Hazmat, risk analysis division A presentation by: Dr. Alexander Cohen

Hazmat, risk analysis divisionHazmat, risk analysis division

A presentation by:A presentation by:

Dr. Alexander CohenDr. Alexander Cohen


In this presentation:In this presentation:

Task analysis goalsTask analysis goals

Failure modes of humansFailure modes of humans

HAZOP of tasksHAZOP of tasks

Basic task analysisBasic task analysis

Quantitative analysisQuantitative analysis


Task analysis goalsTask analysis goals

The term ‘task analysis’ refers to the analysis of the The term ‘task analysis’ refers to the analysis of the human interfacehuman interface with the process. with the process.

Protecting the (human) operator.Protecting the (human) operator.

Human errors reduction.Human errors reduction.

Inherently safe processes.Inherently safe processes.

Human engineering aspects.Human engineering aspects.

Standing operating procedures (SOP) and safety SOP Standing operating procedures (SOP) and safety SOP (SSOP).(SSOP).


In many cases task analysis is only a by-product of In many cases task analysis is only a by-product of the risk analysis due to the complexity of the analysis the risk analysis due to the complexity of the analysis of human behavior.of human behavior.


Failure modes of humansFailure modes of humans


An operator in a plantAn operator in a plant

Plant (perception)Plant (perception)

Information Information processingprocessing

Plant (real)Plant (real)

OperationOperationDetectionDetection


Human errors – Human mistakesHuman errors – Human mistakes

ErrorsErrors

Operator is skilled.Operator is skilled.

Incorrect/absent Incorrect/absent information.information.

Incorrect/absent interface.Incorrect/absent interface.

Environmental conditions.Environmental conditions.

MistakesMistakes

??

And sometimes, the operator just slip, hang on the first thing he can grab and -And sometimes, the operator just slip, hang on the first thing he can grab and -Unfortunately it is an emergency releasing valve, and the rest is history… Unfortunately it is an emergency releasing valve, and the rest is history…


Basic modes of human errorsBasic modes of human errors

Omission of a task (Omission of a task (the the oopsoops syndrome syndrome).).

Commission of an extra action.Commission of an extra action.

Changes in operator’s physical conditions.Changes in operator’s physical conditions.

Changes in operator’s mental conditions.Changes in operator’s mental conditions.


Psychological failure modesPsychological failure modes

Failure to consider special circumstances.Failure to consider special circumstances.

Shortcut invoked.Shortcut invoked.

Stereotype takeover.Stereotype takeover.

Need for information not prompted.Need for information not prompted.

Misinterpretation.Misinterpretation.

Assumption.Assumption.


Psychological failure modes (cont.)Psychological failure modes (cont.)

Forget isolated acts.Forget isolated acts.

Mistake among alternatives.Mistake among alternatives.

Place-losing error.Place-losing error.

Other slip of memory.Other slip of memory.

Motor variability.Motor variability.

Topographic or spatial orientation inadequate.Topographic or spatial orientation inadequate.


Environmental aspectsEnvironmental aspects

Dust.Dust.

Noise.Noise.

Radiation.Radiation.

Ventilation.Ventilation.

Visibility.Visibility.

Heat/cold Heat/cold stressstress

Work at heightsWork at heights

Slippery floor.Slippery floor.

Limited approach.Limited approach.

Hot/cold surfaces.Hot/cold surfaces.

Rails.Rails.

Vibrations.Vibrations.

Repulsive odor.Repulsive odor.


IneffectivenessIneffectiveness

Response to gauge in auto-mode (100%).Response to gauge in auto-mode (100%).

Response to gauge in manual mode (10%).Response to gauge in manual mode (10%).

Failure to confirm shutdown (15%).Failure to confirm shutdown (15%).

Response to multiple alarms (15%).Response to multiple alarms (15%).

Response to single alarms (2%).Response to single alarms (2%).

Critical action under high stress (30%).Critical action under high stress (30%).

Critical action – SOP available (10%).Critical action – SOP available (10%).

Procedure on a checklist (2%).Procedure on a checklist (2%).


Task analysis methodologyTask analysis methodology

This analysis could be carried out in many methods such as:This analysis could be carried out in many methods such as:

HAZOP of operating procedures.HAZOP of operating procedures.

Task analysisTask analysis

Workplace study (occupational health & hygiene).Workplace study (occupational health & hygiene).

Ergonomic (human engineering) surveys.Ergonomic (human engineering) surveys.

Performance analysis.Performance analysis.


