Per D1.1:2025 Table 7.7, minimum Las Fillet Ukuran depends on the thinner part for Hidrogen Rendah processes and the thicker part for Bukan Hidrogen Rendah processes. The four minimums are 1/8 in, 3/16 in, 1/4 in, and 5/16 in by governing Ketebalan range.
Built on AWS D1.1:2025 Table 7.7 — every minimum traced to the Pasal.
Thickness of Part Joined (T)
Minimum Fillet Weld Size
T ≤ 1/4 in [T ≤ 6 mm]
1/8 in [3 mm]
1/4 in < T ≤ 1/2 in [6 mm < T ≤ 12 mm]
3/16 in [5 mm]
1/2 in < T ≤ 3/4 in [12 mm < T ≤ 20 mm]
1/4 in [6 mm]
3/4 in < T [20 mm < T]
5/16 in [8 mm]
Source: D1.1:2025 Table 7.7 — Note (a): for non-low-H processes without Clause 6.8.4 Preheat, size governs by thicker part and single pass is required. Note (b): weld size need not exceed thickness of thinner part. Note (c): for cyclically loaded structures, 3/16 in [5 mm] is the minimum floor; thicker Table 7.7 rows still govern when larger.
Ketebalan mana yang berlaku tergantung pada Proses Pengelasan dan prosedur Preheat Anda — D1.1:2025 Tabel 7.7 catatan kaki (a). Clause 6.8.4 = prosedur Preheat yang memenuhi syarat, bukan hanya menggunakan Preheat.
Reference tool only. Verifikasi against your WPS, contract documents, and the governing D1.1 edition before fabrication or Inspeksi Penerimaan.
Filler metal selection is an essential variable per ASME Section IXQW-404 — changing to a different F-Number or A-Number classification requires procedure requalification.
Required fillet weld volume also drives shop productivity — the weld deposition rate for your wire and parameters tells you how many pounds of Logam Las you can lay per hour, which sets the labor cost per joint.
Per AWS A2.4 §8.2.1, the leg size determined here is the number drawn to the left of the fillet weld symbol on the welder's print — the same dimension the inspector verifies with a fillet weld gauge.
For weld-thermal control during fabrication, the heat input calculator translates your Tegangan, Arus, and Kecepatan Lintasan into the kJ/in (or kJ/mm) value engineers cite when restricting heat on Q&T steels per D1.1 Clause 7.7.
"Table 7.7 is probably the single most-referenced table on any structural steel shop floor. Every fitter checks it before tacking, every inspector checks it during VT. Getting minimum fillet weld size wrong is the fastest path to a rejection tag."
— Widely cited in CWI exam preparation, reflecting D1.1:2025 Clause 7.13 and Table 7.7 minimum fillet weld size requirements
Common Questions
FAQ
Berapa Ukuran Las Fillet Minimum per D1.1?
D1.1:2025 Tabel 7.7 mendefinisikan empat ambang Ukuran Las Fillet Minimum. Ketebalan material T hingga 1/4 in membutuhkan Las Fillet Minimum 1/8 in. Lebih dari 1/4 in hingga 1/2 in membutuhkan 3/16 in. Lebih dari 1/2 in hingga 3/4 in membutuhkan 1/4 in. Lebih dari 3/4 in membutuhkan 5/16 in. Dimensi Ketebalan T mana yang berlaku tergantung pada Proses Pengelasan Anda per catatan kaki (a): untuk Proses Pengelasan Hidrogen Rendah (E7018, SAW, GMAW, FCAW), T sama dengan bagian yang lebih tipis yang disambung dan lintasan tunggal tidak diperlukan. Untuk Proses Pengelasan Bukan Hidrogen Rendah (E6010, E6011) tanpa prosedur Preheat 6.8.4 yang memenuhi syarat, T sama dengan bagian yang lebih tebal yang disambung dan Las Fillet lintasan tunggal diperlukan. Catatan kaki (b) menyatakan Ukuran Las Fillet tidak perlu melebihi Ketebalan bagian yang lebih tipis yang disambung. Catatan kaki (c) menetapkan Ukuran Las Fillet Minimum 3/16 in untuk struktur yang dimuat secara siklis.
