MODULE 1HAZOPTECHNIQUESHazard Operability StudiesBy B. MurtjahjantoConducted at INDORAMA, TBK

The above diagram of inter-relationships shows that there are there are four main areas of hazard study namely : Hazard analysis (HAZAN), Hazard and Operability study (HAZOP), Scenario development, Quantitative Risk Assessment (QRA) and finally Emergency Management Plan (EMP). These inter-relationships are more elaborated in the following diagram :

INTRODUCTION & OVERVIEWFormal, structured approach to identification of potential hazards and operability problemsLine by line / by equipment evaluation of the designTeam exercise - input from all engineering and design disciplines, plus operationsStructured brainstorming to look for deviations from the design intent.

EXIT"....the application of a formal systematic critical examination of the process and engineering intentions of new or existing facilities, to assess the hazard potential of mal-operation or malfunction of individual items of equipment and the consequential effects on the facility as a whole. [courtesy: Chemical Industries Association]

INTRODUCTION & OVERVIEW (CONTD.)The HAZOP method has been widely used in the process industries, particularly in the 1980s and 90s, and has developed a strong reputation as being an effective and thorough means of identifying hazards in process plants A synthetic experience that makes it almost as easy to spot problems in prospect as it is in retrospect.Technique formalized by ICI (UK) in late 60s

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HAZOPS - WHAT ?Essentially the HAZOPS procedure involves taking a full description of a process and systematically questioning every part of it to establish how deviations from the design intent can arise. Once identified, an assessment is made as to whether such deviations and their consequences can have a negative effect upon the safe and efficient operation of the plant. If considered necessary, action is then taken to remedy the situation.EXITTHE BASIC CONCEPT

HAZOPS - WHAT ? (CONTD.)This critical analysis is applied in a structured way by the HAZOP team, and it relies upon them releasing their imagination in an effort to discover credible causes of deviations. In practice, many of the causes will be fairly obvious, such as pump failure causing a loss of circulation in a cooling water facility . The great advantage of this technique is that it encourages the team to consider other less obvious ways in which a deviation may occur, however unlikely they may seem at first consideration. Much more than a mechanistic check-list type of review. The result is that there is a good chance that potential failures and problems will be identified which had not previously been experienced in the type of plant being studied.EXIT

HAZOPS - WHY ?Check the design and consider whether any of the conditions which may occur from either a mal-function or mal-operation, which may cause a general hazard to people working on the installation, to the general public or to plant and equipment;Check whether the precautions incorporated into the design are sufficient to either prevent the hazard occurring or reduce any consequence to an acceptable level;EXITHAZOP studies are mainly intended to :

HAZOPS - WHY ? (CONTD.)consider any safety interfaces which exist with other installations or parts of this installation;ensure that the plant can be started, maintained and shutdown safely, and;where appropriate recommend changes to the process design or its operation that increase process safety or enhance unit operability.

EXITHAZOP studies are mainly intended to :

HAZOPS - WHEN ? new plants where the design is nearly firm and documented;existing plants as part of a periodic hazard analysis or a management of change process. (as for e.g. changes initiated through PCOs etc)

EXITHAZOP studies are best performed on:

When a process is operating within its design envelope, the potential for hazards or operability problems does not exist. It is also a primary assumption that the original process design and the equipment standards applied are correct.EXIT

HAZOPS - HOW ? Select a section (node)Select a ParameterApply guidewords to identify potential deviationsBrainstorm all possible causes (stay within the section)Select the first identified causeDevelop ultimate potential consequence(s) (look inside and outside the section)List existing safeguards (look inside and outside the section)Develop risk rankingPropose recommendations (weigh consequences and safeguards)Repeat for each cause / deviation / parameter / sectionFollow up and recordingEXITHAZOP studies the stages in the conduct of the study

How To Lead A HAZOP His role is to:Organize a teamAct as a facilitator to bring to bear the expert knowledge of the team members in a structured interaction.Get the team to think the unthinkable.Focus more on the human element.Not to identify hazards and operability problems, but rather to ensure that such identification takes place.EXITManage the personal interactions between the team members.Obtain balanced contributions and to minimize the effect on individuals when the design is subject to criticism.

ORGANIZING A HAZOP STUDYPersons needed: ChairmanScribeProcess & Systems Engineer(s)Operations Representative(s)Other engineering disciplines (Control, Electrical, etc.)Documents needed:Design BasisP&IDsCause & Effects DiagramsOperating Philosophy/ Instructions..Dedicated room and facilitiesDedicated (available full time) team members

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ORGANIZING A HAZOP STUDY (CONTD.)Roles and responsibilities:Chairman ensures all are:familiar with technique, directs on selection of nodes, parameters, etc.ensures meeting stays on trackProduces reportScribe:records proceedings,prepares action lists after each sessionTeam members actively and freely participateRecording of Study (HAZOP Software or Manually)Assigning and close out of recommendationsFollow up by Chairman/ designated Project EngineerPrepare close out reportEXIT

Selection of a Team LeaderEXIT Ideally, he should not have been too closely associated with the project under review as there might be a risk of him not being sufficiently objective in his direction of the team.

He should be carefully chosen and be fully conversant with the Hazop methodology and is capable of ensuring smooth and efficient progress of the study

there needs to be a person appointed who will be in overall charge; with Hazop Studies this person is usually called the Chairman or Study Leader.....

Selection of a ScribeEXIT His contribution to the discussion may be minimal, as his main function during the sessions will be to record the study as it proceeds. He will therefore need to have sufficient technical knowledge to be able to understand what is being discussed.

He helps organise the various meetings, takes notes during the examination sessions and circulates the resultant lists of actions or questions.

Another important member of the team will be the Scribe or the Secretary.....

