important (3.2)hazop

7/28/2019 Important (3.2)Hazop

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Introductionto

HAZOP Study

Dr. AAProcess Control and Safety Group


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2

A scenario

You and your family are on a road trip by using a carin the middle of the night. You were replying a textmessage while driving at 100 km/h and it was rainingheavily. The car hits a deep hole and one of your tire

blows.

You hit the brake, but due to slippery road and yourcar tire thread was thin, the car skidded and wasthrown off the road.


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3

Points to ponder

What is the cause of the accident?

What is the consequence of the event?

What can we do to prevent all those things to happen?

What other possible accidents might happen on the road trip?

Can we be prepared before the accident occurs?


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4

Can we make it more systematic?

Parameter Guideword Possible

Causes

Consequences Action Safeguard

Car speed Too fastToo slow

Rushing Skidded whenemergency brake

- Slow down- Speed up

-ABS brakesystem

-Safety belt

- Air bag

Tire No thread

Less thread

Tire too old,

often speeding

and emergency

break

Car skidded - Check frequently

- Have spare tire

Window

visibility

Low

Very low

Rain Cannot see the

road

Car light Dim

No light

-Stop car

-Go to nearest

garage

-Use emergency

signal

Road With holes

Rocky

Breaks the car

tire

- Put a signboard

-Street lights

Travel time Night

Foggy

No street light -Travel during

daylight


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Flash Drum Example

Consider the following Flash drum system. The purpose is to

separate multiple mixture of mostly A and B plus some otherheavy components to produce main product leaving the top at

75 mol % of A. Steam at 5 bar is used to bring the temperature

at the desired saturation temperature of 91 oC. The column

nominal operating pressure is 1 atm.


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6

FCV7

FCV

2

FCV

5

TI

4

FI

1

TI1

FI

6

FI

2

TI3

TI

2

TI

8

FI

8

FI

9FCV

9

FCV

8

Process Fluid Steam

V-40

E-30E-20

XAD= mol %

T9= 90oC

XAF=

50 mol %

T1=60 oC

Flash Drum Example

T4= 90oC

T4= 100oC

T7= 91oC

T8= 90oC

T3= 80oC


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Problem 1 Safety through automation

Consider the Flash Drum Plant. Proposethe required component of safety

through automation to provide safety

and operability.


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8

FCV

5

FCV

2

FCV

7

TI

4

TI

3

FI

1

TI

1

FI

6

FI2

TI

3

TI

2

TI

8

FI

8

LIC

8

FI

9

FCV

9

FCV

8

PIC

9

Process Fluid Steam

V-40

E-30

E-20

XAD= 90 mol %

XAF=

50 mol % TIC

7

Flash Drum Example

Is this good enough?


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Problem 2 - HAZOP

Consider the Flash Drum as the HAZOP Study Node, conduct HAZOP

FCV

5

FCV

2

FCV

7

TI

4

TI

3

FI

1

TI

1

FI

6

FI2

TI

3

TI

2

TI

8

FI

8

LIC

8

FI

9FCV

9

FCV

8

PIC

9

Process Fluid Steam

V-40

E-30

E-20

XAD= 90 mol %

XAF=

50 mol % TIC

7

Study node


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10

HAZOP Terminology 1 Node

A node is the specific location in the process in

which (the deviations of) the process intention areevaluated.

Examples might be: separators, heat exchangers,

scrubbers, pumps, compressors, and interconnecting

pipes with equipment Flash Drum Example

Separator as a node

Other nodes: process to process heat exchanger, utility

heat exchanger Alternatively, each process line can be taken as a node.


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Terminology 2 Design Intent

11

Description of how the process is expected to

behave at the Study Node.

This is qualitatively described as an activity (e.g.,

feed, reaction, sedimentation) and/or quantitatively

in the process parameters, like temperature, flow

rate, pressure, composition, etc.

