Figure 2-99.Completed S-and-drive connection.
Figure 2-100.Duct running parallel to purlins or beams.
sufficient. However, if the duct is of a very large size,
all edges, as illustrated in the figure which shows that
a larger angle may be required.
the duct system hanging from angle rails and that all
The straps that are used as hangers may be
angles be either bolted or tack-welded to purlins or
fabricated from 1/8-inch plate. In a normal
installation, a 1 inch by I/S-inch strap will suffice. All
Strap hangers may be hung directly on purlins or
straps must be connected to the ductwork with
beams when the duct is running transverse] y or across
sheet-metal screws. On all government work, it is
the purlins or beams, as shown in figure 2-101.
required that the screws be placed 1 1/4 inches from
However, the strap hangers must be twisted to turn 90
Figure 2-101.Strap hangers from purlins.