Piping and Instrumentation for
Process Industries
Module II
P&ID
Piping and Instrumentation
Diagram
P&ID
A P&ID IS:
• A tool for detailed engineering and
commissioning
• A Schematic of a Process Plant
• A Communication Tool
– A Basis for Detailed Design
– A Guide for Construction
– A Guide for Operation And Maintenance
• A Graphical Table of Contents to Other
Engineering Documents
Piping & Instrumentation Diagram
• P&ID shows all of piping including the
physical sequence of branches, reducers,
valves, equipment, instrumentation and
control interlocks.
• P&ID Symbols
P&ID
A P&ID should include:
• Instrumentation and designations
• Mechanical equipment with names and numbers
• All valves and their identifications
• Process piping, sizes and identification
• Miscellaneous - vents, drains, special fittings,
sampling lines, reducers, and increasers.
• Permanent start-up and flush lines
• Flow directions
• Interconnections references
P&ID
A P&ID should include:
Contd…
• Control inputs and outputs, interlocks
• Interfaces for class changes
• Seismic category
• Quality level
• Annunciation inputs
• Computer control system input
• Vendor and contractor interfaces
• Identification of components and subsystems
delivered by others
• Intended physical sequence of the equipment
P&ID
A P&ID should not include:
• Instrument root valves
• control relays
• manual switches
• equipment rating or capacity
• primary instrument tubing and valves
• pressure temperature and flow data
• elbow, tees and similar standard fittings
• extensive explanatory notes
Sample P&ID
P&ID
Process
Utility
Off sites
P & ID
Distribution
Auxiliary
Interconnectiing
Packaged Unit
Process Flow Diagram
Ad
d
Ad
d
P & IDs
Sub – System
and
Associated System
Demarcations
By EPC/Vendor
How do we Prepare them…..?
Title Box
P & ID Numbering
Equipment Arrangement
Equipment Details
Equipment Numbering
Equipment Data
Line Numbering
Termination of Line
Line Number
• There are two basic areas - These are the line
number method and the line number elements.
• * Methods - There are two basic line numbering
methods. The first method is based on the
“Purpose or Function” of the line. The second
method is based on the line “Size.”
* Elements - The elements that are most
commonly included in a line numbering scheme
are: Plant Location, Line Identity, Line Class (or
Line Specification), Size, Insulation Type (when
required) and Heat Tracing Type (when
required).
Line Number – Methods….
• Methods – “Purpose or Function” of the line based on
the line “Size.”
An example of this might be a pump suction line. It
might come from a Storage Tank. It travels some
distance and then splits and connects to the two pumps
designated for that one service or function. This is one
line, it serves one purpose or function therefore it has
only one line number.
• Another example would be the pump discharge that
leaves both of these pumps and join to form the single
pipe line that runs to the next piece of equipment. This
line also has one purpose or function therefore it has
only one number.
Line Number – Methods….
• Methods – “Purpose or Function” of the line based on
the line “Size.”
• The “line size” method is, where the line number
changes whenever and wherever the line size changes.
• When compared to the first (purpose or function)
method, the pump suction line might have five line
numbers instead of one.
• The pump discharge might also have five or more
depending on what happens at the destination end of the
line.
Line Number – Elements….
• Elements
• The elements of a line number – Example
10-1021-CA1A-12”- IH
-ST
Where:
10 = the plant Unit or Area (mandatory)
1021 = the numeric line number (mandatory)
CA1A = the line class (mandatory)
12” = the line size (mandatory)
IH = Hot Insulation (only when required) (1)
ST = Steam Tracing (only when required) (2)
Line Number – Elements….
• In this case the “10” refers to a physical plant area
as defined by the project work breakdown structure
document. Other Areas might be 20, 30, 40 or 11,
12, 13, etc.
• The “1021” represents the twenty-first line in this
area. All line numbers on this project will be four
place numbers starting with 1000 in each area.
• The “CA1A” represents the project piping material
line class code for: 300# (C), Carbon Steel (A), 1/32”
corrosion allowance (1) and a specific gasket
type/material (A).
Line Number
In addition to the line identification elements the Line List
should also include some important information
• The phase (liquid or gas)
• The origin & destination of the line
• The line pressure, both the normal operating pressure
and the maximum operation (or Design) pressure
• The line temperature, both the normal operating
temperature and the maximum operation (or Design)
temperature
• An indicator code for Stress Analysis requirements
• The insulation thickness (optional)
• The line schedule (optional)
Application : Calculation of Labour Hour Estimation
Line Identification
Line Service
Designation
Line Tracing
Line Numeric
Pipe Size
Critical Line Descriptor
Global Pipe Spec
Line Insulation
Line Continuation
• Line continuations between different
drawings are shown below: