Abstract
The role of internal (mainly CO2 related) corrosion for offshore and subsea infrastructures is now evolving into a major topic of interest. Corrosion assessment and its control, particularly (but not exclusively) in wet hydrocarbon containing environments, is a critical step in the Integrity Management (IM)process. Typically the focus is on general or uniform corrosion alone since that can be more effectively modeled, and software (private, JIP and public domain) exists to facilitate that accordingly. In real world applications the corrosion that causes the problems is almost entirely localized and multi-mechanistic. Thus there is a major disparity between the modeling corrosion predictions, laboratory testing, and actual field observations. Historically that aspect has been accepted since actual corrosion issues usually occur well into the asset life cycle. However, that is no longer the case with the deeper more demanding high pressure, high temperature, high velocity (HP/HT/HV) conditions and physical flow regimes, transients, excursions etc. present in newer (green field) offshore assets. With such developments inspection and effective monitoring are not always easily adaptable, due to economics, workability, cost and safety issues. Existing (brown field) developments present different challenges, but can also benefit from measured corrosion and integrity data ‘fine tuning’ over the life cycle. In recent years a strong case has been made to utilize the principles of inherently safer designs (ISD), key performance indicators (KPI's), and risk management techniques in terms of fully integrated materials selection, and corrosion assessment in context of the safety driven ALARP condition. The recent spate of high profile corrosion issues and failures has stimulated this move. This paper examines such issues and critically argues the shift in thinking to address this contentious and largely unresolved area of corrosion management.
