--------------+--------+---------+-------+--------------------------
Outside |Area of |Thickness|Strain |
diameter | cross | of tube | in | Method of Fastening.
of end of tube|section | plate .|pounds.|
where fracture|of body | |Mean |
took place. |of tube.| |result.|
--------------+--------+---------+-------+--------------------------
Inches. |Sq. ins.| Inches. |Pounds.|
2-5/8 | .981 | 7/16 | 22650 |Expanded by Dudgeon tool,
| | | | end riveted over.
2-5/8 | .981 | 7/16 | 22150 |Expanded by Dudgeon tool,
| | | | end partly riveted over.
2-3/8 | .981 | 3/8 | 25525 |Expanded by Dudgeon tool,
| | | | end riveted over.
2-3/8 | .981 | 3/8 | 29675 |Expanded by Dudgeon tool,
| | | | ferruled, not riveted
| | | | over.
2-3/8 | .981 | 3/8 | 13050 |Simply expanded by Dudgeon
| | | | tool.
--------------+--------+---------+-------+--------------------------
Mr. C. B. Richards, consulting engineer at Colt’s Armory at Hartford,
Conn., made some experiments as to the holding power of tubes in
steam boilers, with the following results: The tubes were 3 inches
in external diameter, and 0.109 of an inch thick, simply expanded
into a sheet 3/8 of an inch thick by a Dudgeon expander. The greatest
stress without the tubes yielding in the plate was 4,500 pounds, and
at 5,000 pounds was drawn from the sheet. These experiments were
repeated with the ends of the tubes which projected through the sheet
three-sixteenths of an inch, being flared so that the external diameter
in the sheet was expanded to 3.1 inches. The greatest stress without
yielding was 18,500 pounds; at 19,000 pounds yielding was observed; and
at 19,500 pounds it was drawn from the sheet. The force was applied
parallel to the axis of the tube, and the sheet surfaces were held at
right angles to the tube axis.