Using standard maintenance procedure to manage troubled assets

Abstract

There is a constant effort to reduce equipment Mean Time To Repair (MTTR) across industries that depend heavily on physical assets, in order to meet their strategic objectives. Maintainability as a design attribute is widely measured using the MTTR key performance indicator (KPI), which directly impacts the overall asset operational availability, A_o (Uptime). This generic model was conceptualised as a result of efforts to provide a temporary solution for management of critical equipment with a maintainability design flaw in an Extraction Plant. 

Introduction 

The challenges of troubled asset are not new to most organisations whose core operations depends heavily on them. These challenges can either be inherited through design defect (manufacturing organisation), or operation deterioration (operating organisation). On one hand, this could be anticipated considering the operating context of some of these assets, which often involves the meshing together of moving parts, high temperature or pressure operating conditions. As a result, the initiation of failure mode becomes inevitable. However, asset design defects are usually the most problematic, as their causes are outside the operating organisation. This raises the question of how operating organisations manage their negotiations and new equipment procurements from manufacturing organisations (OEM) at the contract or project stage.

Maintainability and reliability are design attributes that can only be influenced at the product design stage. However, the poor attention given to maintainability attribute during equipment procurement makes it even more difficult to achieve equipment ease of maintenance during mission time. Consequently, these lead to increased equipment MTTR, and reduced equipment operational availability (A_o).  

In a bid to manage equipment maintainability design flaws while reducing MTTR, this article suggests the deployment of standard maintenance procedure (SMP) as an effective maintenance management tool to cope with such troubled assets. The proposed model will make it easier for Operation and Maintenance team to, develop and document SMP for any equipment or asset.

Relevance of SMP to Equipment maintainability

Maintainability according to BS 4778 [1] is “the ability of an item, under stated conditions of use, to be retained in, or restored to, a state in which it can perform its required functions, when maintenance is performed under stated conditions and using prescribed procedures and resources”. This definition provided the basis for the conceptualisation of this PM⁴ SMP Development Model. The use of SMP in equipment maintenance provides many positive multiplier effects ranging from the safety of personnel, basis or starting point for incident investigation, training document for new personnel, statutory standards & regulations are met all the time, and tasks are performed to the required degree of precision. In general, this positive multiplier effects saves time (for example; Lost time injury LTI, travel times getting tools from stores, time waiting for permits, and job reworks are minimised), and anticipates the maintainability challenges in the equipment maintenance such as difficult manoeuvres locating components. The accumulation of times saved using SMP as a tool can lead to a tremendous time to repair savings.

PM⁴ SMP Model

The BS 4778 [1] definition of maintainability mentioned “stated conditions”, “procedures”, and “resources”, as factors to be satisfied for effective maintenance. These factors are captured in the PM⁴ SMP model elements. PM⁴ stands for Permit x Manpower x Method x Material & Machine. The “stated conditions” factor is covered in the “Permit” element of the PM⁴, while the “procedures” factor is covered in the “Method” element, and the “resources” factor covered in the “Manpower, and Material & Machine” elements of the PM⁴. Effectively documenting the equipment maintenance requirement under these elements provides valuable input for efficient performance of maintenance task. Equipment with inherent maintainability design defect can be better managed in operation using this approach.

Furthermore, the development of standard maintenance procedure (SMP) requires a feedback process. This enables lesson learned from performing the maintenance task using SMP as a tool to be utilised for subsequent performance improvement as shown in Figure 1. It is important to note that the Input to this programme is the data collated from PM⁴ elements — (Permit required, Manpower, Method, Material and Machine) and maintenance life plan. The Control consists of measurement of key performance indicators (KPI) and management of change (MOC) processes in place for SMP document revision, while the expected Output is the developed and documented equipment or asset SMP. 

Figure 1: PM⁴ SMP Development model

PM⁴ SMP Model Justification and Implementation 

The use of models in engineering solution delivery facilitates communication, thinking, and knowledge retention among cross-functional team involved in the asset value delivery chain. Models augment understanding of problem solution beyond the textual statement of requirement, by providing a holistic visualisation of information flow and points of revision for continuous performance improvement [2]. When effectively utilised, they provide consistency in the implementation of engineering solution, irrespective of the involvement of the original model development team.   

PM⁴ SMP model offers a systematic approach for effective development and documentation of asset standard maintenance procedures. The model is structured into three parts namely; Input, Output, and Control (IOC). The IOC part structuring ensures that the asset SMP Development team or Responsible persons understands the starting requirement (Input); expected result (Output); and opportunity to measure effectiveness of the output in achieving the maintainability goal of reduced MTTR to as low as practicably possible (Control).

