The maintenance of ageing plant and equipment
All plant and equipment will be subject to ageing which, if not managed appropriately, can lead to equipment/plant failure which, in turn, can lead to future financial burdens and pose health and safety, legal and business continuity issues.
As part of their overall maintenance strategy, organisations should identify plant and equipment that represents a high risk in terms of loss and which can be subject to ageing. They should put in place, as part of their maintenance strategy, a regime to maintain such items in a state of good repair and efficient working order.
A business will have many types of assets, including financial, human, information and physical, the latter of which includes items of plant and equipment. According to PAS 55 Asset Management, the management of physical assets is “complex and involves careful consideration of the trade-offs between performance, cost and risk over all stages of the asset’s life cycle”.
An overall asset management plan will include determining the most appropriate and cost-effective maintenance of the physical assets through the development of a maintenance regime. BS 8210 Guide to Facilities Maintenance, states that “a facility and the individual assets that it comprises, should be maintained to deliver the most effective outcomes in terms of minimal cost and risk”.
Maintenance can be defined as “the combination of all technical and administrative actions, including supervision, intended to retain an item or restore it, to a state in which it can perform a required function”.
To achieve this objective, BS 8210 recommends that organisations develop a policy and accompanying strategy for the management of maintenance so as to provide a consistent approach to the planning, management and reporting of asset maintenance. This maintenance policy should clearly specify the guiding principles and objectives for the management and delivery of building maintenance, with subsequent plans being devised “to ensure that the service life of facility assets matches or, where desirable, exceeds their design life”.
However, during its lifecycle, all plant and equipment can degrade due to age-related mechanisms, such as corrosion, erosion and fatigue. It is therefore essential that, as part of the overall maintenance regime, such ageing is identified and appropriate measures taken to manage the risks.
Defining ageing assets
When referring to ageing plant and equipment, it is important to note that this does not necessarily relate to the chronological ageing process, rather ageing “is the effect whereby a component suffers some form of material deterioration and damage, with an increasing likelihood of failure over the lifetime of the asset”.
Ageing plant and equipment are assets for which there is evidence or likelihood of significant deterioration and damage taking place since new, or where there is insufficient data to know the extent to which this is possible. Significance in this aspect relates to the potential effects on functionality, availability, reliability and safety.
The characteristics of an “ageing asset” are defined in the Health and Safety Executive’s (HSE) Research Report (RR) 509Plant Ageing as when:
- Damage due to degradation has accumulated and may have become widespread and be accelerating
- Design or performance margins may have eroded to a point where future acceptable performance cannot be assumed
- A different, more quantitative, approach to inspection and non-destructive testing may be necessary for determining the extent and rate of damage to demonstrate fitness for service
- Proactive ageing management and asset care is required through revalidation, major repairs, refurbishment and replacement of key items at various times.
The same report concludes that managing ageing plant and equipment effectively requires a paradigm shift in the way that asset condition is regarded, assessed and maintained. It suggests that this requires “a proactive approach with a thorough understanding of asset-ageing mechanisms and condition, and the ways in which assets interact”.
The management of ageing plant and equipment therefore begins with an awareness that ageing is not about how old the equipment is, but what is known about its condition, and the factors that influence the onset, evolution and mitigation of its degradation. This suggests that, for those with responsibility for maintaining ageing assets, there is a need to:
- Organise for ageing management in terms of identifying the assets, what they do and their criticality to the business
- Make an assessment of current conditions through appropriate condition surveys, inspections and associated risk assessments, including how conditions may change over the asset lifecycle
- Implement an ageing management programme, including the use of preventative or condition-based maintenance regimes
- Ensure there is feedback and analysis of the process to ensure it remains fit for purpose, including the use of performance indicators.
As well as the physical ageing process, other factors will need to be given consideration. This can include obsolescence and a lack of spare parts, or the disappearance of the original equipment manufacturer, or non-conformance with current safety requirements, codes, standards and procedures. Competency, availability and organisation of the employees responsible for asset management and knowledge management are also essential to ensuring that this understanding of current and predicted asset condition is used when making asset management decisions.
Although aimed at the nuclear industry, HSE Research Report RR912 Management of Ageing contains a number of principles that can be adopted in other industries when managing ageing plant and equipment. This is known as an ageing management programme (AMP).
The AMP should form part of the organisation’s overall asset management plan. It should detail the actions necessary to ensure ageing plant and equipment is maintained in an efficient and cost-effective way. The main elements of such a plan include:
- Scope of the AMP (selection of systems, structures, components and understanding of ageing)
- Preventative actions (operating procedures/controls to minimise ageing)
- Detection of ageing (inspection, testing, plant monitoring)
- Monitoring of trends (data analysis, predictive analysis, etc.)
- Acceptance criteria (performance standards, probability of failure)
- Mitigation actions (maintenance, repairs, replacement, etc.)
- Corrective actions (revised operating procedures, de-rating, refurbishment)
- Feedback of operating experience (failure database)
- Quality management (record-keeping).
It should be noted that, within an AMP, there might be differing schedules to those in relation to statutory compliance requirements. Where this is the case, the AMP needs to interface with such compliance requirements.
The AMP will only be effective if supported by a robust management system. RR823 Managing Ageing Plant. A Summary Guide provides useful information on the key aspects of such a system. In particular, it emphasises the need for a clear, organisational structure and communication routes, and “job continuity plans to retain job knowledge and operational skills”.
In addition, training and competency of employees involved in managing ageing assets is addressed with the recommendation that a competency development programme be developed, and structured training put in place. RR823 also makes suggestions for procedural processes, including the development of a defect reporting system and “technical safety reviews” for critical assets.
It should be noted that management of ageing plant and equipment will require regular monitoring, review and revalidation following any unwanted incidents, major repairs, refurbishment or replacement of key items.