Flash Drum Example:

To separate light components from the heavies (or to collectlight component at the top product stream)


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12

Terminology 3 - HAZOP Log Sheet

Deviation Causes Consequences Protection ActionGuideword +

Parameter

Guideword: No,

Less, More,

reverse etc

Parameter: Flow,

temperature,

level etc

Possible causes

of the deviation

Effect of deviation

of plant safety and

operability

Safety

provision

already

considered.

- Prevent

causes

- prevent/reduce

consequence

- monitor/

detect

Is the protection

sufficient?

If not, propose

suitable action

or

recommendation

Based on the selected NODE and the design intent

of the node, HAZOP study is conducted. Theoutput is summarised in HAZOP Log Sheet

Example: Simplified HAZOP Log Sheet


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Terminology 4 Deviation

13

Deviation is a way in which the process conditions

may depart from their INTENTION / DESIGN

INTENT

Expressed by combining parameters such as FLOW with

Guideword such as MORE to indicate MORE FLOW

meaning the flow is more than the design intent. Expresses as other unwanted condition such as

Contamination or corrosion.

Parameters: any process parameters such as Flow,

temperature, pressure, pH etc Guideword: NO, MORE, LESS, AS WELL AS, PART

OF, OTHER THAN, REVERSE, etc.


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The suggested guide words

No: negation of design intention; no part of design

intention is achieved but nothing else happens More: Quantitative increase

Less: Quantitative decrease

As well as: Qualitative increase where all design intention

is achieved plus additional activity

Part of: Qualitative decrease where only part of the

design intention is achieved

Reverse: logical opposite of the intention

Other than: complete substitution, where no part of the

original intention is achieved but something quitedifferent happens


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When timing matters

Add the following guide words:

Early: something happens earlier in time than intended Late: something happens later in time than intended

Before: something happens earlier in a sequence thanintended

After: something happens later in a sequence thanintended


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Terminology 5 Causes

16

The reason(s) why the DEVIATION could occur

More CAUSES can be identified for one

DEVIATION.

Flash Drum Example Causes for LESS LEVEL in V-40

FCV8 stuck open

LESS inlet Flow

MORE Flow in line 8

etcFCV

7

LIC

8

FCV

9

FCV8

PIC

9

Steam

V-40E-30

TIC

7

P8


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Terminology 6 Consequences

17

The results of the DEVIATION, in case it occurs. CONSEQUENCES may

both comprise process hazards and operability problems, like plantshutdown.

More CONSEQUENCES can follow from one cause and, in turn, one

CONSEQUENCE can have several CAUSES

Consequence for LESS LEVEL in V40 V-40 empty, leading to pump P8 running dry

No separation

FCV

7

LIC

8

FCV9

FCV8

PIC

9

Steam

V-40E-30

TIC

7

P8


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Terminology 7 Protection

Sometimes termed as Safeguard, or Existing Provision

These are facilities that help to reduce the occurrencefrequency of the DEVIATION or to mitigate its

CONSEQUENCES.

There are, in principle, five types of SAFEGUARDS:

Facilities that identify the DEVIATION. eg. alarm instrumentation and

human operator detection.

Facilities that compensate the DEVIATION, e.g., an automatic control

system

Facilities that prevent the DEVIATION to occur. e.g. an inert blanket gas

in storages of flammable substances.

Facilities that prevent a further escalation of the DEVIATION, e.g., by(total) trip of the activity (SIS facility)

Facilities that relieve the process from the hazardous DEVIATION.

These comprise for instance: pressure safety valves (PSV) and vent

systems. 18


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Terminology 7- Protection

Flash Drum Example

Protection against LESS LEVEL

in V40

LIC8 controlling the liquid level

Is it enough???

19

FCV

7

LIC

8

FCV

9

FCV8

PIC

9

Steam

V-40

E-30

TIC

7

P8


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Terminology 8 Action/Recommendation

Where a credible cause results in a negative consequence,

it must be decided whether some action should be taken. It is at this stage that consequences and associated

safeguards are considered. If it is deemed that the

protective measures are adequate, then no action need be

taken, and words to that effect are recorded in the Action

column.

Actions fall into two groups:

Actions that remove the cause.

Actions that mitigate or eliminate the consequences.

