This document discusses conducting a Hazard and Operability (HAZOP) study. A HAZOP study is a systematic technique used to identify potential hazards and operating problems in a process. It involves examining process diagrams and considering how deviations from normal operating conditions could lead to hazardous situations. The document outlines the origins and development of HAZOP studies, their objectives, how and why they are used, and key aspects of conducting one such as focusing on specific nodes, parameters, and guide words to identify deviations, causes, consequences and actions.

1. 1
Hazard and Operabi l i t y
( HAZOP)
St udy
Dr. AA

2. 2
HAZOP
Fundament al

3. 3
A s cenari o…
• You and your family are on a road trip by using a
car in the middle of the night. You were replying a
text message while driving at 100 km/h and it was
raining heavily. The car hits a deep hole and one of
your tire blows. You hit the brake, but due to slippery
road and your car tire thread was thin, the car
skidded and was thrown off the road.

4. 4
Poi nt s t o 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 in the first
place?
(5 minutes for brainstorming ideas)

5. 5
What other possible accidents might
happen on the road trip?
Can we be prepared before the accident
occurs?

6. Can we make i t more sys t emat i c ?
6
Par amet er Gui dewor d Possi bl e
Causes
Consequences Act i on Saf eguar d
Car speed Too f ast
Too sl ow
Rushi ng Ski dded when
emer gency br ake
- Sl ow down
- Speed up
- ABS br ake syst em
- Saf et y bel t
- Ai r bag
Ti r e No t hr ead
Less t hr ead
Ti r e t oo ol d,
of t en speedi ng
and emer gency
br eak
Car ski dded - Check f r equent l y
- Have spar e t i r e
Wi ndow
vi si bi l i t y
Low
Ver y l ow
Rai n Cannot see t he
r oad
Car l i ght Di m
No l i ght
- St op car
- Go t o near est
gar age
- Use emer gency
si gnal
Road Wi t h hol es
Rocky
Br eaks t he car
t i r e
- Put a si gnboar d
- St r eet l i ght s
Tr avel
t i me
Ni ght
Foggy
No st r eet
l i ght
- Tr avel dur i ng
dayl i ght

7. 7
What is HAZOP?
• Systematic technique to IDENTIFY potential HAZard and
OPerating problems
• A formal systematic rigorous examination to the process and
engineering facets of a production facility
• A qualitative technique based on “ guide-word s”
to help provoke
thoughts about the way deviations from the intended operating
conditions can lead to hazardous situations or operability problems
• HAZOP is basically for safety
- Hazards are the main concern
- Operability problems degrade plant performance (product quality,
production rate, profit)
• Considerable engineering insight is required - engineers working
independently could develop different results

8. 8
Ori gi n of HAZOP
• Ini t i al l y prepared by Dr H G Lawl ey
and as soc i at es of ICI at Wi l t on i n
1960’ s .
• Subsequent l y C J Bul l ock and A J D
Jenni ng f rom ChE Dept . Tees i de
Pol yt echni c under supervi s i on of
T. A. Kl et z appl i ed t he met hod at
hi gher i ns t i t ut i on ( pos t - graduat e
l evel ) .
• In 1977, Chemi cal Indus t ri es
As soc i at i on publ i shed t he edi t ed
vers i on.

9. 9
Lat er Devel opment - HAZOP
• ICI expanded t he procedure cal l ed HAZARD
STUDY s t eps 1 t o 6.
• The ICI s i x s t eps :
 Proj ec t expl orat i on / prel imi nary proj ec t
asses sment – t o i dent i f y i nherent hazards of
proces s chemi cal s , s i t e sui t abi l i t y and
probabl e envi ronment al impac t .
 Proj ec t def i ni t i on – t o i dent i f y and reduce
si gni f i cant hazards assoc i at ed wi t h i t ems and
areas, check conf ormi t y wi t h rel evant
st andards and codes of prac t i ces .
USE CHECK LI STS

10. Lat er Devel opment - HAZOP
 Des i gn and procurement – t o exami ne t he PID
10
i n det ai l f or i dent i f i cat i on of devi at i ons
f rom des i gn i nt ent capabl e of causi ng
operabi l i t y probl ems or hazards.
 Duri ng f i nal s t ages of cons t ruc t i on – t o
check t hat al l recommended and ac cept ed
act i ons recorded i n s t eps i , i i and i i i
impl ement ed.
 Duri ng pl ant commi ss i oni ng – t o check t hat
al l rel evant s t at ut ory requi rement s have been
acknowl edges and al l i ns t al l ed saf et y sys t ems
are rel i abl y operabl e.

