To find the bursting pressure of a cylindrical boiler shell, having
given the diameter of shell and the thickness and ultimate strength of
the material.
Set the diameter of the shell in inches on C to twice the thickness of
the plate on D, and under strength of material per square inch on C read
bursting pressure in lb. per square inch on D.
EX.—Find the bursting pressure of a cylindrical boiler shell 7 ft. 6
in. in diameter, with plates ½in. thick, assuming an ultimate strength
of 50,000 lb. per square inch.
Set 90 on C to 1·0 on D, and under 50,000 on C find 555 lb. on D.
To find working pressure for Fox’s corrugated furnaces by Board of Trade
rule.
Set the least outside diameter in inches on C to 14,000 on D, and under
thickness in inches on C read working pressure on D in lb. per square
inch.
To find diameter _d_ in inches, of round steel for safety valve springs
by Board of Trade rule.
Set 8000 on C to load on spring in lb. on D, and under the mean diameter
of the spring in inches on C read _d_^3 on D. Then extract the cube root
as per rule.