Handbook-Fusion Welding Carbon

4 Continued on next page... In pipe welding, if the axis of the pipe is vertical, the welding is done in the horizontal position; if the axis of the sections is horizontal, and the pipe cannot be rotated as the welding proceeds, a single weld involves the flat, vertical, and overhead positions, as defined above. In the piping trade, however, joint positions are officially described in terms of the pipe direction; thus, what a pipe man may term a ”vertical” position calls for welding in the horizontal position. Forehand and Backhand Techniques. For a right-handed operator, forehand welding means that the welding proceeds from right to left, when working in the flat or horizontal positions. (The left-handed operator will do forehand welding from left to right). The flame is angled toward the unfinished end of the weld, the filler rod is angled toward the completed section. Backhand welding is the opposite of forehand. The right-handed operator works from left to right, with the flame angled toward the completed portion, the rod angled toward the unfinished end. Most oxy-acetylene welding is done by the forehand method. There are times when backhand welding may be used effectively, but beginners should stick to forehand welding until they have mastered it. (For more about backhand technique, see the caption for Fig. 13-8.) Flame and Rod Motions. If you watch an experienced oxy-acetylene welder at this work, perhaps the first thing you will notice is that he keeps both the flame and the end of his filler rod in almost constant motion. The flame moves back and forth across the line of the weld, edging forward almost imperceptibly. The end of the rod moves back and forth too, from one side of the puddle to the other. However, the motion of the rod is opposite to the motion of the flame, and often less pronounced. The inner cone of the flame is not pointed directly at the rod for more than a small fraction of each cycle. The neat little ripples that form on the surface of the solidified weld metal are in large part the result of puddle movement generated by the rod. You will also note that if the welder withdraws the end of the rod from the puddle momentarily, he does not draw it away from the puddle very far, but keeps it within the outer envelope of the flame. Flame and Rod Angles. In the sketches which follow, we have tried to indicate, as clearly as possible, the relative angles of the flame and rod with respect to the work. The sketches were made by a skilled artist, observing a skilled welder. The captions for the sketches, especially those covering welding in positions other than flat, will have more to say about flame and rod angles.