Published on 24-Mar-2023



 Humanity’s progress in industry, technology, and infrastructure since the advent of time has yielded a need for the transportation of various fluid resources, as elementary and essential as potable water to more volatile substances like Gaseous fuel, for a variety of purposes and through great distances as civilizations have found harbor in the most remote regions of the planet.

Irrigation Systems used in the Harrapan civilization (image credits:

Human innovation and ingenuity in this field have seen a plethora of changes, from the Complex irrigation canals used in Harappa in 2600 BC during the Indus valley civilization to the Pyramids of Ancient Egypt around the 25th century BC, the first recorded use of Pipes as cylindrical sections for transportation and elaborate Pipeline Systems for drainage made using copper and clay, finding its way to the specialized metals, alloys and other materials used for heavy resource pay-loads aligning with the demands of the present-day industry.  

Evolution of materials used to make pipeline systems (image credits: Fluid Handling Pipes & Its History - Legal Advantage)

Modern Pipeline systems involve intricate designs, which, during fabrication, involve Piping spool drawings that have descriptive specifications and dimensions, which are used by the fabricators and the welders to lay down the systems. Drafting these spool drawings gives rise to the importance of engineering drawing in pipeline systems. The spools relay the most detailed and accurate descriptions of the systems in the form of pipeline isometric drawings.


Complex engineering geometries require graphic illustrations to maintain clarity in the communication of designs. Technical drawing, AutoCAD, Siemens NX, and SolidWorks are extensively used to represent structures, plans, pipeline plans, etc, visually.

Pipeline structures require intricate geometries, manufacturing details, material information, threading data, sectional geometry, hole data, joint data, etc. Manufacturers, installers, and fabricators, along with organization administrators, benefit from these the most in keeping a record of the intricacies of pipeline geometries.


An isometric drawing is a draft of a three-dimensional structure in a two-dimensional drawing. This method of engineering planning involves drafting an orthographic projection along an axis. Pipeline structures are perfectly suited for axonometric projections, and pipeline isometric drawings encompass relatively every feature of the pipeline and its intricacies, providing a thorough understanding of the pipeline plans in a three-dimensional manner.

Example of a Hand-Drawn Pipeline Isometric drawing (Image credits:

Pipeline isometric drawings help organizations understand installing and placement of parts and give a thorough understanding of dimensioning, materials, and load-bearing abilities. 

Both the images show the view of the same pipeline, Image on the right shows a lot more while maintaining simplicity (Image credits: seabirdGroups)

The black dots in the image on the right indicate the butt welds, while the red line shows the same pipeline running as the image on the left in a three-dimensional view; A, B, and C represent the dimensions. Isometric View has benefits over the traditional orthographic views, as observed:

  • The isometric view is simpler as it portrays more information requiring much fewer data for representation, for instance, a single line in the above example.
  • The isometric view gives insight into the pipelines through multiple planes, creating a better understanding of the pipeline structures.
  • Isometric views require far fewer drawings to represent the same amount of data as orthographic views require multiple diagrams for multiple planes and cross-sections. etc.  

Plan and elevation are both portrayed in the isometric with ease (Image credits: Wermac)


Certain documents are essential for creating, studying, and recording pipeline structures. Pipeline isometric drawings are not issued for utilization unless approved and issued an IFC (Issued for construction) certificate. Inaccuracies in the drawings can cause catastrophic losses to the organization regarding time, labor, money, and resources. The documents are as follows:

  • Pipeline and Instrument Diagrams (P&ID documents):

This encompasses data about additional instruments, insulation data, and line data.

  • Line list:

This carries vital data about temperature and pressure, stress zones, water pressure, class of inspection, etc.

  • General Arrangement Drawing (GAD):

This document holds orientation, lines, dimensions, and part location data.

  • Piping Material Specifications:

This document contains extensive data about materials used in the pipeline structure.

  • Equipment Drawing:

This document provides data on connections in the pipeline.

  • Orientation of nozzle:

Nozzle installment requires careful consideration of the angle of orientation and the elevation of the nozzle.

  • Piping Support Drawing:

The supports required for the pipeline structure require carefully considered allotment. This document carries the data required for it.

  • Special Items Detail:

The special additions and parts required in the pipeline structure are logged in this document, along with in-depth material details, load details, and dimensioning data.

  • Instrument Installation Data:

This document contains end users' installation requirements and connector details.


Pipeline Isometric Drawings have certain compulsory components that aid the user in analyzing the otherwise complex pipeline isometric document. These common components are as follows:

  • Title Block
  • Isometric Drawing Area
  • Bill of Quantities (BOQ)
  • Notes section

A detailed description of these sections is as follows:


The title block should have the following data to ensure thorough communication of the pipeline structures:

  • Drawing Number
  • Line Numbers
  • Sheet Data
  • Pipeline and Instrumentation Data
  • General Arrangement and Layout
  • Project Details include the Project name, project number, project code, and area code.
  • In the case of insulation in the systems, the type of insulation should be mentioned.
  • Pipeline Testing Data
  • Class of inspection
  • Pressure data for the fluid that the pipeline is designed for. 
  • Pressure and Temperature of the pipeline design.


