A strategy is the who, what, when where and how of maintaining your assets. Strategies are not “set and forget”, they are living documents that should be reviewed and improved continuously. What methods do you use to review strategies? Do the strategies address the failure modes of your assets? Who is involved in the review process? The review and development of strategies is a critical component of Asset Management.
In years gone by, when maintenance labor was plentiful, there were some very extensive Planned maintenance programs in place, with most being based on the “best guess” of the experienced people in the business. The results were often a plant that was being over serviced or the servicing was occurring on equipment that had very low failure rates. In the last 20 years there has been a significant movement to actions being based on the mitigation of failure modes. Some of these tools are breifly described below.
Tools for Improving Maintenance strategies.
A tool is anything used as a means of accomplishing a task or purpose. The following generic tools are used widely in determining new or revising existing Maintenance Strategies.
Reliability Centred Maintenance. RCM
Reliability Centred Maintenance is defined by John Moubray as “a process used to determine what must be done to ensure that the physical asset continues to fulfil its intended functions in its present operating context” (1993, pg.7). RCM was born from the airline industry in the US in the early 70’s in response to the statutory maintenance requirements that had to be applied to larger aircraft such as Boeings 747. It was determined that the cost of applying the standards to these aircraft would make them uneconomical to operate (Smith and Hinchcliffe, 2004). The basis of RCM is to ensure equipment maintains its function and the process requires that the following seven questions be answered (Moubray, 1993).
1. What is the function of the equipment and what are the required performance standards?
2. In what ways can it fail to perform its function?
3. What could cause each functional failure?
4. What happens when the failure occurs?
5. In what way does the failure matter?
6. What can be done to prevent the failure?
7. What has to be done if the failure can’t be prevented?
Smith and Mobley (2008) highlight the following types of asset management strategies that may be developed from an RCM process.
1. Condition based tasks. E.g. Oil is sampled from a transformer and the results of the analysis determine if further maintenance is required.
2. Scheduled restoration. E.g. A Sheave bank running in a corrosive environment that requires overhaul at fixed intervals.
3. Scheduled Discard. E.g. The replacement of oil in a combustion engine.
4. Failure finding task. E.g. Calibration of instrumentation. The fault may not be discovered until the calibration is done.
5. One-time change. Typically a one off redesign.
RCM in its pure form is a resource hungry process that should only be applied to the most critical of assets. The results from the process if performed properly and coupled with assessment of historical failures will produce efficient and effective maintenance strategies, but this will be at the expense of a significant amount of time for plant staff and the project analyst.
Failure Modes and Effects Analysis. FMEA.
A Failure Mode and Effects Analysis is an integral part of the RCM process and deals with questions 2, 3 and 4 of the 7 RCM questions listed above. Teng and Ho (1996) define FMEA as a technique that identifies the potential failure modes of a device or product, determines the effects of these failures and assesses the criticality of the failure.
An FMEA completed on DC machines in an Australian Steel mill revealed the following most likely causes of DC machine failure to be:
1. Contamination of motor by Dust, Dirt fumes etc.
2. Inadequate maintenance practices. (Internal and contract)
3. Inadequate brush tension
4. Over tensioning of belts or shaft misalignment.
5. Overheating due to ineffective ventilation
6. Neutral axis and compounding issues.
8. Inadequate lubrication (Too much or not enough).
9. Incorrect or ineffective protection devices.
These findings were used to improve the existing PM’s with excellent results. Over a 3 year period there was a 70% reduction in DC motors that failed in service.
Planned Maintenance Optimisation. PMO
Planned Maintenance Optimisation is a process where existing PM inspections and failure history are used to form the basis of a new set of strategies. This can provide a similar output to classical RCM in far less time. As unknown failure modes are not addressed in the first instance the process allows for input of potential failure modes after the initial assessment. This process couples the PMO top down approach with the RCM bottom up approach and in many cases will be the best option for mature businesses with existing PM systems and access to failure history. New businesses with no existing systems or failure history will need to apply more classical methods such as a RCM or a knowledge based process.
Management support of strategy optimization.
The most significant step related to gathering management support for a strategy review process is educating them in the critical elements of asset management. It is common for managers to see maintenance as a cost that can be cut, and not an investment in the future of the operation. Question 57 is aimed at gauging whether management support the review of, and optimization of maintenance strategies.
