How to Read Piping & Instrumentation Diagram for

Beginners
Intended for Engineers who are new in plant or facilities and final year
engineering and OHS students.
By Cahyo Hardo, B.Eng., M.OHS.

Bahasa version had been shared in Indonesian

Association of Oil and Gas Safety and Engineering
Experts forum

August, 2025

Free to distribute
Indeed, with hardship there is ease..
(QS. Al Insyirah : 6)

2
 How to Read Piping & Instrumentation Diagram for
Beginners

References:
• ANSI/ISA-5.1-2009. Instrumentation Symbols and Identification.
• Gunterus, F. (1997). Falsalah dasar: Sistem pengendalian proses. Jakarta: Elex Media Komputindo.
• Hardo, C.H. (2017). The truth is out there. Jakarta: e-book – free download in internet (in Bahasa).
• Hardo, C.H. (2025). How to read piping & instrumentation diagram.
• Hardo, C.H. (2006). Role of Chemical Engineering in Surface Production Facility, SPE Java Section
seminar. Technical Faculty, University of Indonesia.
• John Campbell.(2002). Gas Conditioning and Processing Module.
• ISA (1999). Reading a P&ID – Course-203.
• OPITO. Process Flow & P&ID’s. Part of the Petroleum Processing Technology Series.
• https://www.wika.com/media/Data-sheets/Level/Sight-glass-level-indicators/ds_lm3301_en_co.pdf

TC
PG SD
4106
4120 3
Introduction
• For the upstream oil and gas industry.
• Primary target audience: Final-year engineering and OHS students, and engineers
new to Plant/facilities
• Uses terminology from Chemical Engineering and Process Engineering.
• Challenge: Explaining P&IDs in a relatively short time.

Stages (ideal)
1. Understand Process Flow Diagrams.
2. Understand how common unit operations in a
plant or production facility work.U
3. nderstand safety aspects in P&IDs.
4. Ready to read P&IDs properly.
4
Essential supplies
Being able to read P&IDs is a good foundation for:

Production Process
Other
Supervisor Engineer
Engineers
Process
Production Field Investigation
Safety
Operator Engineer Team
Engineer Member
Maintenance Operation HSE
Supervisor Manager
Field Staff
Maintenance HSE
Safety HAZOP
Staff Manager
Officer Participants
MOC
OIM
Coordinator Auditor

5
 Uses of P&ID
1. Explained plant operating manual 8. Tools for engineer for plant optimisation.
2. Plant protection design guidelines. 9. One of main documents in Facility MOC.
3. Tools for troubleshooting operation. 10. HAZOP main document.
4. Associate document in permit to work. 11. Supporting tools for investigation.
5. Reference in SOP or SOP development. 12. Supporting for emergency situation.
6. Supporting tools for new operator training. 13. Part of documents in technical discussion.
7. Reference for audit. 14. One of interview tools.

6
7
Process Flow Diagram
GAS CO2 and/or
PROCESSING Sulfur

Gas Lift COMPRESSION COMPRESSION Gas Sales or

(optional) (OPTIONAL) (OPTIONAL) Reinjection/
Gas Lift
COMPRESSION
(OPTIONAL) NGLs
NGL Sales
PRODUCTION
RESERVOIR
SEPARATOR

CRUDE OIL/
CONDENSATE Crude Oil/
STABILIZATION Condensate
& DEHYDRATION Sales
Oil
Water

PRODUCED Water to
WATER disposal (sea or
TREATMENT reinjection)

Schematic View of a Typical Integrated Surface Production Facility

8
How Equipment Works
Separator

• Used to separate gas, oil/condensate, and water by exploiting their density

differences.
• Inside the separator:
• Gas will always be at the top and exit at the top of the separator.
• The oil/condensate layer will always be above the water layer.
• The oil/condensate will be discharged from the separator at the end or middle of
the separator, depending on the liquid level control method.
• To ensure proper separation, the following must be observed:
• The pressure inside the separator must be maintained using a pressure control
valve (which maintains the gas outlet pressure) or indirectly controlled by a
suction compressor.
• The liquid level must be maintained using a level control valve.
 FT

FE
Separator PC

PC
Gas
Gas, Crude
oil/Condensate, LIC

Water From
DARI SUMUR
LC

MINYAK/GAS
Gas/Oil
LIC
Wells
LC
Crude
PC
oil/Condensate

LIC
Water LC

Separator Unit with its control system

Separator operation with flow control due to

capacity limitations

10
 Gas, Crude
Separator oil/Condensate, Gas
PC
Water

SEPARATOR C

LC

LIC
Water

Bucket and weir-type Crude oil/

horizontal separator Condensate

11
How Equipment Works
Centrifugal Pump
• A device for transporting liquid fluids (water, oil, condensate).
• The flow rate follows the pump's performance curve—a
parabolic curve.
• The lower the pressure at the pump outlet, the greater the
pump flow rate.
• To increase capacity, additional pumps are used, operated in
parallel or in series.
• To increase discharge pressure, additional pumps are used in
series.
• Requires:
• Sufficient inlet pressure to prevent cavitation (NPSH Available vs. NPSH Requirement).
• Relatively clean fluid.
• Minimum flow rate as specified by the manufacturer.
• Protection against high pump discharge pressure.
• Process Control Objectives:
• Minimum flow control (avoid cavitation and overheating).
• Control of pump output pressure or flow. 12
 Centrifugal Pump

• The pump discharge pressure

is determined by the system
downstream of the pump
(PCV, pressure in the piping).
• The flow rate follows the
discharge pressure.

Pump performance curve - discharge pressure vs flow

13
 FROM TO FLARE 100
FC SLOPE 1
SEPARATORS PSV-F2 (SPARE)
PC SET @
100 PSIG LO
FIRE 100
LC 1 SLOPE
LO
LC LO
PSV-F1
LO
SET @100 PSIG LO
FIRE

FCV B
ANSI 150 ANSI 300
ANSI 150

FO
ANSI 300

LO
SEPARATOR ANSI
LC ANSI LO 150
MAWP 100 PSIG ANSI
150 LO ANSI
600
LSLL 600
PSV-A LC PSV- B (SPARE)
SET @ 740 PSIG LO SET @ 740 PSIG
LO LO LC
FULL BLOCKED LO FULL BLOCKED
DISCHARGE DISCHARGE

Set @ minimum
LALL 5000 bpd
SET @
PI PSHH
700 PSIG FC FC
LO
LO
FE FE ANSI 300 ANSI 150
TI PI
CRUDE OIL
PDI
FC
TANKS
ANSI 300
FCV A
ZLO ZSO
ANSI 150
ZSO ANSI 150
ANSI 300
PUMP A
LO

ZLC ZSC
LO

DRIVER
PUMP A

S/D HS
LC LC

DRIVER
ESD PUMP B

F&G PI

PI

PDI
P&ID Basic control and safety devices
ANSI 300
ANSI 300
of centrifugal pump systems
PUMP B
14
Centrifugal Pump – special duty
• It doesn't shut down even if the power goes out. It has an independent power supply!
• It doesn't shut down even if the ESD or fire signal is active.
• It rarely operates, and will continue operating in the event of a fire, even if the diesel tank level is
low, even if the vibration alarm has been sounding from the start.
• The pump is a fire water pump – its job is to supply firefighting water. OUTLET TO PROCESS

• Most are centrifugal-type, so their design follows that of a centrifugal

pump.
• Generally, minimum recirculation flow installations do not use control
valves and orifices, but instead utilize mechanical principles to regulate
flow with a special valve called an ARV (automatic recirculation valve).

RECIRCULATE

INLET 15
Pompa Sentrifugal – special duty

16
How Equipment Works

Centrifugal Compressor
• A gas fluid transport device.
• Its performance follows a parabolic compressor
curve.
• Specificity:
• Requires a minimum flow rate to prevent
‘surges’.
• Compressor output pressure must not be
too low to prevent ‘stalls’.
• Requires overpressure protection from high
compressor discharge pressures.
• Process Control:
• Control to avoid surges.
• Capacity control.
• Butuh overpressure protection dari tekanan
discharge kompresor yang tinggi
17
 FEED GAS
FROM ANTI SURGE
SATELLITES VALVE

PSV-2 PSV-3 TO
SLOPE 100 1 DEHYDRATION
SYSTEM
SPEED CONTROL
SC
SET @ SET @
420 PSIG 320 PSIG PT

PSV-1 COMPRESSOR COOLER TO

PSHH FLARE
A
BLOWDOWN
VALVE

SET @ LCV-2
SEPARATOR
290 PSIG
LSHH
PT
Barrel-type centrifugal compressor
LCV-1
PLANT RECYCLE
TO SIMILAR VALVE
COMPRESSOR
SYSTEM C, D,X

FE FC SET @
350 PSIG ANTI SURGE
VALVE
TO
FLARE PSV-5 PSV-6
PCV
SLOPE 100 1
SET @ PSV-4
420 PSIG SPEED CONTROL
PSHH SC
SET @ TO
320 PSIG PT FLARE

SEPARATOR COMPRESSOR COOLER

LSHH
B
BLOWDOWN
VALVE
Horizontal-split-type centrifugal
LCV-4 compressor
LCV-5

Simple P&ID - Parallel compressor control system 18

Safety in P&ID
• Maximum Allowable working pressure (MAWP) of pressure vessel, piping, (ANSI
rating, API rating)
• Specification Break
• Pressure Safety Valve
• Safety Devices
• Overpressure protection:
• Equipment (e.g., separators, pumps, compressors)
• By-pass control valves, flow rate controllers (using RO, limited pipe diameter)
• Fail-safe conditions (whether an actuated valve should be open, closed, or
otherwise)
• Safe fluid disposal systems (flares, burn pits).

19
Pressure Vessel
• The P&ID displays the operating unit's Maximum Allowable Working
Pressure (MAWP), including its piping and fittings. So, how do you
determine whether a system with varying MAWPs can operate safely?
• The design pressure of a pressure vessel is also known as its MAWP.
In many cases, the MAWP determines the setting pressure of the PSV.
• The operating pressure of a pressure vessel under normal operating
conditions is called the operating pressure, which is < MAWP. The
operating pressure is determined by the process conditions.
Operating Pressure Minimum difference between operating pressure
and MAWP
Less than 50 psig 10 psi
51 s/d 250 psig 25 psi
251 s/d 500 psig 10% of maximum operating pressure
501 s/d 1000 psig 50 psi
> = 1001 psig 5% of maximum operating pressure
Vessels equipped with a pressure switch shutdown must add 5% or 5 psi to the minimum differential
between the operating pressure and the MAWP, whichever is greater. 20
Piping System
• The MAWP in a piping system is determined by the weakest part of the pipe, the connection.
• The MAWP of a flange connection determines the overall MAWP of the piping system.
• Two pipes made of identical material and with the same diameter will have the same MAWP.
• However, because each flange is different, for example, one is ANSI 150 and the other is ANSI 300,
the MAWP will depend on the MAWP of those flanges.
• If the piping system is connected to a pressure vessel/process, the overall system MAWP is
determined by the MAWP of the weakest piece of equipment/piping in the system.

Note: ANSI is the abbreviation for the American National Standard Institute, an institution from the United
States that issues various standards.