Start on time All peers No bad ideas Safe environment Everyone contributes Do not design it here Leader/facilitator limits opinions Frequent breaksTypical HAZOPS Ground RulesEXIT

Supplementary Ground RulesEXITDiversity is goodPresent your views but avoid arguing for themListen to othersLook for compromiseDo not change your views to avoid conflictBe suspicious of agreements reached too easilyAvoid majority votes, seek consensus

TERMINOLOGYSection/NodeStudy reference section of the process: used to organize the study into manageable segments IntentionsHow the process sections are expected to operateParametersProcess and operating variables such as flow, pressure and temperatureGuidewordsno more less as well as part of reverse and other thanDeviationsDepartures from the design and operating intentions (Guide word + Parameter)CausesReasons why deviations may occur (possible causes)ConsequencesResults of the unique cause - a hazard causing damage, injury, or other loss (potential consequences)SafeguardsDesign and operating features that reduce the frequency or mitigate the consequences (existing systems and procedures)Risk RankingEvaluation of the possibility that an identified consequence will occur, and will cause harmRecommendationsRecommendations for design or operating changes, or further studyEXIT

KEYWORDS/ GUIDEWORDSPrimary Keywords which focus attention upon a particular aspect of the design intent or an associated process condition or parameter. Secondary Keywords which, when combined with a primary keyword, suggest possible deviations.

EXITAn essential feature in this process of questioning and systematic analysis is the use of keywords to focus the attention of the team upon deviations and their possible causes. These keywords are divided into two sub-sets:

The entire technique of Hazops revolves around the effective use of these keywords, so their meaning and use must be clearly understood by the team.

KEYWORDS/ GUIDEWORDSFlowTemperaturePressureLevelSeparate (settle, filter, centrifuge)CompositionReactMixReduce (grind, crush, etc.) AbsorbCorrode ErodeEXITPrimary Keywords:These reflect both the process design intent and operational aspects of the plant being studied. Typical process oriented words might be as follows.

Other operational words that may be added are:DrainIsolateVentPurgeInspectMaintainStart-upShutdown

KEYWORDS/ GUIDEWORDSNo The design intent does not occur (e.g. Flow/No), or the operational aspect is not achievable (Isolate/No)LessA quantitative decrease in the design intent occurs (e.g. Pressure/Less)MoreA quantitative increase in the design intent occurs (e.g. Temperature/More)ReverseThe opposite of the design intent occurs (e.g. Flow/Reverse)AlsoThe design intent is completely fulfilled, but in addition some other related activity occurs EXITSecondary Keywords:when applied in conjunction with a Primary Keyword, these suggest potential deviations or problems. They tend to be a standard set as listed below

(e.g. Flow/Also indicating contamination in a product stream, or Level/Also meaning material in a tank or vessel which should not be there)

KEYWORDS/ GUIDEWORDSOtherThe activity occurs, but not in the way intended (e.g.

FluctuationThe design intention is achieved only part of the time

EarlyUsually used when studying sequential operations, this would indicate that a step is started at the wrong time or done out of sequenceLateAs for EarlyEXITSecondary Keywords: (Contd.)Flow/Other could indicate a leak or product flowing where it should not, or Composition/Other might suggest unexpected proportions in a feedstock)(e.g. an air-lock in a pipeline might result in Flow/Fluctuation)

SELECTING NODES, PARAMETERS AND GUIDEWORDSNodes:(discrete location on the P&ID at which the process parameters are investigated for deviations)Lines between major pieces of equipmentEquipment items (tanks/vessels, columns, reactors)Packages (compressors, chemical injection)Utilities/Services (Air, N2, Steam, Drains,Vents Flare, Sewers..)Parameters: :(Physical or chemical property associated with the process) Flow, Pressure, Temperature, reaction others Applicable to the NodeGuidewords:(Simple words used to qualify or quantify the intention and to guide and stimulate the process for identifying process hazards)No, More, Less, As well as, others Applicable to the ParameterParameter + Guideword = Potential DeviationEXIT

HAZOP REVIEW GUIDELINE TABLETYPICAL NODESEXIT

Deviations

Departure from Design

Intention

Reactor

Fired Heater

Exchanger

Column, Vessel, Tank

Pump & Compressor

Lines

USE THE DEVIATIONS BELOW FOR ALL NODES INDICATED

FLOW

No, Low, More, Reverse

X

X

X

X

X

PRESSURE

No, Lower, Higher

X

X

X

X

X

X

TEMPERATURE

Lower, Higher

X

X

X

X

X

X

LEVEL/INTERFACE

No, Lower, Higher

X

X

START-UP/SHUTDOWN

Using All the Above

X

X

X

X

X

X

CONSIDER THE FOUR DEVIATIONS BELOW FOR ALL NODES INDICATED

CONTAMINANT

More

X

X

X

X

REACTION

Low, High

X

X

X

X

TOXICITY

Sampling, Maintenance

X

X

X

X

CORROSION/EROSION

More

X

X

X

X

BRAINSTORMING CAUSESDeviations are used to help team identify causes of upsets, i.e. how does the process break down ?The same cause may apply to two or more deviationsDo not criticize causes during brainstormingDo not argue about whether or not a cause belongs in a particular deviation (no flow, less flow); develop it when it comes upDo not list the same cause twice; develop it the first time; if a new deviation triggers some thoughts for additional consequences of a previously developed scenario, go back and revise the scenarioEXIT

COMMON DEVIATIONS AND THEIR CAUSES EXIT

Sheet1

Guide Words Process ParametersNo, Not, NoneLess, Low, ShortPart ofMore, HighAs well as, AlsoReverseOther than

FlowWrong routing, blockage, blind flange left in, faulty non-return valve, burst pipe, control valve, isolation valve, pump or vessel failure.Partial blockage (filters), vessel or valves failing, leaks, loss of pump efficiency.N/AMore than 1 pump operating, reduced delivery head, increased suction pressure, other routes, exchanger tube leaks.Mis-direction/routing, leaking isolation valves (see also Composition).Syphon effect, incorrect differential pressure/routing, emergency venting, defective NRV.Wrong material (see also Composition).

PressureOpen to atmosphere.Generation of vacuum by pump drain out of vessels, cooling or condensation from vapour or gas dissolving in a liquid. Pump/compressor suction lines blocked.N/ASurge, relief, leakage from HP connection (lines and flanges), thermal, rate of pressurising lines.N/AVacuum ( see Less Pressure)N/A

TemperatureN/AFreezing, loss of pressure, loss of heating, failed exchanger tubes.N/AFouled cooler tubes, cooling water failure, failed exchanger tubes. Exothermic reaction.N/AAuto refrigeration - endothermic reactionN/A

LevelEmpty tank, vessel.Control valve failure, manual error, pump out.High or Low interface level.Control valve failure, manual error, blocked outlet.N/AN/AN/A

Composition viscosity, density, phaseMixing failure. Additive (e.g. chemical injection) failure.Poor mixing, or interruption during mixing.Passing through isolations, leaking exchanger tubes, phase change, out of spec.Excessive additives, mixing.Ingress of air, leaking isolation valves, filter failure, or carry over.Phase separation.Wrong feed material(s).

