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CDOIF
Chemical and Downstream Oil
Industries Forum
CDOIF is a collaborative venture formed to agree strategic areas for
joint industry / trade union / regulator action aimed at delivering
health, safety and environmental improvements with cross-sector
benefits.
Guideline – Demonstrating Prior Use v4
Page 3 of 30
Contents
1.
EXECUTIVE SUMMARY........................................................................................................ 4
2.
INTRODUCTION AND SCOPE.............................................................................................. 5
2.1
Safety Integrity Levels in BS EN 61511 ...................................................................... 5
2.2
Hardware Fault Tolerance .......................................................................................... 6
3.
PRIOR USE - DEFINITION .................................................................................................... 9
4.
DEMONSTRATING PRIOR USE ......................................................................................... 10
4.1
Manufacturer’s quality, management and configuration management systems ........ 10
4.2
Identification and specification of the components or subsystems ............................ 12
4.3
Demonstration of the performance of the components or subsystems in similar
operating profiles and physical environments ........................................................... 12
4.4
Volume of the operating experience ......................................................................... 13
Appendix A
Failure rate calculations............................................................................................ 15
A.1
Failure rate ............................................................................................................... 15
A.2
Calculating failure rates ............................................................................................ 16
A.2.1
Calculation based on Mean Time Between Failures ................................................. 17
A.2.2
Calculation based on failure data analysis ................................................................ 17
A.3
Assessing the dominant failure mode ....................................................................... 19
A.4
Other techniques for calculating failure rates ............................................................ 21
A.5
Systematic capability ................................................................................................ 21
A.6
Safety manuals......................................................................................................... 21
Appendix B
Worked example....................................................................................................... 23
Appendix C
Abbreviations............................................................................................................ 27
Appendix D
Other relevant publications ....................................................................................... 28