Structural Steel Fabrication Drawings: What They Should Contain

Fabrication drawings exist for the shop, not for the design review meeting. If a sheet cannot answer “what do I cut, drill, weld and mark?”, it is not a fabrication drawing yet, even if it looks complete at arm’s length.

This article lists the information that should appear on piece drawings and related shop documents. It complements shop drawings versus approval drawings and the bill of materials guide.

Keep approval-level story-of-the-frame information on the GA set. Repeat only what the fitter needs to avoid flipping between ten PDFs at the saw.

The piece drawing as a work order

Treat each piece drawing as a work order attached to a shipping mark. It should identify the piece, the material, the finished length, operations (cut, drill, cope, weld, camber) and the destination (paint, galvanize, ship). If your shop runs from CNC files, the PDF still has to match those files at the same revision.

Geometry the shop cannot infer

• Overall cutting length and any camber or sweep
• Hole locations from a stated origin (not “see typical” when the typical does not fit)
• Copes, blocks, mitres and bevels with enough dimensions to program or mark out
• Stiffeners, seats, plates and their weld all-around conditions
• Left/right or mirrored pieces called out explicitly

Welds, bolts and assembled pieces

Shop-welded assemblies need a drawing that shows the assembly, not only the loose parts. Bolt holes that will be used in the shop should be distinguishable from field holes. If a piece is too large for the shop or the truck, the splice on the fabrication drawing must match the erection drawing.

Notes that belong — and notes that do not

Finish, inspection and handling notes belong if they change shop operations. Reprinting the full design criteria on every beam sheet does not. Put criteria on the general notes. Put piece facts on the piece.

Linking fabrication drawings to the rest of the set

A piece drawing that cannot be found from the plan mark is a lost piece. Cross-reference plans, assembly drawings and the BOM. Erection orientation belongs on the erection drawing, with a reminder on the piece if the piece can be shipped upside down.

A practical workflow

1. Freeze approval comments that affect geometry.
2. Generate or draw piece drawings from the same source as the GA.
3. Add shop operations, finish and marks.
4. Reconcile BOM and CNC data.
5. Issue a shop transmittal separate from the approval transmittal.

Engineering tips

• Use one origin per piece for dimensions so the CNC programmer is not resolving conflicting chains.
• Call mirrored pieces out in the mark if the shop has ever flipped one.
• If a weld is field, say FIELD. If it is shop, say SHOP. Implied defaults get forgotten on night shift.

Common mistakes

Sending GA plans to the drill line

The operator will invent hole locations. That is not fabrication information; it is a guess.

Changing a hole on the CNC file only

The next person to plot the PDF will undo your change. Update both.

Omitting finish because “paint is later”

Galvanizing hole sizes, vent holes and weld sequencing are fabrication-time decisions.

Checklist

• Every plan mark has a piece or assembly drawing
• Cutting length and section/grade shown
• Holes dimensioned from a single origin
• Shop vs field welds and bolts flagged
• Finish and no-paint zones shown
• Mark and orientation match erection drawings
• BOM quantities match
• CNC revision matches PDF revision

Frequently asked questions

Are fabrication drawings the same as shop drawings?

In many offices, yes. Some contracts use “shop drawings” for the approval set too. Use the title block to say FABRICATION or SHOP PIECE if there is any doubt.

Do I need a drawing for every clip?

Not always. Standard clips can live on a schedule if the shop agrees. Non-standard clips need a view.

What scale should piece drawings use?

Whatever remains readable at the plot size the shop uses. Over-scaled pretty pictures that crop dimensions are worse than a dense but complete sheet.

Who checks fabrication drawings?

A shop checker who knows the equipment. An engineer reviewing approval drawings is not a substitute for that check.

Where this leaves the work

If the fitter still needs the design drawing open, the fabrication drawing is incomplete. Finish the piece facts, then stop adding review decoration.

Next, read erection drawings so the marks you just painted on the steel still mean something in the field.