Other than / General ParametersReliefInstrumentationSamplingCorrosion / ErosionService FailuresStaticExternal conditions

Relief valve, bursting disc, location of discharge, bellows type, fire.Control, pressure, temperature and flow measurement; trips and testing, alarms, indicators, records, set points.Type, cooling of, response time.Material specifications, fluid velocities, baffles, pipe-guides, hangers, anchors, external attack.Cooling water, instrument air, steam, nitrogen or inert gas; power to machines, control circuits and computers.Electrical grounding, low conducting liquids, insulated conductors, fine strainers, relaxation, dust (pouring, bagging, sieving, etc.).Fire, weather, environmental change, impact, flood, etc.

MaintenancePurging/InertingEmergency ShutdownStart-up

Isolation, drainage, purging, cleaning, drying, slip-plating, access, catalyst change, foundations and supports.Venting and drainage, ability to maintain purge during access.Potential effect(s) of ESD on related equipment and systems.First start and following shutdown. Sequence of actions, introduction of chemicals, pressurising procedures.

Sheet2

Sheet3

DEVELOP CONSEQUENCES WITHOUT SAFEGUARDSIdentify ultimate potential consequences for each deviationCommon error by process hazards review teams is to take credit for safeguards when developing consequencesWhen developing consequences consider the following:Operator is not available or is not paying attentionControl valves are in manualAlarms and safety interlocks do not functionProcedures are not followed or are not understoodEXIT

DEVIATION FROM DESIGN INTENTDesign Intentdefines how a plant or just a part of it is expected to operate. It may be to produce a certain tonnage per year of a particular chemical, to manufacture a specified number of cars, to process and dispose of a certain volume of effluent per annum, etcbut in the vast majority of cases it would also be understood that an important subsidiary intent would be to conduct the operation in the safest and most efficient manner possible.

EXIT

DEVIATION FROM DESIGN INTENT (CONTD.)To illustrate, let us imagine that as part of the overall production requirement we needed a cooling water facility.A much simplified statement as to the design intent of this small section of the plant would be "to continuously circulate cooling water at an initial temperature of xC and at a rate of xx liters per hour".

EXITA deviation or departure from the design intent in this case would be a cessation of circulation, or the water being at too high an initial temperature. Note the difference between a deviation and its cause. In this case, failure of the pump would be a cause, not a deviation.

PRIORITY FOR SAFEGUARDSCause elimination first, Consequence mitigation secondInherent design cushion (better than minimum consensus standards)Written procedures for :Operations MaintenanceInspection TestingEXIT

PRIORITY FOR SAFEGUARDS (CONT.)TrainingHistoryPrevious incidents (lack of)Equipment inspection (i.e. clean or non corrosive service)EquipmentPSVsRedundant/ voting systemsIndependent alarms/ shutdownsControl instrumentsEXIT

QUALITATIVELY ESTIMATING RISKSLRR=risk is an assessment of how serious and how credible is each identified deviation, its causes and consequences; a combination of the likelihood and the severity of the predicted or ultimate consequencesR = S x LS=The severity of the predicted consequencesL=The likelihood of the predicted consequences developing given the safeguards that are currently in place EXIT

RISK RANKING MATRIXEXIT

Severity - Five Point Scheme for Severity Level

Class

Definition

1 V HighIn plant fatality; Public fatalities; Extensive property damage; environmental damage; Extended downtime ( > or = 2 days )

2 HighLost time injury; Public injuries or public impact; Significant property damage; Exceeds MEPA standards; Downtime ( 1 to2 days )

3 Medium Minor injury; Moderate property damage; No environmental impact; Downtime ( 4 to 24 hours ); Off-spec product

4 LowNo worker injuries; Minor property damage; No environmental impact; Downtime ( < 4 hours )

5 V LowNo worker injuries; No property damage; No environmental impact; Recoverable operational problem

Likelihood - Five Point Scheme for Likelihood

Class

Frequency of Occurrence

1 V HighPossible to occur ( < 5 years )

2 HighPossible to occur ( 5 < 15 years )

3 MediumPossible to occur under unusual circumstances ( 15 < 30 years )

4 LowPossible to occur over the lifetime of the plant ( 30 < 100 years)

5 V LowCould occur, however not likely over plant life (1 / 100 years)

Severity

1

2

3

4

5

1

1

2

3

4

5

2

2

4

6

7

8

Likelihood

3

3

6

7

8

9

4

4

7

8

9

10

5

5

8

9

10

10

HAZOPS Study Methodology In simple terms, the HAZOP study process involves applying in a systematic way all relevant keyword combinations to the plant in question in an effort to uncover potential problems. The results are recorded in columnar format under the following headings: EXITIn considering the information to be recorded in each of these columns, it may be helpful to take as an example the following simple schematic.

HAZOPS Study Methodology EXITNote that this is purely representational, and not intended to illustrate an actual system.

HAZOPS STUDY METHODOLOGY (CONTD.)Deviation The keyword combination being applied (e.g. Flow/No).Cause Potential causes which would result in the deviation occurring. (e.g. "Strainer S1 blockage due to impurities in Dosing Tank T1" might be a cause of Flow/No).Consequence The consequences which would arise, both from the effect of the deviation (e.g. "Loss of dosing results in incomplete separation in V1") and, if appropriate, from the cause itself (e.g. "Cavitation in Pump P1, with possible damage if prolonged").

