is quite thick and is of a shape that will allow it to be turned over, the
bevel may be brought from both sides (Figure 31), so that there will be two
grooves, one on each surface of the work. After completing the weld on one
side, the piece is reversed and finished on the other side. Figure 32 shows
the proper beveling for welding pipe. Figure 33 shows how sheet metal may
be flanged for welding.

Welding should not be attempted with the edges separated in place of
beveled, because it will be found impossible to build up a solid web of new
metal from one side clear through to the other by this method. The flame
cannot reach the surfaces to make them molten while receiving new material
from the rod, and if the flame does not reach them it will only serve to
cause a few drops of the metal to join and will surely cause a weak and
defective weld.

[Illustration: Figure 33.--Flanging Sheet Metal for Welding]

_Supporting Work._--During the operation of welding it is necessary
that the work be well supported in the position it should occupy. This may
be done with fire brick placed under the pieces in the correct position,
or, better still, with some form of clamp. The edges of the crack should
touch each other at the point where welding is to start and from there
should gradually separate at the rate of about one-fourth inch to the foot.
This is done so that the cooling of the molten metal as it is added will
draw the edges together by its contraction.

Care must be used to see that the work is supported so that it will
maintain the same relative position between the parts as must be present
when the work is finished. In this connection it must be remembered that
the expansion of the metal when heated may be great enough to cause serious