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1、Part 03 Hazard and Risk Analysis,Heidi Fuglum Certified Functional safety engineer,1 day intro training in Functional safety,Hazard and Risk Analysis,In this module How much safety is enough? Risk management Hazard identification Hazard Analysis Risk Reduction Techniques Risk graph, risk matrix Iden
2、tification safety function,Safety Lifecycle, where are we,SIL Determination,Hazard Identification,SIL Implementation,Overall Operation & Maintenance,Overall Modification & Retrofit,Hazard / Risk Analysis,Objective Identify process hazards, estimate their risks and decide if the risk is tolerableTask
3、 Hazard identification Analysis of Likelihood and Consequence Consideration of non-SIL Layers of protection,IEC 61508 4 A potential source of harmNOTE The term includes danger to persons arising within a short time scale (for example, fire and explosion) and also those that have a long-term effect o
4、n a persons health (for example, release of a toxic substance).AIChE An inherent chemical or physical characteristic that has the potential for causing damage to people, environment or property.Kietz A substance, object or situation that can give rise to injury or damage,Definition of Hazard,What is
5、 a Hazardous Event,A hazardous Event occurs when the potential hazard has happend,What is Risk ?,Risk,Calculated Process Risk,Tolerable Level of Risk,(Defined by user per application),Process Design,Other Risk Reduction, Such as Alarming, and Exception Procedures,Risk Reduction is the Highest Priori
6、ty,Risk is a combination ofConsequence (C) * Likelihood (frequency, F)Risk = C *F Need to determine the risk associated with the hazardous event,Safety Instrumented System,How often can it happened and what is the effect if it does ?,What is tolerable risk,The basis of risk analysis: Tolerable risk
7、How much risk do you tolerate? How can we estimate how much risk reduction we need if we do not know how much we tolerate? Who determines tolerable risk? Society does Risk of smoking Risk of driving a car Risk of doing business,Risk reduction to meet criteria,Risk Target,Increasing risk,Necessary ri
8、sk reduction,Actual risk reduction,Risk reduction left to be handled by the Safety Instrumented Systems SIS,Risk reduction due to other technology: -fire pumps, -foam systems, -water curtains, -deluge systems (hydraulic, pneumatic ),Calculated Process Risk,Tolerable Level of Risk (Defined by user pe
9、r application),Risk reduction due to mechanical equipment like: - relief valve, non return valve,dike ,Mechanical equipment like reliefe valve, non return valve.,Fire pumps, foam systems, water curtains, deluge systems, ventilation emergency equipment and procedures,How do we manage risk,Companies d
10、eal with risk in three ways They reduce the consequence to an acceptable level They reduce the frequency to an acceptable level They reduce the risk to an acceptable level,Risk Management,Three important steps Identify the hazards / hazardous events Analyze the hazards / hazardous events Reduce risk
11、 were necessary How do we do that ? Three categories of techniques Qualitative: Everything expressed in words Quantitative: Everything expressed in numbers Semi-quantitative: a mixture of words and numbers,Hazard Identification,Hazard Identification Once the hazards are identified the job is half do
12、ne Is the first and most important step when identifying the required safety functions for your safety system A safety function is useless if it is not linked to a hazard or hazardous event Safety systems not based on hazards are either Over dimensioned $ Under dimensioned $,Common Hazard identifica
13、tion Methods,Checklist What if? What if? /Checklist HAZOP (Hazard and Operability Study) FMEA (Failure Modes and Effects Anlaysis Fault Tree Analysis Appropriate Equivalent Methods,Not one method fits all often use several methods HAZOP most commoncan use at any lifecycle,Recommendations for good pr
14、ocess,Multi discipline team Process and system engineers Operators and Maintenance safety engineers Often one independent as a facilitator Bring in people with special competence on specific equipment Document process Insure recommendations are acted upon Revisit analysis every xxx period (5 years),
15、Hazard Identification Techniques,Information needed The physical environment including neighbors Equipment under control Basic process control system and its function Information about hazards (toxicity, explosive condition, corrosiveness, reactivity, flammability) Existing safety regulations (laws,
16、 standards, guidelines),Fault Tree Analysis,About fault tree analysis It is a top down technique It starts with an undesired top event and from there try to find out all different ways the top event can occur Can be used to find any combination of events or failures that can cause the TOP event It is a verification technique What is it about The causes of the TOP event are connected though logic gates in a tree Can be performed qualitative and quantitative,