11. 11
Lat er Devel opment - HAZOP
 Duri ng normal operat i on, some t ime
af t er s t art - up – espec i al l y i f any
modi f i cat i on been made. To check i f
changes i n operat i on has not
i nval i dat ed t he HAZOP report of s t ep
i i i by i nt roduc i ng new hazards .
Thi s procedures are adopt ed f ul l y or
part l y by many compani es around t he
worl d.

12. 12
Objective of HAZOP
• For identifying cause and the consequences of
perceived mal operations of equipment and associated
operator interfaces in the context of the complete
system.
• It accommodates the status of recognized design
standards and codes of practice but rightly questions
the relevance of these in specific circumstances where
hazards may remain undetected.

13. • HAZOP identifies potential hazards , failures and operability
problems.
• Its use is recommended as a principal method by professional
institutions and legislators on the basis of proven capabilities for
over 40 years.
• It is most effective as a team effort consists of plant and prices
designers, operating personnel, control and instrumentation
engineer etc.
• It encourages creativity in design concept evaluation.
• Its use results in fewer commissioning and operational problems
and better informed personnel, thus confirming overall cost
effectiveness improvement.
13
How and Why HAZOP is Used

14. • Necessary changes to a system for eliminating or reducing the
probability of operating deviations are suggested by the analytical
procedure.
• HAZOP provides a necessary management tool and bonus in so far
that it demonstrates to insurers and inspectors evidence of
comprehensive thoroughness.
• HAZOP reports are an integral part of plant and safety records
and are also applicable to design changes and plant modifications,
thereby containing accountability for equipment and its associated
human interface throughout the operating lifetime.
14
How and Why HAZOP is Used

15. • HAZOP technique is now used by most major companies handling
and processing hazardous material, especially those where
engineering practice involves elevated operating parameters :
- oil and gas production
- flammable and toxic chemicals
- pharmaceuticals etc
• Progressive legislation in encouraging smaller and specialty
manufacturing sites to adopt the method also as standard
practice.
15
How and Why HAZOP is Used

16. • It emphasizes upon the operating integrity of a system, thereby
leading methodically to most potential and detectable deviations
which could conceivably arise in the course of normal operating
routine
- including "start-up " and "shut-down" procedures
- as well as steady-state operations.
• It is important to remember at all times that HAZOP is an
identifying technique and not intended as a means of solving
problems nor is the method intended to be used solely as an
undisciplined means of searching for hazardous scenarios.
16
Purpose of HAZOP

17. 17
HAZOP - Hazard and operability
HAZOP keeps all team
members focused on the
same topic and enables
them to work as a team
1 + 1 = 3
NODE: Concentrate on one location in the process
PARAMETER: Consider each process variable individually
(F, T, L, P, composition, operator action, corrosion,
etc.) GUIDE WORD: Pose a series of standard questions about deviations
from normal conditions. We assume that we know a safe “normal”
operation.

18. 18
HAZOP - Hazard and operability
NODE: Pipe after pump and splitter
PARAMETER*: Flow rate
GUIDE WORD*: Less (less than normal value)
• DEVIATION: less flow than normal
• CAUSE: of deviation, can be more than one
• CONSEQUENCE: of the deviation/cause
• ACTION: initial idea for correction/
prevention/mitigation
A group
members focus
on the same
issue
simultaneously

19. Question : How can one be certain to identify all possible deviations ?
Answer : No absolute certainty as the study is subjective and 100 %
achievement in this context can have no significance. Any individual or
corporate effort will yield results directly proportional to the
appropriate background experience of those taking part.
However, with the appropriate levels of individual project-related
expertise , such a procedure is fully capable of identifying at least 80
% of potential deviations which could rise during normal operation.
19
Relevant Question About HAZOP

