Introduction to Rcm by l.cherif

7/30/2019 Introduction to Rcm by l.cherif

1/37

GROUPEMENT BERKINEGROUPEMENT BERKINE

SONATRACHSONATRACH //ANADARKOANADARKO

HASSI BERKINE SUDHASSI BERKINE SUD

Introductionto Reliability Centered

Maintenance (RCM)


2/37

Lamine Cherif 1

Maintenance Has Changed

The world of equipment maintenance changed dramatically during the second half ofthe 20th century and it continues to do so today.Several major influences have been responsible for driving these changes:An enormous increase in the number of physical assets (such as buildings, factories,public and personal transport) that require maintenance.

1-Equipment has become extremely complex - for example, it is now rare to findanything that does not contain a computer or some electronics

2-Industries (such as manufacturing and mass transport) now put a much greateremphasis on safety and on operating without damaging the environment.

3-We now have a much better understanding of how equipment behaves, frominstallation to the point at which it fails

When engineers were forced to respond to this wave of change, it became clear thattraditional maintenance methods were no longer adequate - a new approach to

equipment maintenance was required.The commercial aviation industry was the first to realise that change was necessaryand committed significant resources to developing a solution in the 1960s and1970s. The results entered the public domain in 1978 under the name"Reliability Centred Maintenance" or "RCM".

What is RCM?

RCM stands for Reliability Centred Maintenance.

RCM may be defined as:

A process used to

determine the

maintenance

requirements of any

physical asset in its

operating context.

But, if maintenance is defined as ensuring that physical assets continue to do whattheir users want them to do, then the definition of RCM can be expanded to:

A process used to

determine what mustbe done to ensure that

any physical asset

continues to do what

its users want it to do

in its operating

context.

RCM, i.e. "Reliability-centred Maintenance", is so called because it recognises thatmaintenance can do no more than ensure that physical assets continue to achieve


3/37

Lamine Cherif 2

their built-in capability or "inherent reliability". RCM also recognises that identicalassets will have different maintenance requirements in different operating contexts.

Increased Expectations

Looking back to the 1930s, we can divide up the years since then into three

generations. We can then examine the expectations placed on the maintenance function

in each of the three generations as follows:

First Generation:

Prior to the Second World War, equipment was relatively simple and over-designed,so it tended to be reasonably reliable. The failures that did occur didnt matter toomuch and were quick and easy to repair. There was little need for the plannedmaintenance systems that are commonplace today.

Second Generation:The Second World War quickly led to increased demand for many types ofmanufactured goods and severely limited the supply of skilled labour to industry. Inresponse, factory equipment became more mechanised and more complex. Failures

(and their downtime) began to matter more so preventive maintenance systemswere developed in an attempt to prevent them - usually these were fixed intervaloverhauls.

Third Generation:

The last 30-40 years have seen an enormous increase in demand for manufacturedgoods and mass transportation. Industry responded with ever more automation andcomplexity in order to reduce the manpower needed to meet this demand; this inturn greatly increased costs of ownership and maintenance costs.

Advances in Maintenance Techniques

The maintenance techniques available to engineers have grown in number andcomplexity over the three generations:


4/37

Lamine Cherif 3

First Generation:The only real option was to leave equipment running and fix it if it failed.

Second Generation:The pressure for output fuelled demand for higher equipment availability. This in turnled to the development of the first preventive maintenance systems. Large andcumbersome (by today's standards) computers were introduced into themaintenance function in order to manage these systems.

Third Generation:Today there is a vast, and even bewildering, range of highly advanced maintenancetechniques available.The problem for maintenance engineers (besides learning what the availabletechniques are in the first place) is knowing which techniques are appropriate forwhich equipment and how often to use them.RCM helps with this enormously.

Reliability Centred Maintenance (RCM)

The developers of RCM took the unusual view (at the time) that the objective ofequipment maintenance should be to keep the equipment doing whatever its userswant it to do, rather than to prevent failures for the sake of preventing failures.

With this emphasis on preserving what the user wants, Moubray defines RCM as:

A process used to determine what must be done to ensure that any physicalasset continues to do what its users want it to do in its present operating

context.It is, therefore, no surprise that determining the operating context and what the userwants the equipment to do is the starting point for the RCM process, which is appliedby asking and answering the following seven questions:

Abstract

Reliability-Centered Maintenance (RCM) is a phrase coined thirty years ago to

describe a cost effective way of maintaining complex systems. The RCM method usesthe answers to seven very basic questions to help determine the best maintenancetasks to implement in an Equipment Maintenance Plan (EMP). This paper focuses onthose seven questions and how they help determine the EMP.

Introduction

On December 29th, 1978 F. Stanley Nowlan and Howard F. Heap published reportnumber A066-579, "Reliability-Centered Maintenance". The report was theculmination of several years of work aimed at determining a new, more cost effectiveway of maintaining complex systems. They called it Reliability-Centered Maintenance(RCM) because programs developed through RCM "are centered on achieving the

inherent safety and reliability capabilities of equipment at a minimum cost". RCM is atime consuming, resource intensive process. Many practitioners have tried to reducethe amount of time and resources required to accomplish RCM projects with varyingdegrees of success. The most successful ones have focused on understanding thebasic goals of RCM, and on the seven basic questions that need to be asked abouteach asset. In this paper we will concentrate on understanding each of the sevenquestions and how the answers to those questions help determine a Reliability-Centered approach to asset management.


5/37

Lamine Cherif 4

The Definition of Reliability

In the book Maintainability, Availability, and Operational Readiness EngineeringDimitri Kececioglu defines reliability as:

"The probability that a system will perform satisfactorily for given period of

time under stated conditions."

Nowlan and Heap define Inherent Reliability as:

"the level of reliability achieved with an effective maintenance program.

This level is established by the design of each item and the manufacturingprocesses that produced it. "

In The Fault Tree Analysis Guide a system is defined as:

"A composite of equipment, skills, and techniques capable of performing orsupporting an operational role, or both. A complete system includes all

equipment, related facilities, material, software, services, and personnelrequired for its operation and support to the degree that it can be

considered self-sufficient in its intended operational environment."