20


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Terminology 8 Action

21

Existing Protection for LESS

LEVEL is considered notadequate.

Actions Proposed

Add Low level Alarm (LAL

and LALL) Add SIS to stop pump P8

when LALL triggered.

FCV

7

LIC

8

FCV

9

FCV8

PIC

9

Steam

V-40

E-30

TIC

7

P8

T i l 9 C t


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Terminology 9 Comments

22

Various additional columns can be added to the

HAZOP Log Sheet.

Comments

Any remarks to be given to the

ACTIONS/RECOMMENDATIONS or which, in another

way, showed up during the HAZOP sessions.

Action Party is also typically identified and noted

in the HAZOP Sheet.

Fl h D L L l


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23

Flash Drum: Less Level

Deviation Causes Consequences Protection Action

Less Level

(Low Level)

Valve FCV8 stuck

openLess feed

LIC8 malfunction

Level drop

leading to dryseparator, hence

no separation

Risk of pump

running dry

(damage)

LIC8 Install LAL

Install LALLwith SIS to stop

pump P8

Note:

Sometimes, more than one consequences may arise and for each

consequence, different actions are required

Sometimes different causes require different actions

Flash Drum Example


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FCV

7

FCV

2

FCV

5

TI

4

TI

3

FI

1

TI

1

FI

6

FI

2

TI

3

TI

2

TI

8

FI

8

LIC

8

FI

9FCV

9

FCV

8

PIC

9

Process Fluid Steam

V-40

E-30

E-20

XAD= 90 mol %

XAF=50 mol % TIC

7

Flash Drum Example

Now, consider MORE PRESSURE as deviation

Fl h D MORE PRESSURE


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25

Flash Drum: MORE PRESSURE

Deviation Causes Consequences Protection Action

More Pressure

(High Pressure)

Valve FCV9 stuck

Close

PIC Malfunction

increase in

pressure leading to

risk of explosion

PIC8 Install PAH

Install Pressure

relieve valve

More

temperature inFeed

TIC7


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HAZOP STUDY TEAM

HAZOP T


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HAZOP Team

27

HAZOPLeader

HAZOPSecretary

CORE TeamProject Process Engineer

Independent Process

Engineer

Project Instrument

EngineerOperation Representative

(covering maintenance)

Specialists(as required)

Maintenance Engineer

Corrosion Engineer

Pipeline Engineer

Others

R ibilit f HAZOP T M b


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28

HAZOP leader - The leader should be independent (i.e. has no

responsibility for the process and/or the performance of operations)

Responsibility of HAZOP Team Members

Plan sessions and timetable

Agree on the nodes, study approach etc

Be thorough

Manage the HAZOP Team Control and limit discussion when necessary

Encourage team to actively participate, be creative, draw conclusion

Keep team in focus. If conflict arises, handle with care.

Do not let anybody (including the leader himself to dominate).

Judge importance issues

Stop the team trying to redesign the process.

Leader must be strong, yet diplomatic.

Responsibility of Team Members


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Responsibility of Team Members

HAZOP Secretary

Take adequate notes and record documentations

Inform leader if more time required in taking notes

Produce draft report of study

Team Members

Provide inputs based on the discipline that they

represent e.g., instrumentation, process, operation etc.

Questioning Techniques


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Open questions

Help person being asked to think use words how,what and why.

Closed questions

To focus on an issue or problem. Start with words

who, when, where.

Required answer yes or no only.

Question mix

Mix between open and closed questions.



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Things to avoid

Ambiguous or vague questions.

Double barelled/multiple questions.

Long complicated questions.

Interrogation type of questions.

A loaded questions implied judgement.


