Satish Lele
satish.lele@gmail.com

This is a program for Skill Development and Bridging the Gap between Manual and Computer work. I offer Training of Basic Fundamentals and How to Use my Software to a batch of 5 to 10 people in your office. This can speed up Drawing work using my own Software, compared to conventional methods. This is a package, which can run on any CAD program and is very simple and easy to use. The package is given FREE of CHARGE to the company.

Why Isometric Drawings are required?: Generally in the development of a project, a conceptual 2D drawing is first created. In this all pipelines are drawn at zero z co-ordinate. This is then converted into a 3D scale model, to check interference of pipe lines. 2D General Arrangement (GA) drawings are used for fabrication on site. A GA drawing is generally on A0 or A1 size paper and contains a lot of lines, and may not be easy to understand pipe routine. A0 or A1 size drawing is to big to handle. A pipe fabricator can understand GA drawing better only with the help of 3D scale model. But 3D scale model can not be put on a paper, and 3D scale model does not indicate dimensions. To aid pipe fabricator on site, isometric drawings are prepared. An isometric drawing is generally on a A3 size paper. A pipe fabricator can read it and understand pipe routine easily. Also pipe fabricator can pick up material required for fabrication of pipe line from stores, with the help of Bill of Material given in isometric drawing.

    ISO vs ORTHOGRAPHIC
  • Simplicity (Only one pipe line is drawn in one A3 size paper).

  • In a orthographic view it is not a problem if the pipe runs in one plane, but when a pipe runs in two or three planes (north to south, then down and then to the west, etc.) an orthographic view can be unclear.

  • More number of drawings needed in orthographic views than ISO to represent the same piping system.

  • Sectional views are required for clarity of pipe routing

Unlike orthographic drawings, piping isometric drawings allow the pipe line to be drawn in a manner by which the length, width and depth are shown in a single view. Isometrics are usually drawn from information found on a plan and sectional elevation views. The symbols that represent fittings, Valves and flanges are modified to adapt to the isometric grid.
The Iso, as isometric is commonly referred, is oriented on the grid relative to the north arrow found on plan drawings. Because isos are not drawn to scale, accurate dimensions are required to specify exact lengths of piping runs.
Pipe lengths are determined through calculations using coordinates and elevations. Vertical lengths of pipe are calculated using center line elevations of pipe lines, while horizontal lengths are calculated using north-south and east-west coordinates.
Piping isometrics are generally produced from orthographic drawings and are important pieces of information to engineers. In very complex or large piping systems, piping isometrics are essential to the design and manufacturing phases of a project.
Piping isometrics are often used by designers prior to a stress analysis and are also used by draftsmen to produce shop fabrication spool drawings. Isometrics are the most important drawings for installation contractors during the field portion of the project.

    What is an Isometric Drawing?
  • A piping isometric drawing is a 2D drawing in which piping is represented like a 3D drawing. In CAD drawing, only x and y co-ordinates are used to draw entire drawing.

  • Isometric Layout: Isometric lines can be in vertical direction and two other directions at 30 from horizontal. All directions of the pipe may match the three isometric axis lines.

  • It is popular within the process piping industry because it can be drawn and read with ease and shows the piping in a realistic view.

  • It is used along with plans and sectional elevations but typically it is used to supplement the plan drawings.

  • Isometrics are used as fabrication & shop drawings for fabrication of run of a pipe.

  • Isometrics also provide a drafter with the ability to calculate angular offsets in the pipe run.


Isometrics are drawn on b-size paper (11 x 17) in imperial units and on A3 size paper (297 mm x 210 mm) in metric units. Drawing number and revision number is indicated in box on top left corner. It is also shown in title box. The table at bottom indicates the numbers of relevant P&ID drawing and General Arrangement (GA) drawing. The bill of material appears in top right corner. A table is also provided for indicating revisions made. The rectangular area on left is reserved for Isometric drawing.

The line number is shown in space in right column. General notes appear below line number.

Every company has its own template, showing company's name, address, logo etc.,

Arrow showing north direction is shown in top left corner. A north arrow shows North direction with respect to North direction in GA drawing. The direction orientation depends on North Direction of Plan drawing. This helps in reading the Plan and Isometric drawings together.

Preparing a sketch to draft isometric drawing: View the model in the direction of north of model and start sketching pipe lines.


