BOILERS FOR STATIONARY ENGINES.
3 1
62,544 lbs., and the worst 34,000 lbs. per square inch. Taking one-sixth of the mean, or 8045 lbs.—(this is presuming the best platesare used; if the plates are of inferior quality, it is obvious the con-stant is too high proportionally, although it may answer in practicewith a parcel of the best plates untested)—we have, for a boiler6 feet 6 inches in diameter, and with 60 lbs. steam per square inch,the following result (the seams being single-rivetted):—■
1 |^ 2 -=-58, say inch,
as the thickness, or when set in brickwork say of an inch. Thisis allowed on account of the corrosion that takes place with all boilersresting on a brickwork foundation. The ends should be at leastyi inch more than the calculated thickness.
In another form it may be taken thus—
P. Pressure per square inch.
D. Diameter of boiler in inches.
T. Thickness of plates in inches.
C. Constants for varying qualities of plates.
Double Rivetted. Single Rivetted.
C = For Yorkshi.re plates of best quality,. 7800 6200 .
C = For Staffordshire plates of best quality,. 6200 5000
C = For ordinary plates,. 3700 3300
2 C
It will be seen that this formula gives a thickness of the platessomewhat less than the previous rule, using the best quality, a resultnot at all to be desired; yet when the quality of the plates is testedby a strip cut off each plate, one-sixth of the strength of the rivettedjoints, as per following table, may be safely taken as the constant
7 'he Strongest Form and Proportion of Rivetted Joints , as deduced from Experiment
and Practice .
Thickness ofPlates in Partsof an Inch.
Diameters ofRivets inInches.
Length of Rivetsfrom Headin Inches.
Distance of Rivetsfrom Centre toCentre in Inches.
Quantity of Lapin Single Jointsin Inches.
48 =tj
•25 =i
' 3 1 — tV■ 37=1• 5 °=i•62=4
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143
1-38
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2 ' 2 5 1
275 1
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i- 5 o i 6
r63 5
175 ( 5
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