20. Separate consideration is demanded for other operating modes,
such as commissioning, emergency shut-down procedures and
isolation of equipment for maintenance or modification.
Once an installation is endorsed by a properly-conducted HAZOP
study, it is these non-steady state circumstances which benefit
particularly from the technique throughout the life time of the
installation.
' Operability' must also consider the human factors involved as well
as the prediction of equipment behavior.
20
Relevant Question About HAZOP

21. Apart from the uniformity of day-to-day activities , hazards which
could cause major production interruptions and loss, possibly
leading to costly incidents, need to be identified :
• Are there chemicals used in the plant which have not been
classified as hazard because they are handled in small quantities,
are assumed harmless, or are not considered to have long-term
toxic effect upon employees?
• What hazardous materials are transported to or from the site ?
• What routes are taken ?
• What would be the consequences of accidental release?
21
Relevant Question About HAZOP

22. • What effluents are generated by the operation being carried out or
contemplated ? What regulations require to be honored for their
disposal?
• Are chemicals properly packaged & labeled?
• Are the consequences of product misuse made absolutely clear?
• Have all potential God-made events and man-made incidents (e. g
breaches of security, sabotage, electric power failure ) been
considered?
• Are the codes and standards applicable to each facility and relating
to its design , sitting and construction complied with? For example, in
pressure vessel design.
22
Relevant Question About HAZOP

23. 23
Feat ures of HAZOP St udy
Subsys t ems of i nt eres t l i ne and val ve, et c
Equi pment , Ves sel s
Modes of operat i on Normal operat i on
St art - up mode
Shut down mode
Mai nt enance /cons t ruc t i on /
i nspec t i on mode
Tri gger event s Human f ai l ure
Equi pment /i ns t rument /component
f ai l ure
Suppl y f ai l ure
Emergency envi ronment event
Ot her causes of abnor mal
oper at i on, i ncl udi ng
i nst r ument di st ur bance

24. Feat ures of HAZOP St udy
Ef f ec t s wi t hi n pl ant Changes i n chemi cal condi t i ons
Changes i n i nvent ory
Change i n chemi cal phys i cal condi t i ons
24
Hazardous condi t i ons Rel ease of mat eri al
Changes i n mat eri al hazard
charac t eri s t i c s
Operat i ng l imi t reached
Energy source exposed et c .
Correc t i ve ac t i ons Change of proces s des i gn
Change of operat i ng l imi t s
Change of sys t em rel i abi l i t y
Improvement of mat eri al cont ai nment
Change cont r ol syst em
Add/ r emove mat er i al s

25. 25
Feat ures of HAZOP St udy
How woul d hazardous Duri ng normal
operat i on
condi t i ons det ec t ed ? Upon human f ai l ure
Upon component f ai l ure
In ot her c i rcums t ances
Cont i ngency ac t i ons Improve i sol at i on
Improve prot ec t i on

26. Document s Needed f or HAZOP
26
St udy
• For Prel imi nary HAZOP
– Proces s Fl ow Sheet ( PFS or PFD )
– Des cri pt i on of t he Proces s
• For Det ai l ed HAZOP
– Pi pi ng and Ins t rument at i on Di agram ( P & ID
)
– Proces s Cal cul at i ons
– Proces s Dat a Sheet s
– Ins t rument Dat a Sheet s
– Int erl ock Schedul es
– Layout Requi rement s
– Hazardous Area Cl as s i f i cat i on
– Des cri pt i on of t he Proces s

27. 27
Bef ore Det ai l ed HAZOP
• The devel opment of t he det ai l ed P&I
Di agram i s t he l as t s t age of t he proces s
des i gn.
• The devel opment wi l l f ol l ow a normal
s t andard procedure and i nc l ude t he
f ol l owi ng cons i derat i ons :
– Bas i c proces s cont rol sys t em - t hi s i s a c l osed
l oop cont rol t o mai nt ai n proces s wi t hi n an
ac cept abl e operat i ng regi on.
– Al arm sys t em - t hi s i s t o bri ng unusual
s i t uat i on t o at t ent i on of a person moni t ori ng
t he proces s i n t he pl ant
– Saf et y i nt erl ock sys t em - t hi s i s t o s t op
operat i on or part of t he proces s duri ng
emergenc i es .
– Rel i ef sys t em - t hi s i s t o di vert mat eri al

