文档介绍：A ROBUST APPROACH TO PIPELINE INTEGRITY MANAGEMENT USING DIRECT
ASSESSMENT BASED ON STRUCTURAL RELIABILITY ANALYSIS
Andrew Francis, Tim Illson, M A McCallum & M McQueen
Advantica
Loughborough
UK
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ABSTRACT
The management of the threat to integrity of corrosion damage has traditionally
been achieved using in-line inspection (ILI) and the hydrostatic test. However,
these approaches are not always practicable and therefore alternatives are
sometimes necessary.
For external corrosion, valuable information can be obtained using surface
measurement techniques such as Close Interval Survey (CIS), Direct Current
Voltage Gradient (DCVG) and other so-called Direct Assessment (DA)
techniques.
For internal corrosion, multiphase flow modeling can be used to determine the
likely sites of water ‘hold-up’ and hence internal corrosion.
However, both above ground measurement techniques and predictive modeling
are subject to uncertainty and therefore do not always locate the presence of
corrosion. Moreover, it is possible that the presence of corrosion may be
identified erroneously.
In order to account for this, a new technique, based on Structural Reliability
Analysis, has been developed for robustly interpreting the impact of results from
above ground surveys and predictive modeling on the structural reliability levels.
This paper describes the development and application of these techniques for
the purpose of integrity management.
Case studies involving both external and internal corrosion are presented which,
clearly demonstrate the application, and emphasize the value of the technique as
a basis for integrity management.
Keywords: direct assessment, structural reliability analysis, integrity
management
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INTRODUCTION
External Corrosion Direct Assessment (ECDA) has been defi