Dear Sir,
If the nozzle is in the spherical part of the elliptical head, then it should be OK to use WRC 107 to perform the local stress analysis of the junction. You will have to enter in the spherical diameter of the head which is a function of the Aspect Ratio and diameter of the head. See ASME VIII 1 UG-37 for details on computing the spherical diameter. For a 2:1 elliptical head, the spherical diameter would be 1.8 times the head diameter. Enter in the rest of the data as you would for a typical 107 analysis.
Unfortunately, WRC 297 is not applicable for nozzle/spherical junctions. Only cylinder to cylinder intersections are allowed.
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Scott Mayeux
COADE Inc.
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Scott MayeuxCADWorx & Analysis Solutions
Intergraph Process, Power, & Marine