Non-tubular fillet · Figure 5.3

How do you select a prequalified fillet weld detail?

Identify whether the members form a T/corner joint or a lap joint, select the Figure 5.3 process and thickness branch, then check the required weld size against the minimum, fit-up and process limits. A detail number alone is not a complete WPS joint description.

Quick selection: For a non-tubular T or corner fillet, start with TC-F12. At member thickness below 75 mm [3 in], use the F12 branch; at or above 75 mm [3 in], the figure directs to F12a. GMAW/FCAW use the -GF detail; SAW uses -S and is limited by the figure to flat or horizontal positions. Lap joints use L-F12/L-F12a instead.

Choose the detail that matches the joint

Actual joint	Figure 5.3 family	Process suffix	Figure position scope
T or corner	TC-F12 below 75 mm [3 in]; TC-F12a at or above	SMAW no suffix; GMAW/FCAW -GF; SAW -S	A for SMAW/GMAW/FCAW; F/H for SAW
Lap	L-F12 below 75 mm [3 in]; L-F12a at or above	SMAW no suffix; GMAW/FCAW -GF; SAW -S	A for SMAW/GMAW/FCAW; F/H for SAW

For T/corner details, the connected-member angle is limited to 45°–135° by the shared Figure 5.3 note. A non-90° T-joint has a separate Figure 5.4 path and may require a Z-loss correction; use the sloped T-joint geometry guide before finalizing the weld throat. Tubular branch joints use Clause 10 details and are outside this Figure 5.3 selection.

For SMAW, GMAW and FCAW Figure 5.3 details, the design root gap is zero, with the specified design tolerance; fit-up permits a limited gap. Do not treat that fit-up allowance as a design gap or assume the gap needs no weld-size adjustment.

Check minimum weld size independently

Table 7.7 uses different thickness references depending on the stated path: the thinner member applies for a low-hydrogen process or the qualifying 6.8.4 crack-prevention path; without either condition, the thicker member applies and the weld must be single-pass. Use the actual process and conditions; do not infer the controlling member from weld size.

Controlling thickness	Minimum fillet size
Up to 6 mm	3 mm
Over 6 through 12 mm	5 mm
Over 12 through 20 mm	6 mm
Over 20 mm	8 mm

Worked check: for a GMAW T-joint with a 25 mm thicker member and a 12 mm thinner member, assuming the applicable low-hydrogen-process condition, use the 12 mm thinner member. The Table 7.7 minimum is 5 mm. This is a minimum check only. The design may require a larger weld, and applicable single-pass maximums may require multiple passes.

Gap adjustment: Where the root gap exceeds 2 mm, increase the weld leg by the full gap or demonstrate that the required effective throat is achieved. A gap inside the fit-up allowance does not automatically make the nominal design leg sufficient.

What the WPS detail still needs

State the joint type, member orientation, selected Figure 5.3 detail, process and position.
Show the required weld leg and any design throat requirement; do not label leg length as effective throat.
Record the designed root condition, permitted fit-up gap, and the action if the gap exceeds 2 mm.
Check the applicable one-pass maximum, 7.21.1 fit-up conditions, preheat, filler classification and project drawings.
For lap joints, respect the separate maximum weld dimension relative to the thinner edge unless the drawing specifies the permitted full-thickness condition.

Figure 5.3 detail scope does not itself determine structural weld size, fatigue design, filler choice, production parameters or qualification coverage. Those inputs must be resolved for the actual project.

Basis and scope

Basis: AWS D1.1/D1.1M:2025 base edition plus registered July 28, 2026 base-edition errata; AMD1 is excluded. Contract-specified edition governs. The bounded selection above is from Figure 5.3 and its shared notes; minimum size and fit-up checks use Table 7.7, Clauses 7.21.1 and 4.5.2.9, and the Figure 5.3 notes. It is not a complete WPS or a design calculation.

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