  • Isometric drawing
  • Name and location of the pipeline equipment
  • Coordinates for all components
  • Nozzle orientation data
  • Dimensional data of nozzles
  • Direction and allotted angles
  • Elevation of the nozzle using the center axis 
  • Elevations of the base of structures 
  • Axis orientation, offset, and location.
  • Slope involved in the installation, if any.
  • Specifications and line details
  • Breaks in specifications, if any.
  • Dimensional data is involved in the structure.
  • Drawing numbers of continued drawings if the structure drawing spans multiple pages.
  • Locations of individual instruments and their components.
  • Location and structures of control valves
  • Location of grids
  • Data on special items
  • Requirements of orifice meters
  • Ventilation and drainage details and location
  • Weld data for manufacturing of components
  • Weld data for installation
  • Size of branches
  • Size of reducers
  • Gap data for welds
  • Sequencing of components
  • Orientation of taps and the direction of flow of fluid to be carried in the pipes.

Bill of Materials (BOM)

  • Description of individual structural elements
  • Quantities of elements involved in the drawing.
  • Materials that the individual components are made of.
  • Variety and quantity of valves
  • Size and manufacturing rating of components
  • Industry codes followed by the pipeline structure
  • Special components, instruments, and such data must be logged in the Bill of Materials.
  • Length of structure and its dimensions
  • Quantity and variety of structural supporting elements


This section contains data on any specific requirements and additional components. This varies from project to project, and this section can be completely skipped if there is no data to provide. It contains the following data:

  • Data related to the slope and orientation of the structure should be mentioned in the presence of any such special situations.
  • In case the fluid to be carried in the pipeline is specific i.e., corrosive, edible, etc. Unique requirements and related data should be mentioned.
  • Piping and Instrumentation distance, lengths, and pressure can be mentioned in this section.
  • Requirements for unhindered uninstallation and dismantling of the structure can also be mentioned here.



Pipeline isometric generally depicts a large-scale pipeline structure and is never drawn to scale. It should be noted, however, that the dimensioning in the drawings, despite the scaling down is always in proportion. The steps involved henceforth include:

  • Creation of a sample isometric diagram prototype wherein the plane orientation, title blocks, BOM, dimensioning data, snap, and grid are pre-set. 
  • Create a library of the isometric symbols involved, including any additional parts, fittings, valves, etc, that are significant to the drawing. 
  • Dimensioning should be created for all isometric planes.
  • A list and menus for easy access to symbols should be created. 


The process of drafting isometric drawings for a pipeline system involves referencing the arrangements of the pipelines, sections, and elevation drawings during its development. Accurate drawing symbols, callouts, precise coordinates, and elevations provide intricate information to the fabricator. Isometric symbols corresponding to their Orthographic equivalents help the drafter relay elaborate specifications about the routing of the pipelines.

Isometric layout in an Orthographic plane (Image credits: Piping Isometrics - Seabird)

  • It is possible to measure the Above isometric lines.
  • Lines not parallel to the isometric lines in the orthographic plane cannot be measured.

Example isometric layout (Image credits: Piping Isometrics - Seabird)

As stated in the above example, the pipes in the drawing all lie along the directions of the three isometric axis lines.


The location and direction of the lines in the drawing can determine the orientation of the pipelines.

An arrow pointing towards the north in the upper right side of the diagram helps with the orientation.

Orthographic and isometric North arrows (Image credits: "Pipe drafting and design”- Second edition)

Isometric configuration (Image credits: "Pipe drafting and design”- Second edition)

  • Location-providing structural points are drawn in the isometric drawings.
  • Indicating the dimensions for the reference points is compulsory, i.e., Existing equipment, structures, etc. 
  • Isometric drawings involve marking the coordinates of the scaled-down pipe system.


For the orientation of the fittings and valves, it is recommended they are drawn parallel to the last change in direction or branching in the pipeline, as shown in the image : 

Recommend technique for Fitting symbols and valve orientation (image credits: "Pipe drafting and design”- Second edition)

  • Fittings with shapes taken from the plans and elevation drawings are drawn at an isometric angle.
  • Elbows are drawn depending on the industry standard as stated below: 

Different ways Elbows are drawn (Image credits: "Pipe drafting and design”- Second edition)


  • Fittings:

These components are pieces of pipe fabricated according to the thickness of the pipe wall, are used to Branch out from a main pipe (tee), make changes in direction (elbow),  or reduce the size of the line (reducer).

ISO symbols for different Fittings (Image credits: Pipe drafting and design”- Second edition)

  • Flanges:

These components are ring-shaped contraptions used as a substitution for threading or welding various piping components through the pipeline system. Unlike welded connections, they are more reliable than threaded joints and can be inspected and disassembled. 

ISO Symbols for Different Flanges (Image credits: Pipe drafting and design”- Second edition)

  • Valves:

These devices’ primary function is to regulate the flow and change the volume, pressure, and rates at which the fluids flow through the pipeline, insuring no backward flow during structural failure. 

ISO Symbols for Different Valves (Image credits: “Pipe drafting and design”- Second edition)

  • Special Components:

Specific applications require specialized components for usage that come in a variety of forms to carry out multiple functions of the above-stated components, as shown below: