MODULE 3: ISOMETRIC
DRAWING
What is ISOMETRIC drawing?
How to read ISOMETRIC drawing?
WHAT IS ISOMETRIC DRAWING?
• AN ISOMETRIC DRAWING IS A TYPE OF A
PICTORIAL DRAWING IN WHICH THREE SIDE
OF AN OBJECT CAN BE SEEN IN ONE VIEW.
• IT’S POPULAR WITHIN THE PROCESS PIPING
INDUSTRY BECAUSE IT CAN BE LAID OUT AND
DRAWN WITH EASE AND POTRAYS THE
OBJECT IN A REALISTIC VIEW.
WHAT IS ISOMETRIC DRAWING?
ISOMETRIC DRAWING
ORTHOGRAPHIC DRAWING
ISOMETRIC LAYOUT
• ISOMETRIC LINES: ONE VERTICAL AND TWO
AT 30° FROM HORIZONTAL.
PIPING ISOMETRIC LAYOUT
VALVE
FITTING
PIPE
SCALE AND DIMENSION
• PIPING ISOMETRIC DRAWING ARE
RARELY DRAWN TO SCALE.
• HOWEVER, DIMENSION AND
LENGTH SHOULD BE SHOWN
PROPORTIONATELY.
• THE WRITTEN DIMENSIONS ARE
ACCURATE.
DIMENSION
DIRECTION AND LOCATION
•
•
•
•
•
LOCATION AND DIRECTION HELP TO PROPELY ORIENT THE ISOMETRIC DRAWING.
A NORTH ARROW GIVE DIRECTION AND SHOULD ALWAYS POINT TO THE UPPER-RIGHT
CORNER OF THE PAPER.
STRUCTURAL REFERENCE POINT THAT PROVIDE LOCATION CAN BE SHOWN ON ISOMETRIC.
DIMENSIONS MUST ALWAYS BE GIVEN TO POINTS OF REFERENCE; SUCH AS STRUCTURES,
EXISTING EQUIPMENT, ETC.
COORDINATES SHOULD ALSO BE SHOWN ON THE ISOMETRIC DRAWING.
FITTING SYMBOLS AND ORIENTATION
• FITTINGS ARE DRAWN THE SAME SHAPE AS
THEY APPEAR ON THE PLAN AND ELEVATION
DRAWING EXCEPT THEY’RE AT AN ISOMETRIC
ANGLE.
Square
corner
elbows
Curved Elbow
Represent at ion
FITTING SYMBOLS AND ORIENTATION
Not following the “ general
rule” leads to a chaotic
looking isometric …it doesn’t
look professional
ISO SYMBOLS
FITTINGS
ISO SYMBOLS
FLANGES
ISO SYMBOLS
VALVES
ISO SYMBOLS
VALVES
ISO SYMBOLS
SPECIAL COMPONENTS
ISO SYMBOLS
SPECIAL COMPONENTS
ISO SYMBOLS
SPECIAL COMPONENTS
ISOMETRIC DRAWING OFFSET
ISOMETRIC DRAWING OFFSETS
ISOMETRIC OFFSETS
Rout ing st art ing point X
? Pipe runs up
? Pipe runs up and to the east
? Pipe runs up
ISOMETRIC OFFSETS
Rout ing st art ing point X
? Pipe runs up
? Pipe runs up and to the
north
? Pipe runs up
ISOMETRIC OFFSET
Rout ing st art ing point X
? Pipe runs up
? Pipe runs up and to the
north-west
? Pipe runs to the north
BASIC FORMULA FOR DRAWING
OFFSETS
• BASIC TRIGONOMETRIC FUNCTION
c
b
a
𝑐 2 = 𝑎2 + 𝑏2 𝑐 =
𝑎2 + 𝑏2
𝑎2 = 𝑐 2 − 𝑏2 𝑎 =
𝑐 2 − 𝑏2
𝑏2 = 𝑐 2 − 𝑎2 𝑏 =
𝑐 2 − 𝑎2
𝑆𝑈𝑀 𝑂𝐹 𝐼𝑁𝑇𝐸𝑅𝐼𝑂𝑅 𝐴𝑁𝐺𝐿𝐸 = (𝑁 − 2) × 180°
FOR TRIANGLE
𝑆𝑈𝑀 = (3 − 2) × 180°
𝑆𝑈𝑀 = 180°
BASIC FORMULA FOR DRAWING
OFFSETS
• BASIC TRIGONOMETRIC FUNCTION
Sin = SO/ HY
Cos = SA/ HYP
Tan = SO/ SA
CALCULATING ISOMETRIC OFFSETS
Calculat ing Isomet ric Offset s
Start off with what ’s given or what you can determine from
the pipe drawing it self.
a) We are given an 45° angle rise, that
clues us in on the fact that the two
sides of our t riangle are going to be
the same length
b) By doing simple subtraction, we can
come up with the length for side B:
200-100 = 100 m m OR you can
subtract the elevations given and get
the same dimension for side A.
Since B = A: side A = 100 mm as well. So, C= Sq. Rt (100 2+1002) = 141.21 mm
CALCULATING ISOMETRIC OFFSET
𝐴 = 500𝑚𝑚
𝐵 = 600𝑚𝑚
C
A
𝐶=
5002 + 6002
𝐶 = 781𝑚𝑚
B
𝜃=
500
)
600
𝑇𝐴𝑁 −1 (
𝜃 = 39°
CALCULATING ISOMETRIC OFFSET
𝐴 = 800𝑚𝑚
𝐵 = 900𝑚𝑚
C
A
B
WHAT IS VALUE C AND 𝜃?
ISOMETRIC VS PLAN VS ELEVATION
ISOMETRIC VIEWS
Rout ing st art ing point X
• Pipe runs to the east
• Pipe runs up
• Pipe runs to the north
• Pipe runs to the west
• Pipe runs dow n
ISOMETRIC VIEWS
Rout ing st art ing point X
 Pipe runs t o t he sout h
 Pipe runs up
 Pipe runs up and to the west
 Pipe runs up
 Pipe runs to the west
 Pipe runs to the north-west
 Pipe runs to the north
ISOMETRIC VIEWS
Rout ing st art ing point X
 Pipe runs t o t he sout h
 Pipe runs up
 Pipe runs up and to the
north-west
 Pipe runs to the north
ISO DRAWINGS
CONNECTED PIPING
Example of double-line
method showing existing
piping
Elevation to show location of
pipe to be install at site
Spool number
Pg. 220 text
Dimension of pipe to be
fabricated and installed
Dashed line showing pipe
continuation and note
providing reference
drawing information.
Notice spec change between
“ new ” and existing pipe &
note for reference drawing
REFER TO HANDOVER
END