introduction to p&id reading & design

8/10/2019 Introduction to P&ID Reading & Design

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Introduction to P&ID Reading

and Design


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Process Engineering

Process engineering is often a synonym of

chemical engineering.

It focuses on design, operation and

maintenance of chemical and materialmanufacturing processes.

Process engineering also involves developing

new processes, project engineering andProcess troubleshooting.


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Services in Process Engineering

Process conceptual and feasibility study

Process project scope definition

Process design, evaluation and modification

PFD and P&ID development

Process modeling and simulation

Process equipment sizing and selection

Process safety analysis

Process troubleshooting


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Applications of Process Engineering

Chemical plants

Biotech plants

Crude oil refineries

Fertilizer production

Oil & gas processing

Food processing

Pharmaceutical manufacturers

Pulp paper mills

Mineral processing

Water treatment plants

Nuclear power plants

......


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Type of Flow Diagrams

in Process Engineering

Mass Flow Diagram

Block Flow Diagram (BFD)

Also known as Information Flow Diagram

Process Flow Diagram (PFD)

Piping and Instrumentation Diagram (P&ID) Alsoknown as Mechanical Flow Diagram (MFD).

Utility Flow Diagram

This is a type of P&ID for common plant utilities(steam, utility air, fuel oil, etc.)


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An Example of Block Flow Diagram (BFD)

Composed of only blocks (rectangles) and straight lines

Each block represents one or more unit operations

The lines represent the major process flow streams (material/

energy flows)

H2(upgrader)

FG(upgrader)

Syn Gas

Diluent

SCO

Upgrader

Sour Gas

Sulfur

Gasifier H2S

Diluted

Bitumen

Pitch

LVGO

HVGO

Kerosene

Diesel

CDU

VDU

DHT

HC

Treating

SRU

GSFR

NHT

Naphtha

Diesel

GO

SDA DAO EB

Naphtha


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Process Flow Diagram (PFD)

A PFD is a schematic representation of a process using

symbols to illustrate major operation units

and major

process flow lines.

A PFD also tabulates process design values

for the

streams in different operating modes (minimum, normal

and maximum).

A PFD is typically the first drawing developed for a

process, often in the pre-conceptual or conceptual

design phase.


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What should be included in a PFD

A PFD should include:

Major equipment (symbols, names and identification #)

Main process piping and flow direction

Operating pressure and temperature

Major bypass and recirculation lines

Major control and instrumentation (optional)

A PFD should not include:

Pipe line numbers

Minor components and minor bypass lines

Isolation and shutoff valves

Maintenance vents and drains

Relief and safety valves

Code class information


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A Sample of PFD


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Piping & Instrumentation Diagram (P&ID)

Scope

It is a detailed symbolic representation of

process interconnection, including all equipment,piping, and instrumentation.

All items are identified using a standard

numbering system.

It should be developed at the Basic Engineering

stage.

It is the basis for all Detail Engineering work inplant design.


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Synonyms

Process and instrument diagram (P&ID)

Piping and Instrument diagram (P&ID)

Mechanical flow diagram (MFD)

Engineering flow diagram (EFD)

Piping and wiring diagram (P&WD)

Pipe and identification diagram (P&ID)


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Multidisciplinary

Technical contents of P&IDs

rely on multi-

disciplines:

Process

Mechanical

Piping

Control and Instrumentation

Plant Operation


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P&ID

Classification

Process P&ID

Define on-plot process unit design, as well as off-plot tankage

andshipping systems

Utility Plant P&ID

Define utility units such as cooling towers, air compressors, boilers,unit drain collection systems, fire water systems, and watertreatment plants.

Utili ty Distribution P&ID

Show the distribution of utilities within a given process. Valving

andinstrumentation on piping are shown for main headers up to andincluding branch root valves.

Interconnecting (Rack) P&ID

They are the connecting link between individual process, utility

plant,and utility distribution P&IDs. They are usually prepared for theoffsite pipe racks and link the various process and utility plants.

Vendor P&ID

Prepared for systems that support major equipment packages.


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Format

There are no universal format to be used indeveloping P&IDs.

