Flow modelling and corrosion risk assessment are used to study a challenging multiphase pipeline, where the main focus is the identification and prioritisation of critical locations for direct inspection. Using an internal corrosion direct assessment method, we conduct flow modelling and sensitivity studies to identify critical locations with risks of high shear stresses and water holdup. Through corrosion risk assessment, we narrow down the critical locations to four primary locations which, following direct inspection, could provide the information necessary to estimate the overall pipeline condition. We highlight that without ILI data, selection of inspection locations become problematic. However, through flow modelling, together with corrosion risk assessment, a more representative assessment of the pipeline condition can be built to assist engineering decision making.
It is now well-established that corrosion contributes to the overall cost of operation to any industrial asset. For instance, it is estimated that the direct annual cost of corrosion in the USA is approximately 276 billion USD . Corrosion remains a dominant causal factor that compromises reliability and safety [2,3]; e.g. between 1990 and 2013, in the province of Alberta (Canada), up to 64 % of incidents that resulted in pipeline failures were associated with either internal or external corrosion .
Demonstrating the integrity of assets requires both the development and effective implementation of a corrosion management system (CMS). In the United Kingdom the key instruments which manage operational integrity and safety of pipeline assets include Pressure Systems Safety Regulations 2000 and Pipeline Safety Regulations 1996 (PSR) documents. These Regulations, instigated as a result of the Piper Alpha  disaster, implement a goal setting approach to ensure that operators are operating pipelines safely and effectively while associated risks and consequences are controlled and kept as low as reasonably practicable. As a demonstration, one of the main statements covering maintenance is reflected in Clause 13 (Maintenance): "The operator shall ensure that a pipeline is maintained in an efficient state, in efficient working order and in good repair."