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8/31/12
How to Read a P&ID ForRiskAnalysis
8/31/12
P&ID is a Piping and Instrumentation Diagram
8/31/12
To identify risk from a set of P&ID you must have clear understanding of three things…
8/31/12
#1
Understand the process
8/31/12
#2 Understand the failures
8/31/12
#3
Understand the consequence
8/31/12
Lines are used for showing piping, equipment and instrumentation connections…
8/31/12
…so people can communicate the process sequence and the relationship of different equipment
8/31/12
Equipment and instrumentation are connected by lines
Here are some common connections
8/31/12
Pipe
Common Failure Modes:- Collapse- Burst/Rupture- Erosion- Corrosion
8/31/12
Electrical Signal
Common Failure Modes:- Open connection- Electrical shorting- Electromagnetic interference
8/31/12
Pneumatic Signal
Common Failure Modes:- Leakage of internal fluid- High components friction level- Loss of pressure
8/31/12
Data Signal
Common Failure Modes:- Radio interference - Signal filtering- Packets Loss- Loss of signal
8/31/12
Flexible Pipe
Common Failure Modes:- Compressive failure- Tensile failure- Over bending - Rupture
8/31/12
Symbols are used to simplify drawings
From this To this
>>>>>>
>>>
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Some equipment are used to add or reduce energy in the material
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Blower
Common Failure Modes:- Fail to operate on demand- Loss of pressure
8/31/12
Furnace
Common Failure Modes:- Flame out
8/31/12
Pump
Common Failure Modes:- Fail to operate on demand- Loss of pressure- Over pressure
8/31/12
Compressor
Common Failure Modes:- Fail to start- Damage due to liquid- Over pressure- Excessive vibration
8/31/12
Heat exchanger
Common Failure Modes:- Leakage- Corrosion- Plugged
8/31/12
Plate Heat Exchanger
Common Failure Modes:- Leakage- Corrosion- Plugged
8/31/12
Aerial Fan
Common Failure Modes:- Loss of air circulation
8/31/12
Some equipment are used for material storage
8/31/12
Floating Storage Tank
Common Failure Modes:- Overflow- Leakage
8/31/12
Sphere Tank
Common Failure Modes:- Overpressure
8/31/12
Pressurized Vessel
Common Failure Modes:- Overpressure
8/31/12
Some equipment are used to separate material
8/31/12
Horizontal Separator
Common Failure Modes:- Overpressure
8/31/12
Vertical Separator
Common Failure Modes:- Overpressure
8/31/12
Fluid Contacting Column
Common Failure Modes:- Overpressure- Corrosion- Plugged
8/31/12
Tray Column
Common Failure Modes:- Overpressure- Contamination
8/31/12
Valves are used to control the flow of material
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Manual Valve
Common Failure Modes:- External leakage- Internal leakage- Inadvertent position
8/31/12
Control Valve
Common Failure Modes:- Fail to close on demand- Fail to open on demand- Spurious operation- Leakage
8/31/12
Solenoid Valve
S
Common Failure Modes:- Structural failure- Seat Leakage- Seal Leakage- Loss of actuator
8/31/12
Motor-operated Valve
M
Common Failure Modes:- Motor failure- Fail to stroke
8/31/12
Butterfly Valve
Common Failure Modes:- Fail to close on demand- Fail to open on demand- Spurious operation
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Globe Valve
Common Failure Modes:- Fail to close on demand- Fail to open on demand- Spurious operation- Leakage
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Needle Valve
Common Failure Modes:- Fail to close on demand- Fail to open on demand- Spurious operation- Leakage
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Ball Valve
Common Failure Modes:- Fail to close on demand- Fail to open on demand- Spurious operation- Leakage
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Check valve
Common Failure Modes:- Leakage- Stuck at open position
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Some equipment are used to relief pressure in the process
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Relief Valve
Common Failure Modes:- Fail to open
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Curved Gas Vent
Common Failure Modes:- Plugged
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Rupture Disk
Common Failure Modes:- Corrosion
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Control system are used to manage the behaviour of the process
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Programmable Logic Control
Common Failure Modes:- Software error- Execution error
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Shared display, shared Control
Common Failure Modes:- Software error- Execution error
8/31/12
Sensors are used to measure the physical properties of the process and convert it into a signal
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Flow Transmitter
FT
Common Failure Modes:- Spurious measurement- Loss of measurement
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Pressure Transmitter
PT
Common Failure Modes:- Spurious measurement- Loss of measurement
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Level Transmitter
LT
Common Failure Modes:- Spurious measurement- Loss of measurement
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Now lets identify the risk of this process…
8/31/12
LT253
HLL=2550 mmNLL=1650 mmLLL=250 mm
LC
LY LV
Steam
Condensate
To atmosphere at safe location
PSV
D-101
D-101 Re-boiler Condensate Pot
253
253
253
111
Drawing Ref.
Drawing Ref.
LG253
2”
2”
3”
3”
3/4”
3/4”
6” 6”
6”
6”
Size ½SET @ 700kPag
6”
8/31/12
Step 1: Understand the process
• There is low pressure steam flowing into the vessel
• The steam cools and forms condensate in the condensate pot
• The level of the condensate liquid is controlled by a level control loop
• Condensate is drained out the bottom of the vessel
8/31/12
LT253
HLL=2550 mmNLL=1650 mmLLL=250 mm
LC
LY LV
Steam
Condensate
To atmosphere at safe location
PSV
D-101
D-101 Re-boiler Condensate Pot
253
253
253
111
Drawing Ref.
Drawing Ref.
LG253
2”
2”
3”
3”
3/4”
3/4”
6” 6”
6”
6”
Size ½SET @ 700kPag
6”
Start
8/31/12
Step 2: Identify possible failures
The control loop can malfunction causing the valve LV253 to fail in the closed position
8/31/12
LT253
HLL=2550 mmNLL=1650 mmLLL=250 mm
LC
LY LV
Steam
Condensate
To atmosphere at safe location
PSV
D-101
D-101 Re-boiler Condensate Pot
253
253
253
111
Drawing Ref.
Drawing Ref.
PG253
2”
2”
3”
3”
3/4”
3/4”
6” 6”
6”
6”
Size ½SET @ 700kPag
6”
8/31/12
Step 3: Assess the consequence
• The level control valve fails in the closed position blocking the drain line
• Hazard is high level and high pressure in the tank
• Potential consequence of loss of containment and equipment damage with $$$$ losses
8/31/12
Now you have identified the cause of the overpressure hazard, can you identify the safeguard?
8/31/12
The pressure relief with a set point of 700 kPa will open and reduce but not eliminate the risk of rupture
8/31/12
LT253
HLL=2550 mmNLL=1650 mmLLL=250 mm
LC
LY LV
Steam
Condensate
To atmosphere at safe location
PSV
D-101
D-101 Re-boiler Condensate Pot
253
253
253
111
Drawing Ref.
Drawing Ref.
LG253
2”
2”
3”
3”
3/4”
3/4”
6” 6”
6”
6”
Size ½SET @ 700kPag
6”
8/31/12
By understanding the P&ID you can clearly assess risk in your operation and make good decisions
8/31/12
Any Questions?
Click to edit Master subtitle style
8/31/12
Risk. Inspired.
For more lessons go to www.icarus-orm.com