Engineering a solution - corrosion engineering and management
Corrosion is a major threat to the integrity of many hydrocarbon assets such as onshore plants, transfer pipelines, and offshore structures and their corresponding process systems. It adversely affects the safety of personnel and protection of the environment against oil spills.
Corrosion and its related issues can be extremely costly due to necessary repairs, replacements, lifting activities, extra labour and deferred production. Controlling it for any hydrocarbon (HC) asset requires two discrete disciplines – corrosion engineering (CE) and corrosion management (CM).
Corrosion engineering is defined as the ‘design and application of methods to prevent corrosion’. It is closely associated with the asset’s design state and covers design, environmental control and materials selection. Corrosion management for any asset can be defined as the process of reviewing the applied CE considerations, the regular monitoring of their effectiveness and the assessment of their performance post-commissioning.
For any HC asset, corrosion is efficiently and adequately controlled only when both CE and CM are taken into account and properly implemented.
The interactions between CE and CM throughout the asset lifecycle and their blurred boundaries, however, often cause confusion for the body responsible for asset integrity management.
The situation is often compounded by the corrosion engineer’s lack of understanding of the asset corrosion management strategy (Asset CMS), its components and their appropriate and timely implementation. Also, some operators are reluctant to adopt an appropriate asset CMS post-commissioning. They believe the initial CE input has eliminated the requirement. This hesitancy often continues throughout the operation phase until the first signs of corrosion appear, causing equipment failures, incidents and shutdowns.
The implications of such misunderstandings are costly and can increase the risk of failure, leading to lowered personnel safety and impaired environmental protection as well as higher chemical treatment, repair and inspection costs, and a rise in the number and duration of unplanned shutdowns.
The image below, left, illustrates a typical CM scope, including reviewing, monitoring and assessing. The scope is identical for all HC assets, though the implementation may vary depending on condition, its requirements and the systems/procedures in place.
Corrosion management for HC assets is implemented through an Asset CMS. This comprises four stages (see image right). The first step of any Asset CMS is the integrity review process (IRP), where a responsible corrosion engineer collates the relevant design, process, operation, chemical treatment and inspection data. The data is used to create an Asset Corrosion Management Strategy document. This addresses all the inspection, mitigation and monitoring requirements. Many HC assets lack this document, most often because no IRP is carried out.
The third stage involves implementing the Asset CM Strategy document. Regular monitoring and assessment of the applied CE features and their effectiveness and performance constitutes the fourth stage.
Ideally, a corrosion key performance indicator (corrosion KPI) system should facilitate CM implementation. Any major shortcomings or inadequacies identified will be fed back to the next integrity review process while minor issues will be tackled instantaneously to maintain a high KPI compliance.
To effectively and efficiently manage the threat of corrosion for any hydrocarbon asset, an asset CMS is required. While CE and CM are the two indispensable components of any asset CMS throughout its lifecycle, the latter is often neglected. The solution is to have a better appreciation of the CM concept, its scope, applications and the ensuing benefits. Once such an understanding has been developed it will positively impact on overall integrity management. This is even more applicable to those assets which have already passed their design life or have been managed and owned by more than one operator.