The line may start from nozzle of an equipment, such as a vessel or a pump. Indicate nozzle number and equipment tag near nozzle. In some cases, it may originate from some other line. Indicate line number of that pipe line, its center line elevation, and isometric drawing number of that pipe line.

Branches of the pipe run or continuations are placed on other drawings, typically shown as short portion of dashed line on main pipe run. Dashed lines show pipe continuation. Reference drawing information is given for continuation.

One run of pipe is drawn in one isometric drawing. If one pipe run can not be accommodated in one drawing, it is continued in next drawing. Two identical pipe lines (Two similar suction lines of two pumps) are generally drawn in one isometric drawing.

Isometrics are rarely drawn to scale. A longer pipe, (on left), may be shown shorter, if it does not have any fittings in it. However, a small length pipe may be shown with longer length, to show all the fittings in that portion of line. However, pipe lengths should be shown accurately. In this case, it is limited by space, so sometimes proportion may be sacrificed but it is important that the written dimensions are accurate. If the pipe is vertical, the lettering should be written vertically and at 30 obliquing angle. Text in dimension in vertical lines, should always be parallel with dimension line.

Direction & Location: Location and direction helps to orient the isometric drawing properly. Structural reference points that provide location of column along the grid can be shown on isometric. Dimensions must always be given to points of reference, such as structures, center line of existing equipment etc. Co-ordinates should also be shown on the isometric drawing.

When orienting fittings or valves it is important to draw the fittings or valves, so that they are inclined to the last direction change or branch in the pipe. Fittings or valves are drawn the same shape as they appear on the plan & elevation drawings but they are drawn at an isometric angle.

Looking at the orientation of model, go on sketching the line from one end to other. To get the length of each cut pipe, get distance between two ends of 3D pipe. To get the length of pipe from center line of fitting to center line of anathor fitting get distance between insertion points of two fittings.
If you are sketching with the help of plan drawings, use the difference in elevations of two adjacent lines as length of the vertical line. For horizontal lines, use the distance between two pipes, to get length of the pipe. Mark length of each pipeline on each line in the sketch of isometric drawing.

Mark elbows on the drawing. Show location of valves, with type of flange. The location of the valve is shown by dimension of the center of valve. Show direction of flow, with pipe NB. If a horizontal pipe line has a slope, indicate it on that pipe line.


Use branching table to select end connection of Elbows. Normally, Elbows with NB less than 50 are socket weld or secrewed and Elbows with NB greater than 40 have butt weld ends. Elbows can be drawn in a couple of ways.


Add any branch to the drawing, like, Tee, Reducing Tee, Weldolet, Socolet, elbolet etc.


If the line is reduced in its path, add a reducer. Reducer can be concentric, eccentric with flat top or eccentric with flat bottom. Concentric reducer is generally used in a vertical line or line where flow pattern should not get disturbed, as in case of line of Control Valve. Eccentric reducer with flat top is generally used in suction line of a pump. Eccentric reducer with flat bottom is generally used in horizontal lines. It maintains the bottom level of pipe line after reduction in size. Swage is used to connect a pipe with butt weld end to a pipe with a socket weld end.



If there is any Coupling, Union, Hose or trap in a pipe line, draw it on line.

Spec change is generally implemented at isolating valve or at flange of different pressure rating. The spec of valve depends on Fluid in this and next pipe line or pressure ratings of this and next pipe line. Demarcation is shown between new and existing pipe spec and reference line number, drawing number and center line elevation is indicated for new drawing. Usually a note indicates the name or specification of the branch line.

Offsets: To indicate an offset, hatches on isometric drawings are applied, to indicate that a pipe runs at a certain angle and in which direction the pipe runs. It is done with a fitting (typically a 45 elbow).

Horizontal Offset: If a line turns at 30 to 45 in horizontal plane, you draw a pipe with a 45 elbow. But it would look like a vertical line. To avoid confusion, the offset is drawn 22 horizontal offset to give the illusion of the angle.

Vertical Offset: If a line turns at 30 to 45 in vertical plane, you draw a pipe with a 45 elbow. In this case, too, to avoid confusion, the offset is drawn 22 vertical offset to give the illusion of the angle.

Dimensioning: Dimensions should preferably appear above if the pipe line is horizontal and on left hand side, if the pipe line is vertical. Best way to dimension a pipe line is between its center line at the intersection points. Try to keep all dimensions outside the piping view when possible. Dimensions should always be shown between points in the same plane. One of the extension lines of the dimension should be a center line of the run of pipe.


