Maintenance theory has become a complex science that often has assessment and implementation strategies that are identical in principle. Because of the way different companies package these strategies as service offerings, it can appear as if they are competing. The result is that many of the logically sound and easily obtainable advantages of maintenance optimisation are not realised because the competitive nature between service companies often results in complex and over-complicated implementation plans.
At AIE, we believe that up to 80% of maintenance optimisation gains can be achieved by 20% of the effort that would be involved in the implementation of a formal reliability centred maintenance (RCM) process. This can be achieved through a review of the criticality hierarchy, as shown in Figure 1, at a facility with resultant updates to the frequency and the strategy of planned maintenance activities. It is no wonder that facility’s management is often sceptical about service offerings to reduce maintenance costs.
There are, however, other more basic factors that offer low hanging fruit in terms of cost reduction opportunities. Instead of aligning maintenance activity with the criticality hierarchy which is a basic tenet of RCM, it is often the case that recommended maintenance practices from original equipment manufacturers (OEM) are extended well past the warranty period for a wide range of equipment. Such practices are designed to minimise risk to the OEM and not to optimise cost-benefit of maintenance expenditure for the operator of such equipment.
The case for maintenance optimisation revived
In recent years, adverse market conditions have shifted business focus in industrial facilities towards cost reduction and extending the life of existing assets versus replacement projects and as a result, maintenance expenditure and optimisation is once again a focus for management.
This balance sheet challenge frequently compromises business sustainability in favour of short-term cost reductions, by deferring those operating and/or maintenance expenses that have a production impact e.g. shutdowns for essential maintenance or inspection.
There are several disadvantages to such a strategy that have been well proven in the past, including, in many cases, deferred expenditure on maintenance escalates over time and incurs higher future cost (in present value) to rectify the resulting neglect. Additionally, deferral of maintenance activities deviating from established industry practice increases the risk of unplanned plant downtime and the probability of incidents and accidents.
Similarly, for static equipment and structures, the deferral of fabric maintenance and/or increased inspection intervals, carries similar outcomes of higher future repair cost and risk of failure/loss of containment incidents.
Instances of major accidents have historically led to institutional reforms in legislation and regulation. Non-compliance to these measures or the inappropriate application of risk based work processes, poses both business risks to the firm and the threat of personal liability to executive management. Despite the fact that many organisations have adopted responsibility for asset integrity performance into their corporate governance structure to ensure compliance, when hard economic times arise, the executive option of risk acceptance to achieve short-term gains and maintain operating margins often returns.
A leading cost optimisation mechanism across all businesses and industries is efficiency improvement and this has also been a key focus area for plant maintenance. The leading, and arguably most durable concept in maintenance optimisation today is RCM. The concept evolved from a Federal Aviation Administration (FAA) programme in response to a realisation in the 1960s that the airline industry was unable to absorb the cost of maintaining the required levels of reliability with the maintenance practices established at the time.
In response to the finding that the interval length between overhauls was often decoupled from the failure rate, the FAA aimed their maintenance optimisation programme at “control of reliability through analysis of factors that affect reliability”.
Since the development of RCM in the 1970s, there has been extensive refinement and expansion of ideas and methods on maintenance optimisation – and with it an explosion of jargon, discussion forums and published literature often with conflicting ideas and definitions on the taxonomy of maintenance regimes. For this reason, a brief clarification is in order before we look at the trends and implementation gaps of a successful RCM programme.
Taxonomy of maintenance regimes
As maintenance practices became regulated and institutionalised, formal naming conventions were developed for categorising these practices. However, there is a lack of common understanding of the relationships and commonalities between these practices amongst leading institutions and this often leads to confusion amongst practitioners. A taxonomy that is logically consistent with formal definitions is shown in Table 1 for this discussion (showing only a selection of the many formally named practices at the lowest tier).
