Module 01- Introduction to Functional Safety PDF

Module 1 Introduction to Functional Safety 1 Introduction to Functional Safety Introduction to Functional Safety Content: 1.1 Accidents in the Process Industry Sector 1.2 International Safety Standards addressing Functional Safety 1.3 Local Laws and Regulations 1.4 Basic Terms and Definitions 1.5...

Module 1 Introduction to Functional Safety 1 Introduction to Functional Safety Introduction to Functional Safety Content: 1.1 Accidents in the Process Industry Sector 1.2 International Safety Standards addressing Functional Safety 1.3 Local Laws and Regulations 1.4 Basic Terms and Definitions 1.5 Summary Objectives of this training module: - See what we can learn from major accidents in the past - Learn about international Safety Standards - Learn important key concepts and often used expressions of Functional Safety 1 Introduction to Functional Safety © HIMA Paul Hildebrandt GmbH 2024_1 14  1.1 Accidents in the Process Industry Sector Accidents Well known accidents in the past: Seveso, Italy, 1976 (leading to the Seveso-Directive; currently Seveso-III) (Operational failures, poor safety concept, exposure of dioxin in populated areas) Bhopal, India, 1984 (Operational failures, reduced and bad educated staff, non-functional safety systems, exposure of methyl isocyanate (MIC) gas, ~16000 people died, ~500000 people injured) Piper Alpha, North Sea, 1988 (Modified from oil production into gas production, poor risk analysis, careless handling of forms and procedures, blocked fire extinguishing system, no evacuation facility, 167 people died, economic impact: ~15 billion dollar BP Texas City, TX, USA, 2005 (details see next slides…) Buncefield, United Kingdom, 2005 (details see next slides…) Deepwater Horizon, Gulf of Mexico, 2010 (details see next slides…) 1 Introduction to Functional Safety © HIMA Paul Hildebrandt GmbH 2024_1 15 1.1 Accidents in the Process Industry Sector BP Texas City Accident Fact Sheet Location: Texas City, TX, USA Date: 23rd March 2005 Direct consequences: At least 5 explosions occurred 15 killed, over 170 injuries Residence up to 5 miles away felt the explosions Indirect consequences: About 300 alleged violations were found in their safety rules USD 21.3 million fine was paid to OSHA USD 700 million was reserved to compensate the victims > USD 3 billion set aside for development over 5 years at US BP plants 1 Introduction to Functional Safety © HIMA Paul Hildebrandt GmbH 2024_1 16  1.1 Accidents in the Process Industry Sector BP Texas City Accident Headline in the news: Refinery explosion due to several equipment and procedural failures Some factors, which contributed to the accident: Deficiencies in risk analysis: Accommodation container for workers placed near to hazardous area Startup phase of refinery after maintenance works completed Problems during shift change: No experienced operator in control room, bad reporting, lost information Bad indications (operators didn’t judge the real process situation correctly) Inoperative alarms (some alarm devices didn’t work) Ignitions sources in explosive areas https://www.youtube.com/watch?v=goSEyGNfiPM Source: Wikipedia 1 Introduction to Functional Safety © HIMA Paul Hildebrandt GmbH 2024_1 17 1.1 Accidents in the Process Industry Sector BP Texas City Accident – Pictures 1 Introduction to Functional Safety © HIMA Paul Hildebrandt GmbH 2024_1 18 1.1 Accidents in the Process Industry Sector Buncefield Accident Fact Sheet Location: Hertfordshire – Buncefield, United Kingdom Date: 11th December 2005 Obvious problem: Oil depot – overfilling tank due to equipment failure, leading to vapor cloud which got ignited Direct consequences: Explosion led to a large fire which took 5 days to extinguish 23 storage tanks caught fire 43 people injured; 2,000 people evacuated Indirect consequences: Estimated economic impact GBP 1 billion 1 Introduction to Functional Safety © HIMA Paul Hildebrandt GmbH 2024_1 19 1.1 Accidents in the Process Industry Sector Buncefield Accident – Lessons learned At first glance a typical equipment failures: A level gauge had stuck again and again after the tank had been serviced. However, nobody responded effectively to its obvious unreliability. The IHLS needed a padlock to retain its check lever in a working position. If the padlock was not replaced, it was possible for the check lever to be left in the lower position or to fall naturally. In either case the switch would be disabled. At second glance lots of management failures: - No Functional Safety Management (FSM) existing - No proper Hazard and Risk Analysis (H&RA) executed - No