When we look at these definitions in conjunction it becomes very evident that anyasset management program must address system development through all phases ofa systems life. There is no maintenance program that can improve the reliability of apoorly designed system. Additionally, whatever maintenance program is developed isdetermined by the design of the system and the goals of the organization.

The Goal of Reliability-Centered Maintenance (RCM)

The primary goal of Reliability-Centered Maintenance (RCM) should therefore be toinsure that the right maintenance activity is performed at the right time with the

right people, and that the equipment is operated in a way that maximizes itsopportunity to achieve a reliability level that is consistent with the safety,environmental, operational, and profit goals of the organization. This is achieved byaddressing the basic causes of system failures and ensuring that there areorganizational activities designed to prevent them, predict them, or mitigate thebusiness impact of the functional failures associated with them.


6/37

Lamine Cherif 5

The Seven Questions of RCM

There are seven basic questions used to help practitioners determine the causes ofsystem failures and develop activities targeted to prevent them. The questions aredesigned to focus on maintaining the required functions of the system.

1. What are the functions of the asset?

2. In what way can the asset fail to fulfill its functions?

3. What causes each functional failure?

4. What happens when each failure occurs?

5. What are the consequences of each failure?

6. What should be done to prevent or predict the failure?

7. What should be done if a suitable proactive task cannot be found?

What Are The Functions of the Asset?

Every facility is uniquely designed to produce some desired output. Whether it istires, gold, gasoline, or paper the equipment is put together into systems that willproduce the end product. Each facility may have some unique equipment items, butin many cases common types of equipment are just put together in different ways.Within every RCM analysis we have two types of functions. First, the Main or Primaryfunction, this function statement will describe the reason we have acquired this assetand the performance standard we expect it to maintain. Second, are the SupportFunctions, which list the function of each component or maintainable item thatmakes up the system. The Support Functions are provided by the bottom level ofequipment in most facilities such as pumps, electric motors, valves, rollers, etc. Each

of those maintainable items has one or more easily identifiable functions that enablethe system to produce its required output. It is the loss of these functions that leadto variation in the Main or Primary function of the system and the safety,environmental, operational, and profit output of the facility.


7/37

Lamine Cherif 6

The key thing to remember when describing equipment functions is that we areinterested in what the equipment does in relation to its operating context, not what itis capable of doing. For example, a cooling tower pump may be capable of pumping100 gpm at 275 ft of head, but may only need to pump 75 10 gpm at that samepressure. It is necessary to focus on the required and secondary functions within thesystem operating context in order to analyze asset functions. Our main functionstatement for this system would address the functionality within the operatingcontext; Be able to pump cooling tower water at a rate of 75 10 gpm at 275 15ft of head while maintaining all quality, health, safety and environmental standards.

The rate, the head requirement, quality, health, safety and environmental standardsare all performance standards for the pump.

Functions need to be well defined. Statements such as pump water from the ponddont lend themselves well to understanding what functional failure would look like.A statement such as pump 1000 100 gpm at 275 15 ft of head from the pond

make it easy to understand what a functional failure might look like. If we can onlypump 800 gpm then we obviously have an unacceptable variation in output.


8/37

Lamine Cherif 7

In What Way Can the Asset Fail to Fulfill its Functions?

Nowlan and Heap said there are two types of failures. There are functional failuresand potential failures. Functional failures are usually found by operators, andpotential failures are usually found by maintenance personnel. In manyorganizations there are great debates about what constitutes a failure. In theiroriginal work Nowlan and Heap used a very good definition for failure. A failure isan unsatisfactory condition. Using this definition allows us to grasp the idea that

equipment can continue to operate yet be considered failed. Many conditionmonitoring programs dont achieve their desired output because those running theprogram do not recognize that a failure has occurred as soon as an unsatisfactorycondition is detected. They often try to run the equipment as long as possible oruntil they get closer to the F of the P-F curve. At Allied Reliability we call thismanaging to the F. More mature programs manage to the P, meaning that theytake action as soon as the unsatisfactory condition is recognized. Remember, thefurther we go along the P-F curve the higher the level of business risk we areaccepting.

It is equally important to recognize that there is significant value in ensuring thatequipment is installed and commissioned properly.


9/37

Lamine Cherif 8

The I-P-F curve shown above is the standard P-F curve with an I-P portion added.Point I is defined as the point of installation of the component. The I-P portion of theI-P-F curve is the failure free period. This is the time during which the operation isdefect free. The I-P interval for machines that were installed improperly may be justa few seconds. The I-P interval for machines installed by well trained crafts peopleusing well designed procedures, precision techniques, and precise measuringequipment, and commissioned by operators using well designed operatingprocedures may be years.

The graphic above shows what the I-P-F curve for two differently installed identicalmachines might look like. The machine with the longer I-P interval was installed bywell trained crafts personnel using a properly designed procedure and precisionmeasuring devices, and commissioned by operators using a well designed operatingprocedure. The machine with the shorter I-P interval was installed by inadequatelytrained personnel using either no procedure or a poorly designed procedure withoutprecision measuring devices and techniques, and commissioned by operators usingeither no procedure or a poorly designed procedure. The difference in lengths of theI-P portions of the curve for the two pieces of equipment may represent large sumsof money. The dollars represent the additional cost of parts and labor and also theamount of additional foregone production as a result of the extra maintenance workthat had to be performed.

Looking at an organizations shift in focus from F toward I is a more effective way todetermine its maturity than by looking at the age of their maintenance program.Many organizations reactively maintain equipment for a long time. An organizationthat is constantly focused on Point F and staying clear of it, will undoubtedly be areactive culture. Typical things heard around this organization might be How longcan we run it before it fails? and Just how bad is it?.

An organizations first step toward maturity will be to shift its focus from Point F toPoint P. The organization then focuses its efforts on understanding how things failand their ability to detect these failures early. Typical things overheard in thisorganization may be something like: Is this the best way to detect these defects

early? or I appreciate you letting me know about this problem, even though itsvery early.

Further maturation results in a transition from focusing on Point P to focusing onPoint I. Overheard in the hallways of this organization are things like Take the timeto do it right, it will pay big dividends for us not too far down the road and Letsupdate the procedures for that job to reflect what we just learned. Thisorganization is trying to prevent failures from occurring in the first place by applyingbest practices with fits, tolerances, alignment standards, contamination control andwell documented procedures. They will see the step change in performance and theyare the ones we label mature not the organizations that have been doing it poorlybut for a longer period of time.

