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 below (Fig. 3)
can be applied with maximum of (2) #10 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. 4.
Proprietary Flange System Breakaway
Connections
(TDC by Lockformer, TDF by Engle)
TDC and TDF systems (see Fig.
6) 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 diagram (see
Fig. 7). 3/8 in. (9.5mm) metal bolts and nuts may be
used to fasten together corner pieces together (see
Fig. 8).
Duct
Sleeve
6
9
7
7
5
5
5
5
6
Std. Clip
Length
CL
Duct
60 Duct
4 Reqd.
48 Duct
3 Reqd.
36 Duct
3 Reqd.
24 Duct
2 Reqd.
18 Duct &
Smaller
1 Reqd.
Clip Spacing
Typical TDC/TDF
joint
6
Fig. 6
Duct
Sleeve
6
9
7
7
5
5
5
5
6
Std. Clip
Length
CL
Duct
60 Duct
4 Reqd.
48 Duct
3 Reqd.
36 Duct
3 Reqd.
24 Duct
2 Reqd.
18 Duct &
Smaller
1 Reqd.
Clip Spacing
Typical TDC/TDF
joint
6
Fig. 7
Duct End
Flange
Corner Piece
3/8 in. bolt
(optional)
Fig. 8
Fire Damper Sleeve
Neoprene or Butyl gasket
between all angles
Flanged system angles
(Attach per
manufacturer's
instructions)
Duct
3/8 in. bolts in
corners are optional
6 in. long 1/16 in. max.
thickness plastic cleats;
12 in. c-c (min. 1 per side)
Manufactured Flanged System Breakaway
Connections
Flanged connection systems manufactured by
Ductmate, DuroDyne, Ward, and Nexus are approved
as breakaway connections when installed as illustrated.
Fig. 5
Round and Oval Duct Breakaway
Connections
Round or flat oval ducts connected to Type R, CR or
CO damper collars may use no. 10 sheet metal screws
as follows:
• Ducts to 22 in. (559mm) wide (or dia.) and smaller
may use 3 screws.
• Ducts larger than 22 in. (559mm) wide (or dia.) may
use 5 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, Grey
Pookie, Ductmate PROseal® or CL Ward S Seal in
accordance with SMACNA recommendations.
Plain “S” Slip Hemmed “S” Slip
Double “S” Slip
Inside Slip Joint
Standing “S”
Standing “S” (Alt.)
Standing “S” (Alt.)
Standing “S”
Standing “S”
(Bar Reinforced)
(Angle Reinforced)
Fig. 3
BREAKAWAY CONNECTIONS
Drive Slip Joint
Fig. 4
5