error culture existing - No independent assessments & audits executed - … Below some recommendations and “Lessons learned” from accident reports (citations): - Apply important process safety management principles! - There should be a clear understanding of major accident risks and safety critical equipment! - Detect signals of failure in safety critical equipment and respond to them quickly and effectively! - Remove pressure on staff and managers! - Execute frequent and effective assessments and audits! “Buncefield: Why did it happen?” (COMAH) 1 Introduction to Functional Safety © HIMA Paul Hildebrandt GmbH 2024_1 20 1.1 Accidents in the Process Industry Sector Deepwater Horizon Rig Accident Fact Sheet Location: Deepwater Horizon, Gulf of Mexico Date: 20th April 2010 Problem: Hydrocarbon escape from the Macondo well resulting in explosions and fire on the rig Direct consequences: 11 people killed; 17 others injured Massive fire continued for 36 hours until the rig sank Hydrocarbons (about 780 million liters) continued to flow for 87 days causing a huge environment pollution Indirect consequences: BP set up a USD 20 billion relief fund... 1 Introduction to Functional Safety © HIMA Paul Hildebrandt GmbH 2024_1 21 1.1 Accidents in the Process Industry Sector Deepwater Horizon Rig – Movie 1 Introduction to Functional Safety © HIMA Paul Hildebrandt GmbH 2024_1 22 1.1 Accidents in the Process Industry Sector Deepwater Horizon Rig – Pictures 1 Introduction to Functional Safety © HIMA Paul Hildebrandt GmbH 2024_1 23 1.1 Accidents in the Process Industry Sector Deepwater Horizon Rig Failure at cost of life 1 Introduction to Functional Safety © HIMA Paul Hildebrandt GmbH 2024_1 24 1.1 Accidents in the Process Industry Sector Deepwater Horizon Rig Failure at cost of environment 1 Introduction to Functional Safety © HIMA Paul Hildebrandt GmbH 2024_1 25 1.2 International Safety Standards addressing Functional Safety Lessons Learned: We need more Safety : Functional Safety! But isn’t that too expensive? Beside the victims and environmental damage – let’s have a look to the costs: Deepwater Horizon Bouncefield BP Texas City Estimated total costs: Estimated total costs: Estimated total costs: $62 billion 1 billion GBP > $1,5 billion “…if you think safety is expensive, try an accident…” (Dr. Trevor Kletz) Today, the cost of a major accident in the process sector can be more than 10x the investment cost We have had terrible accidents in the past The concepts of Functional Safety help us to avoid similar accidents in the future! 1 Introduction to Functional Safety © HIMA Paul Hildebrandt GmbH 2024_1 26 1.2 International Safety Standards addressing Functional Safety Aim of Functional Safety: Protection of human life, assets and environment Safety (IEC 61508-4:2010 Clause 3.1.11) Freedom from unacceptable risk, which is not tolerable 1 Introduction to Functional Safety © HIMA Paul Hildebrandt GmbH 2024_1 27 1.2 International Safety Standards addressing Functional Safety Functional Safety deals with Active Systems! Functional Safety is the part of the overall safety that depends on a system or equipment operating correctly in response to its inputs. Functional Safety is about the  detection of a potentially dangerous condition resulting in the  activation of a protective or corrective device or mechanism to  prevent hazardous events or to reduce the consequence.  Functional Safety basically relies on active systems. FS Example: The activation of a level switch in a tank containing a hazardous liquid. When a potentially dangerous level has been reached, a valve will be closed to prevent further liquid entering the tank and thereby preventing the liquid in the tank from overflowing.  Safety achieved by measures that rely on passive systems is not Functional Safety. Example: A fire-resistant door or insulation to withstand high temperatures are measures that X FS are passive in nature and can protect against the same hazards are controlled by functional safety concepts but are not instances of functional safety. 