21
 ANSI ANSI
Determining the MAWP of a system 300 600

PSV-3 SET @
ANTI SURGE 1000 PSIG
VALVE
MAWP ANSI
PSV-2 TO DEHYDRATION
1000 PSIG 600 SYSTEM
SET @ 500 PSIG

ANSI 300
MAWP 2000 ANSI 600
PSIG
ANSI MAWP 2000
PSIG
300
TO FLARE
BDV

GAS
TURBINE COMPRESSOR COOLER

SUCTION 330 PSIG

MAXIMUM DISCHARGE
ANSI MAWP
Asumption: 300 500 PSIG PRESS 1100 PSIG
MAWP piping ANSI 300 = 740 psig
SUCTION
MAWP piping ANSI 600 = 1480 psig SCRUBBER

MAWP 500 PSIG MAWP 2000 PSIG MAWP 1000 PSIG

From the P&ID above, it can be seen that what determines the weakest MAWP is the MAWP of the
suction scrubber (upstream) and aftercooler (downstream) - and not the piping system.
22
 TO FLARE
Determining the MAWP of a system
SET @
80 PSIG

SET @
50 PSIG

Assumption: TO LP COMP.

MAWP piping ANSI 150 = 285 psig TO FLARE

PSHH
SET @ ANSI SET @
100 PSIG 150 120 PSIG

LP SEPARATOR
ex-HP SEPARATOR
MAWP 700 psig
ANSI 150

ANSI 150

From the P&ID above, it can be seen that what determines the weakest MAWP is the MAWP of the
piping system, and not the separator.
23
Piping Pressure Rating
ANSI flange
ANSI Flange rating
Rating untuk for material
Material jenis 1.1 1.1
MAXIMUM ALLOWABLE NON-SHOCK WORKING PRESSURE
API Flange ratings
MATERIAL GROUP 1.1
PRESSURE – TEMPERATURE RATINGS
Temp, 0F MAWP
Temperature , 0F
150 300 400 600 900 1500 2500
-20 to 100 285 740 990 1480 2220 3705 6170 0 – 250 300 350 400 450 500 550 600 650

200 260 675 900 1350 2025 3375 5625 2000 1995 1905 1860 1810 1735 1635 1540 1430
MAWP 3000 2930 2860 2785 2715 2505
300 230 655 875 1315 1970 3280 5470
400 635 745 1270 1900 3170 5280 5000 4880 4765 4645

500 600 800 1200 2995 4990

600 550 730 1095 4560 API and ANSI flange comparison
650 535 715 1075
700 710 1065 API Flange ANSI Flange
750 1010
Generally used for higher Faster available and cheaper
800 825
operating pressure
Example of Material (Spec-Grade)
Material Group Materials (Spec-Grade), example
Used for X’mas tree and Sometimes used for manifold
surround flowline
1.1 A105, A181-II, A-216-WCB, A515-70, A-516-
70, A-350-LF2 Sometimes used for manifold Generally used in production
1.2 A216-WCC, A-350-LF3, A203-B facilities
2.2 A-240-317, A-351-CF8M, A182-F316
3.1 B 462, B 463
24
etc Etc.
 Specification Break
SYSTEM DESIGN 2500 PSIG
PRESSURE (WELLHEAD PRESS) 1400 PSIG 450 PSIG 100 PSIG
API 3000 PSI API 2000 OR ANSI 600 ANSI 300 ANSI 150
APPLICABLE
FLANGE & VALVE
DESIGN RATING

What is the purpose of implementing specification breaks?

TO
FLARE

LO
OUTLET TO FLARE
GAS
LO LO OUTLET
WELLHEAD
GAS TO FLARE
LO
HP
SEPARATOR LC
LO
MP OUTLET
SEPARATOR GAS
LC LO

LO
TO
FLARE LC
LO LP
SEPARATOR

Notes:
Design temperatur is 150 0F
Shutdown system not shown
Flowline & manifold not drawn, assumed its rating
design follows wellhead Flange and Valve Pressure Rating Changes
MAWP of each system is based on the weakest
component or equipment
The maximum PSV setting point is MAWP 25
Specification Break TO
FLARE
SET @
LO 1480 PSIG SET @
900 PSIG
PC
LO

HP
SEPARATOR LC

From 12 11 10 9
WELL #1
ANSI 600 ANSI 150
SITP
5000 PSI
2
TO SET @
1 7 40 PSIG
5 API ANSI
FLARE
5000 600 SET @
ANSI ANSI
FROM WELLS

API 5000 API 5000 1480 PSIG SET @

600 150 LO
900 PSIG
From PC
WELL #2 LO

6 4
TO
SITP 3 TEST FLARE
1980 PSI API ANSI SEPARATOR LC
SET @
API ANSI 8 2000 600 230 PSIG
LO SET @
2000 600 ANSI 40 PSIG
API 2000
150 PC
LO
16 15 14 13 ANSI
ANSI 600 150

LP
SEPARATOR LC

HP LP TEST

MANIFOLD

Specification Break in P&ID Manifold and Separator 26

 TO
Specification Break FLARE
SET @
LO 1480 PSIG SET @
900 PSIG
PC
LO

HP
SEPARATOR LC

From
12 11 10 9
WELL #1
SITP 2 ANSI 600 API 5000
5000 PSI
5
TO SET @
1 40 PSIG
API ANSI
FLARE
7 5000 600 SET @
API ANSI
FROM WELLS

1480 PSIG SET @

5000 600 LO
900 PSIG
PC
From LO
WELL #2
6 4

TEST TO
SITP 3
1980 PSI SEPARATOR LC FLARE
API ANSI
API ANSI 8 5000 600 SET @
5000 600 LO 230 PSIG SET @
40 PSIG
PC
LO
16 15 14 13
ANSI 600 API 5000
LP
A SEPARATOR LC

HP LP TEST
ANSI
API 5000
150

MANIFOLD
Specification Break in P&ID Manifold and Separator – Additional
27
valve at upstream of LP Separator
 TO
Specification Break FLARE
SET @
LO 1480 PSIG SET @
900 PSIG
PC
LO

HP
SEPARATOR LC

From
WELL #1 ANSI 600 ANSI 150
SITP
5000 PSI
TO SET @
40 PSIG
API ANSI
FLARE
5000 600 SET @
ANSI ANSI
FROM WELLS

API 5000 API 5000 1480 PSIG SET @

600 150 LO
900 PSIG
PC
From LO
WELL #2
TO
SITP
TO TEST FLARE
1980 PSI API ANSI FLARE SEPARATOR LC
SET @
API ANSI 2000 600 230 PSIG SET @
LO
2000 600 ANSI 40 PSIG
API 2000 LO
150 PC
SET @ LO
LO 285 PSIG
ANSI
ANSI 600 150

LP
A SEPARATOR LC

HP LP TEST

MANIFOLD

Changes in Spec Break with additional PSV installation 28

Specification Break
Case Study

ANSI ANSI
150 300 BDV
TO FLARE
SYSTEM
L.O

ANSI 150
PSV-xxx ANSI
300
FROM GLYCOL SET @ 400 PSIG
CONTACTOR OUTLET PCV Failure
TO FUEL GAS
P = 1000 psig COMPRESSOR
ANSI SYSTEM
ANSI 300 ANSI ANSI
600 600 300

SDV PCV

FUEL GAS
SCRUBBER
MAWP 410 PSIG

29
Specification Break
Case Study

ANSI ANSI
150 300 BDV
TO FLARE
SYSTEM
L.O

ANSI 150
PSV-xxx ANSI
300
FROM GLYCOL SET @ 400 PSIG
CONTACTOR OUTLET PCV Failure
TO FUEL GAS
P = 1000 psig COMPRESSOR
SYSTEM
ANSI ANSI
600 300

SDV PCV

FUEL GAS
SCRUBBER
MAWP 410 PSIG

30
Overpressure Protection
• Excessive pressure in the plant can cause pipes or pressure vessels to burst, which can then cause a
fire/explosion.
• Sources of overpressure:
• Oil and gas wells,Instrumentation failure,
• Pressure generated by compressors or pumps,
• Changes in physical properties,
• hydraulic expansion,
• Fire.

• There are 2 ways to avoid overpressure:

1. Cutting off the source, namely:
• shutting off the gas/oil well or
• shutting off the injection pressure source (from the gas well or compressor) to the oil well.
2. Releasing the pressure to a safe system (usually the atmospheric system).
• The safe system can be a flare, vent, burn pit, or simply venting to the atmosphere.

31
PSV
• A pressure safety valve (PSV) operates according to the second principle: to release excess pressure to a
safe system.
• The PSV has a pressure relief setpoint, determined by the engineer. This setpoint must be greater than
the PSHH setpoint.
• The PSV capacity is determined by overpressure scenario, which will determine the size and number of
PSVs to be installed.
• The PSV design principles are generally stated in the P&ID, including: block-discharge PSV, PCV failure
PSV, fire PSV, thermal PSV, etc.
• Manual valves are installed upstream and downstream of the PSV for isolation during maintenance.
• Plants typically have identical PSVs (as spares) installed at the facility and operated to back up other
PSVs undergoing maintenance.

32
 FC LSS

PSV METERING
SKID
Case Study GLYCOL PC
CONTACTOR

PCV yang
HP SEPARATOR FUEL GAS
SCRUBBER
PSV sedang
was being
GLYCOL dimaintenance
maintained
REGENERATION
SYSTEM DISTRIBUTION

TO FLARE

ANTI SURGE SET @

1000 PSIG
PSV-2 VALVE SET @
1050 PSIG PSV-3
PSHH
SET @ 6789
350 PSIG
PCV-1 SET @ SPEED
CONTROL
320 PSIG
GAS
COOLER
PSV-1 TURBINE
GAS PT
FEED
PSHH
COMPRESSOR

CUSTOMER

MP SEPARATOR

LCV-2
33
LCV-1
PSV
• In facilities/plant where PSVs and their spare parts are installed, an interlock system is often installed.
• Interlocks are installed to ensure that no PSV is accidentally closed while another PSV is isolated (due
to maintenance).
• This system ensures that at least one PSV is always operational at all times.
• As an illustration – see the picture:
• All valves A & B, as well as C & D, are open.
• Valve A & B are closed only if valve C & D are open.
• Valve C & D are closed only if valve A & B are open.

• An interlock system is also installed in the PIG launcher/PIG

receiver system, so that the operation of inserting and
removing pigs does not endanger workers. Note: Several
accidents resulting in fatalities in pigging operations have been
reported.
34
 API 5000 ANSI 600

PSV

API 5000 ANSI 600

PSV A FLARE PSV A FLARE
ANSI BLOCK SYSTEM ANSI BLOCK SYSTEM
150 DISCHARGE 150 DISCHARGE
ANSI ANSI
600 600
SET AT
SET AT
PSV B 1480 PSIG PSV B
1480 PSIG LO (SPARE)
LO (SPARE) ANSI BLOCK
ANSI BLOCK 150
ANSI DISCHARGE
ANSI
150 DISCHARGE LO
LO 600
600
SET AT
SET AT 1480 PSIG LO
1480 PSIG LC
LC
LO

Proper installation
of specification break
LO/LC principle in the area around the installed PSV

35
Safety Devices
• Abnormal plant operating conditions can result in personnel injuries, pollution, and loss of assets.
Safety devices are installed to address hydrocarbon releases and protect the plant.

• They consist of three main components:

• sensing device, TC
PG SD
4106
• a transmission device, 4120
• and an end device.
• Note: Some devices sense and respond as end devices (check valves, PSVs, etc.).

• The primary purpose of a plant safety system:

• is to prevent the initial release of hydrocarbons (HC)
• and to shut off the flow of additional HC that has already been released.

