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NDT Overview - Equipment Reliability
Douglas J. MarshallManaging Director
Canadian Institute for NDE
Hamilton, Ontario, Canada.
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| · Home · Table of Contents · Manufacturing | NDT Overview - Equipment ReliabilityDouglas J. MarshallManaging Director Canadian Institute for NDE Hamilton, Ontario, Canada. Contact |
In an increasingly competitive manufacturing environment there is a need to achieve world-class manufacturing performance. A key element in the drive for improved performance is equipment reliability and the implementation of a maintenance program that is effective in monitoring and maintaining plant equipment. By designing a program which addresses all aspects of asset management, we can achieve our goal and provide maximum reliability of equipment at optimum cost.
Nondestructive testing in equipment reliability can be utilized to concentrate on producing high quality, high value added products. Satisfying customer's quality and delivery requirements are a critical focus of every company's strategy.
KeyWords: Nondestructive Testing (NDT), Predictive Maintenance, Physical Asset Management, Reliability Centred Maintenance (RCM), Predictive Maintenance Technologies (PdM)
The Canadian Institute for NDE is a not-for-profit organization which offers training, government examinations, and professional membership to industry. The headquarters are located in Hamilton, Ontario and include a modern, fully-equipped training facility as well as a test centre for certification examinations. The Canadian Institute for NDE participates on many national and international committees and NDE related organizations to support the views and the best interests of the Canadian NDE profession and will be the host of the 16th World Conference on Nondestructive Testing in 2004.
The Canadian Institute for NDE publishes a technical journal as a vehicle for information on education, technical developments, certification and Chapter news as a service to members. The website at www.cinde.ca also serves members with up-to-date information on certification news, upcoming events and an employment databank.
In manufacturing processes, the purpose of most equipment is to support the production of product destined to downstream customers. Ultimately the focus is on meeting customer needs. Customer expectations are normally defined in terms of product quality, on-time delivery and competitive pricing. By reviewing the composite requirements of all current customers and potential customers in those markets we wish to penetrate, the performance requirements of our physical assets can be defined. Equipment performance parameters can be associated with quality, availability, cost/unit, safety and environmental integrity. To achieve this performance, there are three inputs to be managed.
The first requirement is Process Technology. Process Technology provides capable equipment "by design" (inherent capability), to meet the equipment performance requirements.
The second requirement is Operating Practices that make use of the inherent capability of process equipment. The documentation of standard operating practices assures the consistent and correct operation of equipment to maximize performance.
The third requirement is Maintenance Practices that maintain the inherent capability of the equipment. Deterioration begins to take place as soon as equipment is commissioned. In addition to normal wear and deterioration, other failures may also occur. This happens when equipment is pushed beyond its design limitations or when operational errors occur. Degradation in equipment condition results in reduced equipment capability. Equipment downtime, quality problems or the potential for accidents and/or environmental excursions are the visible outcome. All of these can negatively impact operating cost.
The management of physical asset performance is integral to business success. What we manage are the business processes required to produce results. One of these business processes is responsible for the maintenance of physical asset reliability. It is an integral part of a larger manufacturing process.
The Equipment Reliability Process focuses the maintenance of physical asset reliability on the business goals of the company. The potential contribution of the equipment asset base to these goals is evaluated. The largest contributors are recognized as critical assets and specific performance targets are identified.
The Planned Maintenance Process, represented by the series of six (6) elements on the right of the model aims to deliver targeted performance. Each element within the maintenance process is in itself a sub process. A brief description of each element follows:
Work Identification, as a process, produces technically based Equipment Maintenance Programs. Program activities identify and control failure modes impacting on the equipment's ability to perform the intended function at the required performance level. Activities are evaluated to judge if they are worth doing based on the consequences of failure.
Planning develops procedures and work orders for these work activities. The procedures identify resource requirements, safety precautions and special work instructions required to executive the work.
