[Steam-engine] pressure calculations

[Andy glines]

at the Pawnee steam school Brian Vaughn shared a
formula used to calculate the safe working pressure of
a boiler

P= (tensile strength)(thickness)(joint
efficiency)/(shell radius)(safety factor)

tensile = 55000
thickness = .3125 (new thickness)
Joint efficiency = 82% (lap seam)
radius = 19
safety factor = 8 (lap seam) 

using this formula I get 92.7 psi.  This is on the
boiler in new condition.  The boiler on my Huber
originally carried 125 with a 135 pop.  It seams like
I need a different formula or to adjust this one. 
What do you think?

=====
Andy Glines
Evansville, IN


		
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