Elastic Analyses of Shells near Nozzles Using WRC 107 - CAESAR II - Help

CAESAR II Users Guide

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CAESAR II
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CAESAR II Version
12

Check vessel stresses in shells using WRC 107

  1. Check the geometric limitation to see whether WRC 107 is applicable.

  2. If yes, determine whether the elastic approach as outlined in Section VIII Division 2 AD-160 is applicable.

  3. Compute the sustained, expansion, and occasional loads in the vessel shell due to the applied nozzle loads.

  4. Consider the local restraint configuration to determine whether some or all the axial pressure thrust load P * Ain should be added to the sustained and occasional loads. If you choose, the software can automatically calculate the thrust load and add it to the applied loads.

  5. Calculate the pressure stresses, Pm, on the vessel shell wall in both the longitudinal and circumferential hoop directions for both sustained and occasional load cases.

    Notice that two different pressure terms are required in carrying out the pressure stress calculations. P is the design pressure of the system (sustained), while Pvar is the difference between the peak pressure and the design pressure of the system, which is used to qualify the vessel membrane stress under the occasional load case.

    If you enter the pressure value, the software automatically calculates the Pm stresses.

  6. The processor will calculate the Pl, and Q stresses as defined earlier.

    If needed, you can simultaneously compute the local stresses due to sustained, expansion, and occasional loads.

  7. Obtain the various stress components by combining the stress intensities computed from applying the sustained, expansion, and occasional loads, if applicable.

  8. Then use stress intensities to carry out the stress summations.

    If needed, use the results to determine the acceptability of the local stresses in the vessel shell. Notice how CAESAR II provides the WRC 107 Stress Summation module in line with the stress calculation routines.

The equations used in CAESAR II to qualify the various stress components can be summarized as follows:

Pm(SUS) < Smh

Pm(SUS + OCC) < 1.2Smh

Pm(SUS) + Pl(SUS) < 1.5Smh

Pm(SUS + OCC) + Pl(SUS + OCC) < 1.5(1.2)Smh

Pm(SUS + OCC) + Pl(SUS + OCC) + Q(SUS + EXP + OCC) < 1.5(Smc + Smh)