EXIT

HAZOPS STUDY METHODOLOGY (CONTD.)Safeguards Any existing protective devices which either prevent the cause or safeguard against the adverse consequences would be recorded in this column. For example, you may consider recording "Local pressure gauge in discharge from pump might indicate problem was arising". Note that safeguards need not be restricted to hardware where appropriate, credit can be taken for procedural aspects such as regular plant inspections (if you are sure that they will actually be carried out!).ActionActions fall into two groups:Actions that remove the cause. Actions that mitigate or eliminate the consequences. EXIT

HAZOPS STUDY METHODOLOGY (CONTD.)Always investigate removing the cause first, and only where necessary mitigate the consequences. For example "Strainer S1 blockage due to impurities etc". we might approach the problem in a number of ways:Ensure that impurities cannot get into T1 by fitting a strainer in the road tanker offloading line. Consider carefully whether a strainer is required in the suction to the pump. Will particulate matter pass through the pump without causing any damage, and is it necessary to ensure that no such matter gets into V1. If we can dispense with the strainer altogether, we have removed the cause of the problem. Fit a differential pressure gauge across the strainer, with perhaps a high dP alarm to give clear indication that a total blockage is imminent. Fit a duplex strainer, with a regular schedule of changeover and cleaning of the standby unit.

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PREPARATORY WORKThis preparatory work will be the responsibility of the Chairman, and the requirements can be summarized as follows:EXIT

Assemble the data (PFDs, P&IDs, Layouts, C&E diagrams etc...)Understand the subject (enable him to plan a sensible strategy, duration of the review, etc.......)Subdivide the plant and plan the sequence (Split into manageable sections, endeavour to group smaller items into logical units...)Mark-up the drawings (use distinctive and separate colours, when node spans two or more drawings, the colours used should remain constant)Devise a list of appropriate Keywords Prepare Table Headings and an Agenda ( like reference drawings, parameter, node intention, session no.etc...)Prepare a timetable Select the team (chairman also to ensure the core team members are available for the duration of the review,)

RUNNING A HAZOP STUDYAfter the preparatory work, the chairman should be in a position to easily guide an efficient and comprehensive study through to a successful conclusion.However, there are certain guideline to remember:

EXITForbid team members to illustrate their ideas on the master P&IDs.( Establish the rule right at the beginning of the session)Resist temptation to hasten the process by listing potential cause/ consequences if schedule is slipping.Do not allow a separate meeting to develop, with two team members conversing in low voices at the corner of the table.Ensure that all team members participate, even those who might feel unsure of themselves.Recognize and reward with praise the team member/s who contribute to the discussion wholeheartedly and sensibly. However, do not allow them to overshadow the rest of the team.

RUNNING A HAZOP STUDY (CONTD.)EXITIf discussion wanders away from the matter under consideration, re-focus the attention of the team either by requesting that the Secretary read out what he has recorded, or by asking for an action to be formulated.The Chairman should be independent and unbiased, and should not be perceived as constantly favoring one section of the team as opposed to anotherTake as an example the situation where the client wishes to have an additional High Level Alarm, but the contractor strongly disputes its necessity. Consider the following actions: "Fit a High Level Alarm". In the view of the contractor, the Chairman has sided with the client. He may, wrongly or otherwise, perceive this to be a biased decision. The action "Justify the requirement for a High Level Alarm" is addressed to the client. The Chairman favors the contractor's argument, but is not dismissing altogether the views of the client. Both parties are likely to be content with this formula. The action "Justify the absence of a High Level Alarm" is addressed to the contractor. The Chairman favors the client's argument, but is not dismissing altogether the views of the contractor. As before, neither party will have cause to feel aggrieved.

THE REPORTEXITThe HAZOP Report is a key document pertaining to the safety of the plant. It is crucial that the benefit of this expert study is easily accessible and comprehensible for future reference in case the need arises to alter the plant or its operating conditions. The major part of such a report is the printed Minutes, in which is listed the team members, meeting dates, Keywords applied, and every detail of the study teams findings.However, with this is included a general summary. The contents of such a summary might typically be: An outline of the terms of reference and the scope of study A very brief description of the process which was studied The procedures and protocol employed. A brief description of the Action File should be included General comments Results. (usually states the number of recommended actions) Appendix (master copies of dwgs., studied, tech data used, cals produced, C&E charts, corr. bet contractor to vendor, or client to contractor etc. )

HAZOP Method Flow Chart

HAZOP : DETAILED SEQUENCE OF EXAMINATION(COURTSEY: Chemical Industry Safety and Health Council, 2011/3)EXIT

HAZOP Procedure: Flow diagramEXIT

The reasons for such widespread use of HAZOPS Although no statistics are available to verify the claim, it is believed that the HAZOP methodology is perhaps the most widely used aid to loss prevention. The reason for this can most probably be summarized as follows: It is easy to learn. It can be easily adapted to almost all the operations that are carried out within process industries. No special level of academic qualification is required. One does not need to be a university graduate to participate in a study. EXIT

HAZOP SUMMARYHAZOP is a qualitative, verbal and an interactive group process that attempts to identify hazards and subsequently recommend modifications in order to eliminate unacceptable risk situations Provides a means to reveal potential hazards and operability problems at design stage Creative approach to identifying hazardsSystematic and thoroughEXIT

HAZOP SUMMARYFormal Record of StudyMinimizes cost to implement appropriate safeguards in new or modified facilitiesParticipants gain a thorough understanding of the facility

Always Remember the primary assumption in a HAZOP study is that the original process design and the equipment standards applied are correct.

EXIT

HAZOP is an acronym for Hazards and Operability Analysis

In 1974 the repercussions of a deadly explosion at the "Nypro-Works", Flixborough, England was the catalyst for stringent hazards identification and safeguarding analyses for many chemical process facilities throughout the world. In 1975, HAZard and OPerabilitiy analysis (HAZOP), as a result of ICI's work in England, became the preferred method for hazards identification. HAZOP is a qualitative, verbal and an interactive group process that attempts to identify hazards and subsequently recommend modifications in order to eliminate unacceptable risk situations.

The "bible" on HaZOP studies was developed by the American Institute of Chemical Engineers. Contact them to obtain a copy of "Guidelines For Hazard evaluation Procedures", The Center For Chemical Process Safety, American Institute of Chemical Engineers, 1985.

Hazop studies are a method of providing a form of synthetic experience. They work by using the imagination of members of a team to visualize the ways in which a plant can malfunction or be mal-operated.The imaginations of the team members must be guided and stimulated in a systematic yet creative fashion to cover all parts of the plant and all conceivable malfunctions and mal-operations.This is achieved in what is called the examination.