28. 28
P&ID
• A Pi pi ng and Ins t rument at i on Di agram - P&ID, i s a
s chemat i c i l l us t rat i on of f unc t i onal rel at i onshi p of
pi pi ng, i ns t rument at i on and sys t em equi pment component s .
• P&ID represent s t he l as t s t ep i n proces s des i gn.
• P&ID shows al l of pi pi ng i nc l udi ng t he phys i cal sequence
of branches , reducers , val ves , equi pment ,
i ns t rument at i on and cont r ol i nt er l ocks.
• P&ID i s normal l y devel oped f rom proces s f l ow di agram
( PFD) .
• The P&ID are used t o operat e t he proces s sys t em.
• A proces s cannot be adequat el y des i gned wi t hout proper
P&ID.

29. P&I D
A P&ID shoul d i nc l ude: ( Basi cal l y every mechani cal aspec t of t he pl ant wi t h
29
some except i ons )
• Ins t rument at i on and des i gnat i ons
• Mechani cal equi pment wi t h names and numbers
• Al l val ves and t hei r i dent i f i cat i ons
• Proces s pi pi ng, s i zes and i dent i f i cat i on
• Mi s cel l aneous - vent s , drai ns , spec i al f i t t i ngs , sampl i ng l i nes , reducers ,
i ncreasers and swagers
• Permanent s t art - up and f l ush l i nes
• Fl ow di rec t i ons
• Int erconnec t i ons ref erences
• Cont rol i nput s and out put s , i nt erl ocks
• Int erf aces f or c l as s changes
• Sei smi c cat egory
• Qual i t y l evel
• Annunc i at i on i nput s
• Comput er cont rol sys t em i nput
• Vendor and cont rac t or i nt erf aces
• Ident i f i cat i on of component s and subsys t ems del i vered by ot hers
• Int ended phys i cal sequence of t he equi pment

30. A P&ID shoul d not i nc l ude:
• Ins t rument root val ves
• cont rol rel ays
• manual swi t ches
• equi pment rat i ng or capac i t y
• primary i ns t rument t ubi ng and val ves
• pres sure t emperat ure and f l ow dat a
• el bow, t ees and s imi l ar s t andard f i t t i ngs
• ext ens i ve expl anat ory not es
30
P&I D

31. 31
P&ID and Saf et y
• P&I Di agram
– ISA St andard
– DIN St andard
• Layers of prot ec t i on

32. • Procedure in HAZOP study consist of examining the process
and instrumentation (P&I) line diagram , process line by process
line .
• A list of guide words is used to generate deviations from
normal operation corresponding to all conceivable possibilities.
• Guide words covering every parameter relevant to the system
under review :i.e. flow rate and quality, pressure, temperature,
viscosity, components etc.
• Flowchart for application of HAZOP is shown in figure.
32
HAZOP St udy Procedure

33. 33
HAZOP St udy Fl ow Chart
Select Line
Select deviation
e. g more flow
Is Move on to next more flow possible
deviation
Is it hazardous or does it
prevent efficient operation ?
Will the operator know that
there is more flow ?
What changes in plant or method
will prevent the deviation or make
it less likely or protect against the
consequences ?
Is the cost of the change justified
?
Agree change (s)
Agree who is responsible for
action
Consider other
causes of
more flow
What change in plant
will tell him ?
Consider other
change(s) or
agreed to accept
hazard
Follow up to see action has been
taken

34. 34
Gui del i nes f or Di vi s i on
i nt o Sec t i ons
• Choi ces of l i nes – P&ID mus t be di vi ded
l ogi cal l y. Not t oo many sec t i ons . Fac t ors t o be
cons i dered :
– Each sec t i on shoul d cont ai n ac t i ve
component s , whi ch gi ves ri se t o devi at i ons .
E. g pi pi ng whi ch cont ai ns cont rol val ves can
gi ve ri se t o f l ow devi at i ons , heat exchangers
can cause T devi at i ons .
– Mat eri al s i n sec t i on – cont ai n s i gni f i cant
amount of hazardous mat eri al s .
– Sec t i on based on proces s and s t at es of
mat eri al s . Onl y 1 proces s operat i on per 1
sec t i on.