The functional failure statement describes the loss of the equipments function, notwhat is wrong with the equipment. A good functional failure statement will mostlikely not have the noun name of an equipment part in it.


10/37

Lamine Cherif 9

What Causes Each Functional Failure?

At the end of the day we will be building maintenance tasks designed to preventfunctional failures from occurring. In order to do this we must understand whatcauses each functional failure. The cause may be the failure of some equipmentpart, but it can just as easily be a failure in some human activity. Improperoperation and improper maintenance are likely to be the causes of failures.Remember the definition of a system. Everything and everybody in the facility hassome impact on system reliability.

It is very important to describe these causes or failure modes in a way that allows usto create a living program for improving asset management. Easy to use codes inthe Enterprise Asset Management (EAM) system will allow us to capture data aboutwhat types of failures are occurring and to react to that data by reengineering themaintenance plan, training plan, or equipment design associated with theequipment. A well designed Failure Reporting, Analysis, and Corrective ActionSystem (FRACAS) is a must for continuously improving system performance.

For part failures we may want to use a simple three part code that consists of thepart name, part defect, and defect cause.

What Happens When Each Failure Occurs?

Known as Failure Effects, these statements clearly describe what happens when afailure occurs and what events are required to bring the process back to normaloperating conditions. Different things can happen when a failure occurs. Not all

failures are created equal. When listing failure effect statements we should fulfill thefollowing criteria:

1. Events that led up to the failure Any immediate notable effects of wear orimminent failure

2. First Sign of Evidence Is the failure evident to the operating crew as theyperform their normal duties? If so explain how.

3. Secondary Effects The effects of failure on the next higher indenture levelunder consideration.

4. Events Required to Bring the Process Back to Normal Operating conditions


11/37

Lamine Cherif 10

What Are the Consequences of Each Failure?

What makes failures matter is their impact on the business. Every business hasgoals for profitability, safety performance, environmental performance, andoperational performance. Each failure has a different impact on businessperformance, and it is important for the RCM team to understand the consequencesof each one. Some failures are of little to no consequence, and some can result inthe loss of lives, or in extreme cases total failure of the business.

Most organizations use some sort of severity matrix to define the consequences offailures. The tables below represent just some of the ways this can be done.

How would your company handle creating severity rankings for failures?

In most cases each failure will be ranked according to what is known as criticality.The criticality is the result of combining probability and consequence rankingstogether to yield a single number. The criticality will be a biased towards thebusinesss philosophy of safety, environmental, and operational risk. The tasks in theEquipment Maintenance Plan (EMP) generated from the RCM analysis are designed tolower the criticality of the significant failures in the system. Tasks can be rankordered for implementation by implementing those that yield the higher reduction incriticality first.


12/37

Lamine Cherif 11

What should be done to predict or prevent the Failure?

Each failure mode must be examined to determine what type of maintenance task, ifany, should be used to prevent or predict it. Nowlan and Heap recognized four basictypes of PM tasks.

Scheduled inspection of an item at regular intervals to find any potentialfailures

Scheduled rework of an item at or before some specified age limit Scheduled discard of an item (or one of its parts) at or before some specified

life limit Scheduled inspection of a hidden-function item to find any functional failures

When and how these tasks are performed depends on the failure mechanism that ispresent. In the original report six failure shapes were investigated. The teamdetermined that only 11% of the failure modes present in their study of aircraft partfailures would lend themselves to scheduled rework or replacement. In this instance89% of the failure modes present would require some sort of inspection. Themajority of the failure modes, 63%, could actually be made worse by time basedoverhaul or replacement. Clearly, some good non-invasive method of inspecting for

potential failures would be very beneficial.

Figure 3: Failure Shapes (John Moubray, Nolan and Heap)

In some cases it is not possible to detect functional failures during normaloperations. Those undetectable failures are called hidden failures. Hidden failuresare usually associated with some sort of protective system that is designed tominimize the impact or prevent the high consequences associated with a failure ofthe protected system. Items such as pressure safety valves (relief valves), circuitbreakers, high temperature interlocks, and high level interlocks are just a fewexamples of devices that could have hidden failures. The bad news is that theconsequences of failure can be extremely high. The good news is the probability ofthe catastrophic event is often quite low. It requires that both the protecting and theprotected item fail at the same time. In cases where functional failure is not


13/37

Lamine Cherif 12

immediately detectable during normal operations a failure finding task must be doneto prevent the high consequences associated with multiple failures.

Table 6, reproduced from the Nowlan and Heap report presents a comparison of thefour types of tasks and their applicability. For non-critical failures the order ofpreference will generally be inspection, rework, and lastly discard or replacement ofthe item.

When Nowlan and Heap published their report in 1979 condition monitoring methodssuch as vibration analysis (VA), ultrasonic inspection (UE), ultra-violet inspection(UV), and other non-invasive technology based inspection methods were in theirinfancy and were very expensive to deploy. Now, nearly thirty years later,technology based inspection methods are relatively inexpensive and easy to deploy.These methods are really nothing more than inspection methods that can be used ona periodic basis to determine the condition of equipment. We can be almost certainthat Nowlan and Heap would have recommended extensive use of these technologieshad they been readily available.

In any case, the task chosen must either lower safety, environmental, or operationalrisk to an acceptable level, or for non-critical failures be economically effective. Riskis always the top driver in the decision making process. We may have to spendmore money to ensure that we meet our risk goals.


14/37

Lamine Cherif 13

What should be done if a Suitable Proactive Task cannot be found?

There may be a couple of reasons why we wouldnt be able to find a suitableproactive task. We are either unable to find a task that will lower business risk to anacceptable level, or we are unable to find a task that is economically feasible. Eachcase requires a different response. In the first case, the system will have to beredesigned to that an acceptable level of risk. In the second case, we can choose arun to failure approach for the failure mode. It is important to remember that whena run to failure strategy is employed we should then put in place consequencereduction tasks to mitigate the impact of the failure. The RCM team must ensure

that appropriate steps are taken to have written procedures in place to deal with thefailure mode, and that proper spares levels are maintained.

Conclusion

Answering the seven questions of RCM properly will yield a cost effective EMP thatachieves the business goals for safety, environmental, and operational risk.Answering the questions properly requires a cross-functional team of maintenance,operations, and engineering personnel who have an understanding of how the asset

Applying RCM

It is not possible for one person to answer all the questions that RCM asks. The

solution is to bring together a group of people (the RCM analysis group) who havetechnical knowledge about the equipment, knowledge of its operation (within itscurrent operating context) and a basic understanding of RCM itself (through suitabletraining).

A sound understanding of the RCM process is also required in order to guide the RCManalysis group through the RCM process and achieve consensus in answering thequestions. This role is fulfilled by an RCM facilitator.


15/37

Lamine Cherif 14

RCM analysis group members are drawn from equipment maintainers, operators,possibly manufacturers/suppliers and occasionally specialists. The most importantfactor is that they know and understand the equipment being analysed using theRCM process.The aim is to reduce the size of the black hole in knowledge (i.e. the black area inthe box representing all there is to know about the equipment in the diagram).Inevitably, there will be some gaps in the groups combined knowledge, but at theend of the RCM analysis each group member will usually have acquired useful

knowledge about the equipment from other members of the group.Under the guidance of the RCM facilitator, the group follows the RCM process. Theoutputs of the analysis are:

1-a list of maintenance tasks to be performed by maintenance personnel at specifiedintervals.

2-a list of tasks to be performed by operating personnel at specified intervals.

3-a list of redesigns to be considered for implementation

When the RCM analysis is complete, the output should be audited by whoever hasoverall responsibility for the equipment or system. This is so they can satisfy

themselves that the analysis has been carried out correctly and that it is bothsensible and defensible.

The final step is to implement the results of the RCM analysis when the audit iscomplete.

Teamwork

Cross-functional, highly proactive and self-motivated team. Integrated byMaintenance personnel, Operations personnel, and Specialists (invited by specialrequirements). These people will have to be highly familiar with the subjects thatthey are examining. The team will be directed by a facilitator who may or may notcome from one of these departments.The size of the team should be adequate (typically 4 or 5 people) but not too large--"too many cooks spoil the soup."


16/37

Lamine Cherif 15

Facilitator's Role

The facilitator is the team leader. He will have to facilitate the implementation of anyphilosophies and techniques to be used, making the most of the different skills of thepersonnel who work in the teams. Facilitators will have to be competent in thefollowing areas:

1. Techniques/tools to use2. Analysis3. Managing meetings4. Time keeping5. Administration, logistics6. Communications

The typical functions of the facilitator include:

Organizing and directing all the activities involved in the project. Planning, scheduling and leading meetings. Ensuring that every scheduled

meeting happens. He must, therefore identify alternatives to resolve anyproblems with any team member.

Selecting the level, defining the borders and the work scope for theanalysis, as well as considering the impact, the duration and the resourcesrequired for the project.

Ensuring that all team members understand the process being followed. Ensuring that the process is correctly applied in the right order; avoid taking

short cuts that affect the process integrity.

Ensuring that the project is completed according to the plan, within reason. Co-ordinating all support material required by the team (drawings,

diagrams, etc.), as well as, keeping documentation and sharing it with the

team. Acting as the focal point of communications of the team, centralizing the

information related to the work. Keeping management aware of the planand team progress, generating high quality reports.

Acting as the technical expert that clarifies any doubts about the process ormethodology being followed that may be expressed by the team.

Documenting the data generated if it is needed. Researching deeply on the subject of the project and be prepared not to

accept incomplete information. In many cases verify the informationgenerated in the meetings. So, he must have enough judgment to know ifspecialists are needed.

Ensuring a consensus style of decision making. Managing any problems that may arise: interpersonal conflict, interruptions,

etc.


17/37

Lamine Cherif 16

What type of person makes a good Facilitator?

Facilitators are key people in successful projects. Better results are possible whenfacilitators are involved on a full time rather than part time basis. A good facilitatorhas broad knowledge of the assets. He must have reasonable knowledge of theprocess, but should not necessarily be an expert

About the Meetings:

The team must have common objectives, good knowledge of themethodology, and an action plan/program.

Special care must be taken with specialists invited to the meetings in order toprovide them with enough and clear information before and after the meeting.

The work session must not be longer than 90 minutes. 15 minute breaksshould be held during sessions (if sessions longer than 90 min. are planned).

Remember that the meetings are social events and should be pleasant events If it is not possible for all the team to attend, specialist sessions could be

held, making sure that operations representatives participate.

The facilitator should prepare an agenda, including the objectives to beachieved in the meeting, at the end of the meeting; achievement of thoseobjectives should be checked.

A meeting should never end without fixing the date and time of the nextmeeting.

The meeting should never seek to allocate blame. Avoid making disparaging comments about team member opinions. The team

should solve its internal problems without external interference.

The facilitator will have to encourage the participation of all team members inan enthusiastic way.

The meeting time should be used in an intelligent and effective way. The key information should be validated before taking further steps. Work based on facts and not on suppositions. Work on solutions for problems instead problems for solutions. Assigned activities which are not completed cause serious problems. The

facilitator should find ways to make sure that the responsible team memberdoes the required work.

Defer complex problems until enough information is known about them. Communication is the vital element in this kind of big project. The facilitator could channel communications. Communication should cover the whole organization. The facilitator should be a good salesman of the project and its results, so

that resources are allocated for it.

Notice boards with information about the project and results achieved are aninvaluable help.

A graph with results obtained (e.g. $$ Vs. Time) could be useful.


18/37

Lamine Cherif 17

What RCM Achieves

RCM has been applied in a wide range of industries in most countries throughout theworld. Correctly applied, RCM produces a maintenance schedule that is optimised forthe equipment in its operating context; the aim is to achieve inherent levels ofequipment reliability and availability. The RCM derived maintenance and the processitself bring about the following benefits

Safety - Greater safety and environmental protection due to:Improved maintenance of existing protective devices.The systematic review of safety implications of every failure.The application of clear strategies for preventing failure modes which can affectsafety or impinge upon environmental regulations.Fewer failures caused by unnecessary maintenance.Performance -Improved operating performance due to:An emphasis on the maintenance requirements of critical equipment elements.The extension or elimination of overhaul intervals.Shorter and more focused maintenance tasks resulting in less extensive and costlyshutdowns.Fewer "burn in" problems after maintenance (by eliminating unnecessarymaintenance actions).The identification of unreliable components.Cost Effectiveness - Greater cost effectiveness due to:Less unnecessary routine maintenance.The prevention or elimination of expensive failures.Clearer operating policies.Clearer guidelines for acquiring new maintenance technology.

