Related Resources: pressure-vessel

Circular Flat Head Welded with Internal or External Pressure Equation and Calculator

Structural Design and Analysis
Pressure Vessel Design and Engineering

Circular Flat Head Welded with Internal or External Pressure Equation and Calculator

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Stress in Pressure Vessel Welded Flat Head Section Seam Calculator:

Required minimum wall thickness
t = d ( C P / ( S E) )^0.5

C = 0.33 t_r / t_s

C_min = 0.20

Where:

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
t_h = Actual thickness used in actual design, inches
t_r = Minimum required thickness of seamless shell for pressure, inches
t_s = 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
t_r = 0.243 in. required thickness of seamless shell for pressure.
t_s = 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.

t_s = 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 t_s )^0.5 from the inside face of the head

2 ( 24in. 0.375 in.)^0.5 = 6 in.