Piping Design Basics- Piping Isometric Drawings | Piping Isometrics (PDF) | What is Piping (2024)

What is Piping Isometric Drawing?

Once the three-dimensional (3D) model has been established in piping design software like PDS, PDMS, or SP3D, Piping Designers/Engineers need to convey that information to the yard for fabrication and the site for Construction. The transferred information must have to be sufficient for the fabricator with the vision of what is to be fabricated and how the piping should be connected with other elements, with exact dimensions and a complete build/Bill of materials (BOM). This is where Piping Isometric Drawings play a magnificent role. So piping isometrics are directly used for the following situations:

Types of Pipes | Classification of ...

Types of Pipes | Classification of Pipes (PDF)

• For Construction Services
• For marking up deviation during site modifications/ as-builting.
• For reference as Stress Analysis model built up and the final stress mark up for updating stress requirements.

Piping isometrics indirectly helps to calculate many parameters required during project execution like:

• Inch Meter can be estimated as the Length of pipe (in meters) x Size of pipe ( in inches)
• Inch Dia is calculated as the Size of the Pipe joint ( in inch) x No, of Joints
• Pipe Weight is calculated as π x diameter of the pipe (in m) x length (in m) x thickness (in mm) x density of pipe material. Density of CS = 7.85 g/cm3
• The volume of Water required for hydro testing is estimated as π x {Pipe ID (in meter)}² x Length of Pipe
• Insulation Area (in m²) can be found as [π(Pipe OD+ insulation thickness)] (all in meter) x Length of Pipe (in meter)

By definition, Isometric drawings are a pictorial representation that combines height-width-depth/length into a single view with 30 degrees from its horizontal plane as shown in the below-attached image.

Features of Piping Isometric Drawing

An isometric Drawing is a two-dimensional (2D) drawing that represents the 3D piping system. The important features are

• It is not drawn to the scale, but it is proportionate with the exact dimensions represented.
• Pipes are drawn with a single line irrespective of the line sizes, as well as the other configurations such as reducers, flanges, and valves.
• Pipes are shown in the same size. The actual sizes are notified in the Bill of Material, tagging, call-out, or notes.
• A piping isometric drawing provides all the required information like:
• Pipe Line Number
• Continuation isometric number
• Flow direction
• Piping dimensions
• Piping joint types, weld types
• Flange and valve types
• Equipment connection details
• Piping and Component descriptions with size, quantity, and material codes

Piping Isometric drawings are popular because of their simplicity yet efficiency to convey complex information. The following figure gives an example of how one Isometric drawing can represent three orthographic drawings. That is just a simple piping drawing. Imagine complex design and yet orthographic drawings are used for construction, that is really a headache.

In earlier days, Isometric drawings were hand-drawn. With the innovation and advancement of the digital age, isometrics are drawn by AutoCAD/Microstation software. In recent days, 3D models could automatically extract the Isometric with a single click of a mouse.

How to Read Piping Isometric Drawings?

1. First, imagine that the piping system is built in a box. This basic imagination is required for the piping to have an offset. So, it will help you to imagine, how the piping configuration will look as it travels.

2.Offsethappens when the pipe turns to any angle other than 90 degrees or to accommodate the odd nozzle’s location or tie-in point connections. A popular use is a 45-degree elbow and this is used extensively in piping design. In such cases, piping design may land on Northeast, Southeast, Northwest, or Southwest axes. In order to check the dimension of pipe length with offset, common Pythagoras’s theorem and Trigonometric rule can be used. A sample calculation is shown below as a reference-

Example of offset

If you happened to have difficulties reading the offset, try to draw the imaginary box. It could help you in having a better understanding of which axes the pipe travel and how the piping should look like. In the example given, take the flow from ‘x’, the pipe goes up; then up-northwest; then north. As you get along with Iso a lot, things will come naturally.

3. A North arrowis provided in all piping isometrics to inform the location of the piping system in the piping/ general arrangement drawing.

4. The piping isometrics also hascoordinates & elevation detailed information to verify the exact length of the pipe in horizontal and vertical axes respectively. The dimensions in Isometric drawings are measured from the pipe centreline and not from the outer diameter of the pipe (refer to the image attached below for reference).

With the advancement of technology, there could be minimum or even zero possibilities that the North arrow, coordinates, and elevation in Isometric would differ from the piping arrangement; hence the dimensions and MTO should match exactly if the source 3D model is the same.

However, It is always better to check and verify as there could be some issues with the modeling itself that may cause discrepancies in material and quantity. For example, if double piping is modeled by mistake, it will read the double quantity of material.

5. Isometric drawings also inform which piping should be constructed at the fabrication shop and which should be assembled at the construction/platform field itself. The complete piping system is separated into pieces that are transported to the site for erection. These small pipe pieces are termed piping spools. One sheet of Isometric drawing normally has few spools.

Every weld that is assembled between spools at the construction site is termed afield weld (FW). There is one more type of weld that is known asfield-fit weld (FFW). This FFW is defined by the designer if he/she could foresee that the spool might require some adjustment before the final fit-up, so at the location of FFW that has been marked, it will be given some pipe length tolerance (commonly 150-300mm). Usually, FFW will occur at the nozzle of equipment or tie-in locations.

The whole assembled piping will look like the following after it is assembled at the field.