Quality- Improved quality due to:A better understanding of equipment capacity and capabilityThe clarification of equipment set-up specification and requirements.The confirmation or redefinition of equipment operating procedures.A clearer definition of maintenance tasks and objectives.

Life-Cycle Cost- Reduced life-cycle costs by optimizing the maintenance workloads

and providing a clearer view of spares and staffing requirementsEquipment Life - Longer useful life of expensive items due to an increased use of Oncondition maintenance techniques.

Maintenance Data- A comprehensive maintenance data base which:Provides a better understanding of the equipment in its operating context.Leads to more accurate drawings and manuals.Allows maintenance schedules to be more adaptable to changing circumstancesdocuments the knowledge held by individuals on each piece of equipment.Motivation - Greater motivation of individuals, particularly those involved in thereview process. This gives improved understanding of the equipment in its operatingcontext and wider "ownership" of the resulting maintenance schedulesTeamwork - Better teamwork brought about by the highly-structured group

approach to analysing and addressing maintenance problems.


19/37

Lamine Cherif 18

Implantation of RCM

Armed with the maintenance strategic plan, it is set to do battle against the evils ofbreakdown

All available maintenance option for a plant equipment and machinery should beknown, and then decide which ones are the most appropriateThe most notable techniques is reliability centered maintenance (RCM).

INTRODUCTION

To be competitive, industry must continually improve.

Companies are embracing, like never before, efficiency methods such as just-in-timeand total quality management.

These structured, step-by-step systems can both identify and help implement waysto enhance the business.

They are tools to build on and make better use of employees operating abilities andtechnology knowhow .

Maintenance, too, is being changed by the competitive pressures in the marketplace.

It also has much to learn from the new techniques that are transforming business

practice.And those who use them properly are finding that better maintenance can meanbigger profits.


20/37

Lamine Cherif 19

There are several techniques that apply to maintenance performance.

Their common goal is to continually improve that performance by

Dealing with each type of failure most appropriately, in the most cost effectiveway.

Enhancing productivity with a more proactive and a planned approach.

Ensuring active support and cooperation of people for maintenance, materials,operations, technical, and administrative functions.

One of the most notable techniques is reliability centered maintenance (RCM).

By providing a strategic framework

And using the knowledge and expertise of people in the organization

it can accomplish two important goals.

First, it identifies the maintenance requirements of a physical asset that meets theoperational or production goals.

Then it optimizes the performance, with the results.

RCM works in a progression of related steps.

First, it examines the functions and associated to productivity goals of the assets.

Second, it assesses the ways those goals can fall short and the effects of failing .

Finally, RCM\s detective work deduces the most feasible and effective ways toeliminate or reduce the consequences of failure.

RCM was launched in the U.S. commercial airline industry during the early 1960s.

It developed in response to rapidly increasing maintenance costs, poor availability,and concern over the effectiveness of traditional time based preventivemaintenance.

The problems were obvious, so was the need more reliable maintenance programs.

Studies were conducted of existing engineering techniques and preventivemaintenance practices.

The results are in the right to a surprising fact about the traditional, time based,

preventive maintenance approach:Scheduled all overhaul has little effect on the overall reliability of a complex item,and this failure is frequent.


21/37

Lamine Cherif 20

There are many items for which there is not effective form of scheduledmaintenance.

The results of these initial studies have extended far beyond the airlines.

They were used to develop the basis of a logical preventive maintenance programthat can apply throughout industry.

This approach has since become known as the reliability centered maintenance

RCM was first applied on a large scale to develop the maintenance program of theBoeing 747.

Later, it was used for the L011 and DC10.

The results have been impressive.

These aircraft a cheap significant reduction in schedule and or time-basedmaintenance, with no decrease in reliability.

For example only 66,000 labor hours of structural inspections were required beforefirst heavy inspection at 20,000 flying hours on the Boeing 747, as compared to4,000,000 labor hours over same period on the smaller DC8.

And the DC-10, only seven items were subject to scheduled overhaul, in comparisonwith the schedule and overhaul of the 339 items on the DC8.

RCM (or MSG-3 as it is known in the aerospace industry) is now used to develop themaintenance programs for all major types of aircraft.

Other applications include the navy, utilities, the offshore oil industry, andmanufacturing processes.

RCM is particularly suitable where large, complex equipment is used and whereequipment failure pose significant economic, safety, or environmental risks.


22/37

Lamine Cherif 21

CREATING VALUES FOR CUSTOMERS

As desirable as it may be to have a comprehensive, logically based maintenanceprogram, it is of little use unless it helps maintenance, and the company as a whole,create value for its customers and shareholders.

Typical benefits of RCM are outlined in figure 7-1.

That advantages of instituting an RCM program depend on the nature of the

business, the risks posed by equipment failures, and the state of the existingmaintenance program.

RCM is based on the philosophy that maintenance is a key function of the company.

It is crucial for the expected functional performance and productivity goals to beachieved.

Further, maintenance requirements are best it developed by multidisciplinary teamsfrom production, materials, maintenance, and technical departments, and should befounded on a logical, structural, and engineered approach.

Some of the key precepts of RCM are that equipment redundancy should beeliminated, where appropriate; conditionbased or predictive maintenance tactics arefavored over traditional timebased methods; and runtofailure is acceptable,where warranted


23/37

Lamine Cherif 22

To develop an RCMbased maintenance program for physical resources, we need toanswer the following questions:

What assets are owned and operated by the company and to which of these shouldRCM be applied?

What are the functions and performance expectations of a selected asset?

In what ways can it fail to perform these functions?

What causes it to fail?

What are the consequences of each failure?

What should be done to prevent each failure, and what steps should be taken ifeffective preventive measures cant be found?

These questions are answered through a logical, seven-step review process,illustrated in figure 7-2.

The process begins with an understanding of the business requirements andobjective.

This ensures that the maintenance program meets the productivity goals and thephysical resource under review.

