Welded fabrication cost: measured in weld length, not in pieces

Every other trade here has a natural per-piece cycle. Welded fabrication does not: two assemblies of identical weight can differ several-fold in labor if one has far more weld on it.

So the unit of measure is **weld length**, and nearly every cost line follows it.

Where the weld length comes from

1. The weld schedule on the fabrication drawing — most reliable, and if you have it, always use it.
2. Measured on a finished assembly — use when the drawing does not schedule welds.
3. Estimated as joint count times average length — last resort, and record that it is an estimate.

The ten categories

1. Material — the steel

Plate, section and tube, taken as **weight issued to the job**, not the weight of the finished assembly. The drop from cutting to size does not disappear from the invoice.

2. Material — welding consumables

The line that belongs to this trade alone, and it scales with weld length and joint cross-section, not with steel weight:

What the system cannot know is **consumption**, which depends on your flow setting, joint type and shop habits. That is a number you measure: total consumed over a period divided by total weld length in the same period gives a rate per unit length, which you then apply to this job. Not exact for every joint type, but it is measured rather than guessed.

3. Machine time

Stick, MIG, TIG, spot, laser and robot welding all carry different rates, and the spread is wide.

The trade-specific trap: **machine time is not the same as the welder's shift**. Arc-on time is a fraction of the day — the rest is fit-up, repositioning, slag removal and inspection. Cost the full shift as machine time and your hourly rate is diluted into something that cannot be compared with anyone.

Use arc-on time if you can measure it, and put the rest in labor. If you cannot separate them, combine and say so.

4. Labor — four blocks that do not substitute

• Cutting and edge preparation.
• Fit-up and tacking — often longer than the welding itself, and it determines the accuracy of everything after.
• Welding — the only block that tracks weld length directly.
• Post-weld cleaning — slag, spatter, grinding.

5. Tooling

Cutting discs, grinding wheels, wire brushes, drills, divided by parts between changes. Fixtures built for one assembly are non-recurring — see the machinery guide, the arithmetic is identical.

6. Scrap

Fabrications are rarely scrapped outright; they are cut apart and rewelded. So most of the loss in this trade lands in rework rather than scrap. If scrap really is zero, enter zero rather than leaving it blank.

7. Rework — the heaviest line here

Two causes that must not share a line, because they lead to opposite fixes:

• Weld defects — gouge out, clean, reweld, re-inspect. Costs consumables as well as labor.
• Dimensional error from heat distortion — straighten, or cut apart and reweld in position. This has its own guide.

8. Outside processing

Blasting, hot dip galvanizing, painting, and non-destructive testing if you subcontract it. Include transport both ways — fabrications are heavy and the freight is not small.

9. Packing and freight

Heavy and awkward: the truck runs out of **payload** before it runs out of space, the opposite of furniture. Cost a load and divide by the pieces on it, and record the distance assumed.

10. Shop overhead

Power is unusually large in this trade. If it is already inside the welding machine rate, do not charge it again here — that is the most common double count in welded fabrication.

Three checks

1. Machine time is arc-on time, not shift length — otherwise the rate cannot be compared with anyone.
2. Consumables and gas are entered rather than left blank because they are bought in bulk.
3. Power appears exactly once: in the machine rate or in overhead, not both.