Drag welding ensures a constant arc length. The electrode covering does not conduct electricity. As a result, the arc does not stop when the electrode covering touches the base metal. Striking an arc with a new, thickly covered electrode is the same as with any other shielded electrode. However, when restarting an arc with a thickly covered electrode, you must hit the base metal hard enough to chip away some of the covering. This exposes the electrode wire and allows the arc to begin. The covering is kept in contact with the base metal after the arc is struck. The arc is enclosed by the thick electrode covering. This type of arc is known as a closed arc. The technique for running a weld bead with the drag method is the same as that for running a weld bead with an open arc. It is easier, however, because the arc length is kept constant by dragging the electrode on the fl ux covering. See Figure 12-14. Cleaning the Weld Each weld bead, or weld pass, must be cleaned by chipping and brushing. This cleaning prevents slag from mixing with the following weld passes. Cleaning is also necessary in order to examine a completed weld bead. Chipping should be done after the weld has cooled for a few minutes. Chipping goggles must be worn while chipping and wire brushing. Chipping should be done where other workers are not endangered by fl ying particles. The cooled slag coating is usually hard and brittle. It is removed with a chipping hammer. Small areas of the weld are cleaned with the pick end of the chipping hammer. See Figure 12-15. A wire brush is used to clean the weld bead thoroughly after chipping. Goodheart-Willcox Publisher Figure 12-13. The three steps in restarting an arc. Step 1—Strike the arc 3/8″ (10 mm) in front of the first weld bead. Step 2—Rapidly move backward until the new weld pool touches the old crater. Step 3—Move forward at the correct speed to continue the weld bead. Goodheart-Willcox Publisher Figure 12-14. When drag welding, the electrode covering is kept in contact with the base metal as the electrode is pulled along the metal surface. Rear of old arc crater 1st bead Restarted bead Step 2 Step 3 Step 1 Weld bead Weld pool Welding arc Flux covering Electrode wire Penetration Base metal Goodheart-Willcox Publisher Figure 12-15. Cleaning the slag from a fillet weld using the pick end of the chipping hammer. The chisel end of the hammer can be used on flat weld beads and in larger areas. Chapter 12 SMAW: Flat Welding Position 175 Copyright Goodheart-Willcox Co., Inc.