The maintenance agenda is then undefined.

Once that happens, an ongoing monitoring and review process is established tomake the most of the program.

The major steps in the RCM review process are described below.


24/37

Lamine Cherif 23

Step 1: Select Plant Area that Matter

Businesses typically have thousands of pieces of machinery and equipment.

These can range from pumps and valves to process systems, rolling mills, fleets ofload-haul-dump (LHD) trucks, ships, or buildings.

They may be fixed or mobile.

Each asset will benefit from RCM in varying degrees.

Therefore, the first step in the RCM process is to identify and prioritize the physical

resources owned or operated by the enterprise.

Only then can they be reviewed properly.


This is a national stage involves:

Establishing a structured , comprehensive list of all physical assets owned or used bythe organization that require some form of maintenance or engineering attention.This list is referred to as the plants register, plant inventory, or equipment familytree.

Assessing the Impact of the physical resources of the key business performanceareas. These may include availability, process capability, quality, cost, and safety orenvironmental risks. This ensures that the review focuses on the areas or equipment

in the plant that benefit most from RCM. Although several complimentary methodscan be used in assessment, the precise method is not critical. Of more Importance isselecting a method, documenting it and its results, and then proceeding with thereview. Simplicity is the key . Usually, the highest and lowest priority systems wouldbe obvious. Its not worth the added effort to figure out the exact order of

importance of those between the two.


Establishing the boundaries between equipment systems. Boundaries includeeverything necessary for the physical resource to do its job. This helps define thescope of the review and organizes it into manageable pieces.

One company selected its environmental control and monitoring equipment,

including dust collectors and effluent samplers.

They concluded that this category represented the greatest longterm risk.Step 2: Determine Key Functions and Productivity Goals

Once the physical resource selected, its functions and the associated productivitygoals are determined. This is a key step.

The purpose of a maintenance tactic is to make sure the equipment is workingproperly and producing on schedule.

Every physical asset has a function usually several.

This can be categorized as:

Primary

Secondary

Protective


25/37

Lamine Cherif 24

Step 2: Determine Key Functions and Productivity Goals

Primary - this is why the equipment exist that all. It is usually evident from its name,as well as forms the interfaces that are supported between physical assets. Anexample of a conveyors primary function, for instance, is to transfer rock fromhopper to crusher at a minimum rate of 10 tons/hour.

Secondary - in addition to its a primary purpose, a physical assets usually has anumber of secondary functions. These are sometimes less obvious, but the

consequences of failure may be no less severe. Examples of secondary functionsinclude maintaining a pressure boundary, relying local or control room indications,supplying structural support, or providing isolation.


Proactive - As processes and equipment increase in complexity, so do the ways inwhich they can fail dramatically. Likewise, the consequences of failure. To mitigatethese dire results, protective devices are used. The job of these devices must bedefined before adequate maintenance program can be developed. Typical protectivefunctions Include warning operators of abnormal conditions, automatically shuttingdown a piece of equipment, and taking over a function that has failed.


In addition to defining the functions, this process highlights the expected level ofperformance or the productivity goals.

This can include capacity, reliability, availability, product quality, and safety andenvironmental standards.

While this may sound relatively straightforward, technical and maintenanceperformance are typically judged differently.

Thus, performance can be defined as:

Built-in or inherent what it can do.

Required what we want it to do.

Actual what it is doing.


In many instances, the equipment can deliver what is required of it with propermaintenance.

Situations can arise, though, where whats required exceeds what physical resourceis capable of.

In these cases, maintenance cannot meet the performance events.

If there is a big gap between the performance needed and the builtin ability or theperformance currently being achieved, the equipment assets needs to be modified.

Either it should be replaced with a more capable item, or operating changes must bemade to reduce expectations.


26/37

Lamine Cherif 25


Again, the purpose of the RCM review is to define the maintenance requirements forphysical assets that are necessary to meet the business objectives.

The level of performance, then, reflects what is required or wanted from the asset.

Step 3: Determine Plausible Functional Failures

The third step is to address all plausible ways in which equipment can perform belowexpectations.

Partial and total shortcomings are considered, as well as an inadvertent function.Usually, we tend to think of an item failing when it stops working - a go/no gosituation.

For example, the car doesnt start or a compressor doesnt provide high pressure air.

While some equipment is like this, notably electronic machinery, in other cases whatconstitutes a failure is less clear.

Your car may start and run, but its acceleration is poor and it uses too much gas.

To compress may run but does it provide enough air pressure of volume?


Obviously, an idea of the boundary between acceptable and unacceptable

performance is needed to determine when failure occurs. This bounty in the expectedlevel of performance.

The definition of functional failure is the inability of the physical assets to deliver itsexpected level of performance.

This definition suggests that the function could fail in numerous ways, each with itsown (usually different) modes and effects.


These happen speak or are there may be:

A total loss of function, where the Item stops working altogether. For example, apumping system fails to provide any flow.

A partial loss of function, where the item works but fails to achieve expected level ofperformance. For example, a pumping system fails to provide an adequate flow.

Multiple levels of performance expected of from an individual function.


The expected level of performance defines not only what is considered a failure, butthe amount of maintenance needed to avoid that failure.


27/37

Lamine Cherif 26

As illustrated in figure7-3.

This frequently creates conflict between various departments.

Its essential then, that all concerned the technical, operations, and maintenancedepartments play a part in drafting the performance levels.

The joint seal of approval is essential before proceeding.

Step 4: Determine Likely Failure Modes and Their Effects

The next task is to set forth the likely failure modes and their cause and effect.

The failure mode describes what can or has happened as opposed to what caused itto happen.

For example, one failure mode of a pump could a seized bearing that halts any flow.

Failure modes of spelled out because the process anticipating, preventing, detecting,and correcting failures is applied to any number of different examples.

While many potential failures modes can be listed, only those that are fairly likelyneed be considered.


These include:

Failure modes that have occurred on the same or similar equipment. This isdetermined through a review in of maintenance work order history and experience.


28/37

Lamine Cherif 27

Failure modes that are already the subject of preventive maintenance tasks.

Other failure modes that have not happened but are considered possible because ofexperience or vendor/manufacturer recommendations. The extent to which theseless--thanlikely failure modes are included with depend on their consequences. The

greater the potential setback, the more these what if scenarios count.