• When an abnormal condition is detected:

• a sensing device sends a signal to an end device.
• The end device diverts or shuts off the HC flow, sounds an alarm, or takes other corrective action.

36
Safety Devices
• The previous system is supported by supporting systems, such as:
• emergency shutdown system (ESD),
• fire and gas detection system,
• adequate ventilation,
• liquid containment system,
• containment tank,
• subsurface safety valve (SSSV),
• pneumatic supply shutdown system,
• blowdown system.

TC
PG SD
4106
4120

37
 TO FLARE
Safety Devices
ANSI 150 SET @
How does the safety device work? ANSI 600 800 PSIG

SET @
830 PSIG

PCV- 1235B
ESDV TO COMPRESSOR
FC
F&G FC
PCV-1235A ANSI ANSI 100
1 SLOPE
RO 600 300 TO FLARE
ANSI ANSI
150 600 HEADER
ANSI
TO FLARE
LO FO LO 150
PSV-1234A ANSI
BDV-1235
COMP. S/D SET @ 900 PSIG ANSI 600 PSV-1234B (SPARE)
150 LO LC SET @ 900 PSIG
FULL BLOCKED ANSI
PC DISCHARGE 600 LC FULL BLOCKED
DISCHARGE
SET @
F&G PSHH LO
F&G 850 PSIG
LO LO
ESDV LO
ESD
CLOSE SCSSV LO

LSHH
GAS LO LO
WELLS
FC
HP SEPARATOR LC
ANSI ANSI
900 600
SDV-1234 MAWP 900 PSIG
LSLL
LO LO
ESD

F&G
TO MP
FC FC SEPARATOR
SDV-1235 LCV-1235

ANSI ANSI
600 300

P&ID Example - HP Separator with its safety devices 38

Safety Devices – at HP Separator
Natural gas and condensate flow into the HP separator to separate the gas from the condensate. The
gas flows to the compressor, while the condensate enters the MP separator. The PCV-1235A at the
separator outlet maintains the separator pressure at 800 psig.

If P ops > or = 830 psig:

• The PCV-1235B will open to release excess gas to the flare.

If P ops > the PSHH setpoint (i.e., 850 psig), then:

• The switch in the PSHH will send a signal via transmission (either pneumatic or electrical) to the
SDV-1234 to shut off the flow to the HP Separator.
• The signal from the PSHH will also be sent to shut down the compressor downstream of the HP
Separator.
If the level in the separator rises above the LSHH setpoint, then:
• The switch in the LSHH will send a signal to the SDV-1234 to shut off the flow
to the HP separator.
• A signal will also be sent to shut down the compressor. TC
SD
PG
4106
4120
39
Safety Devices – at HP Separator
If the liquid level drops below the LSLL setpoint, then:
• The switch in the LSLL will send a signal to the SDV-1235 to
close, thus preventing further condensate reduction in the
separator.
• Note: The purpose of maintaining the liquid level in the separator
in an emergency is to prevent gas from entering the operating
unit downstream of the separator, which could cause excessive
pressure. It also provides a time delay for temperature increases
in the vessel wall thickness (caused by a fire), as the latent heat
of vaporization of the liquid requires energy (thermal heat).

40
Safety Devices – In case of fire or gas leak
When a fire and/or flammable gas is detected:
• The plant will be blown down.
• The goal is to reduce the amount of gas/gas inventory within the plant. This action will reduce the
gas pressure, which has increased significantly due to the heating effect of the fire.
• A built-in deluge system sprays water onto the surface of the separator.
• Its purpose: to cool the separator surface, which will reduce the impact of a fire or delay the increase
in the separator wall temperature. Note: The deluge system is usually depicted on a separate P&ID
from the rest of the process system.
• Will activate the F&G (Fire and Gas) system,
• The goal: to isolate the separator, namely by:
• closes SDV-1234,
• closes SDV-1235 outlet at the HP Separator condensate
outlet (to maintain liquid in the separator),
• shutdown the compressor,
• and opens and releases gas (blowdown) to the flare
through BDV-1235.
• Will activate the plant alarm.
41
 FROM TO FLARE SLOPE
100
1
FC
SEPARATORS PSV-F2 (SPARE)
PC SET @
100 PSIG LO 100
FIRE 1 SLOPE
LC
LO
LC LO
PSV-F1
LO
SET @100 PSIG LO
FIRE

FCV B
ANSI 150 ANSI 300
ANSI 150

FO
ANSI 300

e l

LO
SEPARATOR ANSI

s
LC ANSI LO 150
MAWP 100 PSIG

r D
150 LO ANSI
ANSI 600

u
LSLL 600
PSV-A LC PSV- B (SPARE)
SET @ 740 PSIG LO SET @ 740 PSIG
LO LC

o &I
LO
FULL BLOCKED LO FULL BLOCKED
DISCHARGE

Y
DISCHARGE
Set @ minimum

g
LALL 5000 bpd
SET @

P
PI PSHH
FC FC

n
700 PSIG

i
LO

t d
LO
FE FE ANSI 300 ANSI 150

a e
TI PI

e h
CRUDE OIL

p c
PDI
FC
TANKS

a
ANSI 300

e
FCV A
ZLO ZSO

R t
ANSI 150

t
ZSO ANSI 150

a
ANSI 300
PUMP A

y
LO

ZLC ZSC

r e
LO

DRIVER

S/D HS
T t h
PUMP A

r
LC LC

fo
DRIVER
ESD PUMP B

F&G PI

PI
P&ID Basic control and safety devices of
PDI
ANSI 300 centrifugal pump systems
ANSI 300
PUMP B 42
 ANSI
LO 150
TO FLARE ANSI
300
LC

By-pass line LC

• The bypass line is sized similarly to the main pipe. HP SEPARATOR

MAWP 900 PSIG
LC

LSLL
LO LO

• The bypass valve is smaller than the control valve in the

F&G ESD

main pipe, or the same size but with a smaller trim size. TO MP
FC FC SEPARATOR
SDV-1235 LCV-1235

• Its purpose is to protect against excess pressure ANSI ANSI

600 300
downstream, for example, to reduce the rate of gas blowby MEDIUM
PRESSURE

if it occurs. WELLS

TO FLARE
Reducing flow - using RO
• A restrictive orifice (RO) is typically installed after the blowdown
valve (BDV).
• Its purpose is to limit the flow to the flare so it doesn't exceed its C23

capacity.
43
 RS
Sight Glass
• The sight glass is used to monitor the liquid level inside the
separator.
83 82
• It can also be used to check the interface level or possible
contaminants (such as foam).
• If the glass breaks (even if it's relatively strong), two balls at each
end of the valve will move, shutting off the flow of hydrocarbon
gas/liquid.
• These balls act as check valves to protect against leaks.

44
Fail Open or Fail Close or Last Position?
• The P&ID displays the state of the actuated valve when it fails.
• Plant are designed to be failsafe in the event of a failure.
• In engineering, a failsafe system/device will operate in the event of a design feature failure in a
manner that will cause minimal or no damage to other equipment, the environment, or people.

Example: Fail open Fail closed

• Elevators have brakes held against the brake pads

by the tension of the elevator cables. If the cables
break, the tension is lost and the brakes lock the FO FC
rails in the shaft, preventing the elevator car from
falling.
Fail to last
• The isolation valves and control valves used can be position
designed to close or open when power is lost, for
example by using spring force.
• This is known as fail-closed/fail-open when power is lost. FL

45
Fail Open or Fail Close or Last Position?
• The fail-close valve will automatically close when power is lost.
• This will stop the flow of media through the system.
• This design is crucial to prevent potential hazards or contamination
• A fail-open valve opens in the event of a power failure.
• Used to maintain flow or reduce pressure.
• This design is important for safety reasons, for example, in steam boilers or overpressure
protection systems.
• Safety-based selection:
• A thorough risk assessment of the system's operation is conducted
• To ensure that in the event of any failure, the system will return to a safe state.
• Based on operational aspects:
• Process efficiency and
• Operational continuity (which allows the system to be safely shut down until repairs are made or to
continue functioning in fail-safe mode).
• Understanding the nuances between FC and FO valves is crucial for engineers and safety professionals
who aim to design systems that not only meet operational objectives but also prioritize safety and
reliability under all conditions.
46
Fail Open or Fail Close or Last Position?

FAIL OPEN (FO) FAIL OPEN (FO) FAIL CLOSE (FC) FAIL CLOSE (FC)
air to close (A/C) air to close (A/C) air to open (A/O) air to open (A/O)

• From the image, it can be seen that a fail-open (FO) valve will air-close (A/C), and a fail-close (FC)
valve will air-open (A/O).
• Can a valve that's FO become FC and vice versa? Is this possible?

47
Fail Open or Fail Close or Last Position?
Take a guess!!

48
 TO FLARE
Guess – which valve fails open,
ANSI 150 SET @
fails close, and fails at last position? ANSI 600 800 PSIG

SET @
830 PSIG FC FO

PCV-1235B
ESDV TO
F&G COMPRESSOR

RO FC PCV-1235A ANSI ANSI

600 300 TO FLARE
ANSI ANSI
150 600
FLC
F0 ANSI
TO FLARE
LO LO 150
PSV-1234A ANSI
BDV-1235
COMP. S/D SET @ 900 PSIG ANSI 600 PSV-1234B (SPARE)
150 LO LC SET @ 900 PSIG
FULL BLOCKED ANSI
PC DISCHARGE 600 LC FULL BLOCKED
DISCHARGE
SET @
F&G PSHH LO
F&G 850 PSIG
LO LO
ESDV
ESD LO
CLOSE SCSSV LO

LSHH
GAS LO LO
WELLS HP SEPARATOR LC
ANSI ANSI
900 600
SDV-1234 MAWP 900 PSIG
LSLL
FC LO LO
ESD

F&G
FC TO MP
SEPARATOR
SDV-1235 LCV-1235

FC ANSI ANSI
600 300

49
Fail Open at Blowdown valve
• The blowdown valve, or BDV, is designed to fail PI Instrument Air
open for safety reasons. Main line System
• Hydrocarbons in the system it protects will be AIR RESERVOIR
Back-up
line
(MCS) (MCS)
ZLO ZLC
released/blown down to the flare system, XXX XXX

significantly reducing plant pressure.

