LECT 7…PIPING ISOMETRICS
Isometric drawings represent a 3D layout of the piping system on a 2D medium,
typically drawn at a 30° angle from the horizontal in both directions.
Unlike plan or elevation views, isometrics combine vertical and horizontal piping
in a single view, helping workers visualize and fabricate the piping with ease.
7.1 What Is an Isometric?
Used extensively in process industries, including oil and gas, chemical
plants, power plants, and water treatment facilities.
Common in both the design phase and during site installation and
inspection.
Essential for piping stress analysis tools (like CAESAR II), where the
layout of the system is critical to evaluate loads and displacements.
Unlike orthographic drawings, which show only one face or angle of an
object at a time, isometric drawings display the piping layout in a
single view using 30-degree angles from the horizontal to give a
realistic
Characteristics of Piping Isometrics
✓3D Appearance on 2D Medium:- Uses a grid where horizontal lines
are drawn at 30° angles to show depth, and vertical lines represent
height.
✓No Scale, Only Dimensions:- Isometrics are not drawn to scale;
instead, accurate dimensions are provided for fabrication and
installation.
✓Flow Direction:- Usually indicated with arrows, helping users
understand the intended direction of fluid or gas movement.
✓Component Representation:- All key components—such as elbows,
tees, reducers, valves, and flanges—are represented using standard
symbols.
✓Elevations and Offsets:- Vertical and horizontal changes in the
pipeline are clearly shown in a single view.
7.2 Drawing Piping Isometrics
➢Steps for manually sketching isometric drawings.
➢Use of 30° angles for horizontal pipes and vertical lines for elevation
changes.
➢Interpreting flow direction and pipe routes.
➢Common symbols and notations (elbows, tees, reducers, valves).
7.3 Isometric Dimensions, Notes, and Callouts
❖How to represent dimensions (center-to-center, end-to-end).
❖Placement and clarity of dimensions in isometrics.
❖Using notes and callouts for
✓Pipe size and schedule.
✓Material specifications.
✓Welding details.
✓Insulation or coating requirements.
7.4 Isometric Offsets
• In piping systems, it is often necessary for a pipeline to change
direction or elevation to avoid obstacles, accommodate equipment,
or fit within a limited space
• Typical use cases (e.g., obstacle avoidance, elevation changes).
Offsets are usually created using fittings such as
✓Elbows (45° or 90°)
✓Miter bends
✓Wye or tee connections
Types of Offsets
1.Horizontal Offsets
✓A change in direction within the same horizontal plane.
✓Common when pipes must bypass columns, beams, or other pipes.
2.Vertical Offsets
✓A change in elevation, often to pass over or under structures or to connect
equipment at different heights.
3.Combined Offsets (Compound Offsets)
✓A shift that involves both horizontal and vertical direction changes,
represented as a diagonal run in the isometric.
Lec8…Software Application and 3D Modeling of Piping Systems
8.1 CAD Software
❖Overview of CAD tools used in piping
✓AutoCAD Plant 3D
✓AVEVA E3D
✓Bentley OpenPlant
✓SolidWorks for piping
CAD software allows designers and engineers to draft 2D layouts, build
3D models, analyze systems, and generate fabrication and construction
drawings with a high degree of efficiency and precision.
8.2 Advantages of 3D Modeling
✓Improved accuracy and visualization.
✓Enhanced collaboration among design teams.
✓Easier error detection and modification.
✓Streamlined documentation and change management.
✓Develop accurate 2D schematics and 3D models of piping systems.
✓Automate drawing creation and revision control.
✓Generate Bills of Materials (BOM), isometric drawings, and
fabrication details.
✓Support interdisciplinary collaboration among civil, mechanical,
electrical, and structural teams.
✓Facilitate simulation and interference checks in complex projects.
8.3 Checking for Interferences
❖In complex piping systems, especially within industrial facilities such
as Food plants, oil refineries, or power stations, multiple disciplines
such as piping, structural, electrical, and HVAC converge in shared
spaces
An interference (or clash) occurs when
✓Two or more objects (e.g., a pipe and a beam, a valve and a duct)
occupy the same physical space.
✓Required access space (e.g., maintenance clearance, valve operation
area) is obstructed.
✓Safety distances or code-required separations are violated.
8.4 Generating Drawings Automatically from a Model
✓Creating orthographic plans, sections, and elevations from 3D
models.
✓Benefits of automation in drawing creation.
✓Linking models with project databases (BIM/PDM integration).
8.5 Generating Isometric Drawings Automatically
➢How software extracts and generates piping isometrics from the 3D
model.
➢Customizing isometric formats (title blocks, BOMs).
➢Associating isometrics with spool drawings and fabrication plans.
➢Real-time updates when the 3D model changes.