1 Introduction to Functional Safety © HIMA Paul Hildebrandt GmbH 2024_1 28 1.2 International Safety Standards addressing Functional Safety Fundamental Concepts of Functional Safety Functional Safety (IEC 61511-1:2016 Clause 3.2.23) Part of the overall safety relating to the process and the BPCS which depends on the correct functioning of the SIS and other protection layers Fundamental requirements and concepts: Consideration of a plant or a system throughout the overall life-cycle Introduce and apply Functional Safety Management System (FSMS) Organizational Carrying out a “Hazard and Risk Assessment”, leading to a “Safety Requirements Specification” incl. SIL information Ensure correct hardware and software design of the SIS, in particular: - Avoid Random Hardware Failures - Avoid Common Cause Failures - Avoid Systematic Failures Technical Execute “SIL verification” and reliability analysis Ensure resilience against identified security risks 1 Introduction to Functional Safety © HIMA Paul Hildebrandt GmbH 2024_1 29 1.2 International Safety Standards addressing Functional Safety Functional Safety Standards Safety Instrumented Systems for Process Sector Standards Safety Instrumented System Manufacturers and suppliers designers, integrators and of devices end-user IEC 61508 IEC 61511 IEC 61508 - Functional Safety of electrical / electronic / programmable electronic safety-related systems IEC 61511 == ANSI/ISA 84.00.01 Functional Safety - Safety Instrumented Systems for the process industry sector 1 Introduction to Functional Safety © HIMA Paul Hildebrandt GmbH 2024_1 30 1.2 International Safety Standards addressing Functional Safety Relevant Standards for SIS in Process Sector 1 Introduction to Functional Safety © HIMA Paul Hildebrandt GmbH 2024_1 31 1.2 International Safety Standards addressing Functional Safety IEC 61508 – Framework for Safety Standards IEC 61508 IEC 61513, 60880- IEC 61784-3 IEC 61511 2, 61238 EN 50402 Profiles for safe Process Industry Nuclear Power Gas Detection communication plants ANSI/ISA EN 50126, 50128, IEC TS 61000-1-2 S84.00.01 IEC 61800-5-2 50129 EMC for functional Process Industry Power Drives Railway safety USA IEC 61326-3-x IEC 62061 ISO 26262 IEC 62304 Immunity for Machinery Automotive Medical Software functional safety 1 Introduction to Functional Safety © HIMA Paul Hildebrandt GmbH 2024_1 32 1.2 International Safety Standards addressing Functional Safety Overview IEC 61508 Part 1: General requirements Part 2: Requirements for electrical, electronic, programmable electronic systems (E/E/PES) Part 3: Software requirements Part 4: Definitions and abbreviations Part 5: Examples of methods for the determination of safety integrity levels (SIL) Part 6: Guidelines on the application of Parts 2 & 3 Part 7: Overview of techniques and measures 1 Introduction to Functional Safety © HIMA Paul Hildebrandt GmbH 2024_1 33 1.2 International Safety Standards addressing Functional Safety Legal Status of IEC 61511 Standards are never legally binding, merely they are used for guidance, but... Since its release (2003) IEC 61511 is considered State-of-the-Art or Good Engineering Practice State-of-the-Art means, IEC 61511 is Technically feasible and applicable Organizationally possible to plan Economically feasible State-of-the-Art is a legal term in many countries This makes it almost impossible not to comply to IEC 61511 when it comes to Safety Instrumented Systems (SIS) 1 Introduction to Functional Safety © HIMA Paul Hildebrandt GmbH 2024_1 34 1.2 International Safety Standards addressing Functional Safety Overview IEC 61511 Part 1: Framework, definitions, system, hardware and software requirements (normative) Part 2: Guideline for the applications of IEC 61511-1 (informative) Part 3: Guidance for the determination of the required safety integrity levels (informative) Reference number: IEC 61511:1-2016(E) 1 Introduction to Functional Safety © HIMA Paul Hildebrandt GmbH 2024_1 35 1.3 Local Laws and Regulations Local Standards (Module 9) Germany Australia 1 Introduction to Functional Safety © HIMA Paul Hildebrandt GmbH 2024_1 36 1.4 Basic Terms and Definitions BPCS Basic Process Control System (BPCS) (IEC 61511-1:2016 Clause 3.2.3) System which responds to input signals from the process, its associated equipment, other programmable systems and/or operators and generates output signals causing the process and its associated equipment to operate in the desired manner, but which does not perform any SIF. A BPCS typically may implement: - Process control functions, - Monitoring - Alarms - Other protective functions. BPCS typically is not SIL rated and therefore not allowed to execute any safety functions! Risk reduction factor typically ≤ 10 Failure in BPCS can trigger a demand to the SIF (Safety Instrumented Function)! 