PID

1. Piping and Instrumentation
Diagram
Dr. AA
PiCS, UTM
Piping and Instrumentation Diagram
• Similarly to electrical schemas, the control industry
(especially the chemical and process industry) describes its
plants and their instrumentation by a
• P&ID (pronounce P.N.I.D.) (Piping and Instrumentation
Diagram), sometimes called P&WD (Piping and wiring
diagrams)
• The P&ID shows the flows in a plant (in the chemical or
process industry) and the corresponding sensors or actors.
• At the same time, the P&ID gives a name ("tag") to each
sensor and actor, along with additional parameters.
• This tag identifies a "point" not only on the screens and
controllers, but also on the objects in the field.
Plant Operation by Dr. AA, 2008 Page 2.1c - ‹#›

2. Piping & Instrumentation Diagram (P & I)
• P & I should be included with
– All process equipment identified by equipment number
– All pipes identified by a line number. Pipe size and material
of construction should be shown (material may include as a
part of the identification number)
– All valves with an identification no. along with their type &
size should be shown
– Ancillary fittings that are part of piping system such as inline
sight glasses, strainers and stream traps with an
identification no.
– Pumps identified by a suitable code no.
– All control loops and instruments with identification
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3. Instrument Identification
T
M T
yp
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e
as e
of
ur of
C
e C
o
d o
m
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p
ar dit
o
ia io
n
bl n
e
e er
nt
P&ID T
R
=
The P&ID mixes pneumatic / hydraulic elements, electrical elements
and instruments on the same diagram =
F
Tr
= R
It uses a set ofFl
symbols defined in the ISA S5.1 standard. a
ec
ns
o or
Examples of pneumatic / hydraulic symbols: mi
w d
pipe tt
er 350 kWheater
valve er
one-way valve (diode) vessel / reactor
I
binary (or solenoid) valve (on/off) M
L = =
analog valve (continuous)
= In M
heat exchanger
L
pump, also di o
ev ca dif
el to ie
r r
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E
P =
=
= C
El
Pr o
e

4. Instrumentation identification
The first letter defines the measured or initiating variables such as Analysis (A), Flow (F),
Temperature (T), etc. with succeeding letters defining readout, passive, or output functions such
as Indicator (I), Record (R), Transmit (T), and so forth
FIC
V1528
tag name of the
mover corresponding
(here: solenoid) variable
S
function
(here: valve)
ISA S5.1 General instrument or function symbols
Primary location Auxiliary location
accessible to Field mounted accessible to
operator operator
Discrete
instruments
Shared
display,
shared control
Computer
function
Programmable
logic control
1. Symbol size may vary according to the user's needs and the type of document.
2. Abbreviations of the user's choice may be used when necessary to specify location.
3. Inaccessible (behind the panel) devices may be depicted using the same symbol but with a
dashed horizontal bar.
Source: Control Engineering with data from ISA S5.1 standard
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5. Example of P&ID
The output of FIC 101 is an electrical signal to TY 101
located in an inaccessible or behind-the-panel-board location.
TIC 101’s output is connected
via an internal software or
Square root extraction of the data link (line with bubbles) to
input signal is part of FIC 101’s the setpoint (SP) of FIC 101
functionality. to form a cascade control
strategy
FT101 is a field-mounted flow
transmitter connected via
electrical signals (dotted line) to
flow indicating controller FIC TT 101 and TIC 101 are
101 located in a shared similar to FT 101 and FIC 101
control/display device but are measuring,
indicating, and controlling
The output signal from TY 101 temperature
is a pneumatic signal (line with
double forward slash marks)
making TY 101 an I/P (current
to pneumatic transducer)
The ISA code for instrument type
F
M i M
A eA r o
B aB s d
n
s t i
C U
u
a
u l f
D U
s
r D
rl e i
E e
V
s
e
n
y t ei
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o
r
e
s t R
rf
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r
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f
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o
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e
s
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w
a
s i
r
c
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r
g S
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o
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c
a
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h n
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i
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io
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r
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t e
a
n (
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p
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Z P
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6. Common connecting lines
Connection to process, or
instrument supply
Pneumatic signal
Electric signal
Capillary tubing (filled system)
Hydraulic signal
Electromagnetic or sonic
signal (guided)
Internal system link
(software or data link)
Source: Control Engineering with data from ISA S5.1 standard
Many Standards
• DIN
• ISA
• etc
Plant Operation by Dr. AA, 2008 Page 2.1c - ‹#›