    When you create an isometric sketch from a model, use of the following features will make the best use of the system:
  1. Single source for all piping documents: The piping model provides a single central source from which all project personnel can extract and manipulate data. In effect, this is an official master document that is always up to current revision level. Drawings for any purpose are based upon the models geometry.

  2. Three-dimensional geometry: The piping model is a true three-dimensional representation of the piping system. The actual coordinates of every point on the design are available for use in dimensioning individual drawings, checking clearance between modeled objects, making special reports, extracting geometry for pipe stress analysis, and removing hidden lines.

  3. Standard design technique: The model is conducive to proper drafting and design techniques because it promotes a specific method of model creation. In the case of a 3D piping model, certain steps must be followed, thereby promoting a standard technique of model design.

  4. Reduced drafting repetition: Some of the commands used for plant design eliminate many time-consuming steps that arise in drafting an isometric. These include creating fitting symbols, calculating dimensions, dimensioning skew pipes, and extracting a bill of materials.

  5. External software interface: The database of a piping model can be output in a neutral format that is used to interface to external programs. An example of an external program is one for stress analysis.

  6. Project linkage: Data from a piping model can be linked with data from related models in a common project. This allows reporting across adjacent models and data consistency checks between pipelines in different types of drawings such as arrangements and P&IDs.

To create an isometric drawing, first create a true three-dimensional piping model. Although you can use explicit modeling as a conventional drafting system, it is recommended that you use it as an intelligent 3D modeling aid.
Making an isometric involves the following steps:
1. Establishing model defaults: The first step is to establish default parameters for the model. The values set here have a great effect on the appearance of both the model and the isometric and the ease with which they are made. The following is a list of some of the more important items and the commands used to set their values:
Modeling units.
Drawing appearance.
View orientation.
Construction plane origin.
Text width and font.
Component insertion parameters.
Dimensioning parameters.
2. Inserting non-piping items: As a part of your piping model, you may want to insert items at the origin and destinations of pipe lines such as nozzles on vessels or heat exchangers, and other pieces of major equipment. Before inserting the piping, fit the model in the active view window. End points of the piping main line are the likely locations. Then position these points using the ZOOM VIEW or DYNAMIC VIEW commands. Maintain the final orientation with SET VIEW.
3. Inserting piping items: Menu options provide the required data for automatic component selection. Begin routing at the upstream terminus of the main line and route from vertex to vertex in the flow direction until the line is terminated. Going from beginning to end, insert all fittings by inserting these through menu. After completing the main line, route branches off the main line in the same way.
4. Freezing model geometry: After checking the piping layout and the fitting locations, freeze the model geometry.
5. Setting up the isometric: Create a sketch on paper, looking at the model. Measure dimensions on model and note down in sketch. Using the isometric program, create isometric.
6. Dimensioning the isometric: Using different dimension options, write all dimensions.
7. Editing the isometric: Changing the layer scheme, rotating item number labels, translating weld numbers, unblanking pipe segments, and editing dimensions.
8. Inserting a bill of materials: Using automatic bill of material option you can create a table. The values in the table need to be adopted as per sketch. Lengths of pipe, size of reducers and number and lengths of bolts need to be changed using options in BOM menu.
9. Plotting the drawing: You can plot the isometric using standard plot command.


PROGRAM for PIPING ISOMETRIC DRAWINGS

Most CAD packages are prepared in such a manner that these can be easily customized. 4 Programs of OpenPipe are such customized programs. The Iso program is totally based on LISP programs and there are only 4 small symbols or blocks to be inserted as in other programs, due to which there is a lot of saving of Disk space as well as the drawing also has very small size. Since the program is written in LISP, you can even modify it further as per your choice. The different piping entities are arranged on layers 1 to 6 (which is compatible with Microstation). Special Dialogue Boxes are created to make the program more user friendly. The drawing can be converted to Microstation DGN format.
PIPING ISOMETRICS PROGRAM can run on Personal Computers, on a Pentium system with 32 MB RAM. It supports screen, pull-downs and icon menus, as well as, dialogue boxes. The program is specifically written for any CAD program. It can not run on Autocad LT.
Separate Menus are created for Metric and Foot-Inch Units units. The pull-down menu has all the options of isometric drawings. These can be added to main menu using menuload command.

