Free Fault Tree Analysis Maker — Map Causes

See it work

Fault tree analysis examples.

Same tool, four requests. Every drawing below is a real render.

What you type

A fault tree for reactor runaway leading to fire or explosion: a runaway reaction and ignition must both occur. Runaway is loss of cooling (coolant pump failure or line blockage), overpressure (relief valve fails or excess reactant feed), or contamination (water leak or catalyst decay). Ignition is an electrical spark, hot surface or static discharge.

Then tryAdd operator error as a cause of excess reactant feed.Change the coolant pump failure probability to 0.01.

Fault Tree Analysis: Chemical reactor fire and explosion

Fault Tree Analysis · NUREG-0492 Fault Tree Handbook · schematex-faulttree

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The drawing

What a fault tree analysis is.

A fault tree analysis starts with an unwanted top event and works downward to its causes. Gates show the logic between events: an OR gate needs one cause, while an AND gate needs every input condition.

The bottom of the tree contains basic events such as a component failure, operator error or external condition. The tree makes the combinations leading to the top event explicit for a safety or reliability review.

Standard: NUREG-0492 Fault Tree Handbook
Also follows: IEC 61025:2006 · NASA FT Handbook 2002 · MOCUS cut sets (Fussell-Vesely 1972)
Engine: schematex-faulttree
Editable: Double-click text, drag nodes
Export: SVG · PNG · PDF

Fault Tree Analysis: What a fault tree analysis is

Who uses it

Who uses fault tree analysis.

Process safety teams

Scenarios such as loss of containment, ignition and explosion, broken into the failures and conditions that must combine.

Reliability engineers

Component and system failure logic used to identify single points of failure and combinations worth reducing.

Safety reviewers

A clear top-event argument for equipment, fuel-handling or dust-hazard reviews.

How it works

How to make a fault tree analysis in three steps.

Describe it

One paragraph is enough to start.

“A fault tree for reactor runaway leading to fire or explosion: a runaway reaction and ignition must both occur. Runaway is loss of cooling (coolant pump failure or line blockage), overpressure (relief valve fails or excess reactant feed), or contamination (water leak or catalyst decay). Ignition is an electrical spark, hot surface or static discharge.”

See the drawing

Drawn by the right engine.

Say what changes

Every edit keeps a version.

Add operator error as a cause of excess reactant feed.

V2 · DRAWN FROM V1, NOTHING RETYPED

FAQ

Common questions

What is fault tree analysis?

Fault tree analysis is a top-down method for examining how combinations of failures and conditions can lead to one unwanted event.

What is the difference between an AND gate and an OR gate?

An AND gate means every input event must occur for its output event. An OR gate means any one input event can produce its output event.

What is a basic event?

A basic event is a lowest-level cause that is not broken down further in the tree, such as a pump failure or static discharge.

What is a minimal cut set?

It is a smallest combination of basic events sufficient to cause the top event under the logic in the tree.

Can I include event probabilities?

You can label basic events with probability values when you have defensible data. Check assumptions, independence and calculation methods as part of the engineering analysis.

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