industrial safety layers of protection

1

Protection

• Prevention the occurrence of hazardous event.• Stop the event from continue.• Prevention of occurrence (happening) of harm, loss.• Stop escalation (becoming worse) of hazardous event.• Mitigate the damage.(make smaller)

• Contain the event.(stop from becoming bigger).

2

Protection

Prevent HARM to Humans, Environment, Equipments & Safe Production by:

1. Design.

2. Inventory.

3. Containment.

4. Safe operation, commitment to Safe system of work.

5. Skilled & Trained workers.

6. Monitoring, evaluation, inspection.

7. Regular maintenance.

8. Control system.

9. Alarms from normal.

10. Emergency procedures & manual shutdown

Ultimate goal

3

Protection 11. Emergency shutdown system.12. Emergency Pressure Control Devices, (pressure relief valves, bursting

disks..etc)13. Secondary containments, Dikes, Bunkers.14. Local emergency control team.15. Community emergency control.

Ultimate goal

4

Protection

• Hamdi• K:\Unit 51 Emergency shut down\vidoes

on SIL and More\layer of protection• 39.06 alarms.• Good explanation 3rd video

5

Design layer:• Designed with care for safety.• By competent people.• Previous experience.• According to standards.• According to law.• High goals for safety.• Use Hierarchy of control.• Less hazardous conditions.• Simplify.• Cost effective.

Typical Layers of protection

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• Designed with care for safety.• By competent people.• Previous experience.• According to standards.• According to law.• High goals for safety.• Use Hierarchy of control.• Less hazardous conditions.• Simplify.• Cost effective.

Typical Layers of protection Design layer 1:

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Layers of protection

Good design Really ?

Bugatti veyron Top Gear production

Design layer 1:

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Layers of protection Design layer 1: Main concept of design:

• Containment of hazardous substances in all conditions.(toxic, acid, flammable, nuclear, pollutants )

• Containment of unhazardous substances in hazardous states.(high pressure , extreme temperature, pollution)

• Neutralize hazardous conditions.(cool, acid, chemical, • Usage Of secondary containments.( dikes, walls, tanks, wells)• Release to atmosphere within limits of law.• No atmospheric release unless to prevent bigger harm.( last

resort , special conditions, controlled).• Safety by inventory.

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Layers of protection Ultimate protection

Containment

Design layer 1 :

Preventing the material to be released into the open .

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Layers of protection Failure of containment protection

LOSS of Containment

Design layer 1 :

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Typical Layers of protection Basic process control system (BPCS ) 2:

• Controls process functions.• Controls process limits.• Easy to use and operate.• Operator can interfere.• Manual and automatic

functions.• Alarms for deviation.

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Typical Layers of protection Alarms, Operator intervention 3:

• Controls process limits.• Proper monitor of operation.• Easy to use and operate.• Operator stops and stars.• Manual and automatic

functions.• Alarms for deviation.• Response to alarms.• Remote or local.• Wire , wireless.

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Typical Layers of protection Alarms, Operator intervention 3:

Alarm : Audio or Visual means to Alert operators remedial action need to be taken.• Warns about conditions , deviations, critical, increased care , risky,

potential for accident, incident , accident.• Gives time for response. Control valves, thermal, flow of fluids, cooling,

mechanical delay, personal intervention, time for pneumatics, emergency team.

• For operator and controllers…high emergency , evacuations or shutdown.

• Inform operator when ESD takes over.

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Typical Layers of protection Alarms, Operator intervention 3:

• Alarm catch sensor failure.• Alarm must be recorded.• Prioritize response.• Resettable manually only.• Simplify response.• False alarms.• Not too many alarms.• Not sensitive to process function variations, startup, fuel feed, pressure up.• Clear indication of fault.• Clear indication of location of deviation.• Response trained operator.• Clear message of details.

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Typical Layers of protection Alarms, Operator intervention 3:

• Levels of alarms.

High Hazard to people or equip., action required.

Medium Loss of $$, close monitoring required.

Low Investigate when time available.

Example : In a facility 17 alarms per hour for 3 hours , the operator responded only to 4 , only 8%.