These include:

Failure modes that have occurred on the same or similar equipment. This isdetermined through a review in of maintenance work order history and experience.

Failure modes that are already the subject of preventive maintenance tasks.

Other failure modes that have not happened but are considered possible because ofexperience or vendor/manufacturer recommendations. The extent to which theseless--thanlikely failure modes are included with depend on their consequences. Thegreater the potential setback, the more these what if scenarios count.


Possible causes of the particular failure are also identified since they have a directbearing on the maintenance tactics used.

In the example of the seized bearing, the cause of this failure could be a lack oflubrication.

Other typical reasons are wear, erosion, corrosion, fatigue, dirt, incorrect operation,or faulty assembly.


What actually happens when each failure mode occurs is next identified .

The effects are described fully, as if nothing were done to prevent the failure. Thisway, the consequences can be judged fairly .

To do so, the following are described :

The evidence of failure to the operating crew under normal conditions.

The hazards the failure may pose to worker safety, public safety, process stability, orthe environment.

The effect on production output and maintenance.

Step 5: Select Feasible and Effective Maintenance Tactics

Failures of the physical resources owned or used by a company can very enormously.

Their results may be potentially catastrophic or trivial.

How great the Impact influences the way the company views the failure and thesteps deemed necessary to prevent it, such as adding a backup systems.

In some cases, it may not be worth the effort and expense.


To successfully manage a failure, the preventive maintenance tactic must be:

Technically feasible - dealing effectively with the technical characteristics of thefailure.

Cost effective reducing or avoiding pitfalls in line with dollar and operatingconstraints.

Tactical options are discussed more for the inch up to four in.

Whether a particular approach is technically appropriate to solve the failure dependsnot only on the kind of help, but the nature of the problem.

Technically feasible tactics for condition based and time based maintenance


29/37

Lamine Cherif 28

satisfy the following criteria.


Condition based

Its possible to in detect the physical resources degraded condition of performance.

The failure is predictable as it progress from first instance to complete breakdown.

It is practical to monitor the physical resource in less time than it takes for theproblem to develop completely.

The time between incipient and functional failure is long enough to be of some use

that is, action can be taken to avoid the failure.


Time based

There is an identifiable point at which the physical asset shows a rapid increase infailure rate.

Most assets survived to that age. For failures were significant safety orenvironmental risks, there should be no failures before this point.

The task restores the assets condition. (This might mean partially restoration if theasset is overhauled, for example, or complete restoration if the item is discarded andreplaced.)

To be costs effective, preventive maintenance must reduce the likelihood and/orconsequences of failure to acceptable levels, be readily implemented, and stay withinbudget.


Within these limits, that maintenance tactic is considered costeffective if :

For legal problems, it cuts the chance of a multiple failure to an acceptable level.

For failures with safety and environmental effects, the risks are kept to a comfortableminimum.

For failures with production setbacks, the cost of the tactic is, over time, less thanthe production losses. Also, it must be cheaper than repairing the problem it is

meant to prevent.For failures with maintenance consequences, the cost of prevention measures is,over time, less than repairing the failure that would otherwise results.


If maintenance measures are neither technically feasible nor costeffective, then,depending on the risk of failure, one of the following default actions is selected:

For hidden failures, the failure finding tactic to reduce the likelihood of multiplefailures. An example is testing the readiness of standby equipment.

Four failures with unacceptable safety or environmental risks, redesign ormodification.

For failures with production or maintenance consequences, run to failure orcorrective maintenance.

At logic tree diagram is used to integrate the consequences of failure with technicallyfeasible and cost effective maintenance tactics.


30/37

Lamine Cherif 29

A simplified version of this diagram is illustrated in figure 7 4.


In general, tactics to prevent failures for this order:

Condition based maintenance (CBM) tactics These generally have the leastimpact on production, help focus corrective actions, and get the most of theeconomic life of the equipment.

Time based repair / restoration tactics These may work for failures that presentsa significant safety, environmental, or economic risk to the organization. However,this approach is less preferable than the CBM for a number of reasons. It usuallyeffects production or operations, the age limit can mean premature removals, andthe additional shop work required increases the cost of maintenance.

Time based discard tactics These are generally that least coast effectivepreventive maintenance measures. The tend to be used, though, where repair orrestoration is impossible or ineffective, such as for components like filter elements,orings, and, in some cases, integrated circuit boards

Step 5: Select Feasible and Effective Maintenance

Combinations in some cases a combination of tactics may be necessary to reduce

the safety and environmental risks to an acceptable level. In general, this involves acondition based maintenance method along with some form of time basedmaintenance. An example would be the in place inspection of an aircraft engine byborescope every 50 flying hours, combined with time based inspection andoverhaul in a shop every 200 hours.


Once the maintenance tactics have been chosen, next comes deciding how oftenthey are performed initially.


31/37

Lamine Cherif 30

For condition -- based tactics, the frequency is linked to the technical characteristicsof the failure and the specific monitoring technique.

Depending on these factors, the time can vary from weeks to months.

Generally, the more sophisticated (and expensive) the technique, the moreInfrequent.


Time base tactics are applied according to the expected useful life of the physical

assets.That is determined by the age at which wear out begins, when the chance of failuregreatly increases.

How often the failure -- finding tactic is needed depends on how available it is andhow likely a breakdown in the system.

Figure 75 gives an example of how the first five steps might look on a worksheet

Step 6: Implement Selected Tactics

It often requires as much effort and more coordination to put the results of the

RCM in motion than the review itself.The recommendations are compared with the tasks already included in themaintenance program.

The question is whether to add new tasks, change the existing ones (scope orfrequency), and/or delete any.

Step 6: Implement Selected Tactics

Next on the agenda are the actions needed to put the maintenance tactics intoeffect. These may include:

Tweaking maintenance schedules.

Developing or revising task instructions.


32/37

Lamine Cherif 31

Specifying spare parts and adjusting inventory levels.

Acquiring diagnostic or test equipment.

Revising operation and maintenance procedures.

Specifying the need for repair or restoration procedures.

Most significantly, conducting training in the new procedures.

To ensure all this is coordinated smoothly, an integrated plan is developed.