Industries in which the technique is employed Hazops were initially 'invented' by ICI in the United Kingdom, but the technique only started to be more widely used within the chemical process industry after the Flixborough disaster in which a chemical plant explosion killed twenty eight people, many of which were ordinary householders living nearby. Through the general exchange of ideas and personnel, the system was then adopted by the petroleum industry, which has a similar potential for major disasters. This was then followed by the food and water industries, where the hazard potential is as great, but of a different nature, the concerns being more to do with contamination rather than explosions or chemical releases

THE BASIC CONCEPTThis critical analysis is applied in a structured way by the Hazop team, and it relies upon them releasing their imagination in an effort to discover credible causes of deviations. In practice, many of the causes will be fairly obvious, such as pump failure causing a loss of circulation in the cooling water facility mentioned above. However, the great advantage of the technique is that it encourages the team to consider other less obvious ways in which a deviation may occur, however unlikely they may seem at first consideration. In this way the study becomes much more than a mechanistic check-list type of review. The result is that there is a good chance that potential failures and problems will be identified which had not previously been experienced in the type of plant being studied.

HAZOP is an acronym for Hazards and Operability Analysis. The technique was pioneered in the UK (ICI in particular) in the '70s, and has been adopted worldwide as a standard methodology for assessing the hazards of a facility, generally a processing or production facility. This is commonly known as a Process Hazard Analysis (PHA). A HAZOP study is generally 'led' by a HAZOP Team Leader: someone who is qualified to lead these studies by nature of their training and experience. The rest of the study members may comprise process engineering, project engineering, maintenance, operations, inspection, safety, and environmental personnel familiar with the process under study. website at http://www.acutech-consulting.com/training/ - or training courses on HAZOP. Discuss your requirements with (lparchom@acutech-consulting.com) for traingn courses for HAZOP team Leader.

human element how to encourage discussion, how and when to cut off discussion, and how to handle body language and off-the-cuff comments. This monograph is written for those who are leading HAZOPs (as distinct from merely facilitating them). It provides guidance on how to organize a team, and on how to get the team members to think the unthinkable. Therefore, most of the discussion in this monograph focuses on the human element how to encourage discussion, how and when to cut off discussion, and how to handle body language and off-the-cuff comments. Some overview material regarding the mechanics of HAZOPs is provided here, but this is not an introductory guide (see Process Hazards Analysis and Process Safety Management for a complete overview of the HAZOP process). This Monograph is intended to help those leaders and teams that already have considerable experience of the method.Most of the material presented in this Monograph is built from the experience of the author, the teams with which he has worked, and on a review of the available literature. Therefore the material presented here is essentially a set of guidance and suggestions intended to help other experienced leaders develop techniques and methodologies that work for them, and for the teams that they are leading.

THE HAZOP TEAMThe team who will conduct the Hazop study should consist of personnel with a good understanding of the process and plant to be reviewed. The group should ideally contain about six members, with perhaps an absolute upper limit being set at nine. In a study in which both contractor and client are participating, it is desirable to maintain a balance between the two in terms of team membership so that neither side feels outnumbered

The participants should consist of people from a range of disciplines, and this aspect is one of the strengths of the Hazop methodology:With a team of people, each with differing backgrounds and experience, potential problems are likely to be identified which would be missed by one or two people working on their own. It is often the case that one person's solution can become a problem to another department within the project. For example, a Process Engineer conducting his own review in isolation may identify a potential problem for which he considers that another instrument and alarm would be desirable. When this requirement is passed to the Control & Instrumentation Engineer, it transpires that no suitable channels are available within the appropriate section of the electronic control system, which has already been ordered and is currently being manufactured by the vendor. A protracted inter-departmental discussion and correspondence then ensues as to possible alternative remedies, and the potential cost penalty of re-specifying the control system. All of this could have been settled within a few minutes had both departments participated in the study. A spirit of co-operation and common purpose is engendered which crosses departmental boundaries, and this will persist even after the Hazop Study has been completed. Personnel will understand better the views, concerns and constraints within which other disciplines have to work, and will take these into account when making decisions affecting the projectThe actual composition of the Hazop team will vary according to the type of plant being reviewed. One person who should always be included is a representative from Operations. He or she should have first hand experience of day-to-day operations on either the plant being reviewed, or one that is very similar in nature. The contribution of this team member to the discussion can be invaluable, as it introduces an operational perspective to other participants who may have never, for example, had to climb down into a vessel wearing breathing apparatus to carry out repairs or an inspection.To summarise, a team should be selected so that a balanced approach to the study is ensured. In addition, the intention should be that questions raised during the meeting can be answered immediately, rather than having to resort to the time consuming process of referring to outside expertise. It is not of course necessary for the same people to participate in the study from beginning to end. If the "core" of the group consisted of five people, for example, additional members could be called in from session to session as and when their particular expertise was needed.As with all group activities, there needs to be a person appointed who will be in overall charge; with Hazop Studies this person is usually called the Chairman or Study Leader. Ideally, he should not have been too closely associated with the project under review as there might be a risk of him not being sufficiently objective in his direction of the team. As the Chairman's role is of vital importance in the smooth and efficient progress of the study, he should be carefully chosen and be fully conversant with the Hazop methodology.Another important member of the team will be the Secretary. His contribution to the discussion may well be minimal, as his main function during the sessions will be to record the study as it proceeds. He will therefore need to have sufficient technical knowledge to be able to understand what is being discussed.

Note that some words may be included which appear at first glance to be completely unrelated to any reasonable interpretation of the design intent of a process. For example, one may question the use of the word Corrode, on the assumption that no one would intend that corrosion should occur. Bear in mind, however, that most plant is designed with a certain life span in mind, and implicit in the design intent is that corrosion should not occur, or if it is expected, it should not exceed a certain rate. An increased corrosion rate in such circumstances would be a deviation from the design intent.

This latter type of Primary Keyword is sometimes either overlooked or given secondary importance. This can result in the plant operator having, for example, to devise impromptu and sometimes hazardous means of taking a non-essential item of equipment off-line for running repairs because no secure means of isolation has been provided. Alternatively, it may be discovered that it is necessary to shut down the entire plant just to re-calibrate or replace a pressure gauge. Or perhaps during commissioning it is found that the plant cannot be brought on-stream because no provision for safe manual override of the safety system trips has been provided.