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Typical Layers of protection Safety Instrumented System(SIS) 4:

• Independent of BPCS.• Stops processes and overrides operator control.• Automatic.• Shuts down valves, process, unit or plant.• Communicates with Fire/ Gas system.• Intervenes in unacceptable conditions. • Limited access, only authorized persons.• Common cause failure between SIS and BPCS must

be minimized.• Prevents hazardous conditions ( Containment loss,

leaks, breakage of equipment, high and low pressure, over flow, run away reaction, temperature extremes).

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Typical Layers of protection Safety Instrumented System(SIS) 4:

Safety Instrumented System(SIS), Also known as:

• Emergency shutdown system(ESD).• Protective Instrumented System (PIS).• Instrument protection system (IPS).• Functional safety system (FSS).• Trip system• The main material for this course.

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Typical Layers of protection Safety Instrumented System(SIS) 4:

Typical Action from ESD system:• Stop material flow /feed shutdown.• Prevent escalation of event.• Heat stoppage /cooling system on.• Energy ventilation control .• Isolate electric equipment /power down.• Isolate hazardous material/divert flow.• Shutdown part /unit/ plant/facility.• Depressurize / Blow down.• Close water tight and fire doors.

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Typical Layers of protection Safety Instrumented System(SIS) 4:

Possible controls available:• Manual, from a main facility control point.• Manual activation from strategically located station

within facility.• Automatic from Fire & Gas detection system.• Automatic from process instrumentation set points.

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Typical Layers of protection Safety Instrumented System(SIS) 4:

ESD Levels of shutdown:ESD Level

Action Criticality

5 Non-ESD Process and Control Alarms Routine

4 Equipment Protective System Shutdown Slight

3 Equipment Shutdown Major

2 Unit or Plant Shutdown Severe

1 Total Facility Shutdown Catastrophic

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Typical Layers of protection Relief devices( Mitigation) 5 Active Protection:

• Pressure relief valves.( gradual )• Pressure safety valves. ( remains open )• Bursting discs.( too much for PRV )• Neutralizing conditions.• Blowout panels.• Vacuum breakers ( return of fluid back )• Flam arresters.• Reactor kill system.• Flare system.• Atmospheric release of toxic substances.

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Typical Layers of protection Relief devices( Mitigation) 5:• Pressure Relief Device (PRD).

• Pressure Safety Valve (PSV).• Pressure Relief Valve (PRV).

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Typical Layers of protection Relief devices( Mitigation) 5:• Rapture disks,discs

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Typical Layers of protection Physical protection, Passive protection 6:

• Secondary containment ( spillage containments).

• Fire walls.• Dikes.• Collection wells.• Controlled release , controlled

area.• Hazardous condition but under

control.

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Typical Layers of protection Physical protection, Passive protection 6:• Dikes.

• Walls.• Secondary containments

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Typical Layers of protection Physical protection, Passive protection 6:• Dikes.

• Walls.• Secondary containments

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Typical Layers of protection Plant emergency response 7 :

• Hazardous condition out of control , but manageable by plant emergency.

• Local fire fighting ( small fire ).

• Stoppable release of material.• Sufficient control equipment.• Trained teams.• Drills.

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Typical Layers of protection Plant emergency response 7 :

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Typical Layers of protection Community emergency response 8:

• Hazardous condition out of control , NOT manageable by plant emergency.

• Local fire fighting not enough( large fire ).

• Unstoppable release of material.• No sufficient control equipment.• No trained teams.• National or international hazard.

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Typical Layers of protection Community emergency response 8:

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Typical Layers of protection Protection layer failure 000 :

• Disaster.• Multiple fatalities.• Wide spread contamination.• Business stoppage.• Community disruption.• Bankruptcy.

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Typical Layers of protection Protection layer failure 000 :

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Failure of Layers of protection INDUSRTIAL ACCIDENTS:

1. https://en.wikipedia.org/wiki/List_of_industrial_disasters2. March 28, 1979: Three Mile Island accident.3. July 6, 1988: Piper Alpha disaster4. April 26, 1986: Chernobyl disaster5. June 1, 1974: Flixborough disaster6. December 3, 1984: The Bhopal disaster in India is one of the largest industrial

disasters on record. A runaway reaction in a tank containing poisonous methyl isocyanatecaused the pressure relief system to vent large amounts to the atmosphere at a Union Carbide India Limited plant. Estimates of the death toll range from 4,000 to 20,000. The disaster caused the region's human and animal populations severe health problems to the present.