Ageing assets are a challenge globally. Anything that was once ‘brand new’ eventually ages and needs to be repaired, updated or replaced. As engineers it is up to us to ensure that systems and procedures are put in place to prevent corrosion and preserve these assets for as long as possible.
Over the past 50 years several national ‘costs of corrosion’ studies have been conducted. Using different approaches, the studies all arrived at corrosion costs equivalent to 3-4% of each nation's gross domestic product (GDP).
In 2018 global GDP was US$85.9 trillion, therefore the global cost of corrosion can be estimated to be US$2.9 trillion. In Australia alone, the cost of corrosion can be estimated to be about US$50billion.
What can be done to reduce the cost of corrosion?
Managing the Threat of Corrosion on Ageing Assets
Implementing corrosion prevention best practices involves putting in place a Corrosion Management System (CMS). This is a documented set of processes and procedures for planning, executing, and continually improving the ability to manage the threat of corrosion for both existing and future assets.
Realising the maximum benefit in reducing corrosion costs requires more than technology. It requires integrating corrosion decisions and best practices within an organisational management system. This is enabled by integrating a CMS within system elements that range from corrosion specific procedures and practices up through organisational policy and strategy - all levels of the management system pyramid.
Figure 1 – Hierarchy of General and Corrosion-Specific Management Elements
Managing the threat of corrosion requires consideration of both the likelihood and consequence of corrosion events. The consequence and impact of corrosion can be considered the potential or actual monetary loss associated with safety, the environment or asset integrity. This value is typically quantifiable when considering lost revenue, cost of repairs and clean-up costs.
Other aspects of corrosion impact include deterioration of an asset to the point where it is no longer fit for its intended purpose.
To maximise effectiveness, the CMS must manage the threat of corrosion at each of the significant stages of an asset’s lifecycle, from design to decommissioning.
Figure 2 – CMS Framework (Based on ISO 31000).
Identifying Risk in Ageing Assets
Risk is defined as the effect of uncertainty of objectives. There are many varying aspects of risk which include financial, health, safety and the environment. These can be applied on a number of levels such as strategic, organisation-wide, project, product and process.
Risk is often expressed in terms of a combination of the consequences of an event, including changes in circumstances, and the associated likelihood of occurrence.
In order to achieve the desired balance of cost, risk and performance it is important to understand the difference between structural risk and corrosion risk. Corrosion risk is usually associated with the notion there is a probability that corrosion might occur and the extent to which it might occur. However, the occurrence of such corrosion need not have a significant effect on structural risk - that is the risk or probability of significant structural failure or service impairment.
The Importance of Asset Management for Corrosion Prevention
Asset managers, infrastructure owners and stakeholders normally indicate a remaining service life requirement for their assets. To achieve this, useful conclusions and recommendations are necessary to allow the asset owner to act on the observations and findings discovered during any assessment.
To develop meaningful conclusions and recommendations it is important to follow a specific process and procedure appropriate for the asset type and location. These should include inspections, desktop structural assessments, targeted detailed inspections and field testing as a result of the desktop assessment, and remediation scopes as required.
Inspection guidelines throughout industry recognise the necessity for those carrying out the inspections to be appropriately qualified, experienced and competent to ensure suitable recommendations are determined. This indicates that asset owners and custodians consider this to be a vital requirement of a sound assessment.
Desktop structural assessments provide meaningful outcomes that enable targeted future inspection guidelines to assist with inspections and any further assessment.
The desktop structural assessment may involve various scenario analysis to confirm structural redundancy magnitudes for asset elements (i.e. what corrosion can be afforded), providing guidelines regarding tolerable structural losses.
These outcomes can be utilised with site inspection findings to determine risks for the asset, suitable timings and the nature of the repair, strengthening remedial works and any ongoing inspection requirements.
A Five Step Approach lists the steps required during an assessment process. These are as follows:
- Screening and risk ranking
- Detailed examination
- Remediation and repair
- Lifecycle management.
As an experienced Structural Engineer, who has had papers published on assessments of structures and risk management, I have undertaken these steps previously on a number of different corrosion prevention projects for past clients, including ageing assets such as:
- Coal handling facilities
- Water reservoirs
- Storage silos
- Pedestrian footbridges
- Steel sheet pile walls within a working harbour
- Concrete dolphin wharf within a working harbour.
Need Help Implementing a Corrosion Prevention Plan?
Engenium can provide qualified and experienced Structural Engineers to undertake inspections of the structural behaviour, redundancy and load path to identify critical assets for consideration.
We can execute desktop structural assessments to allow the structural risk of assets to be adequately managed, as well as determine a remaining service life for the structure.
Our ‘smart project delivery’ realises the growing challenge of aging assets and considers both corrosion and structural risk, to provide asset owners and stakeholders with a path towards a desired balance of cost, risk and performance.
Principal Engineer, Newcastle NSW
Engenium Pty Ltd