ESDV
ESD S
• However, BDVs can also fail and potentially open RO ZSO ZSC
XXX XXX
suddenly. xxx
ANSI ANSI
• One reason is the loss of instrument air due to a 150 600

failure of the instrument air generator/Instrument

Air System. TO FLARE FO

• This single-mode failure can cause all BDVs in the BDV

-
plant to open simultaneously

• For this purpose, a small process vessel is installed as a temporary reservoir in the event of
instrument air failure.
50
Flare System
• Flares are used to burn flammable, toxic, or corrosive vapors into
less hazardous compounds.
• The design of flare systems and the layout of plant equipment should
minimize the need for operator presence.
• The design of towers or other tall structures exposed to flare
radiation should consider the effects of radiation on the ability to
safely evacuate.
• If personnel exposure to radiant heat is considered hazardous,
protective equipment should be installed.
• It is often most effective to achieve this by placing ladders and
platforms on the side away from the flare.
• The boundaries of restricted access areas are marked with signs
warning of the potential dangers of thermal radiation exposure.
• Personnel entry into such restricted areas must be administratively
controlled (PTW).
• It is essential that personnel within restricted areas have
immediate access to thermal radiation shielding or appropriate
protective clothing to escape to a safe location. 51
 TAG NUMBER ABC-V-8000
FLARE TIP
NOTE 6 NOTE 6
DESCRIPTION HP FLARE KO DRUM

TAG NUMBER P 50A/B DIMENSIONS 10' - 0" ID X 22' - 6" T/T

MECHANICAL DESIGN 150 PSIG @ -50/220 0F
DESCRIPTION HP FLARE KO DRUM PUMPS
NORMAL OPERATING CONDITIONS – PSIG @ -20 – 0F

CAPACITY 60 USGPM
MATERIAL LTCS WITH 0.125" CA Details of the flare system
OP. DISCHARGE 110 PSIG MATERIAL INTERNALS SS 316 L
and its control system
FQI
51
NOTE 3
51 51
SLOPE 100 1
U
NOTE 4,5
2" X 1" 2"
51 51 FUEL GAS

RS
51 LO
2"
NOTE 7 LC 1"

LIQUID LEVELS LC 1"

FROM HP FLARE 1
100
SLOPE RS HLSD (ESD) - 28" FLARE IGNITION PACKAGE 1"
HEADER NOTE 1 HP FLARE KO DRUM HLL - 24", NLL - 16"
NOTE 8
LAHH LLL - 10", LLSD - 6" NOTE 7
ESD LO LO LO
51A
RUN XI XI LOCAL ESD
STOP 52 B 53 B REMOTE NOTE 1 NOTE
NOTE 11
53 52
LIT LIT LAHH LIT LAHH COMMON ALARM
ESD ESD
51B 51B 51C 51C
LOCAL 51A ESD ESD NOTE 9 9 51
MCS MCS RUN XI XI 51
START/STOP 2 EA
STOP 52 A 53 A
HS NOTE 10
51 B REMOTE LO LO LO NOTE 2 52
MCC
LOCAL/REMOTE MCS MCS
STOP START/STOP LEAD / LAG H=7
L=2 51
MCS

HS HS SELECTOR
52 B 51 A LHS I LSH
MCC 52 52 A H = 15
LO MCS LOCAL/REMOTE L=5
SP 24" 51
RO START/STOP STOP
MCS

HS LEAD / LAG LHI PI

51 52 A STATUS 52 I
LSH LIA
51
NOTES:
52 B 52
PI
MCS
START/STOP NOTE 11 1. TWO OUT OF 3 VOTING FOR LAHH.
SP 26"
RO 52 2. VORTEX BREAKER.
52 LSL 3. FLOW COMPUTER IN CCR.
52 4. ULTRASONIC FLOWMETER TO RECORD GAS FLOW TO FLARE.
M SP 10"
5. MINIMUM STRAIGHT LENGTH REQUIREMENT OF 16 D UPSTREAM AND 10 D DOWNSTREAM.
P 50A LO
6. TWO PILOTS PROVIDED FOR FLARE TIPS.
LO 7. INTERCONNECTING CABLE FOR ELECTRICAL IGNITION SHALL BE SUITABLE FOR HIGH TEMPERATURE
RO ½ LC RADIATION.
53 LC 8. LPG CONNECTION FOR LIGHTING PILOTS.
PI 9. COMMON ALARM INCLUDES FLAME FAILURES (1 / 2), PLC FAILURE, AND LOST OF POWER.
RO 53 10. ALL PILOT FLAME (2 EA) OFF SIGNAL WITH LOUD / AUDIBLE ALARM IN DCS.
54 11. ON LSH-82 A ACTUATION, ‘LEAD’ PUMP TO START
M ON LSH-82 B ACTUATION, ‘LAG’ PUMP ALSO TO START
ON LSL-82 ACTUATION, BOTH PUMPS TO STOP
P 50B LO

½ LC

OPEN DRAIN
52
OILY WATER HEADER
 ARAH FLARING
TO FLARE
STACK 2
FLARING
TEMPO HARIWAY
Flare System
Case Study PLANT Z FLARE
HEADER

CHECK TO FLARE
VALVE STACK 1
PASSING

PUMP
CLOSED DRAIN
SET @ PCV-2 SYSTEM
XXX PSIG OPEN DRAIN
PIC
B
TO
PROCESS
PLANT X
FROM
SATELLITE Y

SET @ XXX PCV-1

PSIG
PIC
A

TO
PROCESS
FROM PLANT X
SATELLITE X
53
 FLARE TIP

Flare System – Special

100
• The flare system is designed to ensure a smooth SLOPE
1
100
and unobstructed flow of gas from its sources (such 1

as PSVs, BDVs, and manual valves) to the flare. SLOPE 100 1 U

• All relief lines must slope toward the Flare KO Drum

RS
51
2"

(located upstream of the Flare Stack). FROM HP FLARE

HEADER
1
100
SLOPE RS
HP FLARE KO DRUM
LAHH ESD LO LO LO

NOTE 1 NOTE 1
53 52

• The flare pipe from the KO Drum to the Flare Stack also has a LIT LIT LAHH LIT LAHH
ESD ESD
51A 51B 51B 51C 51C
ESD ESD
51

slope, which is directed towards the KO Drum. LO LO LO

• The purpose:
• To prevent condensed liquid from pooling in the pipe, which could obstruct the smooth flow of gas
to the flare stack.
• To prevent a reduction in the fluid discharge flow by an active PSV, which could potentially cause
overpressure (in the system protected by the PSV).
• Note:
• Slopes are also common at the suction scrubber outlet to the compressor, PSV header, and main
header.
• Condensed liquid is returned to the suction scrubber so it doesn't accumulate in the piping and get
sucked into the compressor (see the compressor P&ID on the previous slide). 54
Flare System – Slope
Slopes are also common at the suction scrubber
outlet to the compressor, PSV header, and main
header.

55
How to read Piping & Instrumentation (P&ID) Diagram
General Information
Symbols

56
 General information in P&ID – Title Block NAMA KONTRAKTOR ENGINEERING (IF APPLICABLE)
• P&ID title block contain informasi of:
• Plant/facility name and its location JLK PROCESS CO.
• Process Area
• Number P&ID NORTHEN AREA DIVISION
(BUSINESS UNIT NAME)
ABC-007 PLANT (SEBATIK, KAL-UT)
(PLANT NAME & LOCATION)

• Revision status LIQUIFIED PETROLEUM GAS PRODUCTION

FLOW DIAGRAM (DRAWING TITLE)
• Those information must be confirmed so we use the proper and STORAGE & DISTRIBUTION (PROCESS DESCRIPTION)

update P&ID. Use invalid P&ID may cause an error in the job or NOTICE
THIS IS A REPRODUCTION OF A
JLK DRAWING AND IS SUPPLIED
ISSUED FOR CONSTRUCTION DATE

may cause an accident. Additional info in P&ID ex: Engineering FOR AUTHORISED JOB ONLY.

THIS REPORDUCTIO SHALL NOT

BE DISCLOSED, USED OR

firm created the P&ID, or one of department in the company REPRODUCTION WITHER WHOLLY
OR PART EXCEPT AS CONNECTED
WITH SUCH USE, OR WITH THE
AUTHORIZATION NO. DRAWING NO. REVISI

who create it. PRIOR WRITTEN CONSENT OF JLK

PROCESS CO. FB-3-C 4
SCALE: NOT TO SCALE

• There are 2 type of information in P&ID:

• Written information: Title, table label, equipment specification
• Information via symbol and drawings.

57
Information in P&ID - Layout
• The layout and amount of information in a P&ID will
vary. This slide shows:
1. Title block
2. Main diagram
3. Equipment description
4. Legal statement (for use/reproduction) 3
5. P&ID revision history
6. Reference drawing
7. Notes
NOTES:
7
• The largest section of the P&ID is section 2, which
contains symbols and lines. In the P&ID, symbols and
6 5 4 1
lines are used to depict: NAMA KONTRAKTOR ENGINEERING (IF APPLICABLE)

• Equipment
JLK PROCESS CO.
• Piping connections NORTHEN AREA DIVISION ABC-007 PLANT (SEBATIK, KAL-UT)

• Instrumentation
(BUSINESS UNIT NAME) (PLANT NAME & LOCATION)

LIQUIFIED PETROLEUM GAS PRODUCTION

FLOW DIAGRAM (DRAWING TITLE)
• Lines connecting instruments STORAGE & DISTRIBUTION (PROCESS DESCRIPTION)
NOTICE ISSUED FOR CONSTRUCTION DATE

• Instruments control loop

THIS IS A REPRODUCTION OF A
JLK DRAWING AND IS SUPPLIED
FOR AUTHORISED JOB ONLY.

THIS REPORDUCTIO SHALL NOT

BE DISCLOSED, USED OR
REPRODUCTION WITHER WHOLLY
OR PART EXCEPT AS CONNECTED AUTHORIZATION NO. DRAWING NO. REVISI
WITH SUCH USE, OR WITH THE
PRIOR WRITTEN CONSENT OF JLK
PROCESS CO.

SCALE: NOT TO SCALE

FB-3-C 4 58
Information in P&ID – Relative Position & Size and Direction of
Process Flow
• The relative size of the symbols represents the relative size of the
equipment installed in the plant/field.

• For example, in the figure, box A is smaller than box B. Therefore, in the
field, the vessel depicted as box A is physically smaller than the vessel
depicted as box B.

• The relative positions of symbols on a P&ID also represent their actual positions in the field,
although the distances are not proportional.
• If the P&ID depicts a pump beneath a vessel, then in the field, the pump is actually located
somewhere beneath the vessel.
• The P&ID does not depict the actual distance dimensions between the pump and the vessel.
• Referring to the image above, if the pump is depicted as a triangle, then in the field, the pump is
actually located beneath vessel C, and not vessel A or B.

59
Information in P&ID – Relative Position & Size and Direction of Process
Flow
• The P&ID shows the direction of flow in the pipe, depicted by arrows
on the lines representing the pipe.
• Each line segment will typically have a flow arrow (created at each
intersection or branching of the line).
• The picture on the right shows the arrow directional from the top of
box B and exiting from the bottom.

• Sometimes an arrow is made at the point where the lines connect.

• The P&D also shows the direction of flow leaving the facility or plant or the direction
the arrow points to the next P&ID drawing.

60
Information in P&ID – Connecting Lines
Piping and lines can be installed in various
directions, crossover, through walls, or
disconnected.

• If two pipes cross over or meet without a

break in the P&ID, it means they are physically
connected.

• In the picture, the arrow labeled 1 indicates an

area where the piping is physically connected,
while the arrow labeled 2 indicates a physical
disconnect.

Explain pipe with label 3,4,5, and 6 !!

61
Information in P&ID – Zone Numbers

• Some P&IDs have zone numbering to

determine the location of a piece of
equipment or the location of two
connected pipes.

• There are other P&IDs that don't have a

zone number at all.

