Mechanical equipment like reliefe valve, non return valve.
Fire pumps, foam systems, water curtains, deluge systems, ventilation emergency equipment and
Risk Reduction is the Highest Priority
© ABB - Page 3
How often can it happened and what is the effect if it does ?
Functional safety
What is Risk ?

Risk is a measure of the likelihood and consequence of an unwanted happening.
© ABB - Page 13
Functional safety
Individual Risk

Individual பைடு நூலகம்isk:

Frequency and individual may receive a given level of harm (usually death) from the outcome of specified hazard The UK HSE Tolerability of Risk framework sets individual risk of fatality limits of
Example A relief valve is another technology safety-related system
© ABB - Page 8
Functional safety
“External risk reduction facility”

External risk reduction facility are those measures to reduce or mitigate the risks which are separate and distinct from, and do not use, E/E/PE safety-related systems or other technology safety-related systems


Risk measurement must address both consequence and likelihood
The consequence usually involve several forms of harm

Harm is effectively defined as the loss of benefits and thus brings benefits directly into the equation

All significant forms for harm must be considered to properly measure risk
© ABB - Page 12
Functional safety
Expression of Consequence

Measure the risk depend on two factors:

How often can it happened what will be the effect (consequence) if it does ?
and

© ABB - Page 4
Functional safety
Risk receptors/Impact

Personnel Environment Financial
Risk
Other Risk Reduction, Such as Alarming, and Exception Procedures
Safety Instrumented System
Tolerable Level of Risk
(Defined by user per application)



Equipment/property damage Business Interruption Business Liability Company Image Lost Market Share
© ABB - Page 5
Functional safety
Why does companies manage risk ?
Functional safety
What is Risk ?
What can happen ? Consequence * Likelihood (frequency) (10 people dead) * (every 200 years)
Calculated Process Risk
Process Design

Who is being exposed to risk ?


Individuals
Society Environment

What is the nature of the risk ?

Fatality / Injury Permanent/Temporary Damage Financial Loss
There is no such thing as zero risk in the real world.

© ABB - Page 11
Functional safety
Measure Risk and Benefits

Both risk and benefits must be measured to intelligently determine what to do in virtually any situation
Example A drain system, a fire wall and a bund are all external risk reduction facilities
© ABB - Page 9
Functional safety
Key terms and concepts “Risk”
Combination of the probability of occurrence of Reduce risk by: harm and the severity of that harm

Prevention Concepts Taking action prior to the hazardous event taking place Mitigation concept Taking action after the hazardous event has taken place

© ABB - Page 14
Functional safety
Levels of Risk and ALARP
Risk cannot be justified except in extraordinary circumstances Tolerable only if risk reduction is impracticable or if its cost is grossly disproportionate to the improvement gained
Make plant as safe as possible, disregard cost
Comply with regulations as written, regardless of cost or actual level of risk
© ABB - Page 6
moral
Legal
Financial



Low risk bound or tolerable region : 1*10-5 per year (1 / 100 000)
High risk bound of tolerable region : 1*10-3 per year (1 / 1 000) The ALARP region (As Low As Reasonably Practicable) typically falls in between these bounds
Actual remaining risk
Necessary minimum risk reduction
Actual risk reduction
Partial risk covered by Other Technology safety-related systems Partial risk covered by E/E/PES protective systems

Companies have a legal, moral and financial obligation to limit risk posed by their operation.

Understanding the way this is expressed in a company helps to develop safety policy consistent with the way that company already works.
Functional safety
“Other technology safety-related system”

Other technology safety-related systems are safety related systems based on a technology other than electrical/electronic/programmable electronic