PM Optimization

Introduction

Planned Maintenance Optimization (sometimes referred to as Preventative Maintenance Optimization, PM Optimization or PMO) is a methodology which focuses on improving maintenance effectiveness and efficiency by review or rationalization of an existing maintenance program (formal or informal) and in most cases adding maintenance tasks to account for failure modes not addressed by the existing program.
The aim of PMO is to provide a comprehensive maintenance program for a physical asset. PMO starts from an existing maintenance program which could have been provided by an equipment supplier, developed by the user or used on similar equipment operating elsewhere.

Historical Background

The PMO ideology or process is not new. It probably originated when maintenance began. Until recently there was no name for the process.
In the early 1990’s, the process of PMO was used extensively by the Kewaunee Nuclear Power plant in Wisconsin USA. The term used to describe the process was Planned Maintenance Optimization.
This work received credit from the North American Nuclear Regulatory Commission in their systematic assessment of Licensee performance (SALP) report in March 1995. This report had the effect of legitimizing PMO. The PMO process has become increasingly popular as a maintenance analysis method since the SALP report.
Currently there are several different PMO systems in use. Some of these systems only rationalize the maintenance tasks that exist and do not add tasks that are missing. For this reason, users should consider what outcomes they require before choosing which PMO process to use. Unlike the Reliability Centered Maintenance (RCM) process, there is no published standard for PMO.
The most widely used PMO process which does add missing tasks is PMO2000™.

Generic Features

The PMO process is generally divided into three distinct phases
Phase 1; Data Collection,
Phase 2; Data Analysis, Review and Grouping, and
Phase 3, Approval and implementation.
Typically PMO is not seen as a single, one time process so after Phase 3, most organizations use PMO as a living program or process of continuous improvement.
The precise workflow contained in each of the stages varies between approaches and organizational needs.

PMO2000™

The PMO2000TM process has nine steps. These are described below and shown as phases.

Phase 1 Data Collection
Step 1: Task Compilation: PM Optimization starts by collecting or documenting the existing maintenance program (formal or informal). At this stage it is also useful to collect and prepare failure history and availability data for use during the analysis and review stages (Steps 2 & 3).

Phase 2 Data Analysis, Review and Grouping
Phase 2 is usually done in teams as on most occasions; no individual has the breadth of knowledge to complete the analysis properly.
When a team approach is taken, it is usual that prior to the analysis, there is a review of the data, a clarification of system boundaries and the operating context and discussion about a host of other important considerations which impact on the analysis.
Step 2: Failure Mode Analysis (FMA): FMA is the process of identifying what failure mode(s) each maintenance task (or inspection) is meant to address.
Step 3: Rationalization and FMA Review: This step is the process of grouping or sorting the failure modes for each component so that task duplication can be easily identified and eliminated. Failure modes that should be addressed, but are missing, can be found and added to the list. The list of missing failures is generated through an analysis of failure history, technical documentation (usually P&IDs) or experience.
Step 4: Functional Analysis (Optional): The functions lost due to each failure mode can be established in this step. This task is optional, and may be justified for analyses on highly critical or very complex equipment items, or for functions that are hidden. For less critical items, or simple systems, identifying all of the functions of an equipment item adds cost and time, but yields no benefits. This is partly because consequence by definition is loss of function so when Step 5 is completed, the function is determined and partly because most of the functions and operating context matters were discussed at the start of the workshop.
Step 5: Consequence Evaluation: The consequence of each failure mode is analyzed to determine whether or not the failure is hidden or evident. For evident failures a further determination is made as to whether the consequence of the failure mode would be a hazard or would only have economic consequences. For hidden failures, consequences are said to be conditional on one failure occurring when a second failure mode (usually in a protective device) is in a failed state already.
Step 6: Maintenance Policy Determination: In this step, each failure mode is analyzed to determine what maintenance, if any, can be directed at the task such that the task is effective either from the perspective of reducing the risks to a tolerable level or from the perspective of economics, when the cost of doing the task is less than the cost of not doing the task. This step establishes new or revised maintenance policies. During this step the following become evident:
• The elements of the current maintenance program that are cost effective, and those that are not (and need to be eliminated),
• What tasks would be more effective and less costly if they were condition based rather than overhaul based or vice versa,
• What tasks serve no purpose and need to be removed from the program,
• What tasks would be more effective if they were done at different frequencies,
• What failures would be better managed by using simpler or more advanced technology,
• What data should be collected to be able to predict equipment life more accurately, and
• What defects should be eliminated by root cause analysis.
Step 7: Review and Grouping: Once task analysis has been completed, the most efficient and effective method for executing or managing the maintenance task is developed. This step involves sequencing the tasks and balancing the resources as well as considering production needs.

