Concave contour
An arc curving in toward the weld symbol: the face of the weld is to be concave.
This explains what a symbol specifies on a drawing. It isn't welding instruction, and a drawing's own notes and the governing code take precedence.
How to read it
Contour symbols show how the face of a weld is to be formed. They sit on the same side of the reference line as the weld symbol they go with. A finish symbol can be added as well: its letter gives the method of finishing, not the degree, such as C for chipping, M for machining and G for grinding.
The international standard has a concave symbol too: India's IS 813:1986, which draws on ISO 2553, lists it and gives a concave fillet weld as an example.
More welding symbols
Sources
- Steelworker, Volume 1, NAVEDTRA 14250, 1996, Naval Education and Training Professional Development and Technology Center, U.S. Navy (Internet Archive), Chapter 3, Drawings and specifications
- Scheme of symbols for welding, IS 813:1986, Bureau of Indian Standards (Internet Archive, Public.Resource.Org), Table 2
Last reviewed September 25, 2026 by Rory Hansen. How we research