Hazard & operability studyHazard & operability study

Carried out as a standard HAZOP with the application Carried out as a standard HAZOP with the application of the guidewords on tasks rather than process nodes.of the guidewords on tasks rather than process nodes.

(In many batch processes a HAZOP of the tasks gives better (In many batch processes a HAZOP of the tasks gives better results than a HAZOP of the process diagrams)results than a HAZOP of the process diagrams)

..


Task HAZOP Task HAZOP Changing a flat tyreChanging a flat tyre


Changing tyreChanging tyreSOP - summarySOP - summary

1. Park the car in a safe place. 2. Jack up car.3. Remove flat tyre and replace with spare.4. Un-jack car.


Changing tyreChanging tyreSOP breakdownSOP breakdown

1. Park in a safe place. 2. Identify flat tyre. Get wheel spanner and jack.3. loose nuts.4. Jack up car.5. Unscrew nuts and remove flat tyre.6. Fetch spare and fit in place.7. Screw nuts.8. Un-jack car.9. Tight nuts.10. Get your staff and …

drive safely …


JACK UP CARJACK UP CAR

GUIDE WORDSMEANINGSNO or NotThe complete negation of theseintentions.MORELESSQuantitative increases or decreasesAS WELL ASPART OF A qualitative increaseA qualitative decreaseREVERSEOTHER THANThe logical opposite of the intentionComplete substitutionFASTER/SLOWER(THAN)Timing and synchronization issues.


HAZOP exampleHAZOP exampleJack up carJack up car

Guideword Deviation Cause Suggestions

No Car not lifted Incorrect jack placement Mark the jack socket.

No Car not lifted Jack malfunctioning Hitchhike!

More Car lifted too high Driver unaware of risks Limit jack max height. Use a car-specific jack.

Less Car hardly being lifted

1) Incorrect jack placement

1) See above

Less Car hardly being lifted

2) Driver hasn't enough power to operate jack.

2) Use a hydraulic jack as a standard


HAZOP exampleHAZOP exampleJack up carJack up car

Guideword Deviation Cause Suggestions

As well as Jack may catch sleeves, dresses etc.

Isolate the jack's mechanism.

Part of Car de-jacked. Jack slides on a greasy surface.

Use rubber to increase friction.

Reverse Car de-jacked. Mechanism has broken while car is up.

1) Revise test criteria. 2) Determine an expiration date.

Other than Malfunctioning at nighttime.

Darkness Add a flashlight to the standard tool kit.

Before After

Car slides forward Driver has forgotten to pull hand break.

Add instruction to the manual.


HAZOP: prosHAZOP: pros

Structural.Structural.

Thorough.Thorough.

Technical solutions to human engineering Technical solutions to human engineering problems.problems.


HAZOP: consHAZOP: cons

Time consuming.Time consuming.

Requires a specific HAZOP team*.Requires a specific HAZOP team*.

Many uncertainties in the design phase.Many uncertainties in the design phase.

Many subjects fall into ‘other than’.Many subjects fall into ‘other than’.

*In many cases, the technical team doesn’t know how to assess human *In many cases, the technical team doesn’t know how to assess human engineering aspects.engineering aspects.


Basic tasks analysis Basic tasks analysis (the WH-questions approach)(the WH-questions approach)

Task analysis keywordsTask analysis keywords

• WHWHATAT

• WHWHENEN

• WHWHEREERE

• HHOOWW

• WHWHOO

&&

• WHWHYY


QuestionsQuestions

WH question

Proposal Why question

Alternative

What What has to be done

Why, for what purpose?

What if omitted? What else might be done as well as? What else might be done instead? What else can go wrong?

When When is it done? Why then? What if done earlier, later, before, after or out of sequence?

What, When, How, Who, WhereWhat, When, How, Who, Where


Questions (cont.)Questions (cont.)

WH question

Proposal Why question

Alternative

How

How is it done? How much is it done? How fast is it done? How often is it done?

Why that way?

What if done some other way? What if more or less done. What if quicker or slower? What if done more or less often?

Who Who does it? Why them? Who else can do it?

Where Where is it done? Why there? What if it done elsewhere?



n-Pentane fillingn-Pentane fillingTGC system, simplifiedTGC system, simplified

…

1.Verify a low level in the tank.

2.Open V1, and the two connected valves V2,3.

3.Activate the pump.

4.Monitor filling and close pump when level reaches high level indication.

…

n-pentaneV1 filter V2,3

Manual pump

vent

LI

HL


n-Pentane fillingn-Pentane fillingAsking questionsAsking questions n-pentane

Question Answer Suggestions

What What has to be done

Operator monitors tank filling and stops the pump when level reaches high-level indication.

