Safety Instrumented System - Research Publishing Services

1 Safety Instrumented System A Critical Barrier Presented by: Sujith Panikkar, CFSE. SIS_APCChe_Draft Copyright Yokogawa Electric Corporation -1- 15-Dec2-011. Contents The Safety Instrumented System A review of Chemical Industry Accidents Evolution of Regulations and Standards Preventing Accidents: Risk Reduction Concept of risk reduction Accidents and Causes: The Human Factor Safety Instrumented Systems as a Safety barrier Design & Engineering SIS: IEC 61508/ 61511 & FSM. Operation & Maintenance Safety Lifecycle expectation & expectations on users SIS_APCChe_Draft Copyright Yokogawa Electric Corporation -2- 15-Dec2-011. Topic The Safety Instrumented System SIS_APCChe_Draft Copyright Yokogawa Electric Corporation -3- 15-Dec2-011. What is a Safety Instrumented System ??? A Safety Instrumented System is a System that provides an independent and predetermined emergency shutdown path in case a process runs out of control Safety System IPS , ESD , SGS etc = SIS.

2 Process pipe Process pipe Logic solver Vent. Input Output Air Protection logic A. D O. Safety valve Transmitter SIS_APCChe_Draft Copyright Yokogawa Electric Corporation -4- Sensors 15-Dec2-011. Final elements SIS: The need for Protection EUC = Equipment Under Control If something runs out of control a dangerous situation can arise ==>. Industrial Process a demand for a protective action Consequences (how serious, how much money, how many injuries, how many fatalities). Control Demand Rate DCS (frequency, how many times per how many year). SIS_APCChe_Draft Copyright Yokogawa Electric Corporation -5- 15-Dec2-011. 5. What has to be Protected ? Society Plant owner Process People outside plant and inside plant Environment Assets Corporate Off-spec image production SIS_APCChe_Draft Copyright Yokogawa Electric Corporation -6- 15-Dec2-011.

3 Topic Chemical Industry Accidents - History SIS_APCChe_Draft Copyright Yokogawa Electric Corporation -7- 15-Dec2-011. Chemical Industry Accidents History Some of the major ones . 1974: Flixborough 1976: Seveso 1984: Bhopal 1988: Piper Alpha And many more . 2010: BP Gulf of Mexico the Consequences . SIS_APCChe_Draft Copyright Yokogawa Electric Corporation -8- 15-Dec2-011. Piper Alpha platform, July 1988. SIS_APCChe_Draft Copyright Yokogawa Electric Corporation -9- 15-Dec2-011. Consequences: Piper Alpha platform, July 1988. 61 survivors, but many badly burnt 167 fatalities Piper Alpha was producing about 125,000 bpd in 1988. Insured losses of over US$ Billion SIS_APCChe_Draft Copyright Yokogawa Electric Corporation - 10 - 15-Dec2-011. Topic Evolution of Regulations and Standards SIS_APCChe_Draft Copyright Yokogawa Electric Corporation - 11 - 15-Dec2-011.

4 History of Functional Safety Standards 1974 1976 1984 1989. Flixborough ( ) Seveso (Italy) Bhopal (India) Piper Alpha ( ). Vapor cloud TCDD cloud MIC cloud Oil platform fire explosion (US company). Accidents 1982 1984 1992 1999. Seveso CIMAH PSM / PSA Seveso directive HSE OHSA directive II. EC EC. Law / rules 1989 1996. 1999 2003. DIN ISA S84. IEC 61508 IEC 61511. Germany Standards 1970 1980 1990 2000. SIS_APCChe_Draft Copyright Yokogawa Electric Corporation - 12 - 15-Dec2-011. Topic Preventing Accidents: Risk Reduction SIS_APCChe_Draft Copyright Yokogawa Electric Corporation - 13 - 15-Dec2-011. RISK Assessment Def. Risk Combination of the frequency of occurrence of harm and the severity of that harm . (IEC 61508 / IEC 61511). Risk= Impact X Frequency Impact = $$, Life, Environment SIS_APCChe_Draft Copyright Yokogawa Electric Corporation - 14 - 15-Dec2-011.

5 How to reduce the Risk? Impact Major Unacceptable risks! Medium Acceptable risks! Low Frequency LOW MEDIUM HIGH. SIS_APCChe_Draft Copyright Yokogawa Electric Corporation - 15 - 15-Dec2-011. Risk Reduction Hazard Rate Hazard Rate Demand Reduction DCS. Low SIS_APCChe_Draft Consequence Consequence Copyright Yokogawa Electric Corporation - 16 - 15-Dec2-011. Process risk Initial process risk Residual Tolerable level risk level drain systems (not tolerable). risk level piping classes fire walls relief valves control systems dykes rupture disks operational Fire and Gas break pins envelopes System . sensor(s) .. logic solver final element(s). Required overall risk reduction SIS (functional Safety ) External Mechanical Design (mitigation). Process Analysed Process Risk SIS_APCChe_Draft Copyright Yokogawa Electric Corporation - 17 - 15-Dec2-011.

