assess pitting corrosion. The two formulae address the two situations when prior information is either available or unavailable. These formulae are compared to the classical method for calculating the sample size through a case study of a pipeline subject to pitting corrosion. The comparison shows that the sample size estimated with the classical method is not large enough to assess the maximum pit size over the entire pipeline.

Item Details

Item Type:Refereed Article
Keywords:Bayesian approach, extreme value method, inspection interval, pitting corrosion, sample size, Bayesian approaches, Bayesian updating, closed-form formulae, confidence levels, extreme value, inspection intervals, inspection sampling, sample sizes
Research Division:Engineering
Research Group:Engineering practice and education
Research Field:Risk engineering
Objective Division:Expanding Knowledge
Objective Group:Expanding knowledge
Objective Field:Expanding knowledge in engineering
UTAS Author:Khan, FI (Professor Faisal Khan)
ID Code:120776
Year Published:2013
Web of Science® Times Cited:5
Deposited By:NC Maritime Engineering and Hydrodynamics
Deposited On:2017-08-30
Last Modified:2017-11-06

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