On a pipe-to-pipe connection with a small slope, the dihedral angle between the walls of the two members, along the joint root, varies from toe to heel zone. In order to maintain a strong connection with a minimum of weld volume along the joint, it is necessary to use a combination of weld types.
When you hear us talking about 3D profiling, we use technical terminology. For example, the names of the zones are inspired by the analogy of a foot. In the video we show you an abstract form of a straightened pipe-to-pipe connection.
By default, a groove weld with full penetration is preferred for its strength and low weld volume.. In the toe zone, this is easily possible for a welder to achieve and a groove weld is applied. This corresponds to a large dihedral angle.
At the heel zone the dihedral angle is much smaller, with limit accessibility. A groove weld is difficult to perform and the members will need impossible cutting angles to suffice. The better option would be a fillet weld. A fillet weld in the heel zone will require less weld volume, is easier to weld and easier to cut.
Somewhere between the toe and heel zone, the two weld types along the joints merge. This zone is called the transition zone.
The two welded faces of the connection will merge smoothly to ensure an optimal weld preparation. In particular when the dihedral angle becomes too small for a groove weld or too large for a fillet weld along the joint root.