Phase 3 Approval and Implementation
Step 8: Approval and Implementation: The analysis is communicated to stakeholders for review and comment. Following approval, the most important aspect of PMO2000™ then commences with implementation. Implementation is the step that is most time consuming and most likely to face difficulties. Strong leadership and attention to detail are required to be successful in this step.
Step 9: Living Program: Through Steps 1 to 9, the PM Optimization process has established a framework of rational and cost effective PM. In the "Living Program", the PM program is consolidated and the plant is brought under control. This occurs as reactive maintenance is replaced by planned maintenance. From this point improvement can be easily accelerated as resources are freed to focus on plant design defects or inherent operational limitations.
During this step, several vital processes for the efficient management of assets can be devised or fine tuned as the rate of improvement accelerates.
These processes include the following:
ïƒ˜ Production / maintenance strategy,
ïƒ˜ Performance measurement,
ïƒ˜ Failure history reporting and defect elimination,
ïƒ˜ Planning and scheduling,
ïƒ˜ Spares assessing, and
ïƒ˜ Workshop and maintenance practices.
In this step it is the intention to create an organization that constantly seeks to improve its methods by continued appraisal of every task it undertakes, and every unplanned failure that occurs. To achieve this requires a program where the workforce is adequately trained in analysis techniques and is encouraged to change practices to improve their own job satisfaction and to reduce the unit cost of production.

Applications of PMO

PMO is suited to new or existing assets.
Specific applications of the process have been successful in the following phases of an asset’s life cycle:
• Reviewing the manufacturer’s recommendations,
• Reviewing the current maintenance program of existing assets,
• Developing the maintenance requirements of assets when the operating context changes.
• Ensuring that maintenance does not overspend when assets are to be retired.

What are the alternatives to PMO

Some of the most common methods used to define an initial maintenance strategy or improve an existing program include:
• RCM: Nowlan and Heap (1978)2 coined the term Reliability Centered Maintenance (RCM) and published the original RCM method. RCM is a zero based analysis technique that starts with functions. RCM was developed for use in the design phase of the asset’s life cycle and was not designed for use with “in service” assets or for assets which are improved models. In the absence of other legitimate methods RCM has become the standard for deriving the maintenance requirements of physical assets. In over 20 years since its derivation, RCM has failed to become a day to day activity performed by most organizations. Few organizations have applied RCM to anything other than their most critical assets which indicates there are serious difficulties associated with applying RCM in organizations with mature plant. By comparison, many PMO programs create the same maintenance program as RCM but do this on average, six times faster and with one sixth of the resources.
• Streamlined RCM: Due to the perception that RCM is a very time consuming and labour intensive activity, a number of shortened versions of RCM have been devised. Such programs attempt to speed up the analysis or increase the overall value of the time committed to analysis. Many of these methods have used the acronym RCM to describe the process but do not conform to the works of Nowlan and Heap (1978)2 or the SAE Standard for RCM. These streamlined approaches are known as streamlined RCM techniques.
• Experience, trial and error. In many cases, capital acquisition programs fail to recognize the need to define the maintenance program prior to the “Operation” stage of the equipment life cycle. Often, the plant is installed and operated without a formal maintenance program. Over time, the operations and maintenance staff begin to conduct inspections and perform various maintenance activities largely at their own initiative. Failures occur and the maintenance program has tasks added to it. In some organizations, the work is formalized by generating electronic or paper based maintenance schedules. In other organizations, the work continues to be done in a completely informal manner. Even though some managers may believe that there is no preventive maintenance done within their plant, this situation is highly unlikely. The confusion is often that the preventive maintenance is not appreciated, as there is no documentation.

Functional Differences between RCM and PMO

RCM and PMO are completely different methodologies with the same aim; to define the maintenance requirements of physical assets. Asset managers should be aware, however, that they have been designed for use in completely different situations. RCM was designed to develop the initial maintenance program during the design stages of the asset’s life cycle whereas PMO has been designed for use where the asset is in use.
As a result, PMO is a method of review whereas RCM is a process of establishment. Whilst arriving at the same maintenance program, PMO is far more efficient and flexible in analysis than RCM where there is a reasonably good maintenance program in place and where there is some experience with the plant operation and failure characteristics.

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