Re-evaluate pump discharge nozzle loads - CAESAR II - Reference Data

CAESAR II Applications Guide (2019 Service Pack 1)

Reference Data
11.0 (2019)

You can now run another API-610 analysis using the updated discharge loads.

  1. Close the Static Output Processor dialog box.

  2. In the main window ribbon, click Analysis > Components/Equipment > Equipment Analysis .

    The Equipment Analysis dialog box displays, containing values from the initial analysis.

  3. Select Load Case Sets in the Equipment pane.

  4. For the Load Cases: Bottoms Pump - Discharge grid at the top of the Load Case Sets tab, click Refresh Linked Cases .

    The force and moment values for each load case update with values from the new static analysis.

  5. Click Analyze .

    As the analysis runs, the software places messages in the Event Log. A report displays on the Output tab when analysis completes.

  6. On the Output tab, click Next Page to advance to new pages.

    The report displays analysis results on the discharge nozzle for the OPE and SUS load cases.

  7. Click Save .

Page 3 of the report shows that while results are improved, the analysis still exceeds API Table 5 limits for the operating load case.

The report shows that the Y-moment on the discharge nozzle is well below the limit. The X-moment remains more than twice the allowable load. The Z-moment also exceeds the allowable.

Exceeding twice the allowable load would be fine if Condition F.1.2.b is satisfied, but it is not, as shown on page 5 of the report.

The sum of the ratios is 2.82, which does not meet condition F.1.2.b, which states that the combined force/moment load ratios must be less than 2.0. The pump loads are still too high.

The spring support in the model might prove the pump loads can be brought within their allowable values. As discussed in Review static output reports for the new analysis, the spring at node 28 directly controls the vertical load on the discharge nozzle. This spring pre-load could be ideally set so that when the pump is in operation, there is no pump load in the Y-direction. For the current analysis, the hanger carries 904 lb. in the operating position while the pump carries 1809 lb. If the spring load carried 2713 lb., the load on the pump would be zero (0) in Y.

For a quick check, you can manually set the Y-load to 0, and then reanalyze the pump in Equipment Analysis. The results show Condition F.1.2.b reduced to 2.33, which remains above the allowable load limits.

Pump loads are still above allowables, and a redesign of the system is needed.