Breakaway Connections
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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4UBOEJOHi4w "MU 4UBOEJOHi4w4UBOEJOHi4w
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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
Proprietary Flange System Breakaway Connections (TDC by Lockformer, TDF by Engle)
TDC and TDF systems are |
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approved as breakaway |
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connections when installed as |
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described in the TDC or TDF | 4MFFWF |
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addendum to the SMACNA Duct |
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Construction Standards except |
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the corners may not be bolted. |
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Standard 6 in. (152mm) metal |
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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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JO |
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3FRE |
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JO |
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JO%VDU |
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3FRE |
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JO |
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JO%VDU |
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3FRE |
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Figure 8: Detail of proprietary flanged system breakaway connections.
Duct End
Flange
Corner Piece
3/8 in. bolt (optional)
Fig. 9
5