62
Information in P&ID – Equipment Description
• The P&ID provides a description of the equipment shown on the P&ID. This description can
be written above the equipment, within the drawing, or below the equipment. Regardless of
where the description is written, it will generally include:
• Unique equipment number ABC-C-0408
• Capacity HP COMPRESSOR A
• Dimensions – MMSCFD
• Materials used 0
– PSIG @ 85 – F
• Model number – PSIG @ 310/330 F 0

• Design temperature and pressure

• Pump power
ABC-V- 2004
PRODUCTION SEPARATOR

WELL NUMBER WELL W-001

200- 300 DESIGN FLOW (MAX/MIN) 70/5 MMSCFD + ASSOCIATED LIQUIDS
PRESSURE LIMITATION SITHP 1705 PSIA
190- 290
FLOWING PRESSURE (MAX/MIN) FWHP 1650/255 PSIA
FLOWING TEMPERATURE (MAX/MIN) 180 / 140 0F

63
Legend
• The P&ID legend contains detailed information about the symbols in the P&ID as well as special notes.
• The legend will be frequently referred to when reading and navigating the P&ID, especially for
beginners. The more frequently you read a P&ID, the less frequently you will need to consult the
legend.
• The information contained in a P&ID legend for one facility/plant location may differ from another,
depending on who created it and the processes involved.
• Even within a single company, P&ID legends can differ from facility to facility, unless the company has
standardized the information.
• In upstream oil and gas production facilities, the legend generally contains the following information:
• Line & valve designation • Compressor symbol
• Line identification • Equipment designation
• Line class & material • System number
• Piping specialty items • Instrumentation – abbreviation
• Valve symbol • Instruments designation
• Piping symbol • Instrumentation symbol
• Vessel symbol and its internal • P&ID/Shutdown definition
• Pump symbol • Special symbol
• Heat Exchanger symbol • Unit of measurement 64
Symbol - Vessel
• The naming of a vessel can be simple (just the first letter followed by the number), or it can also
contain information about its location in the field.

• Symbols on the vessel indicate important parts connected to the vessel. For example, the nozzle in
the picture below, on the left. The nozzle's shape is circular, following the piping because it serves
as the connection point between the pipe and the vessel.

• Nozzle diameters vary. As shown in the picture below, there are four nozzles: 2 inches, 14 inches, 6
inches, and 8 inches in diameter.

Equipment installed rd floor

on thedi 3lantai
Alat terletak

The equipment is located in Baydi14 on thedi3rd

Alat terletak floor
lantai

The type
Jenis of equipment
peralatannya is a tank
adalah

Alatnya
The equipment is theadalah tanktank
second kedua yang terletak
located on thedi3rd
lantai
floor
65
 ABC-V- 2004
PRODUCTION SEPARATOR
Symbol - Vessel
200- 300
190- 290

ABC V-2004
Production Separator

ABC = Plant Name

V = Pressure vessel

20 = Gas cooling & liquid

separation

04 = the 4th unit

66
Symbol - Vessel

67
Symbol - Vessel
• Internal vessels vary in content and have specific names and functions.
• The following sectional diagram explains the components:
• Inlet deflector – functions to separate gas and liquid in the initial stage by utilizing
momentum differences, separating large droplets, distributing the flow, and preventing
foaming.
• Distribution baffle - maintains a laminar or calm fluid flow.
• Coalescer Pack – improves the separation of water from condensate/oil and reduces
residence time in the vessel.
• Vortex breaker – prevents vortex formation at the vessel outlet to prevent gas from
entering the liquid pipe.

INLET
DEFLECTOR

DISTRIBUTION
BAFFLE
COALESCER
PACK

82

VORTEX
BREAKER

68
Symbol – Pump, Compressor, Heat Exchanger

69
Symbol – Line and Valve designation

70
Symbol – Line and Valve designation

PROCESS LINE

71
72
Symbol – Line designation
• Line designations in a P&ID include:
2”-AA-403
• Pipe size
• Letters that represent the material/fluid
flowing in the pipe 2”-inch pipe Fluid: Acetic acid Line number: 403
• Identification numbers, usually related to the
origin of the flow.

• The following P&ID depicts physically connected and

disconnected piping.
• The piping is depicted as a continuous line.
• The 6-inch diameter pipe carries WMUN – Municipal water.
Piping service:
• The upper nozzle of the tank is connected to a 3-inch WWH-
• WMUN =
48 pipe, and the lower nozzle is a 4-inch in size and
Municipal water
connected to a 4-inch WWH-50 pipe.
• WWH = Wash
• The fluid flowing through the 3-inch (tank inlet) and 4-inch water
(tank outlet) pipes is wash water. • PP = Propane
• The fluid flowing through the 4-inch PP-9 pipe is propane.
73
 Symbol – Line designation

Associated gas compression

Process Gas
FROM ANTI-SURGE
RECYCLE VALVE
–C22–PG– -

8-inch pipe diameter

Number 16
Carbon steel pipe, ANSI
600# with C.A. 0.125”

74
Symbol – Line and Valve designation

What kind of this pipe?

HP FLARE HEADER
–A22–FL– -

75
 Piping service:
Symbol – Line designation - alternate HC = Hydrocarbons
PL = Process Liquid
PO = Produced Oil
PG = Process Gas
FG = Fuel Gas
lA = Instrument Air
PA = Plant Air
CW = Cooling Water
SW = Seawater
HM = Heating Medium
• Pipe specification identification methods can be quite complex due to the wide variety of pipe
materials and pressure ratings.
• A commonly used system is one where a letter indicates the pipe material and a specific number
indicates the pressure rating.
• Example:
• CS1 = Carbon Steel - Schedule 40
• SS2 = Stainless Steel - Schedule 80
• CU1 = Copper - Schedule 40
76
Symbol – Valve
• The three services performed by a valve are:
• ON/OFF SERVICE: The valve must ensure full flow through it when fully open, and there must
be no passing when fully closed.
• CONTROL SERVICE: The valve must be able to control fluid flow through it according to its
design. When the valve is fully closed, it must be free from passing.

• ONE-WAY SERVICE: Valves are required to ensure that flow is

maintained in only one direction. The valve must allow the
smooth flow of fluid in the desired direction but block/shut
off the flow in the opposite direction - without any passing.
• On most P&IDs, each valve type is assigned a different symbol.
• The valve type selected depends on the operating conditions,
product, and service type.
• Other factors such as cost, weight, and maintenance
requirements will also be considered.

77
Symbol – Valve
• In some cases, the various valve types are not indicated on the P&ID. When this occurs, a generic
valve symbol, as shown below, is sometimes used.

• A valve that is normally in the OPEN position will generally not be colored.
• Alternatively, the letters "NO" (normally open) are written near the valve.

• A valve that is normally in the CLOSED position will generally be colored (usually black).
• Alternatively, the letters "NC" (normally closed) are written near the valve.

OPEN =
NO

CLOSED =
NC

78
Symbol – Valve – which is used for On/Off service
• The most common valve and used at all pressures.
• Not suitable for dirty flow services because debris can damage
the sealing surface or collect on the bottom of the valve,
preventing full valve closure.
• Gate valves should not be used for control services because flow
across the valve will cut the sealing surface.
• Note: The gate valve symbol can be used as a generic symbol for
all valve types.

• Used at all operating pressures.

• Features a sealant injection point to improve valve
sealing.
• Not suitable for dirty flow services as debris can damage
the seal.
• The special internal design allows the valve to be used to
control flow with relatively low pressure drop.
79
Symbol – Valve – which is used for On/Off service
• Typically used in medium and low pressure operating services.
• It features a sealant injection point to improve valve sealing.
• This valve is not suitable for dirty flow services as debris can
damage the seal.

• Typically used in high-pressure service.

• It is a derivative of the ball valve, featuring a rotary/sliding action
that forces the ball (inside the valve) against the seal surface.
• It performs well in less clean flow service.

• Typically used in dirty, low-pressure service.

• Care must be taken not to overtighten the valve and damage the
flexible diaphragm.

80
Symbol – Valve – used for control
• Used at all operating pressures.
• The most common valve type for control services.
• Suitable for dirty fluid flows.
• Different internal designs can handle all operating and pressure
requirements.

• Used at all operating pressures.

• A derivative of the globe valve.
• Used for very small flow control (e.g., sample points).
• Not suitable for dirty service.

• Primarily used at high operating pressures.

• A derivative of the globe valve.
• Reduced turbulence within the valve results in better flow than
a globe valve.
81
Symbol – Valve – used for control
• Used for high pressure drop services.
• A derivative of the angle valve.
• Widely used to control flow from the well to the
plant/facility.

• Primarily used in low-pressure and low-pressure-drop

applications.
• Some designs are one-way to improve sealing performance.
• Not reliable for tight closures.
• Commonly found in firewater header applications.

82
Symbol – Valve – used for one-way/non-return services
• Valves used for one-way operation are called check valves, non-return valves, or one-way valves.
• These valves ensure free fluid flow in the desired direction and block fluid flow in the opposite
direction.
• Types of valves include:

• Swing check valve.

• This valve contains a hinged, flat circular plate. The plate lifts to allow fluid flow through the
plate in one direction.
• The plate then closes, stopping fluid flow in the opposite direction.
• This valve is the most common type of check valve.

• Titling plate check valve.

• Contains a flat circular plate hinged slightly offset from the center position.
• The offset hinge position causes the valve to open in one direction of flow
and close in the opposite direction.
• Typically used for gas flows with high operating pressures and high flow rates. 83
Symbol – Valve – used for one-way/non-return services
• Ball check valve.
• Contains a freely moving ball enclosed in a cage.
• The ball lifts off the seat to allow fluid flow and falls back into the
seat when the flow is reversed.
• Valves are used for liquid fluids at low flow rates.

• Piston check valve.

• Contains a piston that moves freely up and down within a cage.
• The piston lifts off the seat to allow fluid flow and falls back into the
seat when the flow is reversed.
• Used for liquid fluids at low flow rates and high operating pressures.

• All types of valves can be spring-loaded to aid their function.

• Swing check valves can also be equipped with: a device that allows the valve to be screwed down to
improve its sealing ability, a hydraulic damper that prevents sudden closing.

84
Symbol – Valve – used for one-way/non-return services
• The direction of the arrow shows the direction of flow from left to right

OUTLET TO PROCESS

• Alternative symbol. The arrow indicates the direction of flow

from left to right.

• The main flow is shown from left to right. RECIRCULATE

• The recycle flow is indicated by a vertical arrow – which is

typically used for minimum service flow rates of centrifugal
pumps. INLET

• The check valve can be screwed down to improve sealing.

• Installed on high-pressure pump or compressor installations with a shared header.
• The flow shown is from left to right.
85
Symbol – Specific Valve – Reverse Gate type

OPENED CLOSED

• The image above and to the left shows an

actuated ‘Reverse Gate Valve.’
• It's called reverse because when closed, the
stem protrudes upward (and the stem
enters the valve) when open.
• By closing the gate disc, sand cannot fill the
space below the disc. This makes it
relatively reliable as a reverse gate valve.
86
87
Symbol – Valve
How are valves controlled?
• Controlled by humans/workers – called manual valves
• Valve is also controlled automatically:
Solenoid actuated valve
The valve will open and close when an Solenoid actuated valve with Reset
electrical signal is applied to the actuator. Solenoid valve with local reset facility to
allow signal to be returned to the valve.
Pneumatic diaphragm valve
A diaphragm inside the actuator is operated
by a pneumatic (air) signal. Self acting PCV with downstream tap
PCV uses fluid flow as a signal to the
Piston actuated valve diaphragm to control downstream
Valves are controlled by pneumatic signals. pressure.
Hydraulic piston actuated valve
The controlling signal is hydraulic fluid. Self acting PCV with upstream tap
Similar to the valve above but to
Electric motor actuated valve control upstream/upstream pressure
The valve is controlled by an electric motor. 88
Symbol – Valve
How are valves controlled?

