CBB1052 ENGINEERING GRAPHICS PROCESS FLOW DIAGRAM (PFD) & PROCESS AND INSTRUMENTATION DIAGRAM (P&ID)

CHAPTER 9 WEEK 11

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

(B) 

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.

(B) 

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)

(B)

PROCESS FLOW DIAGRAM

Denomination of flows of incoming & outgoing material or energy flows

Route & direction of incoming & outgoing material or energy flows

Denomination of the equipment

Symbols of process equipment

Operating conditions

Source: EN ISO 10628:2001

(B) 

•

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

(B) 

PROCESS FLOW DIAGRAM

(continued): Density, viscosity

•

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.

(B)

PROCESS FLOW DIAGRAM

Flowrates of process fluids

Data tables

Operating T & P

Supplementary operating conditions (ρ)

Functional demands for process measurement & control

Gate valve

Elevation of platforms & approx relative vertical position of equip Source: EN ISO 10628:2001

Valves in the logical process position with respect to their function

(C) 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.

(C) PROCESS AND INSTRUMENTATION DIAGRAM (P&ID) 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

(C) 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 control & measurement functions with ID no Identification no of equipment

Characteristic data equip table

(C) 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

Flow energy

Elevation

Flowrates

Construction materials

EQUIPMENT DENOMINATION ACCORDING TO BS K1 – Bubble cap tray column  W1 – Circulating evaporator  W2 – Condenser  W4 – Distillate cooler  W5 – Residue cooler  B1, B2 – distillate vessel  P1A-B – Centrifugal pump  P2A-B – Pump  P3A-B – Centrifugal pump 

EQUIPMENT FUNCTION CODE BASED ON PTS

EQUIPMENT FUNCTION CODE BASED ON PTS

Process & eng flow scheme

Utilities & eng flow scheme

DCS=distribution control system

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, 

GENERAL DRAUGHTING RULES ACCORDING TO BRITISH STANDARD (CONT.) 

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.) 

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