To try the program, send a request for trial package. The package is a zip file, iso_demo.zip. There is no setup.exe file as in other packages. Download and unzip iso_demo.zip and copy files in a folder. While running AutoCAD program, click on tools ->Options (or Preferences) -> Files -> + of Support File Search Path -> Add -> Browse -> Select the folder. The iso_demo.zip file contains iso*.lsp, iso.dcl and iso.slb, iso.dwg (Border drawing).
At command prompt run menuload command (Type menuload and press enter). A dialog box will open showing acad as current menu in menugroup tab. Click on browse near file name text box. Change folder to the folder where all program files are located and click on arrow of Files of Type box. Select Menu Template (*.mnu) and select iso_mm or iso_inch as menu to be loaded. Click on load button. Click yes to continue. Click on close.
iso menu will be loaded, and start using pull down menu. The pull-down menu, iso, has all the iso drawing options. The other menu items are not modified.

ASME package Bought so far by 24 parties
ASME, Triclover and Victaulic package Bought so far by 11 parties
Professional Charges for CAD Ad-on Software for
Piping Isometrics for ASME Fittings US$ 50
Piping Isometrics for ASME + Tri-Clover + Victaulic Fittings US$ 70
Sourse programs for all the above are also available for sale. Price will be double the indicated price.
To Buy the package for details.

    Check List for Isometric Drawings

  1. Check whether P&ID number and GA drawing number is correct.

  2. Check Line Number in Title Block.

  3. Check whether direction of flow and other details are as per P&ID.

  4. Check details of vents and drains, dimensions of vent from high point / drain from BOP or low point.

  5. Field weld should be provided for every 12 meters of pipe line.

  6. If some exact dimension is not known, like FOF of pump or length of valve, provide a field fit weld weld. Add 150 mm to the length of pipe line in BOM table and indicate (+150) below tag of dimension.

  7. If straight length of pipe exceeds 4 meters, provide a field fit weld and indicate (+150) below tag of dimension.

  8. Check sizes of all fittings as per standard. Check proper symbols for gate, globe and check valves.

  9. Provide tag numbers to every cut pipe and all fittings. Different types of fittings should have different numbers. These tag numbers should match with those in BOM table. Lengths of pipes should be exact cut lengths.

  10. Spool numbers to be given to all spools. The number is same as drawing number with A,B,C,D etc. added to it.

  11. For instruments, show piping scope and instrument scope. For FE, show tappings in proper directions, size, length and detail. Show spec change, if any. Size for TG should be 200 mm and for PI should be 40 mm.

  12. If line is continuing in other drawing, (C.O.D.), indicate iso number of that pipe line, or write field run for small pipe lines.

  13. Reference elevation should be indicated at least at one point.

  14. Proper symbol for butt weld, socket weld and screwed connection.

  15. If an iso has more than one line, the number of main line should be written in title block, and numbers of other lines under This Drawing Includes:

  16. Match line for split drawings and dotted lines for pipe lines from other drawings.

  17. Hatching for angular details, horizontal hatch for horizontal turn and vertical hatch for verticle turn. Indicate angle of turn. Dimensions should be provided for three sides. Cl El for three lines.

  18. Special fittings should be marked properly with a tag number and tag should reflect in BOM table.

  19. Tag number of valve should be written below the valve and should reflect in BOM table.

  20. Check fittings as per spec and branching table.

  21. Indicate sign of gasket for valves in dimension.

  22. Indicate nozzle number for equipments.

  23. If mating flange of a pump is supplied by pump vendor, indicate it on drawing.

  24. If an end of pipe line is open, indicate it on drawing.

  25. Show spec break, if any.

  26. Show clould for hold.

  27. Show insulation for insulated pipe lines.

  28. Show special specs like rubber lined or SS, 3D bends or part insulation.

  29. For reducing tee and reducers, indicate size and type as per spec and branching table.

  30. For olets, indicate NB of branch.

  31. Check obliquing angle for all texts and dimensions.

  32. Provide weld numbers in direction of flow.

  33. In BOM table, entities should be in order. Pipes, Valves, Fittings, Gaskets and Stud bolts. A line should be left blank between these groups.

  34. Check cross-referenced drawings and check details in title block.

To see drawings created by this program Click
Trial programs are full scale programs without option to insert Valves.
to Request Trial Program.

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