35. 35
Gui del i nes f or Di vi s i on
i nt o Sec t i ons
• General gui del i nes :
– Def i ne each maj or proces s component as a
sec t i on. Usual l y anyt hi ng as s i gned equi pment
number shoul d be cons i dered a maj or proces s
component .
– Def i ne one l i ne sec t i on between each maj or
proces s component .
– Def i ne addi t i onal l i ne sec t i ons f or each
branches of f t he mai n proces s f l ow.
– Def i ne a proces s sec t i on at each connec t i on
t o exi s t i ng equi pment .

36. 36
Gui del i nes f or Di vi s i on
i nt o Sec t i ons
• Suppl ement ary gui del i nes
– Def i ne onl y one proces s sec t i on f or equi pment
i n i dent i cal servi ce. However, pumps i n
di f f erent servi ce wi t h a common spare mus t be
t reat ed separat el y.
– Def i ne onl y one l i ne at t he end of a seri es of
component s i f t here are no ot her f l ow pat hs .
– Def i ne onl y one addi t i onal l i ne sec t i on i f
t here are al t ernat i ve f l ow pat hs , regardl es s of
how many branches t here are.

37. • Do not def i ne l i ne between maj or
equi pment i t ems i f t here are no s i ngl e
ac t i ve component s t hat coul d cause
devi at i ons .
• Do not def i ne sec t i ons f or exi s t i ng
equi pment t hat i s ups t ream of new or
modi f i ed equi pment . Addres s mal f unc t i ons
of such ups t ream equi pment as devi at i ons
i n t he new or modi f i ed equi pment .
37
Gui del i nes f or Di vi s i on
i nt o Sec t i ons

38. 38
HAZOP Study Procedure
GUIDE WORDS *
POSSIBLE CAUSES DEVIATION ( FROM DESIGN AND/OR
OPERATING INTENT )
CONSEQUENCES
ACTION(S) REQUIRED OR RECOMMENDEED

39. Guide Words
NONE No forward flow when there should be
MORE More of any parameter than there should be,
e.g more flow, more pressure, more
temperature, etc.
LESS As above, but "less of" in each instance
PART System composition difference from what it
39
should be
MORE THAN More "components" present than there should
be for example, extra phase, impurities
OTHER What needs to happen other than normal
operation, e.g. start up,shutdown, maintenance

40. Guide Words
NONE e.g., NO FLOW caused by blockage; pump failure;
40
valve closed or jammed : leak: valve open ;suction
vessel empty; delivery side over - pressurized :
vapor lock ; control failure
REVERSE e.g., REVERSE FLOW caused by pump failure : NRV
failure or wrongly inserted ; wrong routing; delivery
over pressured; back- siphoning ; pump reversed
MORE OF e.g., MORE FLOW caused by reduced delivery
head ; surging ; suction pressurised ; controller
failure ; valve stuck open leak ; incorrect instrument
reading.

41. Guide Words
MORE OF MORE TEMPERATURE, pressure caused by external
fires; blockage ; shot spots; loss of control ; foaming;
gas release; reaction;explosion; valve closed; loss of
level in heater; sun.
LESS OF e.g., LESS FLOW caused by pump failure; leak; scale in
delivery; partial blockage ; sediments ; poor suction
head; process turndown.
LESS e.g., low temperature, pressure caused by Heat loss;
vaporisation ; ambient conditions; rain ; imbalance of
input and output ; sealing ; blocked vent .
41
PART OF Change in composition high or low concentration of
mixture; additional reactions in reactor or other
location ; feed change.

42. MORE THAN Impurities or extra phase Ingress of contaminants
such as air, water, lube oils; corrosion products;
presence of other process materials due to internal
leakage ; failure of isolation ; start-up features.
OTHER Activities other than normal operation start-up and
shutdown of plant ; testing and inspection ;
sampling ; maintenance; activating catalyst; removing
blockage or scale ; corrosion; process emergency ;
safety procedures activated ; failure of power, fuel,
steam , air, water or inert gas; emissions and lack of
compatibility with other emission and effluents.
42
Guide Words

