U-groove weld
A U with a stem on the reference line: a U-groove weld, made in a groove with a rounded bottom.
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
A groove weld is made by depositing filler metal in a groove between two members to be joined. A U-groove is shaped with a radius, the groove radius, which is used only for special groove joint designs such as the U- and J-groove. India's IS 813:1986, which draws on ISO 2553, calls it a single-U butt weld, with parallel or sloping sides.
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
- Welding Theory and Application, TM 9-237, 1967, Department of the Army (Internet Archive), Glossary
- Scheme of symbols for welding, IS 813:1986, Bureau of Indian Standards (Internet Archive, Public.Resource.Org), Table 1
Last reviewed September 25, 2026 by Rory Hansen. How we research