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Pressure Vessel Nozzle Design Calculator

Engineering Calculators | Pressure Vessels Menu

The following are equations and a calculator to determine the wall thickness of a welded nozzle connection to a shell, head or similiar geometry.

The nozzle feature design does not have a repad feature and is onlyapplicable for internal pressure only.

The following equations apply:

(Eq. 1)

Nozzle Variables:            
 S [psi] - allowable stress 
 E - nozzle efficiency
 Do [in] - outside diameter of nozzle
 tr [in] - nominal wall thickness of nozzle
 Ca [in] - nozzle corrosion allowance
 Ut [%] - undertolerance allowance (0% for Rolled or Machined)
 P [psi] - interior pressure
Calculated Data:            
U [in] = 
R [in] = 
tn [in] = 
Required Material Thickness:
Tr [in] = 
Tr vs. U =


S = allowable stress

E = joint efficiency for, or the efficiency of, appropriate joint in cylindrical or spherical shells, or the efficiency of ligaments between openings, whichever is less.
For welded vessels, use the efficiency specified in UW-12. For ligaments between openings, use the efficiency calculated by the rules given in UG-53.

Do = outside diameter of nozzle

tr = nominal wall thickness of nozzle

Ca = nozzle corrosion allowance

Ut [%] = undertolerance allowance (0% for Rolled or Machined)

P [psi] = internal pressure

U = tr * Ut = nozzle reduced thickness with undertolence percentage applied

R = Do/2 - (tr - Ca) + Ut = working radius

tn = tr - Ca = nozzle wall thickness less corrosion allowance

Tr = design required minimum thickness (see Eq. 1) per UG-27(c)(1,2)

Nac = tr x (1 - Ut) = acting wall thickness

References: ASME Boiler and Pressure Vessel Code

Contributed by:

Harsh Murugesan
Pune, Maharashtra India.

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