AWS A2.4 ·
§6.13 · Figure 7.15Simbol kontur dan penyelesaian
Simbol kontur menentukan bentuk permukaan las yang disyaratkan: rata, cembung, atau cekung. Tujuh huruf penyelesaian (G/M/C/H/P/R/U) menunjukkan metode mekanis bila diperlukan. Menurut A2.4 Clause 6.13, penanda itu hanya menyebut metode. D1.1 Table 8.1 mengatur kriteria penerimaan profil las pada baja struktur.
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Three Contour Shapes — A2.4 §6.13.1
Flush — level with Logam Induk
Convex — raised above base
Concave — recessed surface
A2.4 §6.13.2–6.13.3
7 huruf penanda penyelesaian
Bila metode penyelesaian mekanis tertentu disyaratkan setelah pengelasan, huruf penanda diletakkan di samping simbol kontur. Menurut §6.13.2, penanda itu hanya menyebut metode — bukan mutu atau kekasaran permukaan.
| Letter | Finishing Method | Common Use |
|---|---|---|
| G | Grinding | Most common — CJP groove welds at moment connections, fatigue-critical joints |
| M | Machining | Precision surfaces — bearing seats, rotating equipment |
| C | Chipping | Removing slag or excess Logam Las with pneumatic chisel |
| H | Hammering | Peening operations — Pelepasan Tegangan in specific applications |
| P | Planishing | Smoothing with a flat-faced tool — sheet metal applications |
| R | Rolling | Rolling to smooth or cold-work the surface |
| U | Unspecified | Mechanical finishing required, method at fabricator’s discretion (§6.13.3) |
Figure 7.15Penerapan kontur pada las alur
A2.4 Figure 7.15 menunjukkan tiga penerapan praktis simbol kontur dan penyelesaian pada las alur:
Figure 7.15 — Flush and Convex ContourFig 7.15(A) — Arrow flush
Fig 7.15(B) — Other flush + M
Fig 7.15(C) — Both sides
Tips ujian CWI: Simbol kontur diletakkan di atas simbol las, bukan di sampingnya. Tanpa huruf penyelesaian, kontur boleh dicapai hanya dengan teknik pengelasan. Huruf G (gerinda) adalah penanda penyelesaian yang paling sering diuji pada ujian CWI.
Common Questions
Pertanyaan simbol kontur
What does the contour symbol mean on a welding symbol?
The contour symbol on a welding symbol specifies the required shape of the finished weld surface. Per AWS A2.4:2020
Section 6.13, there are three contour shapes: flush (flat, indicated by a straight line), convex (raised, indicated by a convex arc), and concave (recessed, indicated by a concave arc). The contour symbol is placed on top of the weld symbol on the reference line. When a contour symbol appears without a finishing designator letter, the contour may be achieved by any method including welding technique alone. When a finishing designator letter is added (G, M, C, H, P, R, or U), a specific mechanical finishing method is required after welding.What does G mean on a welding symbol?
G on a welding symbol is the finishing designator for grinding, per AWS A2.4:2020
Section 6.13.2. When you see G next to a contour symbol (flush, convex, or concave), it means the weld must be mechanically ground to achieve that contour. For example, a flush contour symbol with G means grind the weld flush with the base metal surface. The finishing designator specifies the method but does not specify the quality or roughness of the finish. Grinding is the most commonly specified finishing method in structural steel fabrication, particularly for CJP groove welds at moment connections where flush surfaces are required for fatigue performance.What are the 7 finishing designator letters?
AWS A2.4:2020
Section 6.13.2 and Section 6.13.3 define 7 finishing designator letters: G for grinding, M for machining, C for chipping, H for hammering, P for planishing, R for rolling, and U for unspecified mechanical finishing method. Each letter is placed next to the contour symbol to specify how the weld surface must be finished. The letters do not specify the quality or surface roughness of the finish. U is used when mechanical finishing is required but the specific method is left to the fabricator. These designators apply only to mechanical finishing methods, not to contour achieved by welding technique alone.What is the difference between flush and convex contour?
Flush contour means the weld surface must be level with the base metal, creating a smooth transition with no reinforcement above the plate surface. Convex contour means the weld surface is intentionally raised above the base metal in a rounded profile. Both are specified using contour symbols per AWS A2.4
Section 6.13. Flush contour is required for fatigue-critical connections because weld reinforcement creates stress concentrations at the weld toes. D1.1:2025 Clause 7.23 specifies flush finishing requirements for butt joints in cyclically loaded structures. Convex contour is acceptable for most statically loaded connections where fatigue is not a design consideration.