▲ Field weld
Field weld · Soldadura en plano · ISO 1101 + ASME Y14.5
Example in plan
How to interpret it
On the drawing, “Symbol with triangular flag” states a field weld requirement.
What controls
A flag on the reference line indicating that this weld is not made in the fabrication shop but during erection at the installation site. It is an instruction about where and when the weld is made, not how: the weld type, size and quality level remain those given by the rest of the symbol. Its practical consequence is that the part leaves the shop with that joint unwelded and with the preparation ready.
How to verify
Verification takes place in the field with the same criteria as in the shop: a weld gauge for size and visual inspection of the finish, plus any non-destructive testing the drawing requires, carried out with portable equipment. Traceability is the critical point here: you must record who welded each joint and with which procedure, because these welds never go back through the factory quality control.
Common mistakes when interpreting it
- Welding a flagged joint in the shop because it is more convenient: the assembly can then no longer be erected or shipped as planned.
- Believing the flag lowers the required quality level: the acceptance criterion is the same as for any other weld on the drawing.
- Shipping the joint painted or uncleaned: the preparation is part of what the shop must deliver.
How to get it in the workshop / if it comes out of tolerance
In the shop it means two things: do not weld that joint, and leave it prepared and protected so it fits up in the field (bevels done, surfaces clean, no paint in the weld area). Mark the parts so the erector can identify the joint. In the field the welding position is usually awkward and the environment worse, so the same weld needs more time and more control.
If the joint does not fit up in the field, the cause almost always lies in the shop: stacked-up tolerances or distortion from welds made earlier. Before filling an excessive gap with weld metal, ask: filling gaps with weld metal changes the joint geometry and may fall outside the procedure. Protect the area from wind and moisture; porosity in field welds is usually a gas shielding problem outdoors.
Related symbols
Other symbols in Flat welding
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