FLAT POSITION WELDING

a. General. This type of welding is performed from the upper side of the joint. The face of the weld is approximately horizontal.

b. Bead Welds.

(1) In order to make satisfactory bead welds on a plate surface, the flare motion, tip angle, and position of the welding flame above the molten puddle should be carefully maintained. The welding torch should be adjusted to give the proper type of flame for the particular metal being welded.

(2) Narrow bead welds are made by raising and lowering the welding flare with a slight circular motion while progressing forward. The tip should form an angle of approximately 45 degrees with the plate surface. The flame will be pointed in the welding direction (figs. 11-11 and 11-12).

(3) To increase the depth of fusion, either increase the angle between the tip and the plate surface, or decrease the welding speed. The size of the puddle should not be too large because this will cause the flame to burn through the plate. A properly made bead weld, without filler rod, will be slightly below the upper surface of the plate. A bead weld with filler rod shows a buildup on the surface.

(4) A small puddle should be formed on the surface when making a bead weld with a welding rod (fig. 11-12). The welding rod is inserted into the puddle and the base plate and rod are melted together. The torch should be moved slightly from side to side to obtain good fusion. The size of the bead can be controlled by varying the speed of welding and the amount of metal deposited from the welding rod.

c. Butt Welds.

(1) Several types of joints are used to make butt welds in the flat position.

(2) Tack welds should be used to keep the plates aligned. The lighter sheets should be spaced to allow for weld metal contraction and thus prevent warpage.

(3) The following guide should be used for selecting the number of passes (fig. 11-8) in butt welding steel plates:

Plate thickness, in.	Number of passes
1/8 to 1/4	1
1/4 to 5/8	2
5/8 to 7/8	3
7/8 to 1-1/8	4

(4) The position of the welding rod and torch tip in making a flat position butt joint is shown in figure 11-13. The motion of the flame should be controlled so as to melt the side walls of the plates and enough of the welding rod to produce a puddle of the desired size. By oscillating the torch tip, a molten puddle of a given size can be carried along the joint. This will ensure both complete penetration and sufficient filler metal to provide some reinforcement at the weld.

(5) Care should be taken not to overheat the molten puddle. This will result in burning the metal, porosity, and low strength in the completed weld.