==============+==============+========+==============+=========
Size of Pipe ×| Diameter | Number | Size | Flange
Diam. | of | of | of |Thickness
of Flange. | Bolt Circle. | Bolts. | Bolts. | at Edge.
| | | |
Inches. | Inches. | | Inches. | Inches.
--------------+--------------+--------+--------------+---------
3 × 7-1/2 | 6 | 4 | 5/8 × 2-1/2 | 13/16
3-1/2 × 8-1/2| 7 | 4 | 5/8 × 2-1/2 | 7/8
4 × 9 | 7-1/2 | 4 | 3/4 × 2-3/4 | 15/16
4-1/2 × 9-1/4| 7-3/4 | 8 | 3/4 × 3 | 15/16
5 × 10 | 8-1/2 | 8 | 3/4 × 3 | 15/16
6 × 11 | 9-1/2 | 8 | 3/4 × 3 | 1
7 × 12-1/2 | 10-3/4 | 8 | 3/4 × 3-1/4 | 1-1/16
8 × 13-1/2 | 11-3/4 | 8 | 3/4 × 3-1/2 | 1-1/8
9 × 15 | 13-1/4 | 12 | 3/4 × 3-1/2 | 1-1/8
10 × 16 | 14-1/4 | 12 | 7/8 × 3-5/8 | 1-3/16
12 × 19 | 17 | 12 | 7/8 × 3-3/4 | 1-1/4
14 × 21 | 18-3/4 | 12 | 1 × 4-1/4 | 1-3/8
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Do not drill bolt holes on center line, but symmetrically each side of
it.
On steam and exhaust openings loose flanges threaded for wrought-iron
pipe must be provided.
Where the situation will not permit of a standard flange on exhaust
opening for lack of room, a special flange threaded to fit the proper
size wrought-iron pipe may be used.