§6.13 · Figure 7.15Símbolos de contorno y acabado
Los símbolos de contorno especifican la forma exigida de la superficie de la soldadura: plana, convexa o cóncava. Siete letras de designación de acabado (G/M/C/H/P/R/U) indican el método mecánico cuando se exige. Según A2.4 Clause 6.13, las designaciones especifican solo el método. D1.1 Table 8.1 rige los criterios de aceptación del perfil de la soldadura en acero estructural.
7 letras de designación de acabado
Cuando se exige un método mecánico de acabado después de soldar, la letra de designación se coloca junto al símbolo de contorno. Según §6.13.2, estas designaciones especifican solo el método — no la calidad ni la rugosidad de la superficie.
| 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 Metal de Soldadura with pneumatic chisel |
| H | Hammering | Peening operations — Alivio de Tensiones 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 Fabricante’s discretion (§6.13.3) |
Figure 7.15Aplicaciones de contorno en soldaduras de ranura
A2.4 Figure 7.15 muestra tres aplicaciones prácticas de los símbolos de contorno y acabado en soldaduras de ranura:
Figure 7.15 — Flush and Convex ContourNota para el examen CWI: El símbolo de contorno se coloca encima del símbolo de soldadura, no al lado. Si no aparece una letra de acabado, el contorno puede lograrse solo con la técnica de soldeo. La letra G (esmerilado) es la designación de acabado que más se pregunta en el examen CWI.
Preguntas sobre el símbolo de contorno
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.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.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.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.