Flanged Plain Single bevel Double bevel Thin stock Thick stock A B Figure 5-43.  Edge joints. Figure 5-41.  Types of butt joints. Figure 5-42.  Types of tee joints showing filler penetration. Figure 5-44.  Corner joints. Plain Single bevel Double bevel Closed type Open type A Braced C B 5-31 used for metals from  1 ⁄ 16 -inch to  1 ⁄ 8 -inch in thickness. A filler  rod is used when making this joint to obtain a strong weld.  The flanged butt joint can be used in welding thin sheets,  1 ⁄ 16 - inch or less. The edges are prepared for welding by turning  up a flange equal to the thickness of the metal. This type of  joint is usually made without the use of a filler rod. If the metal is thicker than  1 ⁄ 8 -inch, it may be necessary to  bevel the edges so that the heat from the torch can completely  penetrate the metal. These bevels may be either single  or double-bevel type or single or double-V type. A filler  rod is used to add strength and reinforcement to the weld.  [Figure 5-41] Repair of cracks by welding may be considered just another  type of butt joint. The crack should be stop drilled at either  end and then welded like a plain butt joint using filler rod.  In most cases, the welding of the crack does not constitute  a complete repair and some form of reinforcement is still  required, as described in following sections.  A tee joint is formed when the edge or end of one piece is  welded to the surface of another.  [Figure 5-42]  These joints  are quite common in aircraft construction, particularly in  tubular structures. The plain tee joint is suitable for most  thicknesses of metal used in aircraft, but heavier thicknesses  require the vertical member to be either single or double- beveled to permit the heat to penetrate deeply enough. The  A corner joint is made when two pieces of metal are  brought together so that their edges form a corner of a  box or enclosure.  [Figure 5-44]  The corner joint shown in  Figure 5-44A  requires no filler rod, since the edges fuse  to make the weld. It is used where the load stress is not  important. The type shown in  Figure 5-44B  is used on heavier  An edge joint is used when two pieces of sheet metal must be  fastened together and load stresses are not important. Edge  joints are usually made by bending the edges of one or both  parts upward, placing the two ends parallel to each other,  and welding along the outside of the seam formed by the two  joined edges. The joint shown in  Figure 5-43A  requires no  filler rod since the edges can be melted down to fill the seam.  The joint shown in  Figure 5-43B,  being thicker material,  must be beveled for heat penetration; filler rod is added for  reinforcement. dark areas in  Figure 5-42  show the depth of heat penetration  and fusion required. It is a good practice to leave a gap  between the parts, about equal to the metal thickness to aid  full penetration of the weld. This is common when welding  from only one side with tubing clusters. Tight fitment of the  parts prior to welding does not provide for a proper weldment  unless full penetration is secured, and this is much more  difficult with a gapless fitment.  Edge Joints Tee Joints Corner Joints