[Steam-engine] pressure calculations

[Blake Malkamaki]

Where did you get that safety factor? I think it's too high. My book 
is at work and I'm home sick now, but I remember most older safety 
factors being around 5 or 6 and newer boilers being around 3 or 4.

Blake

>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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Blake Malkamaki  - Girard Township, Pennsylvania
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