89
Symbol – Actuated Valve
Under normal operating conditions:
• The ESD system ensures that there is an electrical power supply to the 3-
way solenoid valve, and the valve is energized and in the normal position.
• The instrument air supply (I/A) is routed to the diaphragm shutdown
valve (SDV) via a 3-way solenoid valve (the normally-closed section of the
solenoid will usually be shaded/blacked out and the section showing
normal flow through the two open sections will be unshaded).
• SDV is in the open (normal) position.

If the ESD system is activated:

• The ESD system de-energizes/cuts power to the 3-way solenoid valve. The solenoid valve is de-
energized and moves to the fail position.
• The solenoid valve changes position to: - shut off the air supply from the instrument air system,
and - bleed instrument air from the SDV diaphragm actuator (the curved arrow indicates the air
route when the solenoid valve is in the fail position).
• The SDV moves to the fail position (in the example, the SDV will fail to the CLOSED position, as
indicated by the downward-pointing arrow – Fail Closed).
90
Symbol – Actuated Valve

ESD
ESD

CLL
PSD
3-PHASE
Note:
PSD = Process Shutdown
SEPARATOR
R

ESD = Emergency Shutdown I.A.S

CLL = Condensate Low-Low SOV SOV
1714A 1714B

Process Shutdown SDV

CLL

PSD 1714
Shutdown level = CLL = Condensate Low-Low

Emergency Shutdown FC
ESD

ESD
Shutdown level = ESD = Emergency Shutdown

Can anyone explain??

91
Answer:
Under normal operating conditions:
• The ESD AND PSD systems ensure electrical power supply/energizing to the two 3-way solenoid
valves (SOV-1741A & 1741B).
• The instrument air supply (I/A) is routed to the SDV-1741 diaphragm valve via the two solenoid
valves.
If the ESD system is activated:
• The ESD system de-energizes/cuts power the SOV-1741B and the valve moves to the fail position.
• The SOV-1741B changes position to: - shut off the air supply from the instrument air system, and -
bleed instrument air from the SDV-1714 diaphragm actuator.
• The SDV-1714 moves and closes (because the SDV is Fail Closed).
• To reactivate the SDV-1714, the Reset lever must be pulled.

If the PSD system is activated:

• The PSD system cuts power to the SOV-1741A, and the valve moves to the fail position.
• The SOV-1741A changes position to: - shut off the air supply from the instrument air system, and -
bleed instrument air from the SDV-1714 diaphragm actuator.
• The SDV-1714 moves and closes.
92
Symbol – Actuated Valve

Can anyone explain??

93
94
95
Symbol – Instrumentation
• The P&ID legend for instrumentation includes abbreviations for instrument designations or
instrument tags.
• The legend table is usually divided into sections based on the process variables monitored by the
instrument.
• Process variables are physical characteristics of the process that can change.
• The process variables we will discuss are temperature, pressure, level, and flow.

The ISA S5.1 standard contains tables and examples of abbreviations used in
P&ID.
• The first letter on an instrument's label stands for the process variable
being measured. For example, "P" stands for pressure, "T" for
temperature, "L" for level, and "W" for weight.
• The second letter stands for function. For example, "V" stands for valve, so
"PV" stands for pressure control valve. Another example: "IT" stands for
indicating transmitter, so "FIT" stands for flow indicating transmitter.
96
97
Symbol – Instrumentation

Where is the partner?

98
 Instruments installed in the field
Symbol – Instrumentation Instruments mounted on a central
or main panel
• In general, the letter and number abbreviations
that identify an instrument in a P&ID are Instruments mounted behind the
symbolized by circles. central or main panel. Usually not
• The differences between each circle are accessible to the operator.
explained in the legend, often along with its
instrument tag. Additional instruments mounted on
the local panel. Accessible by the
• Circle symbols typically represent an instrument
operator.
and also indicate its location within the plant.
Computer controlled function, CSS
Note: installed in the field
BPCS –Basic Process Control System PLC, shared display share control,
SIS – Safety Instrumented System installed in the fied SIS
CSS – Computer System & Software
BPCS, shared display shared control,
installed in the field
BPCS, shared display shared control, PLC, shared display shared control,
mounted on the central or main panel mounted on the central or main panel SIS 99
Symbol – Instrumentation
Symbol example – taken
from ANSI/ISA-5.1-2009.

100
Symbol – Instrumentation – take a guess!!

Pressure gauge installed in the field,

number 1 on the 10/wellhead system.

Temperature indicator installed on the

local panel, number 18 on system 20/ gas
cooling & liquid separation.

Flow indicating controller installed on the

central/main panel, number 10 on system
20/gas cooling and liquid separation.

Computerized level indicating controller,

number 02 on the 40/fuel gas system.

101
How to Read Piping & Instrumentation (P&ID) Diagram
Tracing the lines
Controlling Process

102
 NAME OF OUTSIDE ENGINEERING FIRM (IF APPLICABLE)

Tracing the line

• The entire process in a plant /production facility
typically requires the depiction of more than one
JLK PROCESS CO.
P&D. NORTHEN AREA DIVISION ABC-007 PLANT (SEBATIK, KAL-UT)
• The P&IDs used must be correct and up-to-date. (BUSINESS UNIT NAME) (PLANT NAME & LOCATION)

• Each P&ID has an identification number, area LIQUIFIED PETROLEUM GAS PRODUCTION
FLOW DIAGRAM (DRAWING TITLE)
name, and issue number in the Title Block in the
STORAGE & DISTRIBUTION (PROCESS DESCRIPTION)
lower right corner.
NOTICE ISSUED FOR CONSTRUCTION DATE

• The following title block shows that: THIS IS A REPRODUCTION OF A

JLK DRAWING AND IS SUPPLIED
FOR AUTHORISED JOB ONLY.

• The drawing number is: FB-3-C Revision 4 THIS REPORDUCTIO SHALL NOT
BE DISCLOSED, USED OR
REPRODUCTION WITHER WHOLLY
• The process system depicted is: Liquified OR PART EXCEPT AS CONNECTED
WITH SUCH USE, OR WITH THE
AUTHORIZATION NO. DRAWING NO. REVISI

Petroleum Gas Production. PRIOR WRITTEN CONSENT OF JLK

PROCESS CO. FB-3-C 4
SCALE: NOT TO SCALE

• The P&ID we're currently reading might depict the beginning of a process flow, but it could also begin
elsewhere in the plant (in another P&ID).
• If we need to trace the line/pipeline to find the beginning of the flow, we might need one or more
other P&IDs. 103
 3"-AA-75 1
FS-82-D

Tracing the line 2

• The trace begins at arrow 1 and works backward against the flow
direction of the arrow to the end/edge of the P&ID.
• Each flow/pipeline will have an identification tag or label at the 4

point where it enters the P&ID – see arrow 2.

• The shape of the tag varies, on this slide it is depicted as a 3"-AA-76
FS-86-D
rectangle with pointed ends.
3

• This tag contains the previous P&ID number.

• Note that the incoming pipe is insulated and its number is written near the point where the flow
enters the P&ID.
• The trace starts again at arrow 3 and progresses in the direction of the flow arrow. If the flow
does not terminate at a device on the current P&ID, it will terminate at the edge of the P&ID.
• The end of the flow will be marked by a tag containing the next P&ID number—where we can
continue tracing the flow—see arrow 4.
• Typically, in a P&ID, we will see many process flows and instrumentation. These process flows will
enter and exit the P&D around the outer edges of the diagram.
104
Tracing the line
Note:
VA = Vapour; BR = Brine; TOL = Toluene
TOLC = Toluene-contaminated

Yellow stream
• The VA-3 vapor stream enters this P&ID from the FS-9-
D P&ID.
• This stream enters the E-01 condenser.
• The stream then exits the E-01 condenser and
becomes two streams: the VA-6 vapor stream and the
TOLC3 liquid stream.
• Flow VA-6 exits this P&ID and goes to P&ID number FS-11-D.
• Another flow (TOLC-3) goes to receiving tank T-01.
• From tank T-01, the flow exits into two parts: vapor flow VA-9 and liquid flow
TOLC-4.
• Flow VA-9 joins flow VA-6.
• Flow TOLC-4 leaves the tank and goes to P&ID FS-11-D.
105
Tracing the line
Note:
VA = Vapour; BR = Brine; TOL = Toluene
TOLC = Toluene-contaminated

Green stream
• The BR-1 flow from P&ID FS-10-B goes to condenser
E-01.
• The BR-1 flow from the condenser then goes to
pump 3-13P4.
• The BR-2 flow exits pump 3-13P4 and goes to TV-15.
• From TV-15, the BR-4 flow exits this P&ID and goes to P&ID FS-10-B.

106
Process Control
• To ensure a process plant remains within a safe operating range, control loops are used to monitor
process variables within a system.
• Process variables are physical characteristics of a process that can change, such as flow, pressure,
temperature, level, and composition.
• P&ID drawings for an area will show the lines, instrumentation, and equipment that monitor and
control each process.
• Instruments function to:
• Monitor process variables.
• Inform operators about the current condition of a process.
• Allow process control.
• Instrument control loops are needed to:
• Maintain process variables within safe ranges
• Detect potential hazardous situations in progress
• Provide a means to activate alarms and shut down the process if necessary
• Maintain product compliance with standard specifications.

107
Process Control
Take a guess!!

1. What is the variable being monitored?

2. What does TIT stand for?
3. What type of line are TAH and TSH connected?
4. Where is the TSH instrument installed?
5. Where is the TAH instrument installed?
6. What type of line connects the TIT to the
toluene-filled piping?

1. Temperature TOLC 3, 2. Temperature indicating transmitter, 3. electric signal, 4. behind main panel, 5. control panel,

6. capillary tubing. 108

Process Control – function of the control loop parts
Sensors and Transmitters:
• This is the part of the loop that first detects or measures the process variable.
• The sensor, labeled TE (temperature element) or TI (temperature indicator) on some P&IDs, can be
separated or integrated with a transmitter, which transmits information about the variable.
• In the P&ID, the TIT-15 consists of a sensor and a transmitter.

Controller:
• Information (about the variables) is sent from the TIT-15 to the controller, the TIC-15.
• Controller, then sends a control signal to the pneumatically operated diaphragm valve (TV-15).
• The TV-15 valve controls the brine flow rate in the pipe.

Switch & Alarm:

• The toluene temperature (TOLC) must be maintained at a certain value.
• A switch, the TSH-15, is connected to the transmitter. If the toluene temperature exceeds the set
point, the switch sends a signal to the alarm, the TAH-15.
• The alarm can be visual, such as a red light, or audible.
• The TAH-15 alarm symbol indicates that this instrument is located on the panel.

109
Process Control
Take a guess!!

1. The flowrate of stream TOLC-4 can be controlled E-01

by? CONDENSER
2. In control loop 7, the switch HS is actuated by ?
3. In control loop 15, TIT sends signal to where?
4. The valve TV, changes the temperature of the
toluene stream, TOLC-3 by controlling the?

T-01
TANK

1. Piston-operated valve, 2. Hand, 3. To the alarm (TAH), to the switch (TSH), and to the controller, (TIC),

4. Brine flow rate - output from condenser 110

Process Control

Understanding the process controls in a P&ID will make it easier for the reader to
understand the process.