The P&ID formats vary with industry segments andcontractors.

In reality, every industrial company that develops oruses P&IDs

has its unique formats/guidelines forP&IDs.

The P&ID preparation should follow the formats fromindividual clients.

The P&ID formats are similar for different companies

in the same industry.


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Two Key Elements in P&IDs

Piping:

Physical elements that interconnect equipment and process flow.

In different sizes, normally expressed as nominal sizes

In different materials. The most common material is carbon steel.

Other metals, such as various grades of stainless steel, and

plastic materials, such as PVC, Teflon, are also used.

With thermal insulation, if required.

Instrumentation

Devices used to measure, control, and monitor the process

variables. These variables can be flowrate, temperature,pressure, liquid level, viscosity, and others.

Control valves and relief valves are also an important part of the

instrumentation.


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Relationship between PFD and P&ID

For a process, a PFD is a simple representation, while a P&ID

is a definitive and comprehensive representation.

A PFD shows major equipment and major process lines, while

a P&ID shows all equipment and all process lines.

A PFD shows major operating conditions (flow, temperatureand pressure), while a P&ID shows piping, valves and

instruments that monitor and control the process.

P&IDs

are more important in the design process, but PFDs

provide a basis for P&IDs

development.

PFDs

and P&IDs

use the same symbols and formats.


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What should be included in a P&ID?

All equipment with names and identification numbers

Piping with flow direction and line numbers (pipe specifications

and line sizes are included in line numbers)

All valves

All instrumentation with controlling devices and signal inputs andoutputs

Interconnection references (from one P&ID to another P&ID)

Miscellaneous

vents, drains, special fittings, sample lines, andreducers

Permanent start-up and flush lines

Interfaces for class changes

Vendor and contractor interfaces

Identification of components and subsystems delivered by others

Intended physical sequence of the equipment


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What should not be included in a P&ID?

Manual switches

Equipment rating or capacity

Pressure, temperature and flow data

Supplier package piping which is internal to thepackage and has no operational interface

Elbows, tees and similar standard pipe fittings

Extensive explanatory notes

Physical details and dimensions

Piping connections and type (e.g. threaded, flanged,etc.)


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Basic Steps for P&ID Preparation

Show all equipments with necessary piping to carry outthe process

Show all connecting process piping necessary to carry

out the process

Show all other piping required for auxiliaries

Show all required valves and major non-standard fittings

Show all required instruments and control loops

Mark size, fluid code, material code & identificationnumbers of all pipe lines

Mark interlock numbers as per interlock description

Review P&ID considering all operational, startup/shutdown, safety, maintenance & aesthetic aspects


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Three Key Types of Symbols in P&IDs

Equipment symbols:

Process operation units for mass transfer, heat

transfer, momentum transfer and chemical reaction

Piping symbols:

Relevant to pipe, valves, and connections

Instrumentation symbols:

Sensing, monitoring and controlling

The symbology follows the ISA standard ANSI/ISA-

5.1-1984 (R1992).


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Equipment Symbols in P&IDs

Pumps

Compressors

Fans & blowers

Mixers & agitators

Conveyors & feeders and other material handling

Separation equipment (liquid-liquid, liquid-gas, liquid-solid,

gas-solid, gas-gas)

Tanks & drums (storage)

Heat exchangers

Heating & cooling elements

Reactors

Turbines, generators and motors

Transportation equipment


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Examples of Equipment Symbols


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Piping Symbols in P&IDs

Process flow lines (often combined with signallines for instrumentation)

Valves

P&ID connectors

Reducers/Increasers

Caps

Connections

In-line items

Fire and safety

Miscellaneous labels


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Examples of Piping Symbols


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Instrumentation Symbols in P&IDs

General instrument or function symbols

Signals and lines

Sensors (four basic instrument groups)

Temperature (T)

Pressure (P)

Flowrate

(F)

Level (L)

Self-actuated devices

Pressure (regulators, relief/safety valves)

Temperature, flow, and level (regulators)

Valve actuators

Pneumatic & electric (solenoid, diaphragm, cylinder,motor, etc.)