43. 43
HAZOP STUDY REPORT FORM
TITLE :
Sheet 1 of
LINE 1 :
DEVIATION
CAUSES CONSEQUENCES EXISTING PROVISIONS ACTIONS, QUESTIONS OR
RECOMMENDATIONS
HAZOP Study Form

44. HAZOP study are applied during :
• Normal operation
• Foreseeable changes in operation, e.g. upgrading, reduced
output, plant start-up and shut-down
• Suitability of plant materials, equipment and instrumentation
• Provision for failure of plant services, e. g . steam, electricity,
cooling water
• Provision for maintenance.
44
HAZOP Study

45. • HAZOP is a systematic, reasonably comprehensive and flexible.
• It is suitable mainly for team use whereby it is possible to
incorporate the general experience available.
• It gives good identification of cause and excellent identification
of critical deviations.
• The use of keywords is effective and the whole group is able to
participate.
• HAZOP is an excellent well-proven method for studying large
plant in a specific manner.
• HAZOP identifies virtually all significant deviations on the plant,
all major accidents should be identified but not necessarily their
causes.
45
Strength of HAZOP

46. • HAZOP is very time consuming and can be laborious with a
tendency for boredom for analysts.
• It tends to be hardware-oriented and process-oriented, although
the technique should be amenable to human error application.
• It tends to generate many failure events with insignificance
consequences and generate many failure events which have the
same consequences.
• It stifles brainstorming although this is not required at the late
stage of design when it is normally applied.
• HAZOP does not identify all causes of deviations and therefore
omits many scenarios.
46
Weakness of HAZOP

47. • It takes little account of the probabilities of events or
consequences, although quantitative assessment are sometime
added. The group generally let their collective experiences decide
whether deviations are meaningful.
• HAZOP is poor where multiple-combination events can have
severe effects.
• It tends to assume defects or deterioration of materials of
construction will not arise.
• When identifying consequences, HAZOP tends to encourage
listing these as resulting in action by emergency control measures
without considering that such action might fail. It tends to ignore
the contribution which can be made by operator interventions
47
Weakness of HAZOP

48. 48
Managi ng HAZOP
How to manage HAZOP

49. 49
Prel imi nary HAZOP Exampl e
TC
Cooling Coils
Monomer
Feed
Cooling Water to Sewer
Cooling
Water In
Thermocouple
Refer to reactor system shown.
The reaction is exothermic. A cooling system is
provided to remove the excess energy of reaction.
In the event of cooling function is lost, the
temperature of reactor would increase. This would
lead to an increase in reaction rate leading to
additional energy release.
The result could be a runaway reaction with
pressures exceeding the bursting pressure of the
reactor. The temperature within the reactor is
measured and is used to control the cooling water
flow rate by a valve.
Perform HAZOP Study

50. 50
Prel imi nary HAZOP on
Reac t or - Exampl e
Guide Word Deviation Causes Consequences Action
NO No cooling Temperature increase
in reactor
REVERSE Reverse cooling
flow
Failure of water
source resulting in
backward flow
MORE More cooling
flow
Instruct operators
on procedures
AS WELL AS Reactor product
in coils
Check maintenance
procedures and
schedules
OTHER THAN Another
material besides
cooling water
Water source
contaminated

51. 51
Prel imi nary HAZOP on
Reac t or – Answer
Guide Word Deviation Causes Consequences Action
NO No cooling Cooling water valve
malfunction
Temperature increase in
reactor
Install high temperature
alarm (TAH)
REVERSE Reverse cooling
flow
Failure of water source
resulting in backward
flow
Less cooling, possible runaway
reaction
Install check valve
MORE More cooling flow Control valve failure,
operator fails to take action
on alarm
Too much cooling, reactor cool Instruct operators on
procedures
AS WELL AS Reactor product
in coils
More pressure in reactor Off-spec product Check maintenance
procedures and
schedules
OTHER THAN Another material
besides cooling
water
Water source
contaminated
May be cooling inefffective
and effect on the reaction
If less cooling, TAH will
detect. If detected, isolate
water source. Back up
water source?