6 Of Protection Analysis (LOPA). Community Emergency Response Plant Emergency Response Physical Protection (Bund wall). Automatic SIF (ESD&FGS). Critical Alarms and Manual Intervention Basic Controls(DCS). Process Design TT. SIS_APCChe_Draft Copyright Yokogawa Electric Corporation - 18 - 15-Dec2-011. Topic Case Study: Reliability of Instrumentation : BP AMOCO Texas City Refinery: Isomerization Unit Explosion, March 2005. SIS_APCChe_Draft Copyright Yokogawa Electric Corporation - 19 - 15-Dec2-011. BP AMOCO EXPLOSION MARCH 05. 15 DEAD. 100 INJURED. 30 PUBLIC INJURED. SIS_APCChe_Draft 8 IN CRITICAL CONDITION. Copyright Yokogawa Electric Corporation 15-Dec2-011. 20. - 20 - The total cost of this incident for BP : over $US 2 Billion SIS_APCChe_Draft Copyright Yokogawa Electric Corporation - 21 - 15-Dec2-011. 21.

7 Failure of Raffinate Splitter Level Instrumentation DCS Level High Alarm was ignored Independent Level switch connected to alarm System did not work Source: Fatal Accident investigation Report : SIS_APCChe_Draft Copyright Yokogawa Electric Corporation - 22 - 15-Dec2-011. Topic Accidents and Causes: The Human Factor SIS_APCChe_Draft Copyright Yokogawa Electric Corporation - 23 - 15-Dec2-011. Layers of protection Initiating event Deficiency in the protection Incident SIS_APCChe_Draft Copyright Yokogawa Electric Corporation - 24 - 15-Dec2-011. Causes of Accidents Human failures Random reasons: 26% Equipment failures - wrong material,corrosion,etc. Failure of SIS: 4% - power loss - negligent maintenance - static electricity - sabotage - short circuit - design source: TNO investigations of 216 accidents SIS_APCChe_Draft Copyright Yokogawa Electric Corporation - 25 - 15-Dec2-011.

8 Topic Safety Instrumented Systems as a Safety Barrier SIS_APCChe_Draft Copyright Yokogawa Electric Corporation - 26 - 15-Dec2-011. SIS Function in the Process Boom? Mechanical Safety level Unsafe Condition Trip level Safety Instrumented System (SIS) action Alarm Condition Operator takes action High alarm level Human influence Normal Condition High level Process value Low level Time SIS_APCChe_Draft Copyright Yokogawa Electric Corporation - 27 - 15-Dec2-011. The position of SIS. Process Control System Sensor SCADA. (Fast Tools). Sensor 3X Logic Solver Vnet PAS Operator (ProSafe (Centum Interface RS) CS 3000). Valve Annunciation Valve ESD panel = Safety related SIS_APCChe_Draft Copyright Yokogawa Electric Corporation - 28 - 15-Dec2-011. Topic Design & Engineering SIS: IEC 61508/ 61511 & FSM. SIS_APCChe_Draft Copyright Yokogawa Electric Corporation - 29 - 15-Dec2-011.

9 The IEC 61508 / 61511 Standard IEC 61508 : functional Safety of electrical / electronic /. programmable electronic Safety -related systems. IEC 61511 : functional Safety for the process industry = identical to (except for grandfather clause). PROCESS SECTOR. Safety System . STANDARDS. Manufacturers & Safety Instrumented Mother Suppliers of System Designers, Devices Integrators & Users IEC 61508 Daughter IEC 61511. SIS_APCChe_Draft Copyright Yokogawa Electric Corporation - 30 - 15-Dec2-011. Safety Lifecycle 1 Concept SIS Analysis and Design Phase 2 Overall scope definition 3 Hazard and risk analysis 4 Overall Safety requirements 5 Safety requirements allocation E/E/PE. SIS Realization 9 Other risk Safety System 11. Overall planning requirement reduction Phase Overall measures 6 7 Overall 8 Overall specification operation & Safety installation &.

10 Maintenance validation commissioning 10 E/E/PE Realisation planning planning planning Safety System realization 12 Overall installation & commissioning Back to appropriate overall Maintenance Phase 13 Overall Safety validation Safety lifecycle phase SIS Operation &. Overall operation, maintenance & repair 15 Overall modification &. 14 retrofit source: IEC 61508-1 fig. 2 16 Decommissioning or disposal SIS_APCChe_Draft Copyright Yokogawa Electric Corporation - 31 - 15-Dec2-011. Topic SIS: Analysis and Design phase SIS_APCChe_Draft Copyright Yokogawa Electric Corporation - 32 - 15-Dec2-011. Hazard and Risk Analysis, SIL Allocation 1 Concept HAZOP Study 2 Overall scope definition IEC 61508 : part 5. ALARP. 3 Hazard and risk analysis Identify Risk Graph Safety Risk Matrix 4 Overall Safety requirements Functions Safety requirements allocation IEC 61511 : part 3.