Tactics should be designed to minimize the consequences of equipment failure.
The focus is shifting from maintenance as a cost centre to a value centre. So what adds value? Maintenance expert Ben Stevens, the principal of DataTrak Systems Inc. in Godfrey, Ont., has developed extensive workshop materials on best practices and reliability improvement that point the way forward.
Stevens’ thinking is a company’s mission and objectives must guide maintenance, and one way to do so is to minimize the risk and the long-term cost of failure by making continuous improvement an integral part of the process.
The first best practice to consider is condition-based maintenance (CBM). Preventive and predictive techniques test the condition of the equipment to decide when the appropriate response is triggered, which includes performing an inspection to determine whether a potential failure has occurred, and initiate the appropriate preventive maintenance (PM) action to prevent or delay the consequences of a failure; or recording a failure hasn’t occurred and closing the inspection report.
In most reliability-centred maintenance (RCM) analyses run to failure (RTF) is the best practice if the cost of prevention is higher than the cost of the failure.
Work from a job plan template. Ensure all work elements are included – equipment, tasks, spares, manpower, contractors, materials, tools, special equipment, permits, safety and environmental instructions, supervision, data to be collected, and analysis. Plan the critical path for complex jobs and review it for budget, quality, timeliness, priority and need before releasing it to scheduling.
Schedule work on the basis of priority. Make resources available before issuing the work order and integrate new work with related maintenance and operational schedules to optimize resource use, equipment downtime and production schedules. Be sure to schedule adequate time for each job step.
Whoever is responsible for work assignment sees that safety, environmental and permit requirements are clearly understood by the technicians, and supervises or coaches technicians who have limited skills and experience.
The technician has front-line responsibility for: the quality and timeliness of the work performed; ensuring the work order is followed; ensuring safety and environmental steps are adhered to; ensuring standards for travel time, wait time, wrench time and break time are adhered to; and sign-offs/acceptances are secured.
All this must be followed up by a proper work order analysis, assigning a resource and a priority, and including uncompleted work analysis in the backlog review. When the work is completed, review the details and feedback, then update the key performance indicators (KPIs).
Work improvement requires a fluid transfer of knowledge among the analysts, the planners and the RCM team to ensure the best knowledge is retained and integrated into job plans. It also requires continuous upgrading of knowledge about the equipment’s function and failure modes. Key elements for accomplishing this include the following:
• Pass knowledge about failures, modes and effects to the RCM team for validation and updating of the database and maintenance job plans.
• Ensure work order improvements (content, frequency and priority) are integrated into the maintenance plan for inclusion in the next iteration.
• Check the logic and adjust the plan for this and similar equipment if failure occurs after an RCM analysis.
• Use KPIs to drive changes in behaviour and set new targets.
• Ensure technicians are properly trained when new procedures and tools are introduced.
• If comments have been made on the work order, ensure feedback is provided to the originator.
• Broadcast successes, acknowledge failures and announce new goals.
• Encourage future participation and feedback.
Backlog management ensures work done keeps up with work required. It consists of work started that’s on schedule but not yet completed; work started, not yet complete and behind schedule; work planned and scheduled to be started, but not yet started; and work waiting to be started, but not yet planned and scheduled.
This work should be reviewed on a weekly basis and done according to priority and examine reasons for delay.
Include changes in priority for items that require more timely response, and initiate action for the top priority work orders that are delayed.
Spare parts play a key role in the continuous improvement process. Divide management into the common use, relatively low-cost spare parts and slow-moving high-cost parts.
Manage with CMMS or EAM
Common use low-cost spares are best managed using the spare parts module of a CMMS or EAM system but a different approach is needed for slow-moving, high-cost critical spares. Typically the lead times are extensive and the cost of the spares militates having spares on hand.
Continuous improvement of cost control is also achieved by harnessing the capabilities of the CMMS or EAM system. Costs are accumulated against each work order and rolled up to the equipment, the system and plant levels. With small adjustments, CMMS and EAM also track the cost of failure at the same levels. The systems track exactly where the maintenance costs were incurred and identify “bad actor” equipment.
The priority of non-critical equipment is lower and should be treated as such. Best practices include periodic reviews of: their criticality; PM work orders to optimize the tasks, frequency and accuracy of work orders; and any high-cost repair work to establish the effectiveness of lower cost tactics.
KPIs have become the cornerstone of maintenance improvement. Select them to match the priorities of the business unit. Too many will dilute the effect and frequently result in none of the priorities being achieved. Once selected, define the KPI measurement and calculation process.
Finally there is the ever-present and nagging question of what to do about aging equipment and infrastructure.
With advancing age comes a greater frequency of failure, and the failure modes change. Repeated repair would return the unit to full capacity; hence the amount of time taken to degrade to the functional failure point shortens. This prompts frequent maintenance intervention and higher costs. Also, as equipment ages, new ways of failing emerge.
Stevens recommends: tracking the new failure modes and ascertaining whether they are applicable to the assets under review; developing ways of condition monitoring or testing the potential failure point of these assets; and planning shorter maintenance intervals.
Bottom line, making continuous improvement part of the process while maintaining assets as they’re used minimizes future capital cost, which goes a long way to increasing shareholder value.
Steve Gahbauer is an engineer and Toronto-based freelance writer, the former engineering editor of PLANT and a regular contributing editor. E-mail firstname.lastname@example.org.
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Find this article in the March 2014 issue of PLANT.