Related Resources: pressure-vessel
Flat Circular Head Welded with Internal or External Pressure Equation and Calculator
Circular Flat Head Welded with Internal or External Pressure Equation and Calculator
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Required minimum wall thickness
t = d ( C P / ( S E) )0.5
C = 0.33 tr / ts
Cmin = 0.20
P = Design pressure or max. allowable working pressure, psi
d = Inside diameter of vessel , inches
S = Rated stress value of the material
t = Minimum thickness of shell (wall) exclusive of corrosion, inches
th = Actual thickness used in actual design, inches
tr = Minimum required thickness of seamless shell for pressure, inches
ts = Actual thickness of shell, exclusive of corrosion allowance, inches
E = Weld Joint efficiency
Example Design Calculations:
P = 300 psi design pressure
E= joint efficiency
d = 24in. inside diameter of shell
s =15,000 psi maximum allowable stress value of plate
tr = 0.243 in. required thickness of seamless shell for pressure.
ts = 0.3125 in. actual thickness of shell.
C = 0.330 ( 0.234 in. / 0.3125 in. ) = 0.260
t = 24 in ( 0.26 in x 300 psi / ( 15,000 psi x 1.0 ) = 1.731 in.
Design use 1.75 in. plate
If using a thicker plate for shell, a less thick plate would be satisfactory for the head.
ts = 0.375 in. actual thickness of shell.
C = 0.330 ( 0.234 in. / 0.375 in. ) = 0.214
t = 24 in ( 0.214 in x 300 psi / ( 15,000 psi x 1.0 ) = 1.57 in.
Design use 1.625 in. plate
The shell thickness should be maintained along a distance 2 ( d ts )0.5 from the inside face of the head
2 ( 24in. 0.375 in.)0.5 = 6 in.