This paper outlines methodologies and analytical tools for the Risk Based Inspection and Integrity Management (RBIM) of pipeline systems. The objective of a risk based integrity management (asset management) approach is to ensure and maintain the required confidence in the pipelines integrity and hence maximise its operating availability, whilst optimising the resources used to ensure the pipeline integrity e.g. the planning of inspection intervals and methods, repairs etc. The basic steps of a pipeline system RBIM are:
Establish and define the required levels of confidence in the pipeline's integrity.
Develop as detailed knowledge as possible of the pipelines past, present and future operating condition and environment.
Systematically evaluate and rank the risks of each potential failure mode specific to the particular pipeline, accounting for and highlighting the uncertainties. This is largely performed at a qualitative level.
Time-dependent degradation failure modes (e.g. internal corrosion) considered to be a risk to the pipeline are assessed using spreadsheet based semi-probabilistic structural reliability assessment tools. These are quick and simple to use, predicting the period in which the confidence in pipeline's integrity against a particular failure mode falls below specified levels. A risk based inspection (RBI) planning approach is developed mixing the structural reliability approach with a generic database approach of risk analysis in c) above.
A total production maintenance (TPM) approach is considered linking it with risk-based maintenance (RBM).
Solutions are then considered to reduce / eliminate the risks considered to be unacceptable and the uncertainties in the integrity management, and to maintain confidence in the pipeline integrity.
The design of Pipeline systems is increasingly being optimised through use of advanced design methods, primarily to minimise the CAPEX (particularly on high CAPEX projects such as major trunk lines).
