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Fault Tree Analysis And optimum maintenance decisions.

Presenting by Jyothi.k Goutham

A common tool using graphics and statistics to analyze an event and predict how and how often it will fail.

Used in engineering and business to aid process and system development.

What Is Fault Tree Analysis?

The graphic design allows the fault tree to be easily explained and understood by anyone in the situation that is using it.

Fault tree analysis also provides a unique way of dealing with problems in a process or system flow.

Effective way to diagram problems in a system

Helps to organize possible causes of a problem in the system

Why Do We Use Fault Tree Analysis?

The gates and events range from specific types of events to and/or gates.

Gates are used to progress from one event

to another.

Top-down approach is when the end is at the top and the tree works its way up from the bottom to get to the end event.

How Does It Work?

And Gate

An example of an And gate is that if you are pay your taxes on time and don’t cheat on them the I.R.S. will not fine you.

Or Gate

An example of an Or gate would be if you are late on your taxes or you cheat on your taxes the I.R.S. will fine you. Or gates and And gates can be used with each other in the tree.

Primary Event Intermediate EventExpanded Event

Three Main Events

Made up of basic, undeveloped, and external events A time in the event where the process or system might failBasic Event Nothing is leading up to the event Can be like a machine breaking unexpectedly A circle is used to represent the event in the fault treeUndeveloped Event Events that don’t have a major effect on the system Also events that there is not enough information about Represented by a diamond in the fault treeExternal Event Expected to happen Not considered a fault A house shape in a fault tree

1)Primary Events

A combination of multiple different faults Shown by rectangles in the fault tree Sometimes linked by and/or gates

3.Expanded Event Complex event that needs another fault tree

to explain The fault tree for the expanded event is not

directly shown in current fault tree Shown by a triangle on the fault tree

2.Intermediate Event

Four events that led to faulty tires Design problem in tread Faulty process in Decatur, Illinois Problem with Ford Explorer Customers don’t take proper care of tires

Results Of Inquiry

Preventing the error in the first place After the error in the tire was found, finding

all the things that caused it Preventing similar problems from happening

again

Values Of Fault Tree For Firestone

maintenance Maintenance covers all those operations such as

monitoring, inspecting, adjusting, repairing and /or doing whatever is necessary to keep a machine, a facility, a piece of equipment or transportation vehicle in the proper working conditions.

Maintainability can be defined as the probability with which a component or system is restored to the original or specified condition within a given time period when the maintenance action is taken.

The maintenance action will involve specified procedures and resources

Classification of maintenance Corrective maintenance/breakdown

maintenance

Preventive maintenance

Predictive maintenance

1) Corrective maintenance Breakdown maintenance is remedial or

corrective maintenance that occurs when equipment fails and must be repaired on an emergency or priority basis.

2)Preventive maintenance Preventive maintenance is the work activity

that has been planned and programmed on a regular basis to inspect a system, to uncover potential problems and to make whatever repairs are necessary to ensure that the system does not fail during normal operation

3)Predictive maintenance In predictive maintenance, symptoms or vital

signs are looked for. Once it is found then the appropriate maintenance is carried out. Periodic functional check up alone is done to check whether the machine is working or not

4)Optimum maintenance decisions Maintenance is a cost. It includes salaries of

maintenance crew Inventories kept for the maintenance .Lost time when equipment is down for repairs etc.

Optimum point

•cost

Preventive maintenance frequency

Total cost

Optimum point

Preventive maintenance costs

Maintenance methodology1)Reliability Centered Maintenance

(RCM) It is a systematic process of prescribing a

system’s (machines/equipments) function by applying effective preventive maintenance tasks.

2)Total Preventive Maintenance (TPM) Total preventive maintenance is the process

designed to maximize the productivity of the equipments for its entire life. TPM achieves this by focusing on root causes and by involving everyone in the organization

Objectives of TPM Improve the productivity of the plant Maximize overall equipment effectiveness Train all staff in maintenance skills Reduce the equipment downtime to zero Reduce equipments life cycle cost

Thank you