CHENG5163 :PLANT DESIGN AND ECONOMICS
CHAPTER
2 PROCESS DESIGN DEVELOPMENT
Lecture 6 :Piping and Instrumentation Diagram
Tesfa Nega
Faculty of Chemical and Food Engineering, Bahir Dar
Institute of Technology, Bahir Dar, Ethiopia
Email: tesfanega510@gmail.com
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Faculty of Chemical and Food Engineering
Outline
Piping and Instrumentation Diagram (P&ID)
Representation
Codes and Standards
Symbols
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CHENG5163– PLANT DESIGN AND ECOMONICS
Faculty of Chemical and Food Engineering
Piping and Instrumentation Diagram (P&ID)
The piping and instrumentation diagram shows the engineering
details of the equipment, instruments, piping, valves and fittings
and their arrangement.
It is also called the engineering flow sheet or engineering line
diagram.
P&ID usually does not show:
The process information,
The equipment rating or capacity,
Pressure, temperature, flow data, and
Manual switches.
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CHENG5163– PLANT DESIGN AND ECOMONICS
Faculty of Chemical and Food Engineering
(P&ID): A Key Document
The P&ID acts as a directory to all field instrumentation and
control that will be installed on a process and thus is a key
document to the control engineer.
The P&ID plays an important role in the design, installation and to
day to day maintenance of the control system.
It is a key piece of information in terms of understanding what is
currently being used in the plant for process control and safety.
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CHENG5163– PLANT DESIGN AND ECOMONICS
Faculty of Chemical and Food Engineering
(P&ID): A Key Document
For example
The plant operator sees some malfunctioning with a piece of
valve and reports to maintenance department that a valve on a
piece of equipment is not functioning correctly.
Maintenance person will consult the P&ID to identify the tag
assigned to the valve to can learn how the valve is used in the
control of the process.
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CHENG5163– PLANT DESIGN AND ECOMONICS
Faculty of Chemical and Food Engineering
(P&ID): Representation
Control and measurement instruments are represented by specific symbols
and circles with letters and numbers.
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CHENG5163– PLANT DESIGN AND ECOMONICS
Faculty of Chemical and Food Engineering
(P&ID): It Should Show
All process equipment identified by
equipment number.
The equipment are usually drawn in
proportion. The location of nozzles are
shown.
All pipes are identified by line number
The pipe size and material of
construction should be shown. The
material may be included as part of the
line identification number.
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CHENG5163– PLANT DESIGN AND ECOMONICS
Faculty of Chemical and Food Engineering
(P&ID): It Should Show
All valves, control valves, block
valves are shown with identification
number.
The type and size should also be
shown.
The type may be shown by the
symbol used for the valve or included
in the code used for the valve number.
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CHENG5163– PLANT DESIGN AND ECOMONICS
Faculty of Chemical and Food Engineering
(P&ID): It Should Show
All valves, control valves, block valves
are shown with identification number.
The type and size should also be
shown.
The type may be shown by the symbol
used for the valve or included in the
code used for the valve number.
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CHENG5163– PLANT DESIGN AND ECOMONICS
Faculty of Chemical and Food Engineering
(P&ID): It Should Show
Ancillary fittings that are part of the
piping system such as inline sight
glasses, strainers and steam traps are
shown with an identification number.
Cold and hot insulation are marked.
All pumps are shown with suitable code
number.
All control loops and instruments are
shown with an identification number.
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CHENG5163– PLANT DESIGN AND ECOMONICS
Faculty of Chemical and Food Engineering
(P&ID): It Should Show
For simple processes, the utility lines, also known as service lines
can be shown on the P&ID. Utility connections are identified by a
numbered box in the P&ID. The number within the box identifies
the specific utility. The key identifying the utility connections is
shown in a table on the P&ID.
For complex processes, separate diagrams would be used to show
the utility lines. Then the service connections to each unit should be
shown on the P&ID. The same equipment identification number
should be used on both the PFD and P&ID.
