Problem with UG-37(a)

I am doing nozzle reinforcement calculations for a 8" ID, t=1.125", in a 36" OD semi-elliptical head. The nozzle offset is 3.0" and the angle is 90 degrees. Per Section UG-37(a) and the Codecalc manual, the thickness of an elliptical head is analysed as equivalent spherical head with a radius of K1D. However, Codecalc 6.20 does the thickness calculation using the formula for an elliptical head per App 1-4(c)(2). Shouldn't the formula for a spherical head from App 1-1(a)(2) be used instead?

Dear Neil,

The program will actually perform the calculation either way, but it depends on the input. There is a check box under the "Miscellaneous" tab that asks if the Nozzle (or the diameter limit) is outside of the 80% (spherical) limit of the head. If this is the case, check the box and the program will indeed use the appropriate equation for required thickness due to internal pressure.

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Scott Mayeux
COADE Inc.