Question about ASME section I
Question about ASME section I
(OP)
.Boilers
Could someone help and give the formula wall thickness for an ellipsoidal head ( 2:1).
I was expecting something like
t =( P*L) / [ 2*S -0.2*P])
with L = 0.9*D
D= Boiler diameter corroded
.......I started doubting when I saw THE FORMULA
T = (5*P*L) /( 4*8*S)
Could someone help and give the formula wall thickness for an ellipsoidal head ( 2:1).
I was expecting something like
t =( P*L) / [ 2*S -0.2*P])
with L = 0.9*D
D= Boiler diameter corroded
.......I started doubting when I saw THE FORMULA
T = (5*P*L) /( 4*8*S)





RE: Question about ASME section I
The first formula is for a thick full hemispherical head, the second one for a dished head.
For a 2:1 ellipsoidal head the code requires the minimum thickness being the same as for a cylindrical shell with the same diameter.
You should have the code in your hands if you need to do this type of calculation or check other's calcs: for each calculation there are side rules and limits to be fulfilled.
prex
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RE: Question about ASME section I
thanks for this clarification.
---------------
I have the Code..the point is how to read it !!
For 2:1 ellip heads= are you refering to paragraph PG-29.6 ?
if not please specifiy which paragraph is applicable to ellip. heads
What is the exact definition of a dished head then??
is and 2:1 ellip. head not a dished head ??
RE: Question about ASME section I
A dished head, otherwise called a torispherical head, has a central spherical portion with large radius (usually equal to shell diameter), and a torical knuckle with a small radius that connects to the shell. A 2:1 ellipsoidal has an elliptical shape (theoretically) in a diametral section and the depth is half the shell radius.
prex
http://www.xcalcs.com : Online tools for structural design
http://www.megamag.it : Magnetic brakes for fun rides
http://www.levitans.com : Air bearing pads
RE: Question about ASME section I
The formula in PG-29.1 is the correct one for dished heads unless they are hemispherical. Note that the divisor is 4.8 not 4*8.
EJL