With & without positioners

Miscellaneous labels


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Signal/Line Symbols


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Some Sensor & Control Valve Symbols


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Exercise: Identification of P&ID Symbols


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General Instrument Symbols

Instrument Symbol

A circle --

individual measurement

instruments such as transmitters,

sensors, and detectors for pressure,temperature, flow, level

A square with a circle inside --

instruments that both display

measurement readings and performsome control function (e.g. DCS

connection and control)

A hexagon --

computer functions.

A square with a diamond --

PLC

(Programmable Logic Control)

functions.

Instrument Location

Solid line: Control room panel

No line: Field

Double solid: Remote panel

Dash line: Behind panel in control room

Double dash line: Behind remote panel


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Instrument Identification

Tag Number

Instrument symbols should contain

letters and numbers.

The letters indicate the instrument

type, and the numbers identify thecontrol loop.

Usually 2 or 3 letters are used.

The first letter identifies the

measured or initiating variable,

The second is a modifier,

The remaining letters identify the

function.

Normally a plant # should be

prefixed to the Tag#.

e.g. 265-PI217 (265 is a plant #)

a.

Pressure indicator, Loop 217,located in the field.

b.

Pressure indicator, Loop 217, oncontrol panel, located in the

control room.c.

Pressure indicator, Loop 217,signal to DCS.

PI

217

PI

217

PI

217

a b c

Examples of Instrument #


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Instrument Identification LettersFirst Letter Succeeding Letters

Measured or InitiatingVariable Modifier Readout or PassiveFunction Output Function Modifier

A Analysis Alarm

B Burner, Combustion Users Choice Users Choice Users Choice

C Users Choice Control

D Users Choice Differential

E Voltage Sensory (Primary)

F Flow Rate Ratio

G Users Choice Glass, Viewing Device

H Hand High

I Current Indicate

J Power Scan

K Time Time Rate of Change Control Station

L Level Light Low

M Users Choice Momentary Middle

N Users Choice Users Choice Users Choice Users Choice

O Users Choice Orifice

P Pressure, Vacuum Test Point

Q Quantity Integrate, Totalize

R Radiation Record

S Speed, Frequency Safety Switch

T Temperature Transmit

U Multivariable Multifunction Multifunction Multifunction

V Vibration, mechanical analysis

W Weight, Force Well

X Unclassified x-axis Unclassified Unclassified Unclassified

Y Event, State or presence y-axis Relay, Compute, Convert

Z Position, Dimension z-axis Driver, Actuator


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Some Combinations of Instrument Letters

PC Pressure controller TA Temperature alarm

PI Pressure indicator TI Temperature indicator

PT Pressure transmitter TR Temperature recorder

PR Pressure recorder TY Temperature I/P converter

PY Pressure converter TW Temperature well

PIC Pressure indicating controller TIC Temperature indicating controller

PRC Pressure recording controller TRC Temperature recording controller

PSVPressure safety valve/

Pressure relief valveTCV Temperature control valve

PCV Pressure control valve

I/P: Current to Pneumatic.


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Some Combinations of Instrument Letters

FA Flow alarm LA Level alarm

FE Flow element LAH Level alarm high

FI Flow indicator LAL Level alarm low

FR Flow recorder LC Level controller

FT Flow transmitter LG Level glass

FY Flow I/P converter LI Level indicator

FF Flow ratio LIC Level indicating controller

FCV Flow control valve LRC Level recording controller

FRC Flow recording controller LCV Level control valve


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A Control Loop Example in P&ID

FT123: field-mounted flow transmitter

FIC123: panel-mounted flow indicating

controller located in a shared

control/display device

TY123: temperature I/P converter

located in an inaccessible location

TT123: filed-mounted temperature

transmitter

TIC123: field-mounted temperatureindicating controller. Its output is

connected via an internal software or

data link to the setpoint (SP) of

FIC123.

YIC123: an event indicating controller.

All inputs and outputs are wired to a

PLC accessible to the operator. YIC

typically indicates a controlled on/off

valve.


