Handbook of air conditioning and refrigeration / Shan K

17.16
TABLE 17.3 Transverse Joint Reinforcement
Pressure, 4 in. WG maximum *
Minimum
rigidity Standing Standing S Standing S
class drive slip Standing S Standing S Standing S (bar-reinforced) (angle-reinforced)
Hs � T (min), in. W, in. Hs � T (min), in. Hs � T (min), in. Hs � T (min), in. Hs � T (min) plus reinforcement (H � T), in.
A
B
Use class B
Use class C
Use class D
C 1 — 1 � 0.0187 1 � 0.0187 Use class F
1 1 1�2 � 0.0296
�8 � 0.0296
1�8 � 0.0.187
1�2 � 0.0187
D — — 1 � 0.0236 1 � 0.0236
E — 1 —
1 3�16 �8 � 0.0356
F — 1 —
5 3�16 �8 � 0.0296
G — 1 —
5 3�16 �8 � 0.0466
H — — — — —
1 1 � 8 � 0.0187
1 1 � 8 � 0.0466
1 1 � 2 � 0.0236
1 1 � 2 � 0.0466
1 1 � 2 � 0.0236 plus
1 1 � 2 � 1 � 8 bar
11�2 � 1 1
�8 bar
1�2 � 0.0296 plus
11�2 � 11�2 � 3 1
�16 angle
1�2 � 0.0356 plus
I — — — — — 2 � 0.0356 plus
1 2 � 2 � �8 angle
J — — — — — 2 � 0.0356 plus
3 2 � 2 � �16 angle
* Acceptable to 36 in. length at 3 in. WG and to 30 in. length at 4 in. WG.
Source: Adapted with permission from SMACNA, HVAC Duct Construction Standards—Metal and Flexible and ASHRAE Handbook 1988, Equipment. Refer to SMACNA
Standard for complete details.