Plant Hazard Analysis and Safety Instrumentation Systems

1039 Pages·2017·24.52 MB·English

by  Swapan Basu

Plant Hazard Analysis
and
Safety Instrumentation Systems
Swapan Basu
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Dedicated to Gurudeb I trust
and
to all my gurus in various spheres of my life
and
my loving wife
Foreword
Thereisnofacilityintheworldwhichisfreefromhazardsandrisks.Therehavebeen
anumberofcatastrophesintheworld(e.g.,BhupalinIndia).Afterthese,peoplereal-
izedthatthereshouldhavebeenasystematicapproachtowardsafety.Eachfacilityis
differentfromothers;naturallyhazardanalyseswillbevaryinginnature.Sinceinthe
moderneraofhighcompetition,peopledependalotonelectronicinstrumentation
and control. Keeping these in mind, IEC came outwith IEC 61508and61511with
systematicapproachestowardsafetyinstrumentedsystems(SISs)andsafetyintegrity
level (SIL).
HazardanalysisandSISisavastsubjecttocoverallsectorsofindustrialfacilities.
It is indeed a good idea that the author has felt to put forward his rich industrial
experience in a single book to cover various hazard analysis methods, calculations
ofSILsfor developing SIS.
Thereareafewgoodbooksondifferenttopics,butitisfactthereisnosinglebook
tocoverbothhazardanalysismethodsaswellasdetailedSIS.Thechaptersthisbook
coversincludingriskassignmentfundamentals,hazardanalysismethods,SILcalcula-
tionstodevelopSIS,andeffectsofSISonvariouscomponentsstaringfromsensors,
fieldbus, logic solver, and final elements are really worth praising. The book is well
balanced tocoverbasic mathematicsas well as sector-wise industrial applications.
TheauthorhasrichindustrialexperienceinIndiaandabroad,andisstillintouch
with modern developments. I truly feel that the book,which is developed based on
the author’s experience, would be extremely helpful to the practicing engineers as
wellasforfreshengineers.Also,Iamgladtoknowthatthisbookhasbeenselected
by IChemE in their series ofpublications.
I wish all thesuccess for the effort ofthe author for the book.
Professor S.K. Sen
BE, PhD(LOND.) DIC(LOND.),FIE, FNAE, SMCSI,
Fellow,Imperial College,
London
xvii
Preface
Risksandhazardsareapartofeverydaylife.Anditisournaturaltendencytomake
decisionsaftercalculatingriskfortheaction.Lookingatalongdistanttrafficlight,a
drivercontrolsthespeedandappliesbrakeatthecorrecttimeandplacetostopthe
car within stop line without any jerking. However, the person may not be safe for
long!Intheareaoftechnology,too,therearehazardsandriskseverywhere;nothing
is totally free from hazards or risk. In all of industrial facilities, process plants, civil/
architectural construction sites, transportation systems, aerospace, space craft e
even for a financial decisions there will be hazards in different forms. Accordingly,
there will be associated risks in different forms and in varying nature. Therefore, it
is obvious that hazard analysisis an absolutely necessity inall spheres oflife.
The book has two parts; one part is mainly related to hazard analysis methods
applicable for all disciplines of engineering. The other part is based around recent
IEC standards for life cycle analysis for safety instrumented systems (SISs). The
bookcoversallmajorhazardanalysismethodsandsafetyinstrumentationapplicable
forallindustrialplants.ThebookenjoysgrantedpermissionfromIECSwitzerlandto
utilizesomefiguresfromtheirstandardsIEC61508and61511;thepremierinterna-
tional standardsfor E/E/PEs for SISandlife cycle methods (duly acknowledged). In
view of the total coverage of the book, international society IChemE has included
the book intheir series oftechnical books.
There are a number of books available on hazard analysis as well as quite a few
books on SIS. However, there are hardly any technical books where people get the
tastesofbothinasinglebook.Also,themajoritybooksarewiththeoreticalapproach
withhugemathematicaldetails,oronlypracticaldetailswithoutanybasicapproach.
This book endeavors to act as a balancing means between two extreme lines of
thinking, giving a comprehensive approach toward hazard analysis as well as safety
instrumented systems. The book takes into account basic mathematics, but more
emphasishasbeenputonphysicalexplanations.Hazardanalysiscoversbothqualita-
tivetype,word-basedsystems,andquantitativesystems(includinghumanerrorsanal-
ysis) have also been covered comprehensively with automated processes for hazard
analyses. Hazard analysis part will help instrumentation practicing engineers in
participating in various hazard analysis processes. For each case, both mathematical
approaches as well as physical explanations have been put forward. Step-by-step
SIS determination from various failure modes, reliability, and safety integrity level
(SIL) calculations and selections from various approaches, for example, risk matrix,
risk graph, etc. help to arrive at correct and appropriate SIL calculation. The book
comprehensively discusses each and every stage in different phases, that is, all the
aspects of life cycle process mentioned in IEC 61508 and 61511 for E/E/PEs, with
respect to continuous process and manufacturing industries. The book also covers
safety systems of batch process in line with ISA 88. It also includes an alarm as an
independent protection layer (IPL), area classification including explosion protec-
tion, fire and gas system, process shutdown (PSD) and emergency shutdown
xix
xx Preface
(ESD).Finally,adiscussiononSISwouldbeincompleteunlesscertificationmethods,
FMEDA,proof testing, and partial stroke testing,etc. are notcovered.
