Field Weld Symbol
How to read the field weld flag — placement at the arrow junction, shop vs field weld distinction, and D1.1:2025 field welding requirements.
Shop Weld vs Field Weld
In structural steel construction, members are fabricated in the shop (factory) and then assembled at the erection site (field). The field weld flag on a drawing tells the welder and inspector that this particular joint is to be welded on-site, not during shop fabrication.
Why the Distinction Matters
Shop welds are made under controlled conditions — overhead cranes for positioning, consistent temperature, wind protection, and full equipment access. Quality control is typically more streamlined.
Field welds face additional challenges: weather exposure (wind disrupts shielding gas coverage), limited access (welding in difficult positions), ambient temperature concerns (cold weather affects preheat and interpass temperatures), and inspector access considerations.
Per D1.1:2025, the same quality standards apply to both shop and field welds. The field weld flag does not change acceptance criteria — it alerts the erection team and inspection personnel that this joint requires field attention.
Field Welding Conditions
D1.1:2025 Clause 7 governs fabrication requirements including field welding conditions. Field welds must satisfy the same procedural requirements as shop welds, with additional environmental considerations.
| Requirement | Detail | Source |
|---|---|---|
| Min temperature | 0°F [−20°C] ambient — welding not permitted below this | Clause 7.11.2 |
| Wind protection | GMAW, GTAW, EGW, FCAW-G require shelter reducing wind to max 5 mph [8 km/h] at the weld | Clause 7.11.1 |
| Preheat | Same Table 5.11 requirements — ambient cold may require higher preheat to compensate | Clause 5 |
| Acceptance criteria | Same as shop welds — visual and NDE acceptance criteria both in Clause 8 | Clause 8 |