Tel: (+44) 01492 879813 Mob: (+44) 07984 284642andy@abrisk.co.ukwww.abrisk.co.uk

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Task AnalysisUsing the Flow Loop Simulator

Andy Brazier

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Overview

Develop a method for performing a defined task (1 hour)Consider the potential for human error (30 minutes)Determine how you will communicate your task method to operators and prepare (1 hour)Operators carry out task (1 hour).

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Hierarchical Task Analysis

A systematic way of describing task methodsEnsures the task is properly understoodOnly includes details that are necessaryCan be performed as a group exerciseAn excellent basis for:

Analysing human performance issuesWriting proceduresDeveloping training and competence programsDesign control rooms and interface

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Stages of the analysisDefine the task titleDefine the task’s starting point as a set of preconditionsIdentify the first level of sub-tasks

Should be less than 10Identify which sub-tasks need further analysis

Depends on criticality and/or complexityAgain, less than 10 task steps for each break-downContinue adding detail where required

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Connect tanker to delivery

point

5555555

Transfer fuel from road-tanker to storage

Preconditions• Delivery from

approved supplier

• Tanker located in unloading bay

Transfer fuel using

tanker’s pump

Disconnect tanker from

delivery point

Confirm tanker is OK

to offload

Connect earth to tanker

Connect vapour

recovery hose

Connect delivery

hose between tanker & delivery

point

Open valves Check for leaks

Start tanker’s pump

Standby & monitor

throughout

When complete, stop pump and close

valves

Flow loop simulator

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Pump A

Pump B

Flow Control

Tank (1m3)

Reservoir Tank (1.5 m3)

PI

PI

TI

TT

FL1/DA/003

FL1/DA/008

FL1/DA/011

FL1/DA/016

FL1/DA/018

FL1/DA/001 FL1/DA/055A

FL1/DA/031A

FL1/DA/055B

FL1/DA/031B

FL1/DA/042

FL1/DA/013

NRV

FL1/DA/029A FL1/DA/026AFL1/DA/027A

NRV

FL1/DA/029B FL1/DA/026BFL1/DA/027B

PRV

FL1/DA/R038

PRV

FL1/DA/R039

FL1/DA/024

Return to reservoir tank

FL1/DA/TW01Liquid Supply

M

Manual valve

Motor operated valve

Non-return valve

Relief valve

PI Pressure indicator

PI

FL1/DA/054

Simplified flow

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Pump A

Pump B

Flow Control

Tank (1m3)

Reservoir Tank (1.5 m3)

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Group 1 – Start circulation

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Pump A

Reservoir Tank (1.5 m3)

Group 2 – Change circulation

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Pump B

Flow Control

Tank (1m3)

Reservoir Tank (1.5 m3)

Group 3 – Fill flow control tank to maximum level then shutdown

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Pump B

Flow Control

Tank (1m3)

Reservoir Tank (1.5 m3)

Controls and Instruments

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M

Manual valve

Motor operated valve

PI Pressure indicator

Non-return valve

Relief valve

You will need to use these to complete your task

No need to touch these

These may give some useful information in completing the task

Terminology

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Pump A

Inlet

Outlet

PI

Isolation valve

Key Requirements

Flow control tank must not go above its maximum level at any timeWhenever a pump is running

Reservoir Tank level between minimum and maximumPump inlet and outlet valves opensReservoir Tank outlet and loop valves openValve to either Reservoir or Flow tank open

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Your task analysis

Basic structureCheck it is OK to proceedSet up the loop as requiredConfirm everything is OK

Valve referencesDon’t just use Tag numbersRefer to valve list and include description and Tag number

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Human Error Analysis

A systematic way of identifying potential human errors

Making sure all credible errors are consideredRecording the possible consequencesEvaluating exiting risk control measures and opportunities for further reduction

Simple and effective method of tackling an issue that is often considered to be complex and problematic.

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First – Convert task analysis to tabular

1. Confirm tanker is OK to offload2. Connect tanker to delivery point

2.1 Connect earth to tanker2.2 Connect delivery hose between tanker & delivery point2.3 Connect vapour recovery hose

3. Transfer fuel using tanker’s pump3.1 Open valves3.2 Start tanker’s pump

Consider consequence for each step if

Omitted (not carried out)IncompletePerformed on the wrong objectMistimed (too early or late)Carried out at the wrong speed (too fast or slow)Carried out for the wrong duration (too long or too short)Performed in the wrong direction.

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20202020

Task Step Possible error Existing risk control measuresConsequence Additional

measures

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Connect earth to tanker

Action omitted -

Potential for static discharge to act as source of ignition

Failure to achieve an earth before starting transfer.

Standard practice for all tanker operations.

Consider installing interlocked earth connection.Earth

connection readily available.

212121212121

Task Step Possible error Existing risk control measuresConsequence Additional

measures

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Dis-connect tanker from delivery point

Action omitted or incomplete -

Damage to hoses, plant or tanker.

Not properly disconnected

Driver responsibilityError unlikely

None.

Action too early -Disconnect hose whilst transferring

Release of material being transferred.

Noise will alert operator to fact transfer is ongoing.

None.

How will you communicate your task?

ProcedureSimple and logicalPresented in an easy to follow formatEmphasise hazards and critical steps

Training Task objectivesHazardsCritical stepsDo they understand?

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Human performance and error avoidance tools

Recognise where errors can occur and adopt tools to minimise likelihood

Pre-job briefSTAR (Stop, Think, Act, Review)Self checkingPeer checkingProcedure use, adherence and place-keepingQuestioning attitudeClear communication.

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What you need to do now

Convert your task analysis to tabular formatComplete human error analysis for the most critical stepsDevelop a plan to communicate your task method to operators from another group.

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Practicalities

PPE

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Practicalities

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Valves

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Open Closed

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Open Closed

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