A commonly used definition of RCM is “a process that is used to determine the maintenance requirements of any physical asset in its operating context”. Borrowing from the FAA’s terms of reference, this process essentially involves separating tasks into categories of essential and economic consideration and then to select execution tactics that match life cycle cost considerations of the components and their failure modes (including the consequence of failure).
A number of assessment methods and tools have been devised or adapted over the years to support and harness this process including failure mode and effects analysis; hazard and operability; hazard identification; safety integrity level; fire and explosion hazard analysis; reliability, availability, maintainability and safety; bow-tie; safety criticality elements and qualitative risk assessment.
Activities that fall in the essential category logically demand a strategy that will avoid failure i.e. either preventive or predictive, both of which are data driven processes to identify, assess and manage degradation rates and processes.
Cost regimes of maintenance practices
The cost benefits of different maintenance regimes depend where such equipment ranks on the criticality hierarchy. Maintenance optimisation involves the balance of the direct cost of maintenance spend versus the benefits of failure cost avoidance against many metrics including, regulatory fines in respect of safety and environmental impacts, reputational damage associated with the societal impacts of failures, production revenue losses due to unavailability of failed equipment and replacement cost.
In the case of safety critical equipment, the cost of major accident hazards far outweighs the cost of industry best practices in preventive and predictive maintenance and for this reason, it should not be managed with maintenance practices.
However, for equipment on the lower tiers of the criticality hierarchy, maintenance costs can become comparable or lower than repair/replacement costs. This principle is illustrated in Figure 2 for equipment that is physically similar but with varying criticality.
Key success factors and barriers to effective RCM
A recent industry survey identified the top three operational inefficiencies as: – mismanagement of supplier and contractor relationships, poor asset reliability and integrity as well as inefficient cost management.
All three of these issues have direct links to maintenance strategies. The survey established that insufficient data analytics leads to the substitution of scheduled maintenance for predictive maintenance with the result of an over-abundance in activities and direct expenditure impacts.
Often, unsuccessful implementation of RCM is associated with a lack of appropriate skills; RCM processes require personnel who are skilled in data analytics as well as the theory and practice of failure modes and mechanisms in order to translate observed trends in the condition of facilities into a suitable strategy. This is especially lacking when it comes to predictive strategies – the most cost-effective strategy and an essential part of the RCM mix.
Moreover, effective RCM is a dynamic system requiring methodical interpretation of operational data and plant condition, combined with forward maintenance planning, in a robust management system.
While computerised maintenance management systems go a long way towards facilitating the management of an RCM programme, they require skilled input of data analytics and failure modes to implement RCM successfully.
Unfortunately, firms often do not invest in the skills required for such implementation, with service contracts often awarded to the lowest bidder, lacking the necessary depth and breadth of analytics skills required for the successful implementation of RCM.
This also highlights a shortcoming that is often encountered in bidding practices namely that procurement is often aimed at minimising the direct cost of a service and not at optimising the life cycle cost-benefit of the service to the firm. There are many examples in industry that illustrate the enormous impact when short-term cost savings are favoured at the risk of facilities integrity.
Integrity management programme
The greatest breakthrough in the successful implementation of RCM comes with the acknowledgement that RCM cannot be managed as a stand-alone concept but must be integrated in the greater context of asset management that requires both a robust and intelligent management of complex information flows and analytics that are necessary for the maintenance optimisation process.
A robust integrity management strategy needs to be developed that explicitly addresses key success factors in a clear and totally comprehensive framework with specific focus on the competency of skills required in the various functional roles of the strategy including both RCM oriented roles (e.g. data and failure analytics) as well as traditional integrity related roles (technicians, inspectors and engineers for example), as well as the establishment of a functional hierarchy of equipment in terms of essentiality and economic value.
In addition, there needs to be cost-benefit optimisation strategies and written practices for maintenance activities (including failure avoidance and management strategies) for the full equipment register, plus management of the RCM strategy to govern data gathering, tracking, analytics (including RCA and RLA), interpretation, and feedback to activity schedules.
Finally, there must be clear tracking and reporting of performance indicators that might affect reliability.