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CHENG5163– PLANT DESIGN AND ECOMONICS
Faculty of Chemical and Food Engineering
(P&ID): Equipment Elevation
P&ID, mention elevation of an equipment, when relative height of a
specific equipment is important.
For example, barometric condenser is installed at about 10.5 meter
height from hot well water level in order to remove water and
condensate without losing vacuum.
The barometric leg should be maintained with a hydrostatic head
equal to the difference between vacuum and atmospheric pressure.
Atmospheric pressure corresponds to a hydrostatic head of about
10.35 meters of water and complete vacuum corresponds to zero
hydrostatic head so in order to maintain vacuum, the barometric
condenser installed at about 10.5 meter height from the hot well water
level.
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CHENG5163– PLANT DESIGN AND ECOMONICS
Faculty of Chemical and Food Engineering
Codes and Standards: PFD and P&ID
These are the codes that are used for creating process flow diagrams as
well as P&ID.
Indian standards:
IS: 3232-1999 (Reaffirmed 2005) Graphical symbols for process flow
diagrams, P&ID
IS: 9446 Graphical symbols for pipelines, and instrumentation
diagrams
US Standards:
ANSI Y32.2.3 Graphical Symbols For Pipe Fittings, Valves, and Piping
ANSI Y32.2.11 Graphical Symbols For Process Flow Diagrams
ISA 5.5 Graphical Symbols For Process Displays
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CHENG5163– PLANT DESIGN AND ECOMONICS
Faculty of Chemical and Food Engineering
Codes and Standards: PFD and P&ID
British Standards:
BS: 1646 1 to 4 Symbolic representation for process
measurement, control, functions and instruments
German Standards:
DIN 19227 P1 to P3 Graphical Symbols and identifying letters for
process measurement and functions
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CHENG5163– PLANT DESIGN AND ECOMONICS
Faculty of Chemical and Food Engineering
P&ID: Symbols
Represent of all types of control valves, both
pneumatic and electric actuators
The direction of the arrow shows the
position of the valve when the power
supply fails.
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CHENG5163– PLANT DESIGN AND ECOMONICS
Faculty of Chemical and Food Engineering
P&ID: Symbols for Valve
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CHENG5163– PLANT DESIGN AND ECOMONICS
Faculty of Chemical and Food Engineering
P&ID: Symbols for Valve
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CHENG5163– PLANT DESIGN AND ECOMONICS
Faculty of Chemical and Food Engineering
P&ID: Pump Symbols
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CHENG5163– PLANT DESIGN AND ECOMONICS
Faculty of Chemical and Food Engineering
P&ID: Basic Actuator Symbols
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CHENG5163– PLANT DESIGN AND ECOMONICS
Faculty of Chemical and Food Engineering
P&ID: Definitions
Locally Mounted: The instrument and the
display when located on the plant, near the
location of the measuring (sensing)
instrument.
Main Panel: Instruments located on a
panel in the control room. (more common)
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CHENG5163– PLANT DESIGN AND ECOMONICS
Faculty of Chemical and Food Engineering
P&ID: Definitions
Distributed control system : System is
functionally integrated, but consists of
subsystems that may be physically separated
and remotely located from one another.
Shared display. An operator interface device
(computer screen, video screen) that is used to
display process control information from a
number of sources. Modern plants use shared
display instead of instrument panels.
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CHENG5163– PLANT DESIGN AND ECOMONICS
Faculty of Chemical and Food Engineering
P&ID: Instrument Representation
The P&ID will use symbols and circles to represent each instrument and
how they are interconnected in the process. The type and the function of
the instrument is indicated on the circle by a letter code and tag number.
