How to remove mm from a pipe tag in Revit, and fix pipe size rounding

A Revit pipe size tag that reads 25 mm⌀ is correct and unwanted at the same time. Many standards write the number alone and put the unit in a note. The unit text comes from a few places, and the right fix depends on whether you want to change one tag or the whole project.

This guide gives three fixes, from the widest to the narrowest, then rounding. RayCAD is a Revit plugin for MEPF tagging and annotation, and where a step slows a real project down you will see what RayCAD does about it.

Where does the mm come from?

Three settings write the size you see on a pipe tag.

• Project Units. The unit and the unit symbol for Pipe Size, which gives the mm.
• Mechanical Settings. The pipe size prefix and suffix, which give the diameter symbol.
• The tag label. A tag can override the project settings and add its own prefix or suffix.

How do you remove mm from every pipe tag in the project?

1. Go to the Manage tab and choose Project Units.
2. In the Discipline list, choose Piping.
3. Click the format button for Pipe Size.
4. Set the Unit symbol to None.
5. Click OK twice.

This changes every place the project shows Pipe Size, so schedules and tags change together. Check a schedule before you commit to it.

How do you remove the diameter symbol?

1. Go to Manage, then MEP Settings, then Mechanical Settings.
2. Open Pipe Settings.
3. Clear the Pipe Size Prefix and the Pipe Size Suffix, or set them to the characters you want.
4. Click OK.

The diameter symbol is part of the size string, so this applies to every place the project shows a pipe size.

How do you remove mm from one tag only?

Use this when the schedule should keep the unit and only the tag should lose it.

1. Select a pipe tag in the model and click Edit Family.
2. Save a copy under a new name.
3. Select the label and click Edit Label.
4. The Size value follows the project settings. To format it for this tag only, remove Size from the label and add Diameter instead. You can add a prefix or a suffix here too.
5. Select Diameter and click the format button next to it.
6. Clear Use project settings.
7. Set the Unit symbol to None. Set the Units and Rounding too if they need to differ.
8. Click OK, then Load into Project.
9. Select the pipe tags and pick the new type in the Type Selector.

How do you fix pipe size rounding in a tag?

1. In the same Format dialog, clear Use project settings.
2. Open the Rounding menu. Choose a decimal place, or choose Custom and enter a Rounding increment.
3. Click OK.

Three things to know.

• It rounds to the nearest increment. A value above the halfway mark rounds up. A tag that always has to round down needs a formula in the label, which Revit supports.
• Nominal sizes convert. Change a project from metric to inches and Revit converts the pipe segment's nominal diameter, so a DN80 pipe can read 3 1/4 in rather than 3 in. Set the nominal sizes on the pipe segment to the values you want shown.
• Diameter may not be the parameter you want. One common fix reads the Inside Diameter in a custom tag, with the units and the rounding set on that parameter. The tag then shows an inch size for a metric pipe without changing Project Units.
• Metric names and inch names. A DN80 pipe has no exact inch size, so a tag that shows 3 in needs a lookup. Offices use a calculated value in the tag label, or a project parameter that a Dynamo script fills from a table, and tag that parameter.

What goes wrong with pipe size formats?

What else breaks when you format pipe tags by hand?

The format is a standard, and a standard that lives in three dialogs and a handful of families drifts. One project keeps the symbol, the next drops it, and a drafter fixes tags one by one.

RayCAD handles the placement side. It tags pipes in the views you select, with the family you chose, and lists anything it could not place. It reads the real height of a tag with more than one row before placing it. A click-saver plugin makes each manual click faster, and you still place every tag. With RayCAD you review the result. See pipe tagging, or the guide to tagging pipes for the full steps in Revit.

RayCAD runs on Revit 2021 to 2027. Try it free for 15 days, or email us for a demo. Other pipe tag settings are in how to tag pipes.