When two pipes are joined together as shown in Fig. 10-5, the edges of the joint are beveled and a root bead is first deposited in the usual way to close the joint. The intermediate layers and the cover layers, however, assume the characteristics of a fillet weld.

In effect, four separate joints, two on each side, must be welded.

The weld is started at the bottom of the joint and proceeds toward the top of the horizontal pipe, where the tie-in is made.

In Fig. 10-5A, the intersecting pipe is located on the top of the horizontal pipe. The weld going up the steeper joint is made by using a slant weave, pausing at both edges. A slanted “loop” weave is used to weld up the other joint. The puddle will have a tendency to droop which is overcome by the slanted “loop” weave and by pausing at the upper edge of the joint.

In Fig. 10-5B, both pipes are in a horizontal plane. The bottom of the pipe involves overhead welding which gradually changes to vertical uphill welding. At the top of the joint the welding procedure becomes essentially fiat welding,

To start the weld in the overhead position, a slanted “loop” weave is used to prevent the puddle from dripping. The electrode should pause at the upper edge of the joint. When the tendency of the puddle to droop diminishes, the weave pattern should be changed to a modified slant weave, which is continued to the top of the joint.

The welder must be alert when welding around the 3 o’clock position on both sides of the joint. He must pay close attention to the electrode manipulation and, if possible, he should not stop the bead in this position.