How to tag MEP fabrication parts in Revit, with item numbers

Fabrication models drive the shop drawings that people cut metal from. Every fitting and every length needs an identity on the sheet. Revit models the parts well and tags them poorly, because it ships no fabrication tags.

This guide covers the job in order. You build a tag, read the parameters you need, place the tags, and deal with the values a tag cannot reach. RayCAD is a Revit plugin that automates MEPF tagging. Where a step eats time, a note shows what RayCAD does instead.

What is different about fabrication parts?

A native duct is a Revit duct. A fabrication part is built from a fabrication service and a part catalogue, and it sits in its own categories, such as MEP Fabrication Ductwork, MEP Fabrication Pipework, and MEP Fabrication Hangers. A tag for a native duct does not apply to any of them.

Fabrication parts carry identity properties that native ducts do not, including an Item Number. Autodesk describes the item number as most commonly used to identify fittings for manufacture or location on site.

How do you create a fabrication tag?

Revit exposes the parameters and ships no tag that reads them. You build one.

1. Go to File, New, Annotation Symbol, and choose the Generic Tag template.
2. Click Family Category and Parameters.
3. Scroll to the fabrication tag category you need, such as MEP Fabrication Ductwork Tags, and click OK.
4. Use Label to add a label to the sheet, and in the dialog add the parameter, such as Item Number.
5. Save the family, then load it into the project with Load into Project.
6. Check Annotate, Tag, Loaded Tags and Symbols, and confirm the tag appears next to the fabrication tag category.

Repeat the steps for each fabrication category, because a tag works for one category only.

How do you place fabrication tags?

Once the family is loaded, tagging works the same way as for native elements.

1. Go to Annotate, Tag, Tag by Category, or type TG, and click the part.
2. For many parts, go to Annotate, Tag, Tag All, choose the view scope, and select the fabrication tag category.

Tag All skips parts that already have a tag, and it runs on the active view only.

Which values can a tag read?

A tag reads a parameter if Revit exposes it to tags. Most identity and size values are available. Some are not.

• Item Number. Available as a label parameter in the generic tag approach above.
• Size and length. Normally available.
• Bend extensions and similar fitting values. A 2019 forum thread reports that some of these could not be tagged, and Autodesk Support called it a limitation. The poster's workaround was a shared parameter filled in by hand, which invites input errors. Check your version on a test fitting before you rely on it.

When a value is not available, you have three choices: leave it off the tag, carry it in a shared parameter that something else fills, or use a third-party tool.

How do you tag hangers and spools?

Hangers and spools sit in their own categories, so each needs its own tag family set to that category, and each has its own placement problems. Hangers repeat at a spacing along a run, and a tag on every one fills the sheet. Spools are groupings, and a tag on a spool names the group.

RayCAD does not tag fabrication pipework, hangers, or spools today. You tag them with Revit as above. RayCAD tags the fabrication ductwork on the same sheet.

What goes wrong with fabrication tags?

What else breaks when you tag fabrication parts by hand?

Revisions. Fabrication models change often, and a revised route leaves tags in the old places. RayCAD's Retag tool replaces the tags on the parts you select, so a revised route does not mean tagging the view again by hand. Review Tags lists anything RayCAD could not place.

Missing tags. One fitting without a tag becomes a question in the shop. RayCAD lists every part it could not place, with the reason. See how that reduces RFIs.

How does RayCAD tag fabrication ductwork end to end?

You pick the views. RayCAD finds the fabrication ducts, fittings, and accessories, decides where each tag goes, places it, and lists anything it could not place. You review the result. A click-saving plugin makes each click quicker. The deciding and the placing are still yours.

A fabrication part is named by its service and its CID type, not by a Revit family. In the element setup you map each service and CID type to an element kind and pick the tag family for it. RayCAD lists the identities it finds in your project. Revit does not say whether a fabrication part is a fitting or an accessory, so for parts that could be either, you choose the group. In section views, RayCAD tags fabrication ducts and elbows along with the native elements in the same view.

What should you check before you issue the shop drawing?

• Every fitting and every straight has an item number or the tag your standard requires.
• Values on tags match the cut list.
• No tag covers a part or another tag.
• Hangers and spools are tagged as your standard requires.

Try RayCAD on your fabrication models in Revit 2021 to 2027, or email us for a demo. The fabrication tagging page lists the parts RayCAD covers. Contractors detailing for the shop can read RayCAD for MEP contractors.