Figure3-10.Root penetration and joint penetration of welds.
Figure 3-11.Weld reinforcement.
often referred to as the included angle between the
parts to be joined by agroove weld.
The groove radius is the radius used to form the
shape of a J- or U-groove weld joint. It is used only for
special groove joint designs.
The root opening refers to the separation between
the parts to be joined at the root of the joint. It is
sometimes called the root gap.
To determine the bevel angle, groove angle, and root
opening for a joint, you must consider the thickness of
the weld material, the type of joint to be made, and the
welding process to be used. As a general rule, gas
welding requires a larger groove angle than manual
The root opening is usually governed by the diame-
ter of the
filler material. This, in turn, depends on the
of the base metal and the welding position.
Figure 3-12.Simple weld bead.
Having an adequate root opening is essential for root
Root penetration and joint penetration of welds are
shown in figure 3-10. Root penetration refers to the
depth that a weld extends into the root of the joint. Root
penetration is measured on the center line of the root
cross section. Joint penetration refers to the minimum
depth that a groove (or a flange) weld extends from its
face into a joint, exclusive of weld reinforcement. As
you can see in the figure, the terms, root penetration and
joint penetration, often refer to the same dimension.
This is the case in views A, C, and E of the illustration.
View B, however, shows the difference between root
penetration and joint penetration. View D shows joint
penetration only. Weld reinforcement is a term used to
describe weld metal in excess of the metal necessary to
fill a joint. (See fig. 3-11.)