Detaileddiscussionsatcomponentlevelstartingfromsensors,safetyfieldbus,safe
logicsolvers,andfinalcontrolelementsareauniqueadditiontothebook.Thebook
alsocoversthesecurityaspectsofvariousnetworks,viz.firewallsandzone-conduitto
nameafew,whichisalsoanotheruniquefeatureofthebook.Thebookalsocovers
applicationofSISinvariousplantscoveringfossilfuelpowerstations,nuclearpower
stations,oilandgassectorsuchasupstream,midstream,refinery,andpetrochemicals.
There have been supplementary data and information on statistical approaches,
embedded controls, and cost impact and life cycle cost analysis to take care of
advancement in technologyandsystematic approach toward the problem.
The book is primarily meant for working professionals but budding (fresh) engi-
neers who started their career in industrial plants and process plants will be equally
benefitted. The book covers both hazard analysis and safety instrumentation from
earlystagetomostadvancedstage.Itwouldbebeneficialtoengineersfromotherdis-
ciplinesalsoinalmostallindustrialsectorsewithspecialreferencetoprocessindus-
tries. For this comprehensive coverage, the book has been selected by IChemE in
their seriesof technicalbooks.
Acknowledgments
Attheoutset,theauthorwishestoputforwardhisthanksandhisgratitudetoInter-
nationalElectrotechnical Commission (IEC) and IChemE.
TheauthoristhankfultoIECforgrantingpermissiontousesomeoftheirfigures
fromIEC61,508and61,511inthebook,andwouldliketoacknowledgeasfollows:
The author thanks the International Electrotechnical Commission (IEC) for
permission to reproduce information from its International Standards IEC
61508-1 ed.2.0 (2010), IEC 61508-3 ed.2.0 (2010), and IEC 61511-1 ed.1.0
(2003). All such extracts are copyright of IEC, Geneva, Switzerland. All rights
reserved. Further information on the IEC is available from www.iec.ch. IEC has
noresponsibilityfortheplacementandcontextinwhichtheextractsandcontents
arereproducedbytheauthor,norisIECinanywayresponsiblefortheothercon-
tentoraccuracytherein.
IEC61508-1ed.2.0“Copyright©2010IECGeneva,Switzerland.www.iec.ch”
IEC61508-3ed.2.0“Copyright©2010IECGeneva,Switzerland.www.iec.ch”
IEC61511-1ed.1.0“Copyright©2003IECGeneva,Switzerland.www.iec.ch”
TheauthorisextremelythankfultoInstitutionofChemicalEngineers(IChemE)
forselectingthebookintheirseriesofpublications.Itisagreathonor.Theauthoris
extremelygratefultoMs.AnnMarieofSoftrel(courtesySoftrelLLC)andProfessor
L.JOsterweileUniversityofMassachusettsforgrantingpermissionforutilizingtheir
tablesand figures inthe book (duly acknowledged inrespectiveplaces).
Theauthorwouldliketopaytributeandthankstohisprofessor,Dr.ShankarSen,
whocouldsparetimeingoingthroughthebookandagreedwritetheforewordforthe
book.
TheauthorwouldliketothankProf.(Dr)A.M.Ghosh,Mr.YogendraSasankar,
Mr.AsimSarkar,Mr.AjayKumarDebnath,andMs.RajlaxmiBasu,whocouldspend
theirvaluabletimeingoingthroughthewriteupandcomingoutwithvaluablesug-
gestions, and sharing a lot of information with the author, to enrich the content of
thebook.TheauthorisalsothankfultoMr.DebKumarBasuforguidinganddevel-
oping the cover design and with good suggestions which were extremely helpful in
developing various figures in AUTOCAD. While developing the book, the author
was well supported with information byMr. Sabyasachi Guha.
The author would like to thank the entire team of Elsevier, the publisher who
took all the pains in bringing up the book.
xxi
xxii Acknowledgments
Lastbutnottheleast;theauthorwouldliketothankhischildrenIdai(Raj)and
Piku (Deb) for their continuous inspiration and support. The author would like to
convey special thanks to his wife, Bani, for managing the family show with care
within limited resources and encouraging the author who had to refuse all project
works todedicate their timefor thebook.
The author sincerely acknowledges that without all this support, it would have
been impossibleto publish the book.
CHAPTER
I
Basics of Hazard, Risk
Ranking, and Safety Systems
1.0 INTRODUCTION
This chapter gives the overall view of the entire subject in short form. This will help in
understanding the subsequent details in the following chapters. Also, a few basic issues
have been detailed, such as risk ranking, and risk register. So this chapter is important
forfollowingsubsequentdiscussions.