Developing and documenting a standard maintenance procedure (SMP) for an equipment or asset should be treated as a project with a clear objective, scope, delivery duration, resource requirement, quality checks, and output validation. Although this may not require or incur cost as the resources needed to achieve it are internal. Such project approach helps to ensure that proper attention, and measurable commitment is given to asset SMP development. Many maintenance and/or asset managers often wonder why they have so many backlogs, long MTTR causing asset unavailability and downtime, but see no importance to have a documented SMP for at least their critical assets. 

Components of IOC Parts of the PM⁴ SMP Model

As mentioned, the PM⁴ SMP Model is partitioned into Input, Output, and Control (IOC). Each of these parts interact with one another to have a live Asset SMP to meets the maintenance objective.

Input

The inputs as can be seen in Figure 1 are; the maintenance life plan, and the PM⁴ elements — (Permit required, Manpower, Method, Material and Machine). Both elements are used together to collate the input. The maintenance life plan for the critical asset or equipment offers the failure mode on which the PM⁴ element requirement will be interrogated and documented. Each of PM⁴ elements can constitute a major delay in the performance of maintenance task, which directly increases the MTTR, reduces the asset availability, and reduces return on investment (ROI). For example; knowing in advance the permit required for a maintenance task together with the level of risk assessment required to resolve a particular failure mode in an asset can greatly reduce MTTR. If this is further stretched to a well stepped method or procedure, together with the manpower requirement for the level of task complexity, and materials (Spares - where and how to obtain) and machines (in terms of logistics support for the maintenance task); no doubt there will be tremendous reduction in MTTR. However, it is important to mention that value lie in the quality and accuracy of the information captured under the PM⁴ elements. 

Output

The output of the application of PM⁴ SMP Model is a well written SMP for an equipment asset. The writer should be one who is skilled and knowledgeable on how to communicate the inputs in a fashion that is understandable to the reader and serves the goal of the user. The grammatical structure should be simple (elementary grade), short and verbalised. The use of visual impression (pictures) to highlight the steps is valuable for easy use, not minding the level of experience of the user (maintenance technician).  Finally, the method or procedure should be written in proper sequence that allows for natural order of the job flow. If this constitute too many steps then it is advisable to break them up in sections. A typical example is shown in Table 1 for the maintenance of vibrating screen unit (VSU) visually elaborated in Figure 2 & 3.

Figure 2: VSU Equipment located in an Extraction Plant

Figure 3: Internal Component of VSU Drive Assembly [3]

Control

The control constitute of key performance indicator (KPI) that can be used to measure performance of the PM⁴ elements. In this model there is a feedback process to ensure performance is analysed as to the degree of meeting maintainability objective (reduced MTTR, maximise availability and ROI). In some cases, lessons will be learned during performance of maintenance task using the current SMP and will require a change in the PM⁴ elements of the equipment SMP. The control feedback process ensures that such lessons are captured by revising the equipment SMP to capture the new knowledge. This revision should be governed by management of change (MOC) process. For example; if there is a modification in the equipment or change of functional location during a major shutdown or turnaround event, it is good practice to revise and update the SMP as this will impact how maintenance will be carried out going forward.

Conclusion

Having a well written SMP for critical assets is vital, and has numerous positive multiplier effects on asset value realisation. Using this proposed PM⁴ SMP model will eliminate the challenges many practitioners have in starting the process. In addition, value is not realised until the developed/written SMP is put in use to perform maintenance task. So, maintenance technicians should be mandated to use them once developed as part of task delivery.  

Acknowledgement

This is part of an on-going inter-disciplinary research in Reliability Engineering and Asset management, and Management of Projects at the University of Manchester.

References

[1] BS 4778-3.1(1991). Quality vocabulary. Availability, reliability and maintainability terms. Guide to concepts and related definitions.

[2] Rauzy A.B & Haskins C. (2018). Foundations for model-based systems engineering and model-based safety assessment. DOI: 10.1002/sys.21469. Wiley. 

[3] V. Europe (2010). Technical Manual ViPower Super Screens. Vol. 32, pp. 5–32.

Ogechukwu E. Akaeje¹; Martin Billington²; Obuks Ejohwomu³; Jyoti K. Sinha⁴

¹PhD Student, School of MACE, The University of Manchester, UK Email: [email protected] 

²REAM MSc student, School of MACE, The University of Manchester, UK Email:  [email protected]

³Lecturer in Project Management, School of Mechanical, Aerospace and Civil Engineering (MACE), The University of Manchester, UK Email:  [email protected]