Free AutoCAD pipe isometric symbols (DWG): valves, fittings, joints, supports

About the standard

The symbols follow ISO 6412-2, technical drawings: simplified representation of pipes, part 2, isometric projection. The valve and reducer shapes, the hanger, the crossing with the pipe behind broken, the weld and the weld made on site, the general connection and the flanges take the figures of the standard; the three isometric axes and the way the width of a symbol follows them come from the same part.

The blocks are our own drawings after the figures of the standard, not copies, and the library is not certified. Forms the standard does not show are common practice. Check them against the legend of your project or your customer.

Frequently asked questions

Which valves are included?

Gate, globe, ball, check, butterfly, needle and plug valves, gate valves with handwheel and motor actuator, control valves with diaphragm, piston and solenoid actuators, spring loaded safety valves, and angle and three-way valves. All except the angle and three-way valves come along X and vertical. For the process diagram forms see the P&ID library.

Why is the reducer a trapezoid here and a triangle in the P&ID library?

ISO 6412-2 draws the reducer as a trapezoid in isometric views, while flow diagrams use a triangle. Each library follows the convention of its drawing type, so use this one in isometrics and the P&ID library in flow diagrams.

Can I use the symbols in commercial projects?

Yes. They are free to use and modify in your own projects, including commercial ones. They are provided as is, without warranty.

Do I need to draw the Y axis separately?

No. The Y axis is the mirror image of the X axis. Insert the _X block and mirror it about the vertical axis. Vertical pipes have their own blocks because the symbol width then follows the 30 degree direction.

Can I change a symbol or add attributes?

Yes. Open the DWG, edit a block with BEDIT to change it or add attributes, and save. To update drawings that already contain the block, run ATTSYNC or replace the block. Make a backup first: attribute values can be lost if ATTSYNC is used carelessly.

Where do I find a ready-made set of these symbols for AutoCAD?

AutoCAD itself ships only a small set of sample blocks, so a full symbol set has to come from a library. Download the ZIP on this page and open the DWG: every symbol is a block. Insert one with INSERT (Blocks palette, Libraries tab, then pick the DWG) or drag it from DesignCenter (ADCENTER). You can also download a single symbol on its own.