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What if Check Lists HAZOP FMEA FTA CPQRA

Quantitative Quantitative

FMEA, Failure Mode Effects Analysisis a preliminary qualitative techniquethat may require preliminaryquantitative analysis (Mini-QRA)

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Hazard Evaluation, HE, Techniques

The following are types of HE, techniques:

This presentation only considers the HAZOP technique.

Press Page Down for 9 pages of further information on HAZOPS.

2 HAZOP

HAZOP was developed by Lawley (1974) of ICI. Based on early account by Elliott & Owen (1968)

Hazop studies are carried out by an experienced, multidisciplanary team, who review all physical aspects of a process (lines, equipment, instrumentation) to discover potential hazards and operability problems using a check list approach.

The basis for a HAZOP is a critical examination of information found in a word model, a process flowsheet, a plant layout, equipment specification or a P&ID, (Piping and Instrument Drawing).

The principals of examination include: See tabs D1 to D3 for examples of computer forms.

1 Intention2 Deviation3 Causes4 Consequences

(a) hazards (b) operating difficulties

5 Safeguards6 Recommendations / Actions

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Hazards and Operability Analysis

3

NO or NOT Negation of intention No Flow of A

MORE Quantitative increase Flow of A greater than design flow

LESS Quantitative decrease Flow of A less than design flow

AS WELL AS Quantitative increase Transfer of some component additional to A

PART OF Quantitative decrease Failure to transfer all components of A

REVERSE Logical opposite of intention Flow of A in direction opposite to design direction

OTHER THAN Complete substitution Transfer of some material other than A

More recent computerization techniques use a Standard Set Of Generic DeviationsFor Specific Section Types. See Dev'ns tab for examples.

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Early HAZOP studies used the following set of Guide Words to systematically review the process:

4 Some Common HAZOP Analysis Process Parameters

Flow Time Frequency Mixing

Pressure Composition Viscosity Addition

Temperature pH Voltage Separation

Level Speed Toxicity Reaction

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5 Prepare for the review

AttitudePreparation Meeting Leadership

HAZOPReview By Documentation Follow-up

Team

Knowledge Info for studyExperience Teams HAZOP P&Ids, Layout

Experience

Table

Deviation Causes Consequences Safeguards Action

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6 HAZOP analysis method flow diagram

Select a processsection or operating step

Explain design Repeat for allintention process sections

Select a process Repeat for allvariable or task process variables

Apply guide word Repeat for allto process variable guide words

Examine Develop actionConsequences itemsassociated with

contiue page down deviation

6 con'tList possible Assess acceptabilitycauses of of risk based on deviation consequences

Identify existingsafeguards toprevent deviation

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7 Potential HAZOP Pitfalls

1 Poor understanding by management of the HAZOP procedure

An Ethylene plant has 100 P&IDs, 625 equip't items. 625 items aConsider 5 variables, Pressure, Temperature, FlowComposition and Function. 5 variables bConsider 6 Guidewords, None, More of, Less ofPart of, More than and Other than. 6 guide words cQuestions to be answered = 18750 questions d = axbxcConsider 5 minutes per question = 5 min./question eTime for ethylene plant HAZOP study = 93750 minutes f = dxe4 hour, 240 minutes sessions per day = 250 minutes/day gNo. working of days = 375 days h = f / gDays per week = 5 days/week INo. of weeks to complete HAZOP for plant = 75 weeks j = h / I

2 Inexperienced HAZOP team

3 Inadequately trained or in-experienced leader

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8 Common Mistakes

1 Failing to establish a "safe" environment for team members

2 Consequences of events not carried to conclusion.

3 Taking unwarranted credit for safeguards See example on page 9 - one page down

4 Too little credit given for safeguards

5 Maing recommendations as specific as possible

6 Poor recording of HAZOPS

7 Failure to HAZOP start-up and shut-down procedures

8 Poorly up-dated P&IDs

9 A HAZOP is performed in lieu of properly executed design reviews

10 Wrong technique for system being reviewed (See spreadsheet titled Fig 5.3)continue to page 9

9 HAZOP Example See page 8 - item No. 3

To Compressor Inlet

Teams tend to quickly identify alarms, shut-downsand controls, and claim them for safeguards.

An alarm not tested may not work when called uponInlet Line to do so.

Nuisance alarms are frequently bypassed and arenot effective as safeguards.

Often operators are not monitoring control panel.

