TM 9-4940-444-14 & P
EXAUST PIPING INSTRUCTIONS - cont
4. Flanged Joints. It is permissible to use flanged girth joints for the purpose of removing sections of the piping for
cleaning and inspection. Heavy iron or steel ring flanges are used. The joints are securely bolted together against
suitable gasket material. The minimum number and size of bolts used in flanges are as follows:
Size of Bolts
Diameter of Pipe
No. of Bolts in Flange
Up to 4" inclusive
4
3/8
Over 4" to 6" inclusive
5
3/8
Over 6" to 8" inclusive
8
3/8
Over 8" to 10" inclusive
8
3/8
Over 10" to 16" inclusive
8
1/2
Over 16" to 26" inclusive
12
1/2
Over 26" to 30" inclusive
16
1/2
5. Fan or Draw Band.
The joint connecting the piping to the dust collection equipment or the airflow producing equipment is a draw
band. The band shall be made of similar material and thickness used in pipe. The band shall be securely fitted to
prevent air leakage. The joint laps and bolts used shall conform to the following table:
Girth
Longitudinal
Size of Bolts and
Lap
Maximum Bolt Centers
Diameter of Pipe
Lap
Up to 8" inclusive
4"
2"
1/4" bolts 4" centers
Over 8'" to 18" incl
4"
3"
3/8" bolts 5" centers
Over 18"
4"
3"
1/2" bolts 5" centers
6. Soldering:
All galvanized steel piping for exhaust systems operating at a temperature less than 400F shall have all pipe
joints soldered, except it is permissible to use joint cement to prevent air leakage in field joints or connections.
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