5
Breakaway Connections
Proprietary Flange System Breakaway Connections
(TDC by Lockformer, TDF by Engle)
TDC and TDF systems are
approved as breakaway
connections when installed as
described in the TDC or TDF
addendum to the SMACNA Duct
Construction Standards except
the corners may not be bolted.
Standard 6 in. (152mm) metal
clip may be used with spacing as shown in
Figure 8
. 3/8
in. (9.5mm) metal bolts and nuts may be used to fasten
together corner pieces (see
Fig. 9
).
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Figure 8: Detail of proprietary flanged system
breakaway connections.
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Traditional Breakaway Style Transverse Joints
Transverse joints illustrated at right have always been
approved as breakaway connections. SMACNA testing
has also approved the following variations as breakaway
connections.
• The breakaway connections shown (Fig. 6) can
be applied with maximum of two #10 (19mm)
sheet metal screws on each side and on the
bottom located in the center of the slip pocket and
penetrating both sides of the slip pocket.
• Transverse joints illustrated
can be applied as top and
bottom joints with Drive Slip
- side joints in duct heights
up to 20 inches (508mm)
See
Fig. 5
.
Round and Oval Duct Breakaway Connections
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Fig. 6
Round or flat oval ducts connected to Type R or O damper
collars shall be attached with #10 (19mm) sheet metal
screws as follows:
• Ducts to 22 in. (558mm) wide (or dia.) and smaller
shall have three screws.
• Ducts larger than 22 in. (558mm) wide (or dia.) up to
and including 36 in. (914mm) wide (or dia.) shall have
five screws.
NOTE:
All breakaway connections described may have duct
sealant applied, PA2084T duct sealant adhesive
manufactured by Precision, DP1010 water base duct
sealant manufactured by Design Polymetrics, or Grey
Pookie in accordance with SMACNA recommendations.
Manufactured Flanged System Breakaway
Connections
Flanged connection systems manufactured by Ductmate,
Ward, and Nexus are approved as breakaway connections
when installed as illustrated (Fig. 7).
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Fig. 7
Duct End
Flange
Corner Piece
3/8 in. bolt
(optional)
Fig. 9
