SIL Calculation

CALCULATION NOTE

N° : NCSIL1314094A Rev : 0 Page : 1/5

RELIABILITY STUDY SIL EVALUATION

Application field : Final elements of Safety of  Safety Instrumented System (SIS) as defined in AF13/14094 (SRi reference)

Summary : Calculation note for a SIL evaluation.

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DIFFUSION :

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0 Rev

24/01/2014 Date

L. MAURIANGE Written by

C. RANQUET Checked by

C. RANQUET Approved by

CALCULATION NOTE

Rev

Date

0

24/01/2014

Object Original version

N° : NCSIL1314094A Rev : 0 Page : 2/5

Pages All

CALCULATION NOTE

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SOMMAIRE 1

OBJECT ..................................................................................................................................................................................... 4

2

RELATED DOCUMENTS....................................................... ........................................................... .......................................... 4

3

SIS COMPOSITION AND RELIABILITY DATA ............................................................................................................................ 4

3.1 3.2 4

SIL EVALUATION ...................................................................................................................................................................... 4

4.1 4.2 5

BALL VALVE (FINAL ELEMENT) ..................................................................................................................................................... 4 ACTUATION SYSTEM COMPONENTS  .............................................................................................................................................. 4

THEORY ......................................................... ........................................................... ............................................................ .. 4 APPLICATION ............................................... ....................................................... ................................................................ ..... 5

CONCLUSION  ........................................................................................................................................................................... 5

CALCULATION NOTE

1

N° : NCSIL1314094A Rev : 0 Page : 4/5

OBJECT

This document evaluates the reliability of a of  a final element of a of  a Safety Instrumented System (SIS). 2

RELATED DOCUMENTS

1) 2) 3) 4) 5) 6) 3

IEC61508/61511 FSP 12001‐01 Certificate for SRi Engineering ‐ A90RL Ball Valve BET 090460 C001 EXIDA SIL Certificate ‐ BETTIS CB Series actuators VER 090434 C003 EXIDA SIL Certificate ‐ VERSA Solenoid valves VER 1105071 C001, EXIDA SIL Certificate ‐ VERSA Quick Exhaust Valves 5034544‐001C, Control panel type P1A

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 =

E‐7

1.90 Fail/h E‐7 λDD, Valve = 5.09 Fail/h E‐6 λSU, Valve = 1.91 Fail/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 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

N° : NCSIL1314094A Rev : 0 Page : 5/5

CALCULATION NOTE

PFD Global  1   1  PFD u   u  PFD u  λ DU,u Ti for all the components  PFD Avg  PFD Global  2    λ i,DU     SFF  1  i   100 λ    i,Tot      i 4.2

Application SRi closed in security valve with PVST

5

VERSA Pilot valve CSP‐3301

VERSA Quick Exhaust Solenoid valve Valve – Valve  – QE3‐316 CSG‐3321 VERSA

BETTIS Actuator CBB 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%

CONCLUSION

The criteria which must be respected in order to reach SIL2 are: o PFDAvg<1E‐2 o SFF>60%.

The criteria are respected. Therefore, the different components, including the SRi ball valve, constitute a final element of SIS of  SIS up to SIL2.