GaugePass

Weld symbol

Field weld symbol

A flag at the elbow says the weld is made in the field rather than in the shop. It is a scheduling and quality instruction, not a change to the weld itself.

Interactive drawing

5/16
TitleField weld symbol
ViewAs drawn
Sheet1 / 2
The symbol as it appears on the drawing
arrowarrow sideother side
TitleField weld joint
ViewSection
Sheet2 / 2
The joint it produces, in cross-section

Reads asArrow side: fillet weld, 5/16 size.

How to read it

The field weld flag is drawn at the elbow, flying from the leader where it meets the reference line. Like the all-around circle it modifies the entire reference line rather than any single weld symbol, and it says one thing: this weld is not made in the shop. It is made wherever the assembly is finally erected or installed.

The flag changes nothing about the weld's size, type, or dimensions. A 5/16 fillet with a flag is the same weld as a 5/16 fillet without one. What changes is everything around the weld: the position it has to be made in, the access, the weather, the power available, the process that is practical, and how the weld will be inspected once it is up in the air or in a trench.

For the shop, the flag is a boundary marker. Everything without a flag is fabricated before the assembly ships, and everything with one is deliberately left open so the pieces can be transported and fitted. Welding a flagged joint early can make an assembly too large to move or lock in dimensions that need to float until erection.

For inspection, the flag is a warning. Field conditions make preheat harder to hold, expose low-hydrogen consumables to moisture, and put welders in positions they would never choose in the shop. Joints carrying this flag deserve a closer look at the conditions surrounding the weld, not just at the weld itself.

Where each dimension goes

Flag at the elbow
Says the weld is made away from the shop. It applies to the whole reference line, not to one symbol.
Flag orientation
It flies from the leader at the reference line junction, conventionally pointing back toward the tail end.
Effect on weld dimensions
None. Size, type, length, and contour read exactly as they would on a shop weld.
Combination with the all-around circle
Both can occupy the elbow together and each keeps its own separate meaning.

Worked examples

Each one is a drawing, the sentence it comes out as, and then the mark-by-mark account of why. Read the sheet first and say the sentence yourself before you look down.

  1. Field-welded erection splice

    3/8
    TitleField-welded erection splice
    RefField weld
    Ex1 / 2

    Reads as

    Make this 3/8 fillet on site during erection, not in the shop.

    Which mark says so

    • fillet symbolBelow the reference lineA fillet weld on the arrow side of the joint
    • 3/8Left of the symbolLeg size of the fillet
    • Flag at the elbowWhere the leader meets the reference lineField weld - made on site rather than in the shop

    The flag at the elbow marks the whole reference line as field work. The 3/8 size is unchanged by the flag; only where and under what conditions the weld is made changes.

    And what it does not say

    • No length is given, so each weld runs the full length of the joint.
    • Nothing sits above the reference line, so the far face of the joint stays bare.
    • There is no circle at the elbow, so the weld does not continue around the joint.

  2. Field-welded groove with a procedure reference

    WPS-141/260°1/8
    TitleField-welded groove with a procedure reference
    RefField weld
    Ex2 / 2

    Reads as

    Weld this groove in the field using the procedure named in the tail.

    Which mark says so

    • V-groove symbolBelow the reference lineA V-groove weld on the arrow side of the joint
    • 1/2Left of the symbolGroove weld size - how deep the weld itself goes
    • 60°Beyond the outer face of the symbolIncluded angle the joint is prepared to
    • 1/8Inside the symbolRoot opening - the gap left between the members before welding
    • Flag at the elbowWhere the leader meets the reference lineField weld - made on site rather than in the shop
    • WPS-14In the tailA reference the drawing carries - a process, procedure or specification

    The flag says the joint is made on site and the tail carries the procedure, which matters more in the field where preheat and consumable control are harder to maintain.

    And what it does not say

    • No length is given, so each weld runs the full length of the joint.
    • Nothing sits above the reference line, so the far face of the joint stays bare.
    • There is no circle at the elbow, so the weld does not continue around the joint.

Common mistakes

  • Welding a flagged joint in the shop, which can leave the assembly too large to transport or over-constrain the fit at erection.
  • Reading the flag as a change to the weld's size or type. It changes only where the weld is made.
  • Applying the flag to one weld symbol when it governs the entire reference line.
  • Treating field welds as ordinary shop welds at inspection despite the harder conditions around them.

Typical joints

Erection splices in structural steelPipe tie-ins made on siteSite-welded base plate connectionsAny joint deliberately left open for transport

Related symbols

Weld all aroundA circle at the elbow where the leader meets the reference line means the weld continues completely around the joint, wrapping every side of the attachment rather than stopping at a corner.The tailThe forked tail at the far end of the reference line holds information the symbol itself cannot carry: the process, the procedure, the consumable, or a note the joint depends on.Reference line basicsEvery welding symbol is built on one horizontal reference line with an arrow at one end and an optional tail at the other. Where information sits on that line is what gives it meaning.Fillet weldThe right triangle on the reference line calls for a fillet weld. The number to its left is the leg size, and the side of the line it sits on tells you which face of the joint gets welded.