Required information


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Required information

P & IDs

Process flow diagrams Heat and Material Balances

Layouts

Logic Diagrams

Equipment Data Sheets

Material Hazard Data Sheets

Hazardous area Layouts

Modes of operation to consider


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Modes of operation to consider

The following modes of plant operation should be

considered for each node: Normal operation

Reduced throughput operation

Routine start-up

Routine shut-down

Emergency shutdown

Commissioning

Special operating modes

HAZOP meeting


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HAZOP meeting

Proposed agenda:

Introduction & presentation of participation

Overall presentation of the system/operation to beanalyzed

Description of the HAZOP approach

Presentation of the first node or logical part of theoperation

Analyze the first node/ part using the guide-words andparameters

Continue presentation and analysis (steps 4 & 5)

Coarse summary of findings

Focus should be on potential hazards as well as potentialoperational problems.

Sequence for conducting a HAZOP Study


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Does any other guideword combine with this parameter to give a meaningful deviation?

Specify the section or stage to be examined

Describe & discuss the step/ operation; determine the design envelope.

Develop & record the design intention

From the description and the design intention select a parameter

Combine this parameter with a guideword to develop a meaningful deviation

Seek a possible cause of the deviation and identify the consequences

Evaluate the safeguards and decide if they are adequate of if a change

or further study is needed.

Have all causes of this deviation been considered?

YES

Are there further parameters to consider?

Examination of the steps/ stage is complete

NO

NO

YES

YES

NO

PHASE 2: SELECT A LINE

Record

Divide section into Study nodePHASE 1: DIVIDE SECTION

PHASE 3:

ANALYSIS

PHASE 4: RECORDING

PHASE 5: REEVALUATE

Flow diagram for the HAZOP analysis The parameter-first approach

How to be a good HAZOP participant


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How to be a good HAZOP participant

Be active! Everyone contribution is important

Be to the point. Avoid endless discussion ofdetails

Be critical in a positive way not negative, butconstructive

Be responsible. He who knows should let theother know

HAZOP recording


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HAZOP recording

The findings are recorded during the meeting(s) using aHAZOP work-sheet, either by filling in paper copies, or by

using a computer connected to a projector(recommended).

The HAZOP worksheet may be different depending on thescope of the study generally the following entries(columns) are included Ref. no.

Guidewords

Deviations

Possible causes

Consequences

Safeguards Actions required (or, recommendations)

Actions allocated to (follow up responsibility)

Process HAZOP worksheet


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Process HAZOP worksheet

Hazards and Operability Review

Project Name: Date: Page of

Process :Section: Ref.

Drawing:

Item Study

node

Process

Parameter

Deviations

(guide words)

Possible

causes

Possible

consequences

Action

Required

HAZOP Worksheet


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HAZOP Worksheet

Plant Secretary:

Drawings referred to Team Names:

Equipment Properties: Flow Pressure Temperature

Equipment Tag Numbers Guide Words: No More Less Opposite Also

Other (Early Late)

Special conditions for Hazop:

none, start-up, abnormal operation, maintenance, other (details):

Line

no.

Deviation Cause Consequences Safeguard Action

39

Flash Drum Example


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40

FCV

5

FCV

2

FCV

7

TI

4

TI

3

FI

1

TI

1

FI

6

FI

2

TI

3

TI

2

TI

8

FI

8

LIC

8

FI

9FCV

9

FCV

8

PIC

9

Process Fluid Steam

V-40

E-30

E-20

XAD= 90 mol %

XAF=50 mol % TIC

7

Now, complete the HAZOP Study

Some References


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Some References

Frank P. Lees (1980). Loss Prevention in the Process Industries.

Hazard Identification, Assessment and Control. Volume 1. Butterworth

& Co (Publishers) Ltd.

Frank P. Lees (1980). Loss Prevention in the Process Industries.

Hazard Identification, Assessment and Control. Volume 2. Butterworth

& Co (Publishers) Ltd.

Frank Crawley, Malcolm Preston & Brian Tyler (2000). HAZOP: Guide tobest practice. Guidelines to best practice for the process and chemical

industries. Institution of Chemical Engineers, UK.

Risk Management Group (1992). Hazard & Operability Studies. Basic

2-day Training Course Notes. ICI Australia Engineering Pty Ltd.

Marvin Rausand (2004). HAZOP. Hazard and Operability Study.Department of Production and Quality Engineering, Norwegian

University of Science and Technology.

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