Gap left between the members at the joint root, called out on the welding symbol and in the WPS. Too small and the root will not penetrate; too wide and it sags, burns through or needs backing. Pipe welders typically set about 3/32 to 1/8 inch for open-root stick work, often using a rod or wire of the right diameter as a spacer.
Root opening's an eighth at the top and nothing at the bottom, refit it, you'll never get it in at six.
Also heard as
- gap
- root gap
- root spacing
Related terms
Fit-up
Positioning and holding parts for welding with the right gaps, alignment and clean bevels.
Land
Shop word for the flat root face left at the bottom of a bevel, called the root face in codes.
Root pass
The first weld pass in a joint, laid at the root, which sets the quality of everything above it.
Burn-through
A hole melted through the root of a weld where the molten metal fell out.