What is the effective throat for flare bevel groove T-joints welded flush to the edge of the radii?

• A. 0.3 x Radii
• B. 0.1 x Radii
• C. 0.5 x Radii
• D. 1.0 x Radii

Answer: (A)

In a flare bevel groove T-joint, the effective throat is the minimum amount of weld metal that actually resists the load along the weld, determined by the joint geometry. When the joint is welded flush to the edge of the radii, the geometry constrains how much weld can effectively contribute, so the rule of thumb for this configuration is that the throat equals about 0.3 times the edge radius. This means if the edge radius is, say, 20 mm, the effective throat would be around 6 mm. The other options would require a larger or smaller weld section than this geometry supports: 0.1 r is typically too small for adequate load-cearing capability, while 0.5 r or 1.0 r would imply a thicker weld than the flush radii geometry yields.