52. Case St udy – Shel l & Tube Heat
52
Exchanger
• Us i ng rel evant gui de works , perf orm HAZOP s t udy on
shel l & t ube heat exchanger
Process
fluid
Cooling water

53. 53
HAZOP on Heat Exchanger –
Answer 1
Guide Word Deviation Causes Consequences Action
Less Less flow of
cooling water
Pipe blockage Temperature of process
fluid remains constant
High Temperature
Alarm
More More cooling flow Failure of cooling
water valve
Temperature of process
fluid decrease
Low Temperature
Alarm
More of More pressure on
tube side
Failure of process
fluid valve
Bursting of tube Install high pressure
alarm
Contamination Contamination of
process fluid line
Leakage of tube
and cooling water
goes in
Contamination of process
fluid
Proper maintainance
and operator alert
Corrosion Corrosion of tube Hardness of cooling
water
Less cooling and crack
of tube
Proper maintainence

54. 54
HAZOP on Heat Exchanger –
Answer 2
Guide Word Deviation Causes Consequences Action
NONE No cooling water flow Failure of inlet cooling
water valve to open
Process fluid temperature is
not lowered accordingly
Install Temperature
indicator before and after
the process fluid line
Install TAH
MORE More cooling water
flow
Failure of inlet cooling
water valve to close
Output of Process fluid
temperature too low
Install Temperature
indicator before and after
process fluid line
Install TAL
LESS Less cooling water Pipe leakage Process fluid temperature too
low
Installation of flow meter
REVERSE Reverse process fluid
flow
Failure of process fluid inlet
valve
Product off set Install check valve (whether
it is crucial have to check?)
CONTAMINATION Process fluid
contamination
Contamination in cooling
water
Outlet temperature too low Proper maintenance and
operator alert

55. Consequence
55
HAZOP - Hazard and Operability
ATTITUDE CHECK
HAZOP
Nodes
Parameters
Guide
words
Deviation
All of these terms! This stupid table!
I hate HAZOPS. Why don’t we just
learn the engineering?

56. 56
I suppose that I
should have done that
HAZOP Study!

57. 57
HAZOP - Hazard and Operability
You are
responsible for the
safety team.
Without HAZOP
How will you focus all
members of a team on the
key issues in a systematic
manner?

58. 58
Case St udy
Case study hydrogen plant

59. 59
Sampl e Answers
result HAZOP reactor.doc

60. 60
HAZOP Management

61. 61
Planning for HAZOP Study
What is required?
• Define objectives and scope – define TOR and scope of work.
•To new design – applied to a detailed design.
•To existing design – identify hazards not previously
identified probably because not being HAZOPED.
•To plant modification
• Select team members. Two types of person needed :
•Detailed technical knowledge of the process.
•Those with knowledge and experience of applying highly
structured, systematic HAZOP approach.

62. 62
Pl anni ng f or HAZOP
• Prepare f or t he s t udy. Need suf f i c i ent
i nf ormat i on :
• Pr ocess Fl ow Sheet ( PFS or PFD )
• Pi pi ng and I nst r ument at i on Di agr am ( P & I D )
• Pr ocess Cal cul at i ons
• Pr ocess Dat a Sheet s
• I nst r ument Dat a Sheet s
• I nt er l ock Schedul es
• Layout Requi r ement s
• Hazar dous Ar ea Cl assi f i cat i on
• Oper at i ng i nst r uct i ons

63. 63
Pl anni ng f or HAZOP
• Prepare f or t he s t udy. Need suf f i c i ent
i nf ormat i on :
• Saf et y pr ocedur es document s
• Rel i ef / vent i ng phi l osophy
• Chemi cal i nvol ved
• Pi pi ng speci f i cat i ons
• Pr evi ous HAZOP r epor t

64. 64
Pl anni ng f or HAZOP
• Carry out t he s t udy
• Record t he resul t s ( may need a
secret ary)
• Fol l ow- up of ac t i ons not ed
– f i nal report cont ai n resol ut i on of al l
recommended ac t i ons
– mus t appoi nt someone as l eader t o check
progres s of ac t i on
– t eam may meet agai n i f answers t o
ques t i ons do not s impl y l ead t o an
ac t i on
– t eam may meet agai n i f s i gni f i cant
des i gn changes i n i nt erim report

65. 65
Team Charac t eri s t i c s
– Members share common obj ec t i ves .
– Everybody cont ri but es and knows hi s/her
rol es , not l eader dependent t oo much.
– Each members val ues and respec t s cont ri but i on
of ot hers .
– Members l earn whi l e t hey work.
– Over a peri od of t ime, i ndi vi dual
cont ri but i on l evel are more or l es s equal .
– Di sagreement are worked t hrough by
di s cus s i on.
– The use of vot i ng procedures i s spari ng and
normal l y onl y l as t resort i f hi ghl y
neces sary.
– Members enj oy t eam meet i ngs .