Valve in manual Automatic control routines are often set in manualmode.

end See tab D1 for computer documentation example

FV 1

LAH

LIC 1

Dev'ns

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Table 1 Example Standard Set Of Generic Deviations For Process Section TypesSource Lessons Learned From HAZOPS Reviews of FCCUs by P.E. McCluer et al, Hydrocarbon Processing, Aug 1992, p-140-C

Tank or HeatID No. Deviation Column Vessel Line Exchanger Pump Compressor

1 High Flow X2 High Level X X3 High Interface X4 High Pressure X X X X5 High Temperature X X X X6 High Concentration X X X7 Low / No Flow X X8 Low Level X X9 Low Interface X10 Low Pressure X X X X11 Low Temperature X X X X12 Low Concentration X X X13 Reverse / Misdirected Flow X X14 Tube Leak X15 Tube Rupture X16 Leak X X X X X X17 Rupture X X X X X X

Some other typical HAZOP deviations Press Page Down

More FlowLess FlowMore PressureLess PressureMore LevelLess LevelPart of, wrong concentrationAs well as, contaminantsother than, wrong materialMore ReactionLess ReactionNo ReactionMore MixingLess MixingMore CorrosionMore ErosionSampling

D1

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Company Nova Revision 0 Date 2-Jun-97Location Corunna Dwg No. Cor -123-4567 Page 1Leader RAH Proc Des JB Research Op TechScribe GFR Instr'ts GH Electrical HH OtherProd'n PM Mech FD Safety MN Other

Node No. 1 Describe Transfer Ethane from Deethanizer to C2 KO Pot

Intention The intent is to transfer 150,000 lb/hr of C2/C2= mix at 300 psig and at -30 °F for the startup period.

Guide Wrd High Param Flow Dev'n High Flow

Possible Causes1 FV-1 Wide open23

Consequences1 High level in KO pot with liquid carry-over to compressor with serious damage to rotor. Potential hydrocarbons release.23

Safeguards1 High level alarm LAH-123

Recommendation / Actions Respib By Date1 Consider limiting flow orifice, auto SD trip on High-High level, smart check valve. 1 JB 1-Jan-992 23 3

D2

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Company Nova Revision 0 Date 2-Jun-97Location Corunna Dwg No. Cor -123-4567 Page 2Leader RAH Proc Des JB Research 0 Op Tech 0Scribe GFR Instr'ts GH Electrical HH Other 0Prod'n PM Mech FD Safety MN Other 0

Node No. 1 Describe Transfer Ethane from Deethanizer to C2 KO Pot

Intention The intent is to transfer 150,000 lb/hr of C2/C2= mix at 300 psig and at -30 °F for the startup period.00

Guide Wrd Low Param Flow Dev'n Low Flow

Possible Causes123

Consequences123

Safeguards123

Rec / Actions Respib By Date1 12 23 3

D3

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Company Revision DateLocation Dwg No. PageLeader Proc Des Research Op TechScribe Instr'ts Electrical OtherProd'n Mech Safety Other

Node No. Describe

Intention

Guide Wrd Param Dev'n

Possible Causes123

Consequences123

Safeguards123

Rec / Actions Respib By Date1 12 23 3

Chk List

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Hazard & Operability Studies Check List Example

1 Changes In Quantity a High Flow 1

b Low Flow 2 Operator error

c No Flow 3

d Reverse Flow 4

2 a 1

b 2 same as 1

c Static buildup 3 Source of Ignition, Personnel shock.

3 a 1

b Contaminants 2

4 a Testing 1

b Commissioning 2 Concentration of reactants, intermediates

c Maintenance 3

5 Hazardous Pipelines a 1

Pump racing, delivery vessel pressure lost, suction pressurized, scale dislodged, leak in heat exchanger

Loss of automatic control

Pump failure, scaling of delivery, presence of foreign body, poor suction condition, cavitation, leak in heat exchanger, drain leak, valve jammed

Pump failure, delivery vessel overpressurized, gas blockage, presence of foreign body, scale, sediment, suction vessel empty.

Failure of joint, pipe, valve, trap, bursting disc, relief valve.

Pump failure, pump reversed, delivery vessel over pressurized, poor isolation, gas locking, surging, back siphoning.

Changes in physical condition

High or Low pressure Boiling, cavitation, freezing, chemical

breakdown, flashing, condensation, sedimentation, scaling, foaming, gas release, priming, exploding, imploding. Changes in viscosity, density. External Fire, Weather conditions, Hammer.

High or Low Temperature

Changes in chemical condition

High or Low Conentration

Changes in proportion of mixture, in water or solvent content.Ingress of air, water, steam, fuel, lubricant, corrosion products, other process materials from high pressure system, leakage through heat exchangers. gas entrainment, spray, mist.

Startup and Shutdown Condiotion.

Vacuum, pressure testing with with harmless material.

Purging, venting, sweetening, drying, warming. Access, spares.

Pipeline registration

Should this pipe be considered for registration?