Concave contour
An arc curving in toward the weld symbol: the face of the weld is to be concave.
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.
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.
Read next
- Next in Welding symbolsReference line and arrowThe horizontal line and arrow at the heart of every welding symbol. The arrow points to the joint, and the side of the line a weld symbol sits on says which side of the joint the weld goes on.
- The same shape in African flagsFlag of the ComorosThe Comoros flag is four horizontal stripes, yellow, white, red and blue from the top, with a green triangle along the pole holding a white crescent and four white stars in a line between its tips. Norway’s Store norske leksikon explains the crescent as the symbol of Islam and the four stars as the four islands of the Comoros; Lex says the four stripes are said to stand for the islands too.
More welding symbols
The same shape elsewhere
Browse symbols drawn with arrows, curves and waves, lines or triangles.
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
Researched, edited and approved by Rory Hansen before publishing. Last reviewed September 25, 2026. How we research
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