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Rules of Thumb in P&ID Design

P&IDs

are typically developed from PFDs, so that understandingthe designed process is a key basis for P&ID design.

P&IDs

do not have a drawing scale and usually present only thefunctional relationship, not the relative physical locations ofcomponents.

P&IDs

are done in a single line

format that represents all pipingand ductwork as a single line regardless of size.

P&IDs

should be specific to one system only, i.e. no more than onesystem should be shown on a single diagram.

P&IDs

should be configured such that major flow should generallybe from left to right and from top to bottom, if possible. Primary

flow paths should not suffer major changes in directions on P&IDs.

P&IDs

should start simple and then be enhanced in severalrevisions to address the real process by various disciplines.

Following the style from the existing P&IDs for the same client.


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Line Designation (Line Number) in P&IDs

Line # is required for piping in P&IDs

Position of the line #: normally above piping lines

Different formats of line # for different companies

A line # contains the following basic information:

Plant #

Commodity symbol

Line serial #

Piping/Line size

Piping/Line class (optional)

An example: 6N1-4-CA2B

Plant 6, Nitrogen line 1, 4

pipe, piping class

CA2B


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Styles for Flow Direction in P&IDs

2.

Flow arrow at the end of each line1.

Flow arrow at each turning point

3.

Flow arrow at the middle of each line


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Valve Status for Bypass Lines

Its better to mark the valve status on the bypasslines including safety relief lines:

NC

Normal Closed

NO

Normal Open

CSC

Car Seal Closed

CSO

Car Seal Open

LC

Lock Closed

LO

Lock Open

Relief valves need to indicate their set pressures

e.g. SET @125 PSIG


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Accompanying Deliverables from P&IDs

Equipment List

Line List (Line Designation Table - LDT)

Valve List

Instrument List

Tie-In ListA Tie-in List shall be issued indicating the extent of the Vendor package battery limitseach time a P&ID issue is made starting with IFA. For plant modification, the tie-inpoint is the point where from process or utility is connected in

the existing systems.

Holds ListA "Holds" list must be issued each time a P&ID issue is made starting with IFD. The"Hold" indicates where the information used as input to the P&ID

is preliminary andthe item is used with risk in the downstream design.

Revision list

A Revision List defines the changes made in the design so that appropriate actioncan be taken to accommodate those changes. A Revision List must accompany anyissue of P&IDs

after IFH if the changes are too extensive to be distinguished in therevision box and by clouding.

(IFA -

Issued for Approval, IFD -

Issued for Design, IFH -

Issued for HAZOP)


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As-Built

P&IDs

When there are modifications done in construction,commissioning, qualification, or at any other time after thefacility has been validated and operating, the P&ID must be

modified to indicate the latest information.

Frequently these modifications arise from construction,post-construction, and C&Q walk-downs prior to the

system turn-over from IQ, OQ and PQ.

All changes must be processed through the QualityManagement System (QMS).

All changes on a P&ID must be bubbled, signed and dated.

Often a new revision number should be assigned to a As-Built

P&ID.


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Software for Developing P&IDs

AutoPLANT

P&ID

AutoCAD-based (Bentley)

PlantSpace

P&ID

MicroStation-based (Bentley)

SmartPlant

P&ID

Able to convert AutoCAD orMicroStation

based P&ID to SmartPlant

P&ID

(Intergraph)

CADWorx

P&ID

AutoCAD-based (CodeCAD

Inc.)

AutoCAD P&ID

AutoCAD-based (Autodesk)

CADPIPE P&ID

AutoCAD-based (AEC Design Group)

AutoFLOW

AutoCAD-based (PROCAD)

HexaCAD

P&ID

(Hexagon Software)


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AutoCAD P&ID 2007

for Developing P&IDs1.

Industry standard P&ID symbols

2.

Dynamic process and signal lines3.

Dynamic components

4.

Report and list generation

5.

Import and export to MS Excel

6.

Tag generation and uniqueness

7.

Search and edit using a spreadsheet interface

8.

Easy symbol creation and substitution

9.

Review and approve data edits

http://www.autodesk.com/us/autocadpid/interactiveoverview2008/index.html
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