1 Introduction to Functional Safety © HIMA Paul Hildebrandt GmbH 2024_1 37 1.4 Basic Terms and Definitions Safety Instrumented Function (SIF) Safety Instrumented Function (SIF) (IEC 61511-1:2016 Clause 3.2.66) Safety function to be implemented by a safety instrumented system (SIS) A SIF is designed to achieve a required SIL, which is determined in relationship with the other protection layers participating to the reduction of the same risk. Measure the temperature in the vessel and if the temperature is higher than 100 °C stop the pump and drain the content of the vessel safely. SIF response time is max. 30 seconds. SIL 2 required. A SIF describes (verbal, as a sentence in a document!) a certain expected safety functionality, which typically includes statements about:  Measurement – evaluation – reaction – reaction time – SIL (what must be done, how fast and in which quality…) Additional detailed information for the SIF must be defined (see SRS…): Safe state Proof test interval Demand mode (e.g. low demand) Energize to trip – De-energize to trip etc. 1 Introduction to Functional Safety © HIMA Paul Hildebrandt GmbH 2024_1 38 1.4 Basic Terms and Definitions Safety Instrumented System (SIS) Safety Instrumented System (SIS) (IEC 61511-1:2016 Clause 3.2.67) Instrumented system, used to implement one or more SIFs. SIS usually means technology (or simplified: SIS is the technical implementation of a SIF) SIS consist out of subsystems, minimum: Sensors – Logic solver – Final elements Subsystems consist out of devices (which can be redundant) NP = Non-programmable PE = Programmable electronics (including software) SIS can also include: Communication (e.g. safety protocol) Ancillary equipment – such as - Power supplies - Impulse lines - Heat tracing -… Human action as part of a SIF Realistic SIS example see next slide… 1 Introduction to Functional Safety © HIMA Paul Hildebrandt GmbH 2024_1 39 1.4 Basic Terms and Definitions Example for SIF and SIS Primary function (SIF) The flow in pipe Y is measured and evaluated by a controller, located in plant section A. When threshold X is reached, another controller in plant section B must close the inlet A and inlet B. Secondary function: Flow XV46 should be also closed due to operational reasons. SIS subsystems needed for execution of above SIF: Flow transmitter FT33 XV44 PLC A (HIMA, HIMax) Material A Chemical FT33 SafeEthernet protocol Process XV45 PLC B (HIMA, HIMax) Material B Valve XV44 Valve XV45 XV46 Operational PLC-B Safe communication PLC-A 1 Introduction to Functional Safety © HIMA Paul Hildebrandt GmbH 2024_1 40 1.4 Basic Terms and Definitions Control Loop versus Safety Loop - Example BPCS: A SIS must be able to: Control loop detect the process going into a hazardous condition move the process to safe state act independently of other systems / protection layers. LZT-2 LT-1 CV-1 XV-2 Safety Loop (SIF) executed by SIS 1 Introduction to Functional Safety © HIMA Paul Hildebrandt GmbH 2024_1 41 1.4 Basic Terms and Definitions Demand, Probability of Failure on Demand (PFD), EUC Demand: Process going out of control (due to a process upset or a failure of BPCS) which requires a safety action (for example executed by a SIF) to move the process to a safe state. Average probability of dangerous failure on demand – PFDavg (IEC 61508-4 3.6.18) Mean unavailability of the SIS to perform the SIF when a demand occurs from the EUC or EUC control system (the real value of PFDavg for the SIF must be calculated, see training module 5) EUC - Equipment under control (IEC 61508-4 3.2.1 Equipment, machinery, apparatus or plant used for manufacturing, process, transportation, medical or other activities 1 Introduction to Functional Safety © HIMA Paul Hildebrandt GmbH 2024_1 42 1.4 Basic Terms and Definitions Typical Problems in a SIS 65 = 1000001 97 = 1100001 Bit Flip (RAM) failure (e.g. due to cosmic rays or radiation) SIF: If the temperature goes over 65 °C close the valve within 10 seconds. SIL2 required. 1 Introduction to Functional Safety © HIMA Paul Hildebrandt GmbH 2024_1 43 1.4 Basic Terms and Definitions SIS States A SIS can be in 4 different states: OK: No internal failures  Process protected and in operation Safe: The SIS fails in a way that the SIF is carried out without a demand  Process shutdown (In previous example: Imagine the bit failure occurs in the input device and compromises the field value in a way, that the SIF is executed without a demand) Dangerous: The SIS fails in a way that the SIF cannot be carried out in case of a demand  Process in operation but unprotected (In previous example: Imagine the bit failure occurs in the physical memory where the trip value is saved) Intermediate: The SIF can still be carried out despite one or more internal SIS failures (e.g. because of existing redundancy),  Process in operation, reduced SIS performance, repair required! 