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CHENG5163– PLANT DESIGN AND ECOMONICS
Faculty of Chemical and Food Engineering
P&ID: Instrument Representation: Convention
TIC 103 Instrument Identification or Tag Number
T 103 Loop Identifier
103 Loop Number
TIC Function Identification
T First Letter
IC Succeeding –Letters
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CHENG5163– PLANT DESIGN AND ECOMONICS
Faculty of Chemical and Food Engineering
P&ID: Instrument Representation
The presence or absence of a line determines the location of the physical
device. For example, no line means the instrument is installed in the field
near the process
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CHENG5163– PLANT DESIGN AND ECOMONICS
Faculty of Chemical and Food Engineering
P&ID: Same Number in a Control Loop
Same number is used in all instruments of a
particular control loop.
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CHENG5163– PLANT DESIGN AND ECOMONICS
Faculty of Chemical and Food Engineering
P&ID: Instrument Representation: Convention
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CHENG5163– PLANT DESIGN AND ECOMONICS
Faculty of Chemical and Food Engineering
P&ID: Instrument Representation: Convention (Cont’d)
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CHENG5163– PLANT DESIGN AND ECOMONICS
Faculty of Chemical and Food Engineering
P&ID: Instrument Representation: Convention (Cont’d)
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CHENG5163– PLANT DESIGN AND ECOMONICS
Faculty of Chemical and Food Engineering
P&ID: Line Code
The P&ID will use symbols and circles to represent each instrument and
how they are interconnected in the process.
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CHENG5163– PLANT DESIGN AND ECOMONICS
Faculty of Chemical and Food Engineering
P&ID: Abbreviation for Secondary Flow Lines
AS Air Supply HS Hydraulic Supply
IA Instrument Air NS Nitrogen Supply
PA Plant Air SS Steam Supply
ES Electric Supply WS Water Supply
GS Gas Supply
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CHENG5163– PLANT DESIGN AND ECOMONICS
Faculty of Chemical and Food Engineering
P&ID: Control Valve
The usual way for the characterization of control valves for liquids is the
Cv value (flow coefficient), which is defined as the number of gallons
per minute (gpm) at 60 ℉ that will pass through a fully open valve with
the pressure drop of 1 psi.
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CHENG5163– PLANT DESIGN AND ECOMONICS
Faculty of Chemical and Food Engineering
P&ID: Example
Piping and Instrumentation Diagram for Benzene Distillation (adapted from Kauffman, D., Flow Sheets and Diagrams)
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CHENG5163– PLANT DESIGN AND ECOMONICS
Faculty of Chemical and Food Engineering
P&ID: Example: A Simple Mixing Tank
Identify the instruments, whether
they are pneumatic type, or
electric type. Identify all
the lines and the instrument types.
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CHENG5163– PLANT DESIGN AND ECOMONICS
Faculty of Chemical and Food Engineering
Alarm and Safety Trips
Audible and visual alarms are used to
alert operators of serious and
potentially hazardous deviations in
process conditions.
Some key instruments are fitted with a The figure shows that on a high
trip system to take action temperature, the high temperature
automatically to avoid hazardous alarm will operate a solenoid valve
situation such as shutting down to release the air on the pneumatic
pumps, closing valves, operating activator and thus close the valve.
emergency systems.
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CHENG5163– PLANT DESIGN AND ECOMONICS
Faculty of Chemical and Food Engineering
False Alarm
Alarms that actuate because of faulty sensors, or because the
alarm limit is set too close to normal operating conditions
frequently provide false alarms.
It is difficult to tell when these unreliable alarms are warning of a
real deviation that requires action.
If a display is crowded with many such nuisance alarms
operators may fail to notice a real alarm that requires action
Never ignore safety alarms.
If your plant has alarms that do not require a response, evaluate
the need for the alarms.
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CHENG5163– PLANT DESIGN AND ECOMONICS
Faculty of Chemical and Food Engineering
P&ID: How Many Errors Can You Find Here?
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CHENG5163– PLANT DESIGN AND ECOMONICS
Faculty of Chemical and Food Engineering
THANK YOU..
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CHENG5163– PLANT DESIGN AND ECOMONICS
