Starting the Root Bead

Since the weld is started at the lowest position on the pipe, it is usually necessary for the welder to be in a kneeling or crouching position. Whether kneeling or crouching, he should be situated comfortably in order to avoid any unsteadiness in manipulating the welding electrode. Getting into a comfortable position, then, is the first step in welding a root bead (see Fig. 5-5).

With the machine setting and all of the electrical connections made, the welder starts by striking an arc between the 6 and 6:30

Starting the Root Bead

Fig. 5-5. Starting to weld the pipe joint.

Starting the Root Bead

5 °-10 °


Fig. 5-6. Correct electrode angle for welding in the 6:30 position.

Starting the Root Bead



position on the pipe joint. The arc should be struck in the joint and never on a tack weld. A long arc length should be maintained for a short period after the arc has been struck. During this time he should weave the electrode backward and forward to preheat the bevel ahead of the weld.

In addition to preheating the bevel, maintaining the long arc length stabilizes the arc and allows the gaseous shield to form. No filler metal is transformed from the electrode to the workpiece when the long arc is maintained in the overhead position.

After the arc has been stabilized and the gaseous shield has formed, the electrode is brought back to the 6:30 position, which is the actual starting position for the root bead. With the electrode held at the correct angle (see Fig. 5-6), it is carefully moved toward the root bead until the correct arc length is established. If necessary, the electrode is held momentarily in this position, long enough to form the keyhole and the puddle of molten metal. Then the electrode is advanced at a slow, steady pace to form the weld bead.

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