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:
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)