This is a key foundation for:

• Process optimization
• Process troubleshooting

111
How to read Piping & Instrumentation (P&ID) Diagram
Read P&ID

112
How to Read Piping & Instrumentation (P&ID) Diagram

P&ID reading exercise - 1

113
Reading P&ID - Reducing Turbine & Condensate Collection

Note:
HPS – High pressure steam
LPS – Low pressure steam
PRL – Process liquid
LCR – Low pressure condensate return

114
Reading P&ID - Reducing Turbine & Condensate Collection

1. The P&ID above shows three large pieces of

equipment. Place the letter of the symbol from
the right column next to the correct word(s) in
the left column. You may use a symbol more than
one answer.

2. Numerous symbols appear on this P&ID. Place

the letter of the symbol next to its name.

115
Reading P&ID - Reducing Turbine & Condensate Collection
Choose the correct answers:
3. _______ (Low pressure steam, High pressure steam) enters the turbine at the top of the equipment and ______ (low
pressure steam, high pressure steam) leaves the equipment at the bottom.
4. The steam leaving the turbine is used for in the heat exchanger to heat the ______ (condensate, process liquid).
5. You would expect the material in piping PRL2 to be ________ (warmer, cooler) than the material in piping PRL1.
6. The material leaving heat exchanger and going to the tank is ______ (LPS, PRL, low pressure condensate)
7. The piping LPS and PRL2 are insulated in order to _________ (retain heat of the material, prevent overheating of the
material).
8. The level of liquid in the condensate tank is controlled by _______ (pump 17-P4, instrument loop 17).
9. If you wanted to find out what happens to condensate that leaves the tank, you would look on P&ID number
________ and ______ (FS-6-B, FS-10-B, FS-12-A, FS-15-B).
10. LT-17 is a _______ (level transmitter, light indicator).
11. TE-9 and TE-10 measure the temperature of ________ (process liquid, LPS, low pressure condensate/LCR).
12. Opening LV-17 allows some condensate to ___________ (recycle through the turbine, recycle through the tank, stay
in the heat exchanger).
13. Steam _________ (can, cannot) be recycled through the turbine. Why?
14. Before servicing the pump 17-P4, close both ______________ (check valve, level element, globe valve) on the line
entering and leaving the pump.
15. The pipe that physically join line C2 are ______ (PRL1, C1, PRL3, LPS, HPS).
116
How to Read Piping & Instrumentation (P&ID) Diagram

P&ID reading exercise - 2

117
Reading P&ID –
Reactor

118
Reading P&ID – Reactor

Note:
WC – Cooling water
CH – Chemical
WCR – Cooling water return
PRL – Process liquid

119
Reading P&ID – Reactor

1. Place the letter of the symbols in

the right column next to the
correct name or label in the left
column. You may use a symbol
more than once.

120
Reading P&ID – Reactor
Choose the correct answer. Some questions have more than one answer.
2. CH1 comes into this P&ID from ________ (another reactor, a tank truck, 15-0-45, 16-1-29).
3. The interlock will be activated by the __________ (1-14P2, agitator, low flow of CH2, FSHL-7).
4. CH2 flow that being added to the reaction is controlled by ________ (FV-7, product analysis, flow of CH1, improper
function of the agitator).
5. The function of 3-6HE1 is to ________ (heat CH2, cool CH2, heat CH1, cool CH1).
6. If the temperature of stream 3”-CH2-2 is too high, _________ (TV-19, FC-8, TV-27, LV-9) is opened more to allow
additional cooling water to flow into the exchanger.
7. 1-10P1 increases the pressure in line _________ (4”-CH-1, 3”-CH2-1, 3”-PRL-2).
8. The function of LV-9 is to __________ (maintain desired level of PRL in the tank, allow vapor to leave the tank)
9. If the temperature of the reaction becomes too high, an alarm will go off __________ (at the reactor, on a
computer control panel, near the tank car, TAH-19).
10. If analysis of the process liquid indicates that PRL did not meet specification, ________________ (TV-27, FV-7, AV-
8, 1-10P1, PAH-17) changes the flow of ________________ (CH2, CH1, PRL, PRL-3) into the reactor.
11. If PRL is too warm, ___________ (TV-17, TV-27, 1-10P1, AE-8) opens more to allow increased cooling flow through
____________ (3-6HE1, 2-9T4, 3-12RE1, 2-15HE2).
12. If the interlock is activated, a signal is sent to ____________ (FAL-29, 3-12A1, AIC-8, FIT-7, FIC-7, 3-12RE1).
13. The title of this P&ID is ______________ (JTS Process Co., Engineering Drawing/Reactor, PRL-1 Reactor); this
diagram covers a process occurring at the _______________ (Acme Plant, Engineering Firm, coordinate FS-5-D).
121
Reading P&ID – Reactor
Choose the correct answer. Some questions have more than one answer.
14. Specific information about the line 5”-PRL-1 can be found in the ____________ (Title Block, Line Schedule, Issue
Description).
15. Line 2”-CH1-1 is made of ___________ (carbon steel, copper, stainless steel) and carries the material ___________
(cooling water, CH1, CH2, PRL) at a pressure of ____________ (60 psig, 65 psig, 45 psig).
16. Any excess liquid left in the tank truck hose after unloading is completed, must go to ____________ (the reactor,
the holding tank, the environmental collection sump, the sewer drain).
17. The changes in the process system that was made with this issue was _____________ (addition of an
environmental collection sump, a new source of CH1, addition of line ½”-CH1-3 and drain, additional CH1).
18. The serial number of the holding tank is __________ (2-9T4, T4, T2-344, FS-5-D).
19. The diameter of the nozzle where CH1 enters the reactor is _________ (4 inches, 3 inches, 5 inches, 2 inches).
20. To locate the changes made on main diagram of issue 2 of P&ID number FS-5-D, look for __________ (a cloud-like
sketch around specific areas on the P&ID, an arrow with FS-5-D, a triangle with a 2 in it, two changes).
21. Material in line CH2 enters the heat exchanger at approximately __________________ degrees Fahrenheit (45,
220, 140, 65).
22. During the reaction, the material _____________ (PRL, cooling water, vapor) is allowed to recycle between the
holding tank and the reactor.
23. 3-12RE1 has a working pressure of _____________ (45, 80, 65) psig and a shell made of __________ (stainless
steel, carbon steel).

122
Reading P&ID – Reactor
Choose the correct answer. Some questions have more than one answer
24. Trace the flow of PRL from where it is created to where it leaves the current P&ID by arranging the following pieces
of equipment in the proper order. Place a “1” next to where PRL is created, “2” where it goes next, and so on..
___2-15HE2 ____3-6HE1 ____16-1-29 ____TV 27 ____2-9T4

___3-12RE1 ____16-1-42 ____1-10P1 ____1-14P2 ____15-0-45

123
How to Read Piping & Instrumentation (P&ID) Diagram

P&ID reading exercise - 3

124
Reading P&ID
SHUTDOWN
Try to explain the following P&ID: SYSTEM
SHEET NO R
1000-03
6" FC I.A.S
SDV
3214 SOV
3214 TAH
3214

TY TIC
3214 3214
TV
TAL
3214 3214

TI
3256
SET @
TW 75 0C PI
3206 TAHH TE
TSHH 3255
3211 3214
3211

PSV
TI 3273
3252

E = 3201A
PDSL
3227 TI
3207
PDI
3227 PI
8" 3204
PDAL
3227

E-3201A – Plate-Plate Heat Exchanger

125
Finished…
Note:
If you want to improve yourself, it is recommended that you:
• Practice reading P&IDs extensively under the guidance of a process engineer or
someone who is an expert in interpreting P&IDs.
• Go on site to compare the P&ID on paper with the actual installation.

Next level:
• Able to read control types: closed vs. open control loops, feedback, feedforward,
low vs. high switch selectors, cascade control.
• Identify errors in a P&ID.
• Improve processes in P&IDs.
• Review P&ID.
126
How to Read Piping & Instrumentation Diagram for
Beginners
Answer to the questions

By Cahyo Hardo, B.Eng., M.OHS.

Free to distribute
It's a good idea to try answering the following questions before opening them.
This will improve your memory and test your understanding.

Happy Learning!
Answer to slide 42

130
 100
FROM TO FLARE SLOPE 1
FC
SEPARATORS PSV-F2 (SPARE)
PC SET @ 100
100 PSIG LO 1 SLOPE
FIRE
LC
LO
LC LO
PSV-F1
LO
SET @100 PSIG LO
FIRE

FCV B
ANSI 150 ANSI 300
ANSI 150

FO
ANSI 300

LO
SEPARATOR ANSI
LC ANSI LO 150
MAWP 100 PSIG ANSI
150 LO ANSI
600
LSLL 600
PSV-A LC PSV- B (SPARE)
SET @ 740 PSIG LO SET @ 740 PSIG
LO LO LC
FULL BLOCKED LO FULL BLOCKED
DISCHARGE DISCHARGE

Set @ minimum
LALL 5000 bpd
SET @
PI PSHH
700 PSIG FC FC
LO
LO
FE FE ANSI 300 ANSI 150
TI PI
CRUDE OIL
PDI
FC
TANKS
ANSI 300
FCV A
ZLO ZSO
ANSI 150
ZSO ANSI 150
ANSI 300
PUMP A
LO

ZLC ZSC
LO

DRIVER
PUMP A

S/D HS
LC LC

DRIVER
ESD PUMP B

F&G PI

PI P&ID Basic control and safety devices of

PDI
ANSI 300
centrifugal pump systems
ANSI 300
PUMP B 131
Safety Devices – in centrifugal pump system
Crude oil from various separators flows to the final separator to separate the gas. The gas flows to the
flare, while the oil flows to two centrifugal pumps. The control concept is to maintain the level in the
separator by regulating the pump output flow rate (cascade control).

The oil flow rate at the pump output is controlled by FCV A. FCV A receives input from the FC, which
receives flow rate measurement data from the FE and the set point from the LC.

The minimum pump flow rate is controlled by the FC (set point 5000 bpd) which receives input from the
FE which then forwards an electronic signal to FCV B to recycle low to the tank. If the pump output flow
rate is still or below the set point, then FCV B will remain open. If the flow rate is above the set point,
FCV B will start to close until fully closed and the LCV-FCV instrument will control the separator level and
pump flow rate.

The two installed pumps can be operated individually or simultaneously in parallel operation by setting
them on the HS (hand switch) in the field. The two pumps can also be operated in series by opening two
valves, normally set to LC, and closing two valves at the pump inlet, normally set to LO.

132
Safety Devices – in centrifugal pump system
When the pump discharge pressure reaches 700 psig, the PSHH setpoint, the switch sends an electronic
signal to the shutdown system, shutting down the operating pump, or both pumps in parallel or series
operation.

If the pump discharge pressure continues to rise to 740 psig, PSV A or PSV B (depending on which is
operating) will discharge crude oil into the flare system to prevent overpressure.

If the level in the separator drops to the LSLL setpoint, the switch also sends an electronic signal to the
shutdown system, shutting down the pumps.

133
Safety Devices – In case of fire or gas leak
When fire and/or flammable gas is detected:
• Will the plant be blown down??
• It turns out the separator isn't blown down when the Fire or Fire & Gas Signal is activated. This is
because the operating pressure in the separator is already relatively low, which doesn't require
blowdown.
• The installed deluge system sprays water onto the separator surface.
• The purpose: to cool the separator surface, which will reduce the impact of a fire or delay the
increase in separator wall temperature.

• Will activate F&G (fire and gas) system.

