Why SIL3? Josse Brys TUV Engineer j.brys@hima.com
Agenda Functional Safety Good planning if specifications are not right? What is the difference between a normal safety and SIL3 loop? How do systems achieve safety? Layers of protection Are you safe if you buy a SIL3 PLC? Safety & non safety in one application or separate safety and non-safety Cyber security 2
Introduction : HIMA helps to prevent: HIMA SIS 3
Introduction HIMA HIMA is focused on Safety Systems SIS HIMA SIS Others HIMA: Safety Systems Others: Safety is small part of their business 4
Introduction HIMA SIL 3, SIL4 Safety PLC s HIMA solutions for Railways TMC BCS ESD F&G HIPPS Pipeline Logistics Nuclear 5
Safety? Why should we invest in safety? You think safety is expensive, try an accident Today an accident cost more than 10x the investment in the process We have had terrible accidents in the past We learned, but accidents with serious impact still happen today 6
Functional Safety Standards 7
Safety Integrity Level - SIL SIL is how we measure the performance of safety functions carried out by safety instrumented systems SIL has 3 sides to the story Process owners: Which safety functions do I need and how much SIL do I need? Engineering companies, system integrators, product developers: How do I build SIL compliant safety devices, functions or systems? Process operators: How do I operate, maintain and repair safety functions and systems to maintain the identified SIL levels? 8
SIL levels Risk reduction 9
SIL levels Most famous SIL requirement is the Probability of Failure on Demand PFDavg = Probability of Failure on Demand average 10
Functional Safety A safety instrumented system is 100% functionally safe if All random, common cause and systematic failures do not lead to malfunctioning of the safety system and do not result in Injury or death of humans Spills to the environment Loss of equipment or production 100% functional safety does not exist but SIL 1, 2, 3 or 4 does 11
Common cause does not happen? Complete plant flooded because of heavy rainfall, bad drainage and dike 12
Good planning if specifications are not right? IEC 61508 Lifecycle Concept 13
Good planning if specifications are not right? Lifecycle & Frequency of Failures 14
Good planning if specifications are not right? Think the following: Your specifications = a red car with a horse What would you get? 15
A red car with a horse 16
A red car with a horse 17
What is the difference between a normal safety and SIL3 loop? NORMAL LOOP SIL 1 Typically easy to achieve using standard components Through the selection of certified components, can achieve SIL 2 with single channel sensing or final elements Still need to consider the systematic capability for the devices, however these are less stringent for SIL 1 or 2 Lifecycle cost typically the same as a normal BPCS loop. BPCS = Basic Process Control System 18
What is the difference between a normal safety and SIL3 loop? SIL 3 LOOP Redundancy requirements for sensing and final elements Required by Tables 2 and 3 of 61508-2. Based on SFF Safe Failure Fraction = A measure of the effectiveness of the fail safe design and/or the built-in diagnostic tests Depending on the logic solver, can be single channel Proof Test Coverage can be a limiting factor Systematic requirements higher Requires careful selection of devices to ensure this is achieved. May rule out your normal supplier Life cycle cost much higher 19
What is the difference between a normal safety and SIL3 loop? The higher the SIL the more techniques and measures are required to detect, control and avoid human error SIL 1 Typically easy to achieve using a standard QMS system with added competence requirements SIL 2 requires an advanced system with competence management and reliance on testing SIL 3 has stringent requirements governing diversity in design, competence of a high order and stringent testing requirements 20
How do systems achieve safety? Safety Instrumented System 21
How do systems achieve safety? 1oo3 22
How do systems achieve safety? Input Input A B C Diag. µp µp Diagnostics Diagnostics Diagnostics 2oo3 Voting Diagnostics Diagnostics 2oo3 1oo2D Output Voting systems Output Diagnostic systems 23
How do systems achieve safety? 24
Layers of protection mitigate prevent Increase safety and cyber security 25
Layers of protection Specific must be specifically designed to be capable of preventing the consequences of the potentially hazardous event Independent must be completely independent from all other protection layers Dependable must be capable of acting dependably to prevent the consequence from occurring (systematic and random faults) Auditable must be tested and maintained to ensure risk reduction is continually achieved 26
Layers of protection The 3 ENOUGHS Big Enough Must be big enough to cope the with the potential hazard Fast Enough Must be fast enough to sense and react to prevent the potential Strong Enough Must be able to survive all arising situations when preventing the hazardous event. 27
Are you safe if you buy a SIL3 PLC? NO!!! Need to consider Sensing and final elements Need to consider Systematic Capability This applies to the integrator of the Logic Solver important to look at their quality system Apples to the installer of the Safety Integrated Functions important to look at their quality system Need to carefully consider Proof Test Intervals and Proof test coverage Short proof test intervals should be avoided as the testing requirements often require plant shutdown Incorrect to assume that the proof test is perfect This can have a profound effect on the result because we are dealing with very small numbers 28
Safety & non safety in one application or separate safety and non-safety Considerations for separating: Hazards are caused by the non safety application Risk assessment not able to separate the causes Required by Buncefield recommendation 3 physical and electrical independence Need for Cyber security Considerations for systematic capability!!! Often the same person programming the non-safety will be programming the safety! 29
Safety & non safety in one application or separate safety and non-safety mitigate prevent 30
Safety & non safety in one application or separate safety and non-safety The risk we talk about is related to a hazard Risk is a combination of The severity of consequences (C) The frequency of occurrence (F) Risk = C x F Risk safety = probability of a damage * potential of the damage 31
Security is a foundation for safety. Functional safety Risk safety = probability of a damage * potential of the damage World Sys. + Cyber security Risk security = threat * vulnerability * potential of the damage World Sys. Safety World Sys. 32
Compartmentalize. Avoid universal access. Conduit Enterprise Plant DMZ Internet Control Center Conduit SIS Conduit BPCS Plant 33
Security is a process. React Detect Risk analysis Conduit Enterprise Internet Protect Security is a process to reduce the risk of damage due to external influence. This process can be supported by technical measures. Control Center Plant DMZ Conduit Both the IEC 61511 (safety) and the draft of the IEC 62 443 (security) demand to build systems in multiple layers of protection. (Defense in the Depth) SIS Conduit Plant BPCS Source: IEC 62443-3-3 34
Segregation of non safe networks. Safety-Net Field Net DCS-Net Besides the usage of VLAN HIMax offers a complete segregation. This interference free implementation guarantees segregated networks even for non safe protocols. RJ45 Max. Safety (SIL3). Max. Availability for safeethernet. X-CPU X-SB X-COM X-COM Max. Availability for non safe communication. RJ45 RJ45 35
Security is supported by HIMA Products: High quality development process HIMA products are developed for safety following the four eyes principle Only documented ports for communication available no backdoor Minimal attack surface, only required services are integrated. Systematic use separate system supports the avoidance of common cause failures and the multi-layer protection concept. Products with Security Features Segregation of safety network (CPU) and non safety network (COM) Standard Ethernet protocols can be used with any firewall. blocking of control function via key switch Display of program changes in the DCS system via CRC Unused physical ports can be closed by using port-based VLAN. High-quality programming environment SILworX checks all software components prior to use. Code comparison to detect changes in the user program. 2-level user management Simple Project backup (one file) User access in Windows is sufficient. Secure OPC Server runs as a service, no login to Windows is required. 36
Be reluctant to trust. even vendors of secure products have to admit failures. 37
Always the right solution? HIMA can help you getting the right solution and have the right safety system you need! Maximum security and availability 38