It should be noted that not all combinations of Primary/Secondary words are appropriate. For example, Temperature/No (absolute zero or -273C !) or Pressure/Reverse could be considered as meaningless.

With this in mind equipment is designed and constructed which, when it is all assembled and working together, will achieve the desired goals. However, in order to do so, each item of equipment, each pump and length of pipework, will need to consistently function in a particular manner. It is this manner which could be classified as the 'design intent' for that particular item.

Consequence: Always be explicit in recording the consequences. Do not assume that the reader at some later date will be fully aware of the significance of a statement such as "No dosing chemical to Mixer". It is much better to add the explanation as set out above.Consequence: Always be explicit in recording the consequences. Do not assume that the reader at some later date will be fully aware of the significance of a statement such as "No dosing chemical to Mixer". It is much better to add the explanation as set out above.Actions: 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.

Consequence: Always be explicit in recording the consequences. Do not assume that the reader at some later date will be fully aware of the significance of a statement such as "No dosing chemical to Mixer". It is much better to add the explanation as set out above.Actions: 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.

Three notes of caution need to be borne in mind when formulating actions. Do not automatically opt for an engineered solution, adding additional instrumentation, alarms, trips, etc. Due regard must be taken of the reliability of such devices, and their potential for spurious operation causing unnecessary plant down-time. In addition, the increased operational cost in terms of maintenance, regular calibration, etc. should also be considered (the lifetime cost of a simple instrument will be at least twice its purchase price for more complex instrumentation this figure will be significantly greater). It is not unknown for an over-engineered solution to be less reliable than the original design because of inadequate testing and maintenance.Finally, always take into account the level of training and experience of the personnel who will be operating the plant. Actions which call for elaborate and sophisticated protective systems are wasted, as well as being inherently dangerous, if operators do not, and never will, understand how they function. It is not unknown for such devices to be disabled, either deliberately or in error, because no one knows how to maintain or calibrate them.