• Purpose: to isolate the separator, by:
• Turning off Pump A and Pump B.
• Closing the SDV-XXXX outlet from the separator in the upstream system (not pictured).

• Will activate plant alarm.

134
Answers to slides 47 - 48

135
 FAIL OPEN (FO) FAIL OPEN (FO) FAIL CLOSE (FC) FAIL CLOSE (FC)
air to close (A/C) air to close (A/C) air to open (A/O) air to open (A/O)

Can a valve that is FO become FC and vice versa?

Is this permissible?
Answer:
Yes, as long as the trim valve model is the same. In the example above, the valve with the leftmost
actuator can be changed to the valve and actuator positioned third from the left.
This is permissible as long as a prior risk assessment is conducted.
136
Fail Open or Fail Close or Last Position?
Take a guess!!

Answer:
ATO = Air to Open = Fail Close
ATC = Air to Close = Fail Open

137
Answer to slide 61

138
• Pipe 3 is physically connected
• Pipe 4 is not physically connected
• Pipe 5 is not physically connected
• Pipe 6 is physically connected

139
Answer to slide 93

140
Symbol – Actuated Valve

Can anyone explain????

Answer:
The P&ID above is the P&ID regarding BMS

The BMS is a burner management system installed to manage fuel flow to the combustion system in
the burner. It consists of a pressure and flow/throttling control system, as well as two shut-off valves
and one vent valve. When the flame-off signal from the burner is sent to the BMS, the two shut-off
valves close, and the vent valve opens, releasing fuel gas to the atmosphere.

141
How to Read Piping & Instrumentation (P&ID) Diagram

Reading practice answer P&ID - 1

142
Reading P&ID - Reducing Turbine & Condensate Collection

1. The P&ID above shows three large pieces of

equipment. Show the three drawings of the
equipment on the right to match them to the
choices on the left. Each piece of equipment may
have more than one answer.

2. Numerous symbols appear on this P&ID. Place

the letter of the symbol next to its name.

143
Reading P&ID - Reducing Turbine & Condensate Collection
Choose the correct answers:
3. _______ (Low pressure steam, High pressure steam) enters the turbine at the top of the equipment and ______ (low
pressure steam, high pressure steam) leaves the equipment at the bottom.
4. The steam leaving the turbine is used for in the heat exchanger to heat the ______ (condensate, process liquid).
5. You would expect the material in piping PRL2 to be ________ (warmer, cooler) than the material in piping PRL1.
6. The material leaving heat exchanger and going to the tank is ______ (LPS, PRL, low pressure condensate)
7. The piping LPS and PRL2 are insulated in order to _________ (retain heat of the material, prevent overheating of the
material).
8. The level of liquid in the condensate tank is controlled by _______ (pump 17-P4, instrument loop 17).
9. If you wanted to find out what happens to condensate that leaves the tank, you would look on P&ID number
________ and ______ (FS-6-B, FS-10-B, FS-12-A, FS-15-B).
10. LT-17 is a _______ (level transmitter, light indicator).
11. TE-9 dan TE-10 measure the temperature of ________ (process liquid, LPS, low pressure condensate/LCR).
12. Opening LV-17 allows some condensate to ___________ (recycle through the turbine, recycle through the tank, stay
in the heat exchanger).
13. Steam _________ (can, cannot) be recycled through the turbine. Why?
14. Before servicing the pump 17-P4, close both ______________ (check valve, level element, globe valve) on the line
entering and leaving the pump.
15. The pipe that physically join line C2 are ______ (PRL1, C1, PRL3, LPS, HPS).
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How to Read Piping & Instrumentation (P&ID) Diagram

Reading practice answer P&ID - 2

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Reading P&ID – Reactor

1. Place the letter of the symbols in

the right column next to the
correct name or label in the left
column. You may use a symbol
more than once!

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Reading P&ID – Reactor
Choose the correct answer. Some questions have more than one answer.
2. CH1 comes into this P&ID from ________ (another reactor, a tank truck, 15-0-45, 16-1-29).
3. The interlock will be activated by the __________ (1-14P2, agitator, low flow of CH2, FSHL-7).
4. CH2 flow that being added to the reaction is controlled by ________ (FV-7, product analysis, flow of CH1, improper
function of the agitator).
5. The function of 3-6HE1 is to ________ (heat CH2, cool CH2, heat CH1, cool CH1).
6. If the temperature of stream 3”-CH2-2 is too high, _________ (TV-19, FC-8, TV-27, LV-9) is opened more to allow
additional cooling water to flow into the exchanger.
7. 1-10P1 increases the pressure in line _________ (4”-CH-1, 3”-CH2-1, 3”-PRL-2).
8. The function of LV-9 is to __________ (maintain desired level of PRL in the tank, allow vapor to leave the tank)
9. If the temperature of the reaction becomes too high, an alarm will go off __________ (at the reactor, on a
computer control panel, near the tank car, TAH-19).
10. If analysis of the process liquid indicates that PRL did not meet specification, ________________ (TV-27, FV-7, AV-
8, 1-10P1, PAH-17) changes the flow of ________________ (CH2, CH1, PRL, PRL-3) into the reactor.
11. If PRL is too warm, ___________ (TV-17, TV-27, 1-10P1, AE-8) opens more to allow increased cooling flow through
____________ (3-6HE1, 2-9T4, 3-12RE1, 2-15HE2).
12. If the interlock is activated, a signal is sent to ____________ (FAL-29, 3-12A1, AIC-8, FIT-7, FIC-7, 3-12RE1).
13. The title of this P&ID is ______________ (JTS Process Co., Engineering Drawing/Reactor, PRL-1 Reactor); this
diagram covers a process occurring at the _______________ (Acme Plant, Engineering Firm, coordinate FS-5-D).
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Reading P&ID – Reactor
Choose the correct answer. Some questions have more than one answer.
14. Specific information about the line 5”-PRL-1 can be found in the ____________ (Title Block, Line Schedule, Issue
Description).
15. Line 2”-CH1-1 is made of ___________ (carbon steel, copper, stainless steel) and carries the material ___________
(cooling water, CH1, CH2, PRL) at a pressure of ____________ (60 psig, 65 psig, 45 psig).
16. Any excess liquid left in the tank truck hose after unloading is completed, must go to ____________ (the reactor,
the holding tank, the environmental collection sump, the sewer drain).
17. The changes in the process system that was made with this issue was _____________ (addition of an
environmental collection sump, a new source of CH1, addition of line ½”-CH1-3 and drain, additional CH1).
18. The serial number of the holding tank is __________ (2-9T4, T4, T2-344, FS-5-D).
19. The diameter of the nozzle where CH1 enters the reactor is _________ (4 inches, 3 inches, 5 inches, 2 inches).
20. To locate the changes made on main diagram of issue 2 of P&ID number FS-5-D, look for __________ (a cloud-like
sketch around specific areas on the P&ID, an arrow with FS-5-D, a triangle with a 2 in it, two changes).
21. Material in line CH2 enters the heat exchanger at approximately __________________ degrees Fahrenheit (45,
220, 140, 65).
22. During the reaction, the material _____________ (PRL, cooling water, vapor) is allowed to recycle between the
holding tank and the reactor.
23. 3-12RE1 has a working pressure of _____________ (45, 80, 65) psig and a shell made of __________ (stainless
steel, carbon steel).

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Reading P&ID – Reactor
Choose the correct answer. Some questions have more than one answer
24. Trace the flow of PRL from where it is created to where it leaves the current P&ID by arranging the following pieces
of equipment in the proper order. Place a “1” next to where PRL is created, “2” where it goes next, and so on..

_4__2-15HE2 ____3-6HE1 _5___16-1-29 ____TV 27 _2__2-9T4

_1_3-12RE1 ____16-1-42 _3__1-10P1 ____1-14P2 ____15-0-45

149
How to Read Piping & Instrumentation (P&ID) Diagram

Reading practice answer P&ID - 3

150
Reading P&ID
Flowchart tracing shows:
• A 6-inch heating medium (HM) line, made of carbon steel (CS), 6"-HM-6098-CS5-1, flows from an 8-inch
diameter heating medium supply header made of the same material (8"-HM-6011-CS5-1) into and out of
a plate-type heat exchanger, E-3201 A, to exchange heat with the Produced Oil (PO) stream. (Note: The
name "heating medium" suggests this.)
• After passing through E-3201A, the heating medium, 6"-HM-6099-CS5-1, flows to the 8-inch heating
medium return header (8"-HM-6012-CS5-1).
• The letter E in E-3201A in the P&ID Legend indicates the equipment designation, including the Unfired
Heat Transfer Equipment (UHE) heat exchanger.
• The number 32 in E-3201A in the system numbering in the Legend indicates the Condensate and Oily
Water System area.
• The heated stream, an 8-inch produced oil (PO) stream, also made of CS (8"-PO-1077-CS5-1), flows from
the 10"-PO-1011-CS5-1 production header line into E-3201A, then exits as the 8"-PO-1078-CS5-1 stream
to the 10"-PO-1012-CS5-1 production header line.
• The 6-inch HM stream has a 1-inch drain to the open drain at the outlet of E-3201A, while the drain from
the 8-inch PO stream located at inlet to E-3201A, and its drain line goes to the closed drain header.
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Reading P&ID
Instrumentation tracing shows:
• The temperature of the Produced Oil leaving the E-3201 A is measured by a locally installed
temperature element (TE-3214). The electronic signal from the TE-3214 is forwarded to a
temperature indicator controller installed in the control room panel (TIC-3214). The TIC-3214 will
control the temperature of the Produced Oil at 65°C. The electronic signal coming out of the TIC-3214
is forwarded to a locally installed temperature relay (TY-3214). The temperature relay converts the
electronic signal into a pneumatic signal (indicated by the letters "I/P"). The pneumatic signal flows to
the control valve (TV-3214) to regulate the amount of heating medium entering the E-3201A.
• The electronic signal from the TE-3214 is also used to generate a high temperature alarm (TAH-3214)
set at 70°C and a low temperature alarm (TAL-3214) set at 60°C. A locally installed high-high
temperature switch (TSHH-3211) is another over-temperature protection device. The TSHH-3211 is
set at 75°C.
• If the temperature of the oil produced reaches 75°C, the TSHH-3211 will activate an alarm (TAHH-
3211) on the control room panel and also send a signal to the Shutdown System.

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Reading P&ID
Instrumentation tracing shows:
• Another input to the Shutdown System is generated by a locally installed low-pressure differential
switch (PDSL-3227). Low differential pressure may indicate a leak within the E-3201A heat exchanger. If
low differential pressure occurs, the PDSL-3227 will activate an alarm (PDAL-3227) on the control room
panel and also send a signal to the Shutdown System.
• If the Shutdown System is activated by the TSHH-3211 or the PDSL-3227, power to the SOV-1014 will
be disconnected. Instrumentation air will be vented by the SOV-3214 (as indicated by the small curved
arrow). The SDV-3214 will then close as indicated by the letters "FC."
• Other features include:
• Spectacle blinds installed on the E-3201A inlet and outlet lines to isolate the equipment during
maintenance.
• The PSV-3273 is set to release pressure at 12 barg. This device protects against overpressure in
the produced oil side of the E-3201A.
• Note: The system doesn't have a spec break.
• The E-3201A doesn't have a MAWP value. Can you guess what it might be?
• Answer: The MAWP of the E-3201A can be estimated from its PSV setting, which is 12 barg.
Therefore, the maximum MAWP of the vessel is 12 barg. 153