CBB1052 ENGINEERING

GRAPHICS

PROCESS FLOW DIAGRAM (PFD)

& PROCESS AND INSTRUMENTATION

DIAGRAM (P&ID)

OBJECTIVES

At the end of this lecture, students should be able

to:

Explain what is PFD and P&ID

Construct PFD given a process statement or from

block diagram

Understand and apply general draughting rules

PROCESS FLOW DIAGRAM

In the process flow diagram (PFD), processes

and/or process plants are shown as graphical

symbols, interconnected by flow lines.

The graphical symbols represent equipment and

the lines represent flows of mass or energy or

energy carriers.

PROCESS FLOW DIAGRAM

The process flow diagram should consist of the

following basic information:

• symbols of process equipment

• denomination of the equipment

• route and direction of the incoming and

outgoing material, energy and/or carrier flows

• denomination of flows of incoming and outgoing

materials, energy and/or carriers

• operating conditions (T and P)

PROCESS FLOW DIAGRAM

Source: EN ISO 10628:2001

PROCESS FLOW DIAGRAM

The process flow diagram may also contains:

• denomination of flow directions and flow rates

of process fluids between the process steps

• essential valves in the logical process position

with respect to their function

• functional demands for process measurement

and control at essential points

PROCESS FLOW DIAGRAM

(continued):

• supplementary operating conditions ( , )

• denomination of equipment and characteristic

data of equipment

• denomination of drives (e.g., gears, conveyors,

belts, chains, cranes) and their characteristics

• elevation of platforms and approximate

relative vertical position of equipment.

PROCESS FLOW DIAGRAM

Source: EN ISO 10628:2001

PROCESS AND INSTRUMENTATION DIAGRAM

(P&ID)

• The piping and instrumentation diagram (P&ID) is

drawn based on the process flow diagram (PFD).

• The P&ID represents the technical realization of a

process by means of graphical symbols for equipment and

piping together with graphical symbols for process

measurement and control functions.

The piping and instrument diagram should consist of the following

basic information:

• function or type of equipment, including drives,

conveyors as well as installed spares

• identification number of equipment

• characteristic data of equipment

• indication of nominal diameter, pressure rating,

material and type of piping

PROCESS AND INSTRUMENTATION DIAGRAM

(P&ID)

PROCESS AND INSTRUMENTATION DIAGRAM

(P&ID)

Basic information (continued):

• details of equipment, piping, valves and fittings,

thermal insulation

• process measurement and control functions with

identification number

• characteristic data of drives, given in separate lists if

necessary

PROCESS AND INSTRUMENTATION DIAGRAM

(P&ID)

The piping and instrumentation diagram may also contains:

• denomination of flow rates or amounts of energy or energy

carriers

• route and direction of flow of energy or carriers

• type of essential primary elements and sensors

• essential construction materials for equipment

• elevation of platforms and approximate relative vertical

position of equipment

• reference designation for valves and fittings

• denomination of equipment

EQUIPMENT FUNCTION CODE BASED ON

PTS

EQUIPMENT FUNCTION CODE BASED ON

PTS

GENERAL DRAUGHTING RULES ACCORDING

TO BRITISH STANDARD

Dimensions

Should reflect the actual relative dimensions with

respect to scale and elevation (exclude valves,

pumps and measurement unit)

Location

Devices to be expected at the uttermost level of the

plant shall appear at the top of the drawing

Those devices at the lowest level are expected to be

shown at the bottom of the drawing

Logical position

GENERAL DRAUGHTING RULES ACCORDING

TO BRITISH STANDARD (CONT.)

Line Widths 1 mm for main flow lines

0.5 mm for Graphical symbols of the equipment, except valves, fittings,

and piping accessories

Energy carrier lines and auxiliary system

Subsidiary flow lines

Rectangular frames for illustrating unit operations

0.25 mm for Graphical symbols of valves, fittings and piping accessories

Symbol for process measurement and control functions, control and data transmission lines

Reference lines

Other auxiliary lines,

Flow Direction

Flow direction shall start from left to right or top to bottom

Line Spacing

Line should not be spaced less than twice the width of the lines

Line spacing (parallel lines) > 10 mm is highly desirable

Arrows

For better understanding, arrow may be located at the inlet of the equipment and upstream of pipe branches

GENERAL DRAUGHTING RULES ACCORDING

TO BRITISH STANDARD (CONT.)

GENERAL DRAUGHTING RULES ACCORDING

TO BRITISH STANDARD (CONT.)

Lines Connection

GENERAL DRAUGHTING RULES ACCORDING

TO BRITISH STANDARD (CONT.)

Auxiliary system lines

Lines shall be shown as dashed lines with the

indication of the direction of flow and reference to

type of the energy carrier

Lettering

Height of letters shall be 5 mm for reference

designations of major equipment

2.5 mm for other inscriptions

INSTRUMENT NOMENCLATURE

SUMMARY

PFD

P&ID

General Draughting Rules

EXERCISE

Draw the process flow diagram of the cumene

manufacturing process according to the

draughting standards outlined in BS.

Use the given block diagram to assist you

BLOCK DIAGRAM FOR CUMENE

MANUFACTURING PROCESS