Here’s an example on how to draw a very simple P&ID Heat Exchanger symbol in Inkscape. Open Inkscape.
Click the Circle icon in the left toolbar, hold CTRL to draw a perfect circle in the middle of the screen like this:
When selected, you will have the object properties on the right. Select the “Fill and Stroke” tab and set the ‘Stroke style’ like Width for example to 1,000.
Set the fill color to grey for example:Set the stroke color to black:Now let’s draw some straight lines, click the line tool and draw a line like this:
You can adjust the lines a little bit using the Edit Paths button like this:
Color the stroke paint black and set the stroke style width when necessary. It also has a fill color, you should set this to a transparent color, but as an example we’ll do this later here. Press CTRL+SHIFT+D to open the Document Properties, and click the Resize to content button. This will resize the document to the outer shape of the object.
Save the symbol as a Plain SVG type (not as an Inkscape SVG).
Now open the SVG with a text editor like Notepad++. Note the circle and path that we have drawn. All fill or stroke colors that we wish to animate, we need to replace its value with currentColor. If we wish to hide a fill color, we need to set its fill-opacity to 0.
Now import, and done!