Piping isometric drawing symbols

For reading and understanding a piping isometric drawing, one should learn the piping isometric drawing symbols thoroughly. Usually, all these piping and pipeline drawing symbols are constant and do not vary much from one organization to another. Knowing the piping drawing symbols will provide various information like:

• Type of Piping Joint: Piping and pipeline drawing symbols throw lights on the type of joint like Buttweld, socket weld, or Threaded.
• Type of Piping Components: Isometric drawing piping symbols serves as a ready reference for the type of fittings and components.
• Instrument items: Knowing the piping isometric symbols will help in recognizing the instrument and special piping items in the isometric.
• Equipment Connection: Equipment connected to a piping system is also understood with piping symbols.
• Knowing piping symbols for isometric drawing is useful in preparing MTO/BOM.

Commonly used piping isometric drawing symbols are shown below for reference purposes

Online Video Courses on Piping Isometrics

If you wish to explore more about piping isometrics, you can opt for the following online video course

Video Tutorial of Basics of Piping Isometric Drawing

The following video tutorial on the basics of piping isometric drawing will clarify some of your doubts.

Some more Resources for you…

Salient Points to check while reviewing Piping Isometric Drawings
Preparation of Piping Isometrics
Types of Piping Drawings

References

• Credit to other sources: svlele.com, wermac.org, pipingengineer.org, thepiping.com, spedweb.com, enggcyclopedia.com, rishabheng.com

FAQs

What are the standards for isometric drawings? ›

There are three main rules to isometric drawing:
• horizontal edges are drawn at 30 degrees.
• vertical edges are drawn as vertical lines.
• parallel edges appear as parallel lines.

What is the difference between P&ID and isometric drawing? ›

P&IDs and isometric drawings are complementary tools used in the engineering design and construction of industrial plants and systems. P&IDs focus on the functional relationships and process flow, while isometric drawings provide a detailed representation of the physical layout and dimensions of the components.

What are the angles of isometric piping? ›

Pipe drawings are presented in an Isometric view (ISO.) This view is drawn in order to show a pictorial view of what is needed. Commonly these are drawn at a 30 degree angle from the horizontal plane.

What are the three lines used in isometric drawing? ›

Isometric drawings include three axes: one vertical axis and two horizontal axes that are drawn at 30 degree angles from their true position. The application of this type of drawing extends to many fields, such as engineering, mechanics, physics, and architecture.

How do you identify isometric views? ›

In an isometric drawing, the object appears as if it is being viewed from above from one corner, with the axes set out from this corner point. Isometric drawings begin with one vertical line along which two points are defined. Any lines set out from these points should be constructed at an angle of 30 degrees.

What are the rules for isometric design? ›

In isometric designs, as the axes angles are equal, the parallel lines never converge. As we explained before, the 120° rule is the soul of isometric designs. This technique works by always respecting this rule: vertical lines remain vertical while horizontal lines slope at 30°, so X, Y, and Z together add up to 120°.

What are the rules for isometric dimensioning? ›

Aligned dimensions should be parallel to the isometric axes or the feature being dimensioned. The dimension lines should be placed outside the object, with ample room for the dimension values and symbols. For features not aligned with the isometric axes, such as holes, chamfers, or fillets, leader lines should be used.

What does ISO mean in isometric drawing? ›

One way is to use an isometric view, which is derived from the Greek words iso, meaning equal, and metric, meaning measurement. When using an isometric view, you line up the drawing along three axes that are separated by 120-degree angles from each other.

What are the two types of isometric drawing? ›

There are two common techniques generally used for isometric drawings. These are the box and the centerline layout techniques, but the box technique is the most common construction technique. The box technique is also known as the coordinate technique.

What is isometric in piping? ›

An isometric drawing provides a three-dimensional layout of the equipment and piping. Usually, piping isometrics are drawn on preprinted paper, with lines of equilateral triangles form of 60°. Isometric drawings are particularly important during the construction phase of a project.

Why do plumbers use isometric drawings? ›

An isometric sketch is a two dimensional drawing that provides plumbers with the most information about piping layout. Being able to create accurate isometric drawings is a difficult, yet valuable tool for any plumbing professional.

How many degrees is isometric? ›

Isometric drawing is a particular drawing style where the angle between the x, y, and z axes are all 120°, and there is no perspective. An isometric drawing is a pictorial representation of an object in which all three dimensions are drawn at full scale.

What is the perfect isometric angle? ›

An isometric view of an object can be obtained by choosing the viewing direction such that the angles between the projections of the x, y, and z axes are all the same, or 120°.

What is another name for an isometric drawing? ›

isometric drawing, also called isometric projection, method of graphic representation of three-dimensional objects, used by engineers, technical illustrators, and, occasionally, architects.

What is line number in isometric drawing? ›

The Line Number – The Line Number becomes the drawing number for the isometric. The line number comes from the P&ID and the Line List. Only part of the line number is included as the “Drawing Number” for the isometric.

What is isometric analysis in plumbing? ›

An isometric sketch is a two dimensional drawing that provides plumbers with the most information about piping layout. Being able to create accurate isometric drawings is a difficult, yet valuable tool for any plumbing professional.

How do you read a spool drawing? ›

How to Read a Pipe Spool Drawing. Pipe spool drawings are oriented on the grid relative to the north arrow shown on drawing plans. The pipe line number (ex. 2”-WPR-8547-01) indicates the fluid service, piping class and material, insulation details, and is usually drawn in a single isometric right.

References

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