Reliability Allocation and Assessment of Safety-Instrumented Systems

94 Pages·2014·3.14 MB·English

by  Jon Mikkel Haugen

Reliability Allocation and Assessment of
Safety-Instrumented Systems
Jon Mikkel Haugen
Mechanical Engineering
Submission date: December 2014
Supervisor: Marvin Rausand, IPK
Co-supervisor: Mary Ann Lundteigen, IPK
Norwegian University of Science and Technology
Department of Production and Quality Engineering

BNTNU
2014.08.25 MARIKEDA
FacultyofEngineeringScienceandTechnology
DepartmentofProduction andQualityEngineedng
MASTERTHESIS
Autumn2014
rorstud.techn.JonMlkkel Haugen
Reiabifity allocation and assessment ofsafety-instrumented systems
(Pilltellghetsallokerlngog-vurderingavinstrumenterteslkkerhetssystemer)
Reliabilityis an importantpropertyofany safety-instrumented system (515) and reliability
considerations have tobeintegrated into asafetylife cycle. Reliabilityrequirements are specifiedin
asafetyrequirementspecification(SRS) and allocatedtoequipmentand SIS subsystemsbasedon
thepotentialrisk. Thegeneralrequirementstoa515 in thevariousphases ofthe safetylifecycleare
giveninthegeneric standardIEC 61508 andin application-specificstandards suchas IEC61511 for
theprocess industry and ifiC62061 formachinerysystems. A 515 is installedto perform oneor
moresafety-instrumentedfunctions (SIPs) thatshouldbe activatedwhen specificdemandsoccur.
Whenthedemandsoccurmoreoften than once peryear, theSIPis said tobe operatingin high-
demandmode, and when thedemands occurmore seldom, the SIPisoperated in low-demandmode.
Thecurrentmasterthesis isdelimitedto low-demand modewheretheaverageprobabilityoffailure
on demand (PFD)isused asreliabilitymeasure.
Theobjectiveofthis masterthesisis tostudy and evaluatemain activitiesin thesafetylifecycleofa
low-demand SIP.
Aspartofthismaster’sthesis,thecandidateshall:
1. Give adescription ofthesafetylifecycleandthe activitiesrequired within selectedphases.
2. Listthemain elementsofatypical SRS.
3. Describerelevantapproachesforthe allocation ofthesafetyintegritylevel (511.) ofadefined
SIPand discusspros andconsrelated toeach approach.
4. Selectasuitable casestudy(in agreementwith thesupervisors) and (i) identifytherelevant
demands and SIPs and(ii)determinethe averagePFDforeach SIP.
5. Discuss whetherthecasestudysystemin item4is abletofulfil theotherrequirementsin
IEC61508 (e.g., architectural constraints)
6. Discuss uncertaintiesrelatedto thecalculated averagePFD.
Date Ourreference
Master Thesis Spring 2014 for stud. techn. Jon Mikkel Haugen 2014.08.25 MAR/KEDA
Following agreement with the supervisor(s), [lie six tasks may he given different weights.
The assignment solution must be based on any standards and practical guidelines that already exist
and are recommended. This should be done in close cooperation with supervisors and any other
responsibilities involved in the assignment. In addition it has to be an active interaction between all
parties.
Within three weeks after [lie date of the task hand—out, a pre—study report shall be prepared. The
report shall cover the following:
• An analysis ofthe work task’s content with specific emphasis ofthe areas where new
knowledge has to he gained.
• A description of the work packages that shall be ierforrned. This description shall lead to a
clear definition ofthe scope and extent ofthe total task to be performed.
• A time schedule for the project. The plan shall comprise a Gaiitt diagram with specification
ofthe individual work packages, their scheduled start and end dates and a specification of
project milestones.
The pre—study report is a part of the total task reporting. It shall be included in the final report.
Progress reports made during the project period shall also be included in the final report.
The report should be edited as a research report with a summary, table ofcontents, conclusion, list of
reference, list of literature etc. The text should be clear and concise, and include the necessary
references to figures, tables, and diagrams. It is also important that exact references are given to any
external source used in the text.
Equipment and software developed during the project is a part ofthe fulfilment ofthe task. Unless
outside parties have exclusive property rights or the equipment is physically non—moveable, it should
be handed in along with the final report. Suitable documentation tbr the correct use ofsuch material
is also required as part ofthe final report.
The student must cover travel expenses, telecommunication, and copying unless otherwise agreed.
IC the candidate encounters unibreseen difficulties in [lie work, and if these difficulties warrant a
reformation of the task, these problems should immediately be addressed to [lie Department.
The assignment text shall be enclosed and be placed immediately after the title page.
Date Ourreference
Master Thesis Spring 2014 for stud. techn. Jon Mikkel Haugen 2014.08.25 MAR/KEDA
Deadline: 12 January 2015
Two hound copies ofthe final report and one electronic (pdf-format) version are required according
to the routines given in DAIM. Please see http://www.ntnu.edu/ivmaster-s-thesis-regulations
regarding master thesis regulations and practical information, inclusive how to use DAIM.
Responsible supervisor: Professor Marvin Rausand
E-mail: [email protected]
Co supervisor: Professor Mary Ann Lundteigen
E-mail: [email protected]
DEPARTMENT OF PRODUCTION
AND QUALITY ENGINEERING
Per SchjØlberg
Associate Professor/Head ofDepartment
Marvin Rausand ,7
Responsible Supervisor

i
Preface
Thismasterthesisiswrittenduringthefallsemesterof2014inReliability,Availability,Maintain-
ability,andSafety(RAMS)attheDepartmentofProductionandQualityEngineering(IPK).This
is the final step of the five year master program in Mechanical Engineering at the Norwegian
UniversityofScienceandTechnology(NTNU).Themainmotivationforchoosingthistopicwas
togetextensiveknowledgeonsafety-instrumentedsystemsandrelevantstandards.
Thethesisismainlywrittenforpeoplewithbasicknowledgeonreliabilitytheory. However,
thestandardIEC61508isintroducedinamannerthathopefullymakesthethesisenjoyablefor
peoplewithnopriorknowledgeonthistopic.
Trondheim,2012-12-22
JonMikkelHaugen

iii
Acknowledgment
I would first of all thank my supervisor Professor Marvin Rausand. I am extremely grateful for
his intelligent and reflective inputs. His guidance has been of great importance both for this
masterthesis,butalsoonapersonallevel. Iwishhimallthebestonhisupcomingretirement.
Gratitude is also expressed to Professor Mary Ann Lundteigen for meaningful discussions and
valuableinputsonthismasterthesis.
Finally I would like to thank my friends, family and SO for supporting me and making the
masterthesisperiodaspainlessaspossible.
J.M.H