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在UG-45中规定了接管颈部的最小厚度
t a = minimum neck thickness required for internal and external pressure using UG-27 and UG-28 (plus corrosion allowance), as applicable. The effects of external forces and moments from
supplemental loads (see UG-22) shall be considered.Shear stresses caused by UG-22 loadings shall not exceed 70% of the allowable tensile
stress for the nozzle material.
tb1 = for vessels under internal pressure, the thickness (plus corrosion allowance) required for pressure (assuming E = 1.0) for the shell or
head at the location where the nozzle neck or other connection attaches to the vessel but in no case less than the minimum thickness specified
for the material in UG-16(b).
tb2 = for vessels under external pressure, the thickness (plus corrosion allowance) obtained by using the external design pressure as an equivalent internal design pressure (assuming E = 1.0)
in the formula for the shell or head at the location where the nozzle neck or other connection attaches to the vessel but in no case less than
the minimum thickness specified for the material in UG-16(b).
tb3 = the thickness given in Table UG-45 plus the
thickness added for corrosion allowance.
tUG-45 = minimum wall thickness of nozzle necks
不是很理解为何要求tb1和tb2,是出于什么考虑?望各位大神解答!
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