Scheduling evaluates the availability of all resources required for work "due" in a specified time frame. Often this work requires the equipment to be shut down. A review of production schedules is required. Resources are attached to a specific work schedule. The use of resources is balanced out.
In the Execution process, the required work is carried out by trained, competent personnel.
The Follow-up process responds to information collected in the execution process. Work order completion comments outline what was done and what was found. Actual time and manpower, to complete the job, is documented. Job status is updated as complete or incomplete. Corrective work requests, resulting from the analysis of inspection data, are created. Requests are made for revisions to drawings and procedures.
The process of Analysis evaluates maintenance program effectiveness. Gaps between actual process performance and the required performance are identified. Historical maintenance data is compared to the current process performance. Maintenance activity costs are reviewed. Significant performance gaps are addressed by revisiting the Work Identification function.
Each element is important to provide an effective maintenance strategy. Omitting any element will result in poor equipment performance, increased maintenance costs or both. For example, Work Identification systematically identifies the "right work" to be performed at the "right" time.
Without proper Work Identification, maintenance resources may be wasted and unnecessary or incorrect work may be planned. Once executed, this work may not achieve the desired performance results, despite significant maintenance costs. Without planning, the correct and efficient execution of the work is left to chance.
The Planned Maintenance Process is a cycle. Maintenance work is targeted to achieve required asset performance. Its effectiveness is reviewed and improvement opportunities identified. This guarantees continuous improvement in process performance impacted by maintenance.
Within the Planned Maintenance Process, two internal loops exist. Planning, scheduling, execution and follow-up make up the first loop. Once maintenance activities are initially identified, an Equipment Maintenance Program, based on current knowledge and requirements, is initiated. The selected maintenance activities will be acted upon at the designed frequency and maintenance tolerance limits. The process is self-sustaining.
The second loop consists of the Work Identification and Analysis elements. This is the continuous improvement loop. Actual Process Performance is monitored relative to the demands placed on the process (driven by facility goals). Performance gaps are identified. The root cause of these gaps is established and corrective action recommended. The criteria for defining the maintenance activities, established in the Work Identification process, is revisited using updated information. The Equipment Maintenance Program is revised to optimize its effectiveness.
Determine what is the right work, at the right time to avoid failure consequences and minimize cost.
Reliability-centred maintenance is "A structured process used to determine what must be done to ensure that any physical asset can continue to do what the user wants it to do in its present operating context".
This definition complements the requirements of Physical Asset Management and identifies the need to manage equipment design capability, operating practices and maintenance practices to attain the performance requirements of our equipment.
The RCM Analysis process addresses each of these requirements by answering seven (7) questions of any physical asset in its present operating context:
The product of a completed RCM analysis is a set of recommendations defining what must be done to deliver the targeted asset performance. Each recommendation is assessed against criteria for technical feasibility and worth doing so the most effective actions are defined. These actions can consist of:
What equipment should have Predictive Maintenance Technologies applied to it in order to minimize intrusive maintenance?
A maintenance program must do more than simply react to breakdowns. Although there are instances where running to failure can be acceptable, most times it is necessary to anticipate equipment failures well in advance of their ever occurring. To that end some routine maintenance tasks such as inspecting, rebuilding or replacing equipment can be planned and scheduled as time based preventative activities. When any combination of these approaches cannot keep equipment operating in a cost-effective manner, then machine condition indicators can be used to predict when it is in the early stages of failure. Technologies such as vibration analysis, lubricant analysis, thermography, ultrasound and motor circuit analysis are successful in indicating the onset of failures before they occur. However, the main stumbling block to their use is deciding how much of which to use, and when to use them.
To achieve company goals of producing high quality, high value added products to satisfy our customer's quality and delivery requirements, we must have superior equipment reliability supporting excellence in manufacturing. This can only be accomplished with organizational commitment at all levels and with the use of enabling technologies. To be successful the equipment reliability process must be synonymous with the business process. This process must integrate both human and technology interventions. This is a living process and therefore always subject to continuous improvement.
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