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SIL ANALYSIS
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CALCULATION NOTE N° : NCSIL1314094A Rev : 0 Page : 1/5
RELIABILITY STUDY
SIL EVALUATION Application field : Final elements of Safety Instrumented System (SIS) as defined in AF13/14094 (SRi reference) Summary : Calculation note for a SIL evaluation.
This document belongs to SRi and cannot be reproduced without authorization.
DIFFUSION : Engineering department Customer
\\Bureau_etudes\aqbe\Notes de calcul fiabilité\Affaire\AF13‐14094\NCSIL1314094A.doc
0 24/01/2014 L. MAURIANGE C. RANQUET C. RANQUET
Rev Date Written by Checked by Approved by
CALCULATION NOTE N° : NCSIL1314094A Rev : 0 Page : 2/5
Rev Date Object Pages
0
24/01/2014 Original version
All
CALCULATION NOTE N° : NCSIL1314094A Rev : 0 Page : 3/5
SOMMAIRE
1 OBJECT ..................................................................................................................................................................................... 4
2 RELATED DOCUMENTS ............................................................................................................................................................ 4
3 SIS COMPOSITION AND RELIABILITY DATA ............................................................................................................................ 4
3.1 BALL VALVE (FINAL ELEMENT) ..................................................................................................................................................... 4 3.2 ACTUATION SYSTEM COMPONENTS .............................................................................................................................................. 4
4 SIL EVALUATION ...................................................................................................................................................................... 4
4.1 THEORY .................................................................................................................................................................................. 4 4.2 APPLICATION ........................................................................................................................................................................... 5
5 CONCLUSION ........................................................................................................................................................................... 5
CALCULATION NOTE N° : NCSIL1314094A Rev : 0 Page : 4/5
1 OBJECT
This document evaluates the reliability of a final element of a Safety Instrumented System (SIS).
2 RELATED DOCUMENTS
1) IEC61508/61511 2) FSP 12001‐01 Certificate for SRi Engineering ‐ A90RL Ball Valve 3) BET 090460 C001 EXIDA SIL Certificate ‐ BETTIS CB Series actuators 4) VER 090434 C003 EXIDA SIL Certificate ‐ VERSA Solenoid valves 5) VER 1105071 C001, EXIDA SIL Certificate ‐ VERSA Quick Exhaust Valves 6) 5034544‐001C, Control panel type P1A
3 SIS COMPOSITION AND RELIABILITY DATA
3.1 Ball valve (final element)
The valve's failure rates are defined in Ref[2].
Normaly open valve closes in response to actuation with PVST :
λDU, Valve = 1.90E‐7Fail/h
λDD, Valve = 5.09E‐7Fail/h
λSU, Valve = 1.91E‐6Fail/h
λSD, Valve = 0
3.2 Actuation system components
The valve is equipped of a BETTIS type CBB actuator with control panel Ref[6]. The parts involved in the moving in security position are 1 VERSA CSG 3321 3/2 solenoid valve, 1 VERSA CSP 3301 3/2 pilot valve and 1 VERSA Quick Exhaust Valve EQ‐3‐316. The data used for the calculation are defined in Ref[3] and Ref[5].
4 SIL EVALUATION
4.1 Theory
In order to estimate the SIL of a SIS, two parameters need to be calculated : the Average Probability of Failure on Demand (PFDavg) and the Safe Failure Fraction (SFF). Ti = Test Interval = 1 year
CALCULATION NOTE N° : NCSIL1314094A Rev : 0 Page : 5/5
100λ
λ1SFF
2
PFDPFD
components theallforTλPFD
PFD11PFD
iToti,
iDUi,
GlobalAvg
iuDU,u
uuGlobal
4.2 Application
SRi closed in security valve with PVST
VERSA VERSA VERSA Quick Exhaust
Valve – QE3‐316
BETTIS Actuator
Pilot valve Solenoid valve CBB
CSP‐3301 CSG‐3321 SR with PVST
λDU 1.90E‐07 4.91E‐07 5.94E‐07 5.00E‐08 1.98E‐07
λDD 5.09E‐07 0.00E+00 0.00E+00 0.00E+00 2.28E‐07
λD 6.99E‐07 4.91E‐07 5.94E‐07 5.00E‐08 4.26E‐07
λSU 1.91E‐06 1.67E‐06 2.35E‐06 2.27E‐07 7.58E‐07
λSD 0.00E+00 0.00E+00 0.00E+00 0.00E+00 3.73E‐07
λS 1.91E‐06 1.67E‐06 2.35E‐06 2.27E‐07 1.13E‐06
λTot 2.61E‐06 2.16E‐06 2.94E‐06 2.77E‐07 1.56E‐06
DCpvst 72.82% 0.0% 0.0% 0.0% 53.5%
Ti 8760 8760 8760 8760 8760
SFF 92.7% 77.3% 79.8% 81.9% 87.3%
PFD 1.66E‐03 4.30E‐03 5.20E‐03 4.38E‐04 1.73E‐03
PFDGlobal 1.33E‐02
PFDAvg 6.64E‐03
SFF 84.04%
5 CONCLUSION
The criteria which must be respected in order to reach SIL2 are: o PFDAvg<1
E‐2 o SFF>60%.
The criteria are respected. Therefore, the different components, including the SRi ball valve, constitute a final element of SIS up to SIL2.