A Framework for Estimating Piping Reliability Subject to Corrosion Under Insulation

Ainul Akmar Mokhtar,Abu Bakar Zainordin,Mokhtar Che Ismail,Shahrullizam Shahid,S Karuppanan,M Ovinis,A Tesfamichael Baheta,Z A Abdul Karim

doi:10.1051/matecconf/20141303001

Ainul Akmar Mokhtar, Abu Bakar Zainordin + Show 6 more

Open Access

https://doi.org/10.1051/matecconf/20141303001

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Abstract

Corrosion under insulation (CUI) is one of the serious damage mechanisms experienced by insulated piping systems. Optimizing the inspection schedule for insulated piping systems is a major challenge faced by inspection and corrosion engineers since CUI takes place beneath the insulation which makes the detection and prediction of the damage mechanism harder. In recent years, risk-based inspection (RBI) approach has been adopted to optimize CUI inspection plan. RBI approach is based on risk, a product of the likelihood of a failure and the consequence of such failure. The likelihood analysis usually follows either the qualitative or the semi-qualitative methods, thus precluding it to be used for quantitative risk assessment. This paper presents a framework for estimating quantitatively the likelihood of failure due to CUI based on the type of data available.

Highlights

For insulated piping systems, optimizing the inspection schedule is one of the major challenges faced by inspection engineers as well as corrosion engineers since the damage mechanisms take place beneath the insulation which makes it hardly to detect and to predict
The followings are the results of the study: 3⁄4 A good quantitative model that can be applied with the current corrosion under insulation (CUI) data is the structural reliability analysis model where the reliability calculation is based on the design and operating data as well as the wall thickness data to estimate the corrosion rate
In the case where the wall thickness data is abundant, the degradation analysis is proposed to be used. 3⁄4 The Markov model seems to be a potential model in the future

Summary

Introduction

For insulated piping systems, optimizing the inspection schedule is one of the major challenges faced by inspection engineers as well as corrosion engineers since the damage mechanisms take place beneath the insulation which makes it hardly to detect and to predict. One of the serious degradation mechanisms experienced by insulated piping systems is corrosion under insulation (CUI). Risk is defined as the product of the likelihood of failure and the consequence of such failure. The assessment of the likelihood of failure for CUI follows either the qualitative or the semi-qualitative methods, precluding it to be used for quantitative risk assessment. The objective of this paper is to propose a framework for quantitatively assessing the likelihood of CUI failure

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