Assemble the dataAll relevant documentation should be collected beforehand. Typically this might consist of:A Process Flow Diagram. A comprehensive Process Description containing operating parameters, flow rates, volumes, etc., as well as a brief summary of how each plant item functions. P&IDs. Cause & Effect Charts setting out how control and trip systems operate. Details of vendor packages if available. Plant layout diagrams. Understand the subjectThe Chairman should take as much time as is necessary to gain a good understanding of how the plant is meant to operate, by studying the assembled data and if necessary talking to the design personnel involved. As he performs this task, it is very likely that he will notice potential problem areas. Private notes should be made of these, as they might possibly be missed during the course of the study. In such an event, it can only serve to enhance the Chairman's standing if he demonstrates his grasp of the subject by pointing out potential problems that the team have overlooked.This stage of preparation is perhaps the most important, because it is the foundation upon which the other steps in the preparation process will be built. Without a reasonable understanding of how the plant functions, it will be impossible to plan a sensible study strategy, decide how long the review is likely to take, or who needs to be included in the study team.Some proponents of the Hazop methodology state that there is no need for the Chairman to have any knowledge of the plant being reviewed, his function being only to ensure that the meeting progresses smoothly. An analogy to this approach would be a leader attempting to guide an expedition without a map, no plan of action other than to get to the destination, and with no knowledge of the terrain to be traversed. Such a leader would command very little respect from other members of the team, and at the first sign of trouble he would likely be sidelined and marginalised by those with a better understanding of the situation. Once that has happened it will be almost impossible for him to regain control of the group.Subdivide the plant and plan the sequenceIn all but the simplest of plants, it is too much to expect any study team to deal with all aspects and operations in the process simultaneously. Therefore, it must be split into manageable sections (referred to as Tables because of the tabular means of recording the study). Also, the sequence in which these sections are studied is important.With continuous plant, one usually progresses from upstream to downstream, with services such as drains, vent headers, instrument air, cooling water, etc. being considered separately and last. With regard to splitting the plant into sections, there is no need to consider each line and every single minor item of equipment under a separate Table. This will be wasteful of time, and boring and tedious for the team.Instead, endeavour to group smaller items into logical units. Therefore, a minor pump with its suction, discharge and kick-back lines might be grouped together in a Table. However, with a major compressor, the recycle line and its in-line cooler should perhaps be studied separately. Also, when studying a vessel the Table should encompass those inlet/outlet lines up to and including any control/isolation valve/s, all level bridles, as well as vent lines up to the PSV.If a number of streams converge on a vessel, the study sequence should if at all possible deal with all of those streams before the vessel is considered. The rule is "never study a vessel until the incoming deviations are known".With batch operations, an entirely different approach is needed. In such a case the plant drawings are an accessory rather than the prime focus of the study. Of greater importance instead will be a detailed flowchart or operational sequence of steps to be accomplished. It is these batch sequences which will need to be split into manageable sections, and keywords may well target sequential operations such as Prepare, Charge, React, Transfer, Centrifuge, Dry etc. This methodology is required because an individual plant item is very likely to be put into differing states and serve different purposes at various stages of the sequence.Mark the drawingsWhen the study strategy has been decided, the plant items encompassed by each Table should be marked in distinctive and separate colours, with the Table Numbers alongside in the same colour. Lines should be paralleled, and equipment and vessels outlined in the chosen colour. Where a Table spans two or more drawings, the colour used should remain constant.This prior marking is a departure from the more usual practise of doing such work whilst the study progresses. However, it serves two purposes. Firstly, it will save time during the meeting, both in the actual marking and the discussion as to where a Table should begin and end. Secondly, the Chairman will be assured that in planning the study strategy nothing has been inadvertently missed.Devise a list of appropriate KeywordsHaving completed the work above, it will be a simple matter to formulate a comprehensive list of the Keywords required to cover all aspects of the process to be studied.Some companies, because most of the plant that they operate is of a similar nature, will have a standard set of Keywords. Such a list should be checked to ensure that it is covers all aspects of the system to be studied. Any redundant Keywords should be removed. For example, if the subject of the review is to be a pumping station, the inclusion of a keyword such as 'Absorb' is unnecessary.The finalised list should be duplicated and a copy given to every team member. Also included should be a schedule of appropriate keyword combinations (i.e. which Secondary keywords will be applied with each Primary keyword). Where there are likely to be semantic problems as to what meaning/s a particular combination is intended to convey, then a full explanation should be given.When devising the list, bear in mind that the smaller the number of words utilised, the more speedy the study. That is not to say that aspects of the process should be discounted. Instead, to illustrate what is meant, imagine a plant containing a separation vessel, some pump suction filters, and an environmental scrubber. Rather than have three keywords 'Separate', 'Filter', 'Absorb', have instead one keyword 'Separate'... that, after all, is the basic function of all those equipment items. Similarly, 'Temperature' can cover heat transfer aspects of Heaters, Coolers, and Heat Exchangers.Prepare Table Headings and AgendaTable Headings reference the relevant drawings, and contain a brief description of the design intent of the relevant plant section, with process parameters, flow rates, and any other potentially informative details.The agenda is a list of those headings. A copy should be handed to each team member. In addition to being informative and an aid to full participation, it will serve to put into perspective the amount of work to be accomplished in the time allotted. Hopefully this will induce an appropriate sense of urgency.Prepare a timetableFor all but a one day study, the Chairman should devise a timetable showing what needs to be accomplished at each study meeting if the schedule is to be maintained. In devising this schedule he will need to call upon his experience when assessing how much time the review will take. A great deal will depend upon the complexity of the plant as well as the experience of the team.As a rough guide, with straightforward plant and with P&IDs which are not too 'cluttered', on average three drawings can be studied in a day. If the system to be reviewed is complex, or if each P&ID seems to have been drawn with the intention of not wasting any space (i.e. as many plant items as would fit are included on the drawing), then almost certainly only two or perhaps even one drawing will be completed in a day.Be prepared for time slippage at the start of the study. Progress is always slow to begin with, whilst the team are acclimatising themselves to this novel role of casting critical eyes over their own or their colleague's design efforts. After the first day everything will speed up, and the schedule should be on target by the end of the week. Do not, however, allow the timetable to reflect this expectation of a slow start... better for the team to realise that they must increase their efforts, rather than go home thinking that this first slow day is the norm.Select the teamHaving gained a good appreciation of what will be involved in the study, both in terms of content and timetable, the Chairman can ensure that the core team members have suitable expertise and will be available for the duration of the review. In addition, he can also ascertain which personnel with additional expertise are likely to be needed during the course of the meetings, and when their assistance will be required. With regard to the latter aspect, in certain circumstances the study sequence may need to be tailored around the availability of such personnel.RUNNING A HAZOP STUDYAfter all the above preparation, the Chairman should be in a position to easily guide an efficient and comprehensive study through to a successful conclusion. However, there are a few guidelines to remember:It is always a temptation for team members to illustrate their ideas by quickly drawing on the master P&ID which has been so painstakingly marked up. Establish the rule right at the beginning that this is forbidden, even in pencil. Similarly, with tie-ins and vendor packages, a team member may endeavour to help by roughly illustrating the upstream/downstream plant or the internal workings of the package. Be firm in the rejection of such help... it is dangerous to pretend to have studied something when all that is available is a few scribblings on a sheet of paper. If the schedule is slipping, resist the temptation to hasten the process by listing potential causes/consequences yourself. All that results is that the team sits back and listens to you dictating to the Secretary, and they will continue to do so until you force them to participate again. Do not allow a separate meeting to develop, with two team members conversing in low voices at the corner of the table. If this happens, stop the general discussion and ask them to share with the rest of the team the benefit of their deliberations (always assume that they are discussing something directly relevant to the study, although the likelihood is otherwise). This will usually elicit an apology and bring them back to full participation. If they persist, request that the rest of the team members be completely silent whilst the private discussion continues. If even this does not produce the required result, call a coffee break. Then speaking privately to the persons concerned, politely but firmly insist that they leave the meeting. Such members usually have nothing to contribute to the study, and they will only irritate and demotivate the remainder of the team. Ensure that all team members participate, even those who might well feel unsure of themselves. Do this by asking questions such as "Do you agree with that solution, Bob?", or "What severity would you attach to this consequence, Fred?". Alternatively, and less potentially contentious, you could request "John, could you help the Secretary by summarising in a few words the agreed action". Once such team members realise that they are not going to be contradicted as soon as they open their mouths, they participate to the best of their ability. Recognise and reward with praise the team member/s who contribute to the discussion wholeheartedly and sensibly. However, do not allow them to overshadow the rest of the team. If discussion wanders away from the matter under consideration, re-focus the attention of the team either by requesting that the Secretary read out what he has recorded, or by asking for an action to be formulated. The latter usually concentrates the mind and encourages the team members to get to the heart of the problem. Where a particularly intractable problem arises, or consequences of a serious nature are uncovered, too often an inordinate amount of time is devoted to formulating potential remedies. Solutions and counter solutions are proposed and discussed, there is much speculation as to costs and other related aspects, and generally no satisfactory conclusion is reached. Before too much time is wasted, such situations should be dealt with by placing an action upon a specific person to investigate and report upon what alternatives are available, together with the advantages/disadvantages of each. Any discussion, gathering of additional data, reliability calculations, etc. can thereby be accomplished outside of the Hazop meeting, allowing the team to progress steadily with the review. The Chairman should be independent and unbiased, and should not be perceived as constantly favouring one section of the team as opposed to another. This is of particular importance when personnel from both client and contractor are participating. If a difficult situation arises, where, for example, there is a heated dispute over whether an action should be undertaken, in some cases one of the parties to the dispute will request that the Chairman makes the final decision. If, in the Chairman's estimation, the reasons on one side of the argument are so strong as to be indisputable, then he should say so. On the other hand, should the situation be finely balanced, then the dispute can be defused by careful wording of an action. Take as an example the situation where the client wishes to have an additional High Level Alarm, but the contractor strongly disputes its necessity. Consider the following actions: "Fit a High Level Alarm". In the view of the contractor, the Chairman has sided with the client. He may, wrongly or otherwise, perceive this to be a biased decision. The action "Justify the requirement for a High Level Alarm" is addressed to the client. The Chairman favours the contractor's argument, but is not dismissing altogether the views of the client. Both parties are likely to be content with this formula. The action "Justify the absence of a High Level Alarm" is addressed to the contractor. The Chairman favours the client's argument, but is not dismissing altogether the views of the contractor. As before, neither party will have cause to feel aggrieved. By effectively postponing a final decision until a later review of Action Responses, it is often the case that the two sides will get together after passions have cooled to discuss the matter rationally. Almost invariably the situation will then be amicably resolved