66. 66
Ques t i oni ng Techni ques
• Open ques t i ons
– Hel p person bei ng asked t o t hi nk – use
words how, what and why.
• Cl osed ques t i ons
– To f ocus on an i s sue or probl em. St art
wi t h words who, when, where.
– Requi red answer yes or no onl y.
• Ques t i on mi x
– Mi x between open and c l osed ques t i ons .

67. 67
Ques t i oni ng Techni ques
• Thi ngs t o avoi d
– Ambi guous or vague ques t i ons .
– Doubl e barel l ed/mul t i pl e ques t i ons .
– Long compl i cat ed ques t i ons .
– Int errogat i on t ype of ques t i ons .
– A l oaded ques t i ons – impl i ed j udgement .

68. Respons i bi l i t y of HAZOP Team
68
HAZOP leader
Members
• Plan sessions and timetable
• Control discussion
• Limit discussion
• Encourage team to draw conclusion
• Ensure secretary has time for taking note
• Keep team in focus
• Encourage imagination of team members
• Motivate members
• Discourage recriminations
• Judge importance issues

69. 69
Checkl i s t f or HAZOP Leader
• Al ways prepare s t udy program i n
advance.
• Agree on t he f ormat or f orm t o be
used.
• Prepare f ol l ow up procedures .
• Bri ef members about HAZOP duri ng
f i rs t meet i ng.
• St op t he t eam t ryi ng t o redes i gn
t he proces s .
• HAZOP i s a t eam exerc i se. Do not
l et anybody ( i nc l udi ng t he l eader
himsel f t o domi nat e) .

70. Checkl i s t f or HAZOP Leader
• If conf l i c t ari ses , handl e wi t h
care.
• Avoi d l ong di s cus s i ons by recordi ng
areas whi ch need t o be resol ved
out s i de meet i ng.
• Leader mus t be s t rong, yet
di pl omat i c .
• Speak c l earl y. Make you poi nt .
• Bet t er have experi ence worki ng as
t eam member previ ous l y.
• Do not ski p anyt hi ng…. some t ime
70
smal l t hi ngs may cause bi g

71. Respons i bi l i t y of HAZOP Team
71
HAZOP Secretary
Members
• Take adequate notes
• Record documentations
• Inform leader if more time required in taking notes
• If unclear, check wording before writing
• Produce interim lists of recommendations
• Produce draft report of study
• Check progress of chase action
• Produce final report

72. Respons i bi l i t y of HAZOP Team
72
Process Engineer
Members
• Provide a simple description
• Provide design intention for each process unit
• Provide information on process conditions and design conditions
• Provide a simple description
• Provide design intention for each process unit
• Provide information on process conditions and design conditions

73. Respons i bi l i t y of HAZOP Team
73
Members
Mechanical Design Engineer
• Provide specification details
• Provide vendor package details
• Provide equipment and piping layout information
Instrument Engineer
• Provide details of control philosophy
• Provide interlock and alarm details
• Provide info on shutdown, safety features

74. Respons i bi l i t y of HAZOP Team
Plant Engineer or Manager
• Provide information on compatibility with any existing adjacent
plant
• Provide details of site utilities and services
• Provide (for study on existing plant) any update on maintenance
access and modifications
Shift Operating Engineer or Supervisor
• Provide guidance on control instrumentation integrity from an
operating experience view point
• Provide (for study on existing plant) information on plant stability
at the specified control parameters
• Provide information on experienced operability deviations of
hazard potential
74
Members

75. Respons i bi l i t y of HAZOP Team
75
Chemist
Members
• Provide details of process chemistry
• Provide details of process hazards (polymerisations, byproducts,
corrosion etc)
Project Engineer
• Provide details of cost and time estimation and also budget
constraints.
• Ensure rapid approval if required