What if omitted?

If reaches overflow level the liquid should run to the suction line and therefore flooding is prevented.

What else can go wrong?

If overflow line fails to discharge excess of fluid pentane might be spilled out through the vent causing a series danger of gas explosion.

Consider on site gas detector + alarm

When When is it done?

It should be done immediately after low-level signal indicate low-level. If done later, might affect the TGC performance.

Consider installing a LALL.


n-Pentane fillingn-Pentane fillingAsking questions (cont.)Asking questions (cont.) n-pentane

Question Answer Suggestions

Who Who does it?

Normally by the TGC operators. However, during nights and weekends, any other operator can carry it out.

Make sure that all operators are well trained.

How What if done some other way?

It is strictly prohibited to use any alternative way for filling the tank (due to static electricity hazards).

Make sure that manhole is sealed and cannot be opened easily.

Where What if done elsewhere?

Impossible.


n-Pentane fillingn-Pentane fillingCleaning the filterCleaning the filter

…

1.NEVER open filter cop when pump is operating.

2.Insert a large metal bowl below the filter to collect possible spillage.

3.Unscrew the cap cautiously by hand.

4.If stuck DO NOT attempt to use any tools.

5.Wash the cop with small portions of pentane until well cleaned.

6.Re-screw the cop by hand.

7.Activate the pump for 5 seconds (V2,3 closed!) and see if cop leaks.

…

n-pentane


n-Pentane fillingn-Pentane fillingCleaning the filter (cont)Cleaning the filter (cont) n-pentane


•Unscrew the cop Unscrew the cop cautiouslycautiously by hand. by hand. •If stuck DO NOT attempt to use any tools.If stuck DO NOT attempt to use any tools.


Quantitative analysis of human activitiesQuantitative analysis of human activities

In fault trees.In fault trees.

In event trees.In event trees.


Failure densitiesFailure densities

Generic task Range Average

a) Totally unfamiliar, performed at speed, with no real idea of consequences. 0.35-0.97 0.55

b) Shift or restore system to a new or original state on a single attempt without supervision or procedure

0.14-0.42 0.26

c) Complex task requiring a high level of comprehension or skill. 0.12-0.28 0.16

d) Fairly simple task performed rapidly or given scant attention. 0.06-0.13 0.09

e) Routine, highly practiced, rapid task involving relatively low level of skill. 0.007-0.045 0.02


Failure densities (cont.)Failure densities (cont.)

Generic task Range Average

f) Restore or shift a system to original or new state following procedures, with some checking.

0.0008-0.007 0.003

g) Completely familiar highly practiced routine task performed by well -trained individual with time to effect rec overy.

0.00008-0.009 0.0004

h) Miscellaneous task for which no description can be found 0.11-0.008 0.03

i) 2nd order error* 0.04-0.27 0.088

*2*2ndnd order errors are errors composed by a sequence of ‘simple’ human errors. order errors are errors composed by a sequence of ‘simple’ human errors.


n-Pentane fillingn-Pentane fillingEvent treeEvent tree n-pentane

Operator fills OK 0.95

Failure to detect HL 0.05

Overflow failure 0.01

Overflow functions 0.99

Alarm sounds 0.9

Alarm fails 0.1

Operator stops 0.9

Operator fails 0.1

0.95

0.00041

0.0000045

0.00005

0.0495


Task AnalysisTask AnalysisWORKSHOPWORKSHOP


TasksTasks

Task analysis or HAZOP of SOPs.Task analysis or HAZOP of SOPs.

•Uranium oxide / graphite – mixing.Uranium oxide / graphite – mixing.

•Uranium oxide / graphite – pill makingUranium oxide / graphite – pill making

•Methylal fillingMethylal filling

•Isobutane inspectionIsobutane inspection

Action items

1. Task analysis or HAZOP of SOPs.

2. Event tree for the task.


Tasks (alternative)Tasks (alternative)

Do it yourself…Do it yourself…

•Choose a task that you are familiar with.Choose a task that you are familiar with.

•Write your own SOP (name it Write your own SOP (name it draftdraft and keep it). and keep it).

•Analyze your task (choose a method as convenient).Analyze your task (choose a method as convenient).

•Rewrite the SOP (if required, and name it Rewrite the SOP (if required, and name it finalfinal).).

•Compare the draft SOP with the final SOP.Compare the draft SOP with the final SOP.

Documents

Hazmat, risk analysis division A presentation by: Dr. Alexander Cohen