§6.13 · Figure 7.15Simboli di contorno e finitura
I simboli di contorno specificano la forma richiesta della superficie del giunto: piana, convessa o concava. Sette lettere di finitura (G/M/C/H/P/R/U) indicano il metodo meccanico quando è richiesto. Secondo A2.4 Clause 6.13, le designazioni specificano solo il metodo. La D1.1 Table 8.1 regola i criteri di accettazione del profilo di saldatura per l'acciaio strutturale.
7 lettere di designazione della finitura
Quando dopo la saldatura è richiesto un metodo meccanico di finitura, la lettera di designazione si pone accanto al simbolo di contorno. Secondo §6.13.2, queste designazioni specificano solo il metodo — non la qualità né la rugosità della 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 Metallo di Saldatura with pneumatic chisel |
| H | Hammering | Peening operations — Distensione 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 7.15Applicazioni del contorno sulle saldature a gola
A2.4 Figure 7.15 mostra tre applicazioni pratiche dei simboli di contorno e finitura sulle saldature a gola:
Figure 7.15 — Flush and Convex ContourSuggerimento per l'esame CWI: Il simbolo di contorno si pone sopra il simbolo di saldatura, non accanto. Senza lettera di finitura, il contorno può essere ottenuto solo con la tecnica di saldatura. La lettera G (molatura) è la designazione di finitura più frequente all'esame CWI.
Domande sul simbolo di 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.