The IEC 61511 / ISA 84 Approach to Functional Safety Mike Boudreaux DeltaV SIS Brand Manager
The IEC 61511 / ISA 84 Approach to Functional Safety - ChemInnovations 2010
Sep 12, 2014
IEC 61511 and ISA 84, the modern functional safety standards for the process industries, are based on the concept of a safety instrumented function (SIF). Considering safety functions independently from each other isn't all that new, but taking a SIF-based approach to functional safety lifecycle management provides exceptional benefits in the analysis, implementation, and operation phases of a safety instrumented system. The IEC 61511 approach enables more practical safety lifecycle management, ensuring that just the right amount of technology, complexity, and effort is applied where it is needed. The result of this kind of approach is optimal safety reliability, reduced total lifecycle cost, and better protection against systematic failures that can disable even the most well designed SIL 3 rated safety instrumented system.
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The IEC 61511 / ISA 84 Approach to Functional Safety
Mike Boudreaux
DeltaV SIS Brand Manager
Process industry environment
Process
Industry
Risk to personnel,
assets, environment,
business
Fines, lawsuits,
insurability
Public perception
Unplanned shutdowns
Economic downturn
Increased complexity
Aging / unskilled workforce
Increasing ROI drives yourprocess safety needs
FallPrevention
PersonalProtectiveEquipment
StructuralDesign
Ergonomics WorkSchedules
EmployeeTraining
MechanicalIntegrity
ManagementOf Change
Policies &Procedures
InherentlySafer
Design
FunctionalSafety
RiskAssessment s
FacilitySiting
Total Recordables
EmergencyResponse
SafetyAudits
Occupationalsafety
FallPrevention
PersonalProtectiveEquipment
StructuralDesign
Ergonomics WorkSchedules
EmployeeTraining
MechanicalIntegrity
ManagementOf Change
Policies &Procedures
Process safety
Personalsafety
InherentlySafer
Design
FunctionalSafety
RiskAssessment s
FacilitySiting
Total Recordables
EmergencyResponse
SafetyAudits
Process safety
EmployeeTraining
MechanicalIntegrity
ManagementOf Change
Policies &Procedures
InherentlySafer
Design
FunctionalSafety
RiskAssessment s
FacilitySiting
EmergencyResponse
SafetyAudits
Process safety
EmployeeTraining
MechanicalIntegrity
ManagementOf Change
Policies &Procedures
InherentlySafer
Design
FunctionalSafety
RiskAssessment s
FacilitySiting
EmergencyResponse
SafetyAudits
FunctionalSafety
Functional safety
IEC 61511
PFDavg
LOPA
RRF
SIS
HAZOP
SRS
PHA
IEC 61508
FMEDA
BPCS
SIL
SIF
Safety function
Process conditions What to do SIL
SIF #1 High level Drive output 1 1
SIF #2 High pressure Drive outputs 1 + 2 3
SIF #2
SIF #1
SIL 151%
SIL 232%
SIL 38%
SIL 41%
No SIL8%
Process Industry I/O by Safety Integrity Level
Source: Exida Safety and Critical Control Systems in Process and Machine Automation July 2007
PHA
• Identify hazards• Evaluate safeguards
SRS
• Define SIF’s• Define SIL for each SIF
Design
• Specify devices• Design architecture
Verify
• Verify SIL meets SRS
PFDSIF1 = PFDPT-101 + PFDlogic solver + PFDFV-101
SIF #1
FV-101
Logic solver
PT-101
Optimized process reliability • Optimal safety integrity and availability• Meet the specific needs of the process
Flexibility to meet project needs• Staged implementation• Phased maintenance/testing
Reduced engineering and complexity• Simplify and standardize• Reduction of over-engineered designs• Isolation of process equipment
Easier regulatory compliance• Simplified management of change• Practical document management
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