RUNNING A HAZOP STUDYAfter all the above preparation, the Chairman should be in a position to easily guide an efficient and comprehensive study through to a successful conclusion. However, there are a few guidelines to remember:It is always a temptation for team members to illustrate their ideas by quickly drawing on the master P&ID which has been so painstakingly marked up. Establish the rule right at the beginning that this is forbidden, even in pencil. Similarly, with tie-ins and vendor packages, a team member may endeavour to help by roughly illustrating the upstream/downstream plant or the internal workings of the package. Be firm in the rejection of such help... it is dangerous to pretend to have studied something when all that is available is a few scribblings on a sheet of paper. If the schedule is slipping, resist the temptation to hasten the process by listing potential causes/consequences yourself. All that results is that the team sits back and listens to you dictating to the Secretary, and they will continue to do so until you force them to participate again. Do not allow a separate meeting to develop, with two team members conversing in low voices at the corner of the table. If this happens, stop the general discussion and ask them to share with the rest of the team the benefit of their deliberations (always assume that they are discussing something directly relevant to the study, although the likelihood is otherwise). This will usually elicit an apology and bring them back to full participation. If they persist, request that the rest of the team members be completely silent whilst the private discussion continues. If even this does not produce the required result, call a coffee break. Then speaking privately to the persons concerned, politely but firmly insist that they leave the meeting. Such members usually have nothing to contribute to the study, and they will only irritate and demotivate the remainder of the team. Ensure that all team members participate, even those who might well feel unsure of themselves. Do this by asking questions such as "Do you agree with that solution, Bob?", or "What severity would you attach to this consequence, Fred?". Alternatively, and less potentially contentious, you could request "John, could you help the Secretary by summarising in a few words the agreed action". Once such team members realise that they are not going to be contradicted as soon as they open their mouths, they participate to the best of their ability. Recognise and reward with praise the team member/s who contribute to the discussion wholeheartedly and sensibly. However, do not allow them to overshadow the rest of the team. If discussion wanders away from the matter under consideration, re-focus the attention of the team either by requesting that the Secretary read out what he has recorded, or by asking for an action to be formulated. The latter usually concentrates the mind and encourages the team members to get to the heart of the problem. Where a particularly intractable problem arises, or consequences of a serious nature are uncovered, too often an inordinate amount of time is devoted to formulating potential remedies. Solutions and counter solutions are proposed and discussed, there is much speculation as to costs and other related aspects, and generally no satisfactory conclusion is reached. Before too much time is wasted, such situations should be dealt with by placing an action upon a specific person to investigate and report upon what alternatives are available, together with the advantages/disadvantages of each. Any discussion, gathering of additional data, reliability calculations, etc. can thereby be accomplished outside of the Hazop meeting, allowing the team to progress steadily with the review. The Chairman should be independent and unbiased, and should not be perceived as constantly favouring one section of the team as opposed to another. This is of particular importance when personnel from both client and contractor are participating. If a difficult situation arises, where, for example, there is a heated dispute over whether an action should be undertaken, in some cases one of the parties to the dispute will request that the Chairman makes the final decision. If, in the Chairman's estimation, the reasons on one side of the argument are so strong as to be indisputable, then he should say so. On the other hand, should the situation be finely balanced, then the dispute can be defused by careful wording of an action. Take as an example the situation where the client wishes to have an additional High Level Alarm, but the contractor strongly disputes its necessity. Consider the following actions: "Fit a High Level Alarm". In the view of the contractor, the Chairman has sided with the client. He may, wrongly or otherwise, perceive this to be a biased decision. The action "Justify the requirement for a High Level Alarm" is addressed to the client. The Chairman favours the contractor's argument, but is not dismissing altogether the views of the client. Both parties are likely to be content with this formula. The action "Justify the absence of a High Level Alarm" is addressed to the contractor. The Chairman favours the client's argument, but is not dismissing altogether the views of the contractor. As before, neither party will have cause to feel aggrieved. By effectively postponing a final decision until a later review of Action Responses, it is often the case that the two sides will get together after passions have cooled to discuss the matter rationally. Almost invariably the situation will then be amicably resolved

THE REPORTThe Hazop Report is a key document pertaining to the safety of the plant. The number of man-hours spent on the study is usually considerable. It is crucial that the benefit of this expert study is easily accessible and comprehensible for future reference in case the need arises to alter the plant or its operating conditions.The major part of such a report is of course the printed Minutes, in which is listed the team members, meeting dates, Keywords applied, and of course every detail of the study teams findings. However, it is usual to include with this a general summary. The contents of such a summary might typically be:An outline of the terms of reference and scope of the study. A very brief description of the process which was studied. The procedures and protocol employed. The Keyword combinations applied should be listed, together with the explanatory meanings given to the team at the start of the study. Also the fact that Action Sheets have been produced and responses will be recorded should be explained. A brief description of the Action File (described in the following section) should be included. General comments. If, for example, the team were assured that high point vents and low point drains would be universally provided, mention that statement and its source. If certain details of vendor packages were not available, explain and list the items which were not reviewed. Results. This usually states the number of recommended actions. Also included in the Hazop Report would be an Appendix containing:Master copies of the drawings studied. Copies of technical data used. Cause and Effect charts (i.e. matrices showing the executive action of safety related instruments and trips). Any calculations produced. Relevant correspondence between departments, from contractor to vendor, or client to contractor. Each of the above should be signed and dated by the Chairman.

Considering all Keywords - The Hazop procedure Having gone through the operations involved in recording a single deviation, these can now be put into the context of the actual study meeting procedure. From the flow diagram below it can be seen that it is very much an iterative process, applying in a structured and systematic way the relevant keyword combinations in order to identify potential problems.