The results here were surprising with 54% rating a 4 or a 5. This indicates management have a clear understanding of the importance of optimisation of maintenance strategies. A further 30% support strategy review but do not have a clear understanding of the benefits. With this high level of management support there should be little reason not to progress with improvements.
Scheduled review of strategies.
How many businesses have been using the same strategies with little or no review processes in the last 10 years? When your tradesmen suggest a change to a strategy is there a system in place to review the suggestion for suitability? There needs to be a systems in place to review older PM’s to determine if they are still relevant and are addressing known or potential failure modes.
There also needs to be a system in place to capture and review feedback gathered from the tradesmen who are doing the task. One of the most significant contributors to work instructions not having any feedback left on them is that when comments had been made before, no actions followed. This is an incredible demotivator for many. Question 58 will determine how often maintenance strategies are reviewed.
With 39% of respondents scoring a 4 or a 5 the level of formal review of strategies was higher than expected. 52% of respondents indicated a less formal or more ad-hoc manner of strategy review, with 9% having no process at all. To remove the waste from maintenance strategies and ensure actions within these strategies are effective a process involving the identification and mitigation of failure modes must be applied. This can be in the form of FMEA, RCM, and PMO etc. The other point to remember is that strategies will need to be changed to accommodate changing production demands. For this reason, a formal review schedule should be put in place. This could be in the form of regular audits of work instructions or detailed reviews of total strategies.
Maintenance supervisors and strategy review.
With strategy review being a critical component of this element, it becomes clear that someone needs to be responsible for the review process. Question 59 questions whether the development and review of Maintenance strategies is included in the job responsibilities of Maintenance supervisors.
The telling result here is that 39% of maintenance supervisors that review their strategies in an ad-hoc manner and a further 30% that do little review or none at all. With only 31% scoring a 4 or 5 this is an area of significant opportunity for many businesses.
Include the review of maintenance strategies in the job goals of maintenance supervisors at all levels. The Maintenance Team Leader may be responsible for feedback on work instructions, the Area Supervisors could arrange regular work instruction audits, where the maintenance manager may include large formal strategy review processes in the maintenance budget. Making people responsible for strategy review will make it occur and the benefits will come.
Involvement in Strategy review.
An effective strategy review process will only occur if a representative of all stakeholders are involved in the process. This will gain a significant amount of local knowledge as well as building ownership of any revised strategy. Questions 60 will determine to what degree operations and maintenance employees are involved in the development of strategies.
What is pleasing here is that 35% of respondents indicated that operations and maintenance personnel are regularly or always involved in strategy review. 32% of respondents indicated some input while 33% have little or no involvement. The aim here should be that there is always involvement with stakeholders. When strategy review processes occur in isolation it is unlikely that the outcome will be as best as it could be, as one persons view will be not uncover all possible failure modes or the actions that will prevent the failures. The ideal situation is to have a senior mechanical fitter, an electrician, an operator and maintenance leader involved in the review process. The important aspect here is to get a total understanding as to what failures occur and whether the actions currently occurring address these failures. If no actions are currently in place the group should decide on what actions to implement, and making these decisions as a group will build ownership of the strategy. It is worthwhile considering the use of a strategy review tool and experienced facilitator during these reviews.
Maintenance strategies and the CMMS.
If you have a CMMS, it will have the ability to store and manage the work instructions that are working documents of your asset management strategies. Question 61 is aimed at understanding the level at which strategies and work instructions are stored in the CMMS.
With only 40% scoring a 4 or a 5 in this question there is clear room for improvement. As your CMMS is generally made to manage your strategies it is the obvious this is where they should be kept. If there are some work instructions or operating procedures that are kept in other systems, then these should be linked to the CMMS. This may be the case if a third party is providing software tools to help with strategy development.
More sections of this survey will be posted in the blog over the next few weeks.
Welcome to the The Asset Reliability Roadmap Blog. Our goal is to provide free useful information to maintenance professionals that will simplify the journey to asset management excellence and improved reliability.
For further free information and asset management tools visit www.thereliabilityroadmap.com
For further free information and asset management tools visit www.thereliabilityroadmap.com
Saturday, December 5, 2009
Friday, December 4, 2009
This article from Fluke via reliable the plant website is a must read for electrical workers. In my industry we have moved on from alot of this thinking, but old habits die hard.