Assets are normally acquired against a lot of efforts, toil, and monetary cost.
People always wish to protect these. Unfortunately, this is not always possible on
accountofhazardsinvariousforms.Nonedesirestolosethem,sopeoplealwaysplan
to take safety measures to protect them. Until recently, in process industry, people
would incorporate necessary safety measures in the form of protections under basic
process control systems (BPCSs). In the arena of industrial hazard and risk analysis,
“system” is defined as a subject of risk assessment, which includes mainly process,
product,facility,andenvironmentalandlogicalgroups.So,safetyassociatedwithit
needs to be treated separately from BPCS. This is more clear from subsequent dis-
cussions. Sometimes people incorporate redundancy in the system design so that in
caseoffailureofone,therewillbeothersavailableasbackup,thatis,tofallback.This
isnottruealways,asisthecasewithcommoncausefailure.Later,inthe1980speople
tried to interface safety systems to BPCS to have better connectivity and safety
controls.Initiallythesewerebasedonproprietaryprotocol,andlaterpeopleadapted
openprotocolsystems.Althoughthismadeabetterconnectivity,atthesametimeit
made the system vulnerable to external attacks such as viruses, cyber attacks, etc.
After1995,peoplefelttheneedforintegrationofsafetysystemswithBPCS,without
compromising functional independence between the two, to get best secured in-
dustrialsystems.Therefore,peoplefeltitwasnecessarytohaveastandardwhichshall
be based on safety planningand safety goals based onrisk assessment. As a result of
this, several international standards, IEC 61508, IEC 61511, ISA 84, etc. evolved.
These standards are developed mainly for electrical, electronics, and programmable
electronics(E/E/PE).Theprimaryprinciplebehindthesestandardswasthatthereisa
process which may pose risk on human, machinery, asset, and environment safety,
should anything goes wrong with the process, equipment, and/or operation. Natu-
rally,thesestandardsareaimedatprocessupset,orsystemorequipmentfailure,and
PlantHazardAnalysisandSafetyInstrumentationSystems.http://dx.doi.org/10.1016/B978-0-12-803763-8.00001-7 1
Copyright©2017ElsevierInc.Allrightsreserved.
2 CHAPTER I Basics of Hazard, Risk Ranking, and Safety Systems
allow the process safety to be managed in systematic way following a risk-based
management system.
Again, the global financial debacle in 2008 demonstrated how important risk
management is! Risk management is an increasingly important business driver, and
stakeholdersareextremelyconcernedaboutit.Slowly,riskmanagementisbecoming
a part of strategic decision-making, and/or has been incorporated as an embedded
element in routine activity. An organizational approach towards risk management
enables all concerned to consider the potential impact of all types of risks on all
processes, activities, services, and stakeholders through enterprise risk management
(ERM).Organizationswillgetbenefitfromwhatisoftencalledtheupsideofrisk.An
ERM initiative helps all concerned to know the likelihood and severity of risk
materializing as well as being better informed of strategic decisions, reduced cost of
capital (otherwise due to loss), more effective financial reporting, maintaining edge
over competitors, and ability to maintain brand value. This is also clear from the
report of Aberdeen group research on, “operational risk management (ORMe7930
Ismail)”inNovember2012,whereit hasbeenfound thatallgoodindustrialhouses
startedreceivingbenefitsfromriskmanagement.Assuch,riskmanagementisavast
areacoveringalmostallaspectsofbusiness;inordertorestrictthevolumeofthebook,
the discussion is mainly concerned with industrial plants and processes. After risk/
hazardanalysis,controlactionsneedtobetaken.Safetyinstrumentedsystems(SISs)
play a great role in mitigating technical risks in industrial plants. Since the book is
concerned with technical risk management in industrial plants, so the role of SISs
cannotbeoverestimated.AnSISconsistsofawell-engineeredhardwareandsoftware
control system used to monitor the condition of plant within the operating limit
Whenanyriskconditionarises,ittriggersanalarmandwilltaketheentiresystemto
safeconditiontomitigateallkindsofrisksasfaraspossible.Asstatedearlier,SISisa
well-engineered system so it ensures that SIS is effective in mitigating risk level at
moderate cost duringtheentire system lifeasshown inFig. I/1.0-1andI/1.0-2.
RRIISSKK AASSSSEESSSSMMEENNTT
((PPHHAA,, SSIILL DDEETTEERRMMIINNAATTIIOONN))
DDEESSIIGGNN EENNGGGG
((EEXXEECCUUTTIIOONN && EEVVAALLUUAATTIIOONN))
MMOODDIIFFIICCAATTIIOONN
IINNSSTTAALLLLTTIIOONN && CCOOMMMMIISSSSIIOONNIINNGG
((FFAATT,, SSAATT,, PPRROOOOFF TTEESSTT))
DDEECCOOMMMMIISSIIOONNIINNGG
OOPPEERRAATTIIOONN && MMAAIINNTTEENNAANNCCEE
FIGUREI/1.0-1
SafetylifecycleofSIS.