Apakah Ukuran Las Fillet tergantung pada pelat yang lebih tipis atau lebih tebal?
It depends on your welding process per Table 7.7 footnote (a). For low-hydrogen processes (E7018, GMAW, FCAW, SAW), T equals the thickness of the thinner part joined. For non-low-hydrogen processes (E6010, E6011) without a qualified Clause 6.8.4 preheat procedure, T equals the thickness of the thicker part joined. This distinction matters because governing by the thicker plate produces a larger minimum weld size. Footnote (b) adds a practical cap: the required weld size need not exceed the thickness of the thinner part. For example, if a 1 in plate is fillet-welded to a 3/16 in plate using E6010 without 6.8.4 preheat, Table 7.7 would require a 5/16 in fillet based on the thicker plate, but footnote (b) allows a 3/16 in fillet since the thinner plate is only 3/16 in thick. This prevents overwelding thin members and potential burn-through or distortion.
Bisakah Anda menggunakan Las Fillet yang lebih kecil dari Minimum Tabel 7.7?
Generally no — Table 7.7 minimums are mandatory. The only code-permitted reduction is footnote (b), which states the weld size need not exceed the thickness of the thinner part joined. Note that when using non-low-hydrogen processes (E6010, E6011) without a qualified Clause 6.8.4 preheat procedure, the governing thickness is the thicker part and single-pass welds are required per footnote (a) — this typically results in a larger minimum size compared to low-hydrogen processes where the thinner part governs. Using a weld smaller than the applicable minimum is a code violation that would be rejected during visual inspection per Table 8.1 item (6) Undersized Fillet Welds and Clause 8.9. The Engineer may approve alternative sizes through WPS qualification per Clause 6, but this is uncommon for standard fillet welds.
What is the difference between fillet weld leg size and throat size?
Leg size is the distance from the weld root to the toe along either face of the joint. For an equal-leg fillet weld, both legs are the same dimension, and this is the number specified on the welding symbol per A2.4. Throat size is the shortest distance from the root to the face of the weld — for a flat or slightly convex equal-leg fillet at a 90-degree joint angle, the theoretical throat equals leg size multiplied by 0.707. D1.1 Table 7.7 specifies minimum leg size, not throat size. However, effective throat is what carries the load in design calculations per Clause 4.5.2.6. For deep-penetration GMAW or SAW processes, engineers may increase the effective throat beyond the theoretical value using the provisions in Clause 4.5.2.6, which addresses throat calculations for various joint geometries.
Kapan Las Fillet lintasan tunggal diperlukan?
Table 7.7 footnote (a) governs when single-pass fillet welds are required. For non-low-hydrogen processes (E6010, E6011) without a qualified Clause 6.8.4 preheat procedure, single-pass welds are mandatory at all thickness ranges — this is not optional. For low-hydrogen processes (E7018, GMAW, FCAW, SAW), the single-pass requirement does not apply, and multi-pass welds are permitted at any size. Footnote (a) makes no reference to welding position — the single-pass requirement applies regardless of whether the weld is in the flat, horizontal, vertical, or overhead position. In practice, single-pass fillets up to about 5/16 in are common in production because they reduce labor time and heat input. For larger fillets, multiple passes are typical to avoid lack of fusion at the root, excessive convexity, and poor toe tie-in — all rejectable conditions under Table 8.1.
Berdasarkan AWS D1.1:2025 Tabel 7.7: “Ukuran Las Fillet Minimum ditentukan oleh bagian yang lebih tebal dari bagian yang disambung, kecuali bahwa Ukuran Las Fillet tidak perlu melebihi Ketebalan bagian yang lebih tipis yang disambung.”
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