This plan underscores the actions required and assigns the responsibilities and targetdates for their completion

Step 7: Optimize Tactics and Program

Once the RCM review is complete and the maintenance work identified, periodicadjustments are made.

The process is responsive to change in plant design, operating conditions,maintenance history, and discovered condition.

In particular, the frequency of the tactics is adjusted to reflect the operating andmaintenance history of the physical resource.

The objectives of this ongoing activity are to reduce equipment failure improvedpreventive maintenance effectiveness and the use of the sources, identify the needto expand the review, and react to changing industry or economic conditions.

Step 7: Optimize Tactics and Program

To achieve these goals, two complimentary activities are integrated into a livingprogram.

The periodic re-assessment and revision of the RCM review results. The frequency ofthe re-assessment depends to some degree on the equipment age but is usuallyconducted in the tool to five years.

A continuous process of monitoring, feedback, and adaptation. This process analysesand assesses the data produced by production and maintenance activities for failurerates, causes, and trends. It includes variances between actual and targetperformance. Corrective actions can then be taken. These may include changing thetask type, scope, or frequency; revising procedures; providing additional training; or

changing the design.Continually reviewing and improving the initial maintenance program is akin to aquality management process that continuously improves product quality


33/37

Lamine Cherif 32

RCM ELEMENTS: PHILOSOPHY TO PRACTICE

Some of the key success factors in previous RCM programs are listed in

Figure 7-6.

To achieve such success and manage change effectively, the RCM program must bephased in and constantly improved.

The continuous improvement strategy is long-term, involving people from

production, materials, maintenance, and technical functions in the RCM reviewprocess.

The program involves the use. Of a parttime review team, under the direction of afulltime facilitator.

As a result, it can take a few years to review the critical physical resources in acompany.

This approach complements other improvements initiatives, such as just in time (JIT)and total quality management (TQM). It provides :

A high degree of support from people in production, materials, maintenance, andtechnical departments for RCM, ensuring acceptance of change.

Many part-time review teams under the direction of fulltime facilitator to review

important plant areas. Thus, it is easier to obtain the right people to conduct thereview.

Flexibility and cost-effectiveness, minimizing the need for full-time staff.

The basic building block of this strategy is the cross functional RCM review team ofcompany employees.

The RCM review process addresses six questions about a physical asset.

To answer these questions, input is required not only from maintenance but also theproduction, material, and technical departments.


34/37

Lamine Cherif 33

As a result, the RCM review is best conducted by small teams (five to sevenmembers), with at least one member from each of the above functions who isknowledgeable about the physical resource under consideration.

The other key member of the review team is that facilitator who provides expertisein the RCM methodology and guides the review process.

The RCM review team meets on a parttime basis.

Typically, this involves one to two meetings per week of about three hours duration

each.Team members also spend about three to four hours per meeting on individualpreparatory to follow up work.

The RCM review process takes about ten to fifteen meetings to complete.

The physical resource chosen may be studied in sections, by subgroups, so that thatif you can be accomplished in this time.

The RCM review team also coordinates how the commendations are carried out.

Team meetings during this phase are of similar duration but less frequent.

In addition, the phasedin approach is used to manage change successfully. Thisapproach is employed to :

Establish the need for RCM and build support for its implementation.

Establish a vision of excellence.Customize RCM methods to meld with existing structures and systems.

Promote technology transfer and commitment to RCM through an initial cadre ofpeople trained and experienced in its methods.

Achieve immediate results to build credibility.

The major phases in this implementation approach and general tasks are

Illustrated in figure 7-7.


35/37

Lamine Cherif 34

The following is an example of the use of RCM in manufacturing

One mining company with a fleet of 240 ton trucks in continuous operation wantedto reduce unplanned downtime.

They analyze the data in the truck dispatch system to determine the highest delaycauses, and selected an assembly that was both significant and reasonablystraightforward.

Their choice was the hydraulic box dump assembly.

With a team of in-pit and shop maintainers led by a facilitator with RCM expertise,they met for about two to three hours every week over thirteen weeks.

The primary function was defined as: provide hydraulic power to smoothly andsymmetrically raise and lower a loaded (240t) dump tray. The maximum overallcycle is 47 seconds for an empty tray at the regulated pressure of 2400psi 50psiwith the prime mover at 1910 rpm.

The function is a stated crisply, with several standards of performance that make thedefinition of a function failure clear:

Fails to raise the dump tray at all with a regulated pressure of 2400psi 50psi.

Tray is raised too slowly (overall cycle time >47s empty) at a pressure of less than2350psi.

Tray is raised too slowly (overall cycle time >47s empty) at a pressure of less than2400psi but with the engine


36/37

Lamine Cherif 35

RCM is successful

The commercial airline industry in the 1960s:

60 crashes per million take-offs

40 of those (66%) were due to equipment failure

85% of aircraft maintenance was fixed interval

Today:2 crashes per million take-offs

0.3 of those (15%) are due to equipment failure (the rest are human error)

< 20% of aircraft maintenance is fixed interval

Toronto Hydro

Using RCM since 2002. Reducing maintenance costs by 22%

Canadian Navy

Used RCM for new ships in late 1980s

Reduced crew size, reduced maintenance workload, extended ship refit

intervals by over a year,

Increased ship availability by 17%

Saved $C200 million per year in operating costs and $C2 billion in capital

costs

GE Plastics (Holland, 2000)

MTBF increased from 8 hours average to over 80 days!

Costs dropped by 50% and staffing was reduced by 30%

Team composition & analysis meetingsTeams are made up of operators and maintainers trained in RCM analysis

Teams are facilitated by a highly trained RCM facilitator

Analysis meetings are 3 to 4 hours each

Each project requires 10 15 meetings


37/37

Audit of results

Management makes certain that it is

Happy with the results obtained by

RCM analysis teams.

ConfirmSuitability of all maintenance tasks

Suitability of all operator tasks

`Suitability of any run-to-failure decisions

Suitability of any re-designs suggestions

Recommended Reading

Moubray, John: Reliability-centred maintenance, 2nd edition, 1997, Butterworth-Heinemann, UK

Campbell, John & Reyes-Picknell, James: Uptime, Strategies for Excellence inMaintenance Management, 2nd edition, 2006, Productivity Press, NY

Documents

Introduction to Rcm by l.cherif