TM 9-4940-444-14 & P
EXHAUST PIPING INSTRUCTIONS - continued
2. Girth Joints:
All girth Joints of pipe shall be made so the outlet end of one length fits into the inlet end of the next length in the
direction of airflow. The minimum lap size of rivets and spacing shall be as per the following table:
Length of Lap in
No. of Rivets
Diameter of Pipe
Girth Joint - Inches
per Joint
Up to 7" Inclusive
1"
4
Over 7" to 13" inclusive
1"
8
Over 13" to 19" inclusive
1"
12
Over 19" to 25" inclusive
1"
16
Over 25" to 32" inclusive
1"
20
Over 32" to 37"
1"
24
Over 37" to 42"
1"
28
Over 42"
1"
approx. 4" centers
U. S. Gage No.
Size of Tinners
Sheet Metal
Rivets to be Used
20 ga
4 lb
18 ga
6 lb
16 ga
8 lb
14 ga
10 lb
3. Riveted Elbows:
Elbows of riveted construction shall be
constructed with at least the minimum number
and size of rivets as required for the
corresponding pipe diameter and thickness of
sheet steel used.
Elbows of seven piece
construction or equivalent should be used as
shown.
7 PIECE ELBOW
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