1 Introduction to Functional Safety © HIMA Paul Hildebrandt GmbH 2024_1 44  1.4 Basic Terms and Definitions Safety Integrity Level (SIL) Safety Integrity Level (SIL) (IEC 61511-1:2016 Clause 3.2.69) Discrete level (expressed on a scale of SIL 1 to SIL 4), allocated to the SIF for specifying the safety integrity requirements to be achieved by the SIS. From SIL 1 to SIL 4 increases the level of safety integrity Needed SIL is an outcome from hazard and risk analysis SIL applies to the complete SIF and defines the requirements for the SIS SIL is how we measure the performance of a SIF carried out by a SIS There are technical and non-technical requirements defined per SIL level Example for technical requirements: SIS design (HFT, PFDavg, suitable devices…) Example for non-technical requirements: Expected grade of independence for assessments SIL defines target Probability of Failure on Demand (PFD) and required Risk Reduction Factor (RRF): IEC61511-1 Table 4 1 Introduction to Functional Safety © HIMA Paul Hildebrandt GmbH 2024_1 45  1.4 Basic Terms and Definitions SIL Story at a Glance Documented in SRS: Needed SIL is an outcome from hazard and risk analysis: SIL defines requirements on the SIS But SIL is not only a technical requirement (e.g.): hardware: HFT, SC, PFDavg … 1 Introduction to Functional Safety © HIMA Paul Hildebrandt GmbH 2024_1 46 1.4 Basic Terms and Definitions Human Error Human Error (IEC 61511-1:2016 Clause 3.2.29) Intended or unintended human action or inaction that produces an inappropriate result. Mistakes Slips Lapses are examples of human errors. Human error can be one cause for common cause failures or systematic failures Human error can be one cause for security problems Human error must be considered during the hazard and risk analysis (e.g. consider “alarm & operator protection layer during a LOPA or HAZOP) Human error is neither “random failure” nor “systematic failure”, but is often the root cause for systematic failures! 1 Introduction to Functional Safety © HIMA Paul Hildebrandt GmbH 2024_1 47 1.4 Basic Terms and Definitions Protection Layers (PL) Plant emergency Emergency response layer response Mitigation Embankment Bunker Passive protection layer Controlled relief valve, rupture disk, Active protection layer F&G system Safety Instrumented Isolated protection layer Emergency shutdown action System (SIS) Trip level alarm Alarm and operator Process parameters out of Process control layer Prevention intervention control High level alarm High level Basic Process Control Normal process behaviour Process control layer System (BPCS) or DCS Low level Plant and process Inherent safe plant design design 1 Introduction to Functional Safety © HIMA Paul Hildebrandt GmbH 2024_1 48 1.4 Basic Terms and Definitions Deepwater Horizon Rig – Protection Layers Fail 1 Introduction to Functional Safety © HIMA Paul Hildebrandt GmbH 2024_1 49 1.4 Basic Terms and Definitions Process Safety Time – Diagram Process Value Intolerable error range BPCS out of Possible Sensor Logic system Actuator Process delay time control operator Input Reaction time Reaction time Intervention processing (typically of contacts, (incl. delays) 2 cycles) valves etc. e.g. 1 Sec. e.g. 0,5 Sec. e.g. 2 Sec. Tolerable error range Time until the SIF Reaction Time safeguard really effects e.g.: 3,5 Sec. the process SIF Trip Point Alarm limit Good range Process Safety Time Time e.g. 60 Sec. 1 Introduction to Functional Safety © HIMA Paul Hildebrandt GmbH 2024_1 50 1.4 Basic Terms and Definitions Process Safety Time – SIF Response Time Process Safety Time (IEC 61511-1:2016 Clause 3.2.52.1) Time period between a failure occurring in the process or the basic process control system (with the potential to give rise to a hazardous event) and the occurrence of the hazardous event if the SIF is not performed. Property of the process (process knowledge required, usually gained during H&R Analysis) Basic information for SRS Consider process lags (e.g. cooling of a vessel). SIF response time must be fast enough to prevent the hazardous event Process safety time >> expected SIF response time SIF response time includes times for: sensing – evaluation – reaction 1 Introduction to Functional Safety © HIMA Paul Hildebrandt GmbH 2024_1 51 1.5 Summary Lessons Learned… Horrible accidents in the past triggered safety culture in process industries Definition of Safety and Functional Safety Two international standards define safety approach in process industries: IEC 61508 (addresses mainly for manufactures of safety devices) IEC 61511 (addresses mainly end-users, system integrators and programmers) Basic terms: SIL SIS SIF System states Protection Layers Process Safety Time SIF Response Time 1 Introduction to Functional Safety © HIMA Paul Hildebrandt GmbH 2024_1 52