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Sil assessment Risk Graph and LOPA Training iFluids
This document provides an overview of SIL assessment and LOPA (layer of protection analysis) techniques. It discusses the differences between HAZOP and SIL studies, and the relationship between HAZOP and LOPA. Key aspects covered include safety integrity levels (SIL), risk matrices, consequence analysis, likelihood analysis, establishing tolerable risk levels using the ALARP principle, and control measure prioritization. Examples are provided of a SIL-3 assessment and applying the risk graph method.
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Sil assessment Risk Graph and LOPA Training iFluids
- 1. SIL ASSESSMENT-RISK GRAPH andLOPA Training
- 2. Course contents Whatis a SIL assessment Study? Relation between HAZOP and SIL assessment study Understanding Safety Integrity Level (SIL) Risk matrix/ALARP principle Layers of protection/Safeguard Hierarchy of controls (with simple example) LOPA study Example Brief introduction to Risk Graph Method
- 3. DIFFERENCE BETWEEN HAZOP& SIL SESSIONS Both HAZOP and SIL Sessions deal with Risk scenario for Analysis. But there exists a Difference in the Concept related to the Safety Instrumented Function (SIF). The HAZOP Session looks at the Safety Instrumented Function (SIF) from Positive side and expects the SIF to Perform its function Successfully to avoid a Hazardous Incident from occurring. Where as the SIL Session looks at the Negative side, i.e Failure or Absence of the SIF under study, explores all the consequences in the absence of the SIF and establishes the Criticality Rating (SIL) on this basis. The HAZOP Session deals with all the modes of Operation of a facility, including the Steady state operation, Bypass mode, Maintenance mode etc. But SIL Session primarily deals with the Plant’s Steady state operation.
- 4. Relation between HAZOPand LOPA
- 6. Understanding Safety IntegrityLevel (SIL) What does SIL mean? – Safety Integrity Level – A measure of probability to fail on demand(PFD) of the SIF. – It is statistical representation of the integrity of the SIF when a process demand occurs. – A demand occurs whenever the process reaches the trip condition and causes the SIF to act. – There are 4 SIL levels. SIL Levels are measures of how we achieve function safety. – Applies to the complete safety function/loop – Higher SIL means • Stricter requirements. • Safety Function fails less and thus plant protection is available more.
- 7. Safety integrated Function-SIF • PT-100A/B/C-initiating elements- sensors • LOGIC solver • XV-100 and PV-200 Final elements
- 8. 1 in 10means, the function will fail once in a total of 10 process demands 1 in 1000 means, the function will fail once in a total of 1000 process demands
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- 14. What is theconsequence ???
- 15. What is theconsequence ??? •Can it Kill someone..? •How much it is going to cost…both direct/indirect/insured/uninsured •Is it going to cause any Environmental issues..? •Is it going to cause any public relation issues or Regulatory actions
- 16. What is thelikely hood the event can occur • Is there any inherent design to the equipment..? • Is there any BPCS to control it..? • Is there any alarm to alert the operator for intervention..? • Is there any safety instrumented system..? • Is there any emergency response plan
- 17. RISK ASSESSMENT MATRIX(RAM) CONSEQUENCE LIKELIHOOD Rating Severity People Equipment damage Production loss Environment Reputation A B C D E More than100 years (Never heard of the incident) Once in 100 years (Heard of Incident in Industry) Once in 20 years (Incident has occurred in Our Company) Once in 4 years (Happened several times in the Company) More than once in a year 5 Catastrophic Multiple worker fatalities / permanent total disabilities or single public fatality Extensive damage, prolonged loss of production or > Rs. 10 Crore More than a month of outage for one unit Massive effect over a large area or constant breach of regulatory limits International impact. Adverse attention in International media 5A 5B 5C 5D 5E 4 Major Single worker fatality / Permanent disability or serious injury to public Major damage, disruption to operations or < Rs. 10 Crore More than one week to one month outage for one unit Major Effect, Short term breaches of regulatory limits Major Impact. On National TV / National Press 4A 4B 4C 4D 4E 3 Serious More than one LTI Local damage, unit shutdown or < Rs. 1 Crore 48 hrs. to one week outage for one unit Localized effect. Has significant impact on Environment but no permanent effect Considerable impact. Major concern in National Press / Local TV 3A 3B 3C 3D 3E 2 Minor One Loss Time Incident (LTI) Minor damage or < Rs. 50 Lakhs 24 hrs. to 48 hrs. outage for one unit Minor effect, has impact on Environment but no permanent effect Limited impact. Public concern in neighborhood. Reported in local newspaper 2A 2B 2C 2D 2E 1 Notable Slight injuries (First aid case) / Short term effect Slight damage or < Rs. 10 Lakhs Less than 24 hours Slight effect; 100% cleanup possible Slight impact, Public awareness exists, no public concern 1A 1B 1C 1D 1E Demonstrate ALARP Incorporate Risk Reduction Measures Manage for Continuous Improvement Intolerable Zone
- 18. Consequence Category People Target Risk Frequency (Occurrences per year,per event) P6 n/a 1.00E-07 P5 Multiple fatalities or Permanent illness 1.00E-06 P4 Single fatality or Chronic illness or Over exposure for more than 8 hrs 1.00E-05 P3 Serious illness or acute illness or high exposure (Entire shift - 8 hrs) 1.00E-04 P2 Local offsite treatment / Temporary illness / Intermittent Exposure (15 min/hr) 1.00E-03 P1 Minor injury or First aid cases 1.00E-02 E6 n/a 1.00E-07 E5 Widespread, Permanent Ecological damage 1.00E-06 E4 Some Permanent Ecological damage (continous emission not contained w ithin the organization) 1.00E-05 E3 Major sustained environmental release 1.00E-04 E2 Controlled environmental release(w ithin license limits) 1.00E-03 E1 Minor spillage or Fugitive emission 1.00E-02 F6 n/a 1.00E-06 F5 Plant outage more than 1 w eek,>5 Cr 1.00E-05 F4 Less than 1 w eek outage for 1 section;or 48 hrs to 1 w eek for the plant,2 Cr to 5 Cr 1.00E-04 F3 48 hrs to 1w eek outage for single section; or less than 48 hrs for plant,< 1Cr to 2Cr 1.00E-03 F2 12 hrs to 48 hrs outage for single section,< Rs. 50 lakhs to 1 cr 1.00E-02 F1 Less than 12 hour outage for single section (w ithin 1 plant),< Rs. 50 lakhs 1.00E-01
- 19. ALARP PRINCIPLE “As LowAs Reasonably Practicable” ▪ Involves weighing risk against the trouble, time and money to control ▪ Describes level to which workplace risk is to be controlled. ▪ Not prescriptive ▪ Challenging because it requires employers to exercise judgment. What is Acceptable Risk? We accept/ tolerate risk when: 1. We don’t know that it exists 2. The Risk is insignificantly low 3. When it’s worth the Risk (?)
- 20. Risk Reduction As LowAs Reasonably Practicable or Tollerable Risk (ALARP ZONE) Fundamental Concepts
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- 24. PFDs for IPLsadapted from CCPS
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