Shop weld vs field weld: how to count each on an ISO
A shop weld is made in the fab shop. A field weld is made on site, during erection. They are made by different crews under different conditions, so they are counted and priced separately.
Cory LaChance
Founder, TakeOffTrak ·
Three welds to tell apart
| Weld | Where it is made | Weld types |
|---|---|---|
| Shop weld | In the fab shop, before the spool ships | BW, SW, olet |
| Field weld (FW) | On site, when spools are set and joined | BW, SW, olet |
| Field fit weld (FFW) | On site, after the pipe is cut to fit | BW or SW only |
A field fit weld is a field weld where the pipe ships long and is cut to length on site before it is welded. Every field fit weld is a field weld. Not every field weld is a field fit weld.
How to count them on the drawing
- 1
Read the legend
The legend on the ISO defines its weld symbols and field weld callouts.
- 2
Count every weld by type and size
Butt welds, socket welds, and olet welds, each by nominal pipe size. This is your total.
- 3
Mark the field welds
Move each weld with a field weld callout to the field count.
- 4
Mark the field fit welds
Move each weld with a field fit weld callout to its own line under field welds.
- 5
Tie out the totals
Shop plus field equals the total weld count.
Shop scope is about who welds it
A fitting is shop material when the fab shop buys it and welds it into a spool. If one end of that fitting is welded on site, the weld on that end is a field weld. The fitting stays shop material.
How TakeOffTrak handles it
TakeOffTrak finds the welds on the ISO and marks each one on the drawing. Each weld gets a type (BW, SW, or olet), a size, and a shop or field section. You can mark a field butt or socket weld as a field fit weld. You check the marks against the drawing and change any weld that is wrong.
The Weld Takeoff export counts shop and field welds by type and size on every drawing. Each field fit weld adds 6 inches of pipe to the materials export for the trim. More on the weld takeoff page.
Common questions
- What does FW mean on a piping isometric?
- Field weld: a weld made on site during erection, not in the fab shop.
- What is a field fit weld?
- A field weld where the pipe ships long and is cut to fit on site before it is welded. It applies to butt welds and socket welds only.
- Is an olet weld a shop weld or a field weld?
- Either. It depends on where the branch is welded. For counting, the olet weld is its own weld type, separate from butt and socket welds.
Keep reading
- How to take off a piping ISOA piping takeoff from ISO drawings, step by step: title block, BOM, shop and field split, weld count, supports, and the MTO rollup.
- What is a piping MTOWhat a piping MTO is, what goes in one, how it differs from a BOM, and how to build one from the BOMs on a set of ISO drawings.
- Weld takeoffCount butt, socket, and olet welds on every piping ISO, split shop and field, and export the weld takeoff to Excel. Every weld is marked on the drawing.
- Piping MTOTurn the BOM on every piping ISO into an Excel MTO, split shop and field. Each row is highlighted on the drawing it came from, so every quantity traces back.