Q. How to perform an ANSI Check Flange Analysis with AutoPIPE


 

Applies To    
Product(s): AutoPIPE,  
Version(s): ALL  
Area: analysis  
Original Author: Bentley Technical Support Group  

Problem:

How do I perform an ANSI Check Flange Analysis in AutoPIPE?

Solution:

As mentioned in AutoPIPE's online help:

AutoPIPE has the ability to perform a flange loading check for standard ANSI B16.5 and B16.47 flanges to verify that the effective pressure calculated from the combined load of operating pressure and external loads is less than or equal to the maximum allowable pressure at a given temperature.

The flange external loads are converted to an equivalent pressure and added to the operating pressure to calculate the total flange pressure. The equivalent pressure for external moment and force can be calculated according to B31.7, Nuclear piping code Par 1-704.5(a),

The flange loading check essentially involves determining the effective pressure in the flange due to operating pressure and external moment and force loads, and comparing it with the allowable pressure in the Table 2 of the ANSI B16.5 and 16.47. If the effective pressure is greater than the allowable pressure, then the flange is operating beyond its rated capacity. When the effective pressure is greater than the allowable pressure, the program will automatically increase the pressure rating to the next highest and perform the flange loading check again. This procedure is repeated until either the effective pressure is less than the allowable pressure, or the highest pressure rating is reached.

The data required to check the loading on a flange are nominal rating, material, operating temperature, gasket load reaction diameter, external axial force, and external moment. 

For complete details and equation used see AutoPIPE help:

Help > Contents> Search Tab> enter "ANSI Flange loading calculations" (include the quotes), press List Topics button, double click on "ANSI Flange loading calculations" from the list provided to see more information.

AutoPIPE Standard does not have the ability to perform a Flange Analysis to ASME Section VIII Div. 1 / 2 or Appendix XI, see the following AutoPIPE help section for details on features

Help > Contents> Contents Tab> Getting Started > AutoPIPE V8i Standard vs Advanced vs Nuclear.

However all editions of AutoPIPE can perform an ANSI Check flange analysis using the following procedure:

  1. Open existing AutoPIPE model WALKTHRU.DAT from one of the following locations:

                A. C:\Bentley\AutoPIPE V8i SELECTseries\

                B. C:\Bentley\AutoPIPE V8i SELECTseries\Examples\

  2. Analyze the model. Analyze> Analyze ALL.

  3. Start the command:

    AutoPIPE v11.xx and higher:
                    Select Results ribbon> Flange> Flange Check

                     

    AutoPIPE v10.xx and lower
                          Select Tools> Flange Analysis.

  4. Change Analysis Method from "ASME Section VIII, Division 1" to "ANSI Flange Check" and press the TAB button

  5. Select the ANSI CHECK tab from the grid.

  6. Select Flange material = A105 from the drop down listing and press the TAB keyChange Gasket Type = "Spiral-Wound" and press the TAB key.

      1. Note, for non-library data, select "NS" or "User" and enter the values in the respective fields

  7. Re-select the Analysis Tab from the grid.

  8. Place a check mark in the column for "Analyze"

  9. Press the "Analyze" button in the top right corner to analyze the flange. The following should be displayed if everything was correctly configured:

  10. Press the "Show Results" button in the top right corner to automatically display the output report for the flange analysis only.

Note: when adding User Pressure Temp. Data, the data must be entered by first selecting "Use Pmax" button in the lower right corner of the dialog screen, shown bellow:

After the data has been entered, press OK button to create Flange_User_Data.mdb in the same folder as the model. 

To associate the newly entered data with a flange, select the flange row, in the corresponding "User Pmax" column, press the "Select" button, this action will open a dialog where the user can select a Table Name from the drop down listing of existing tables with the correct flange rating created by the previous step. This dialog will not allow the user to modify the table data. Complete the process by pressing the Select button to close the dialog and now place a check in the column labeled "User Press Temp. Data" for the selected flange.

 Finish by analyzing the flange using the steps mentioned above.

Flange Analysis Output report

ANSI Flange check will evaluate each flanges per the non-code combinations whose print flag is enabled. All other combinations will be ignored

In addition, scroll down to the Results section for each flange, look for an * as the last chartacter.

Example:

Radial Flange Stress, SR = 161.968 115.142 1.407*

Average Stress, (SH+SR)/2.0 = 150.616 115.142 1.308*

This * at the end of a line means that these calculation results have exceeded the calculated allowable, i.e. the flange has failed. Avoidance, review the report and code to see how this calculation is performed, adjust the Flange Analysis input values that go into calculating this value.

Notes: 

1. See FAQ #14:   My ANSI flange check shows several flanges have increased from class 600 to 900, what does this mean?

Please see the following AutoPIPE help section:

Help > Contents> Contents Tab> Bentley AutoPIPE> Frequently Asked Questions> FAQ document>

2. There is a known issue where an ANSI Flange Analysis cannot be performed for flange that are inserted on points already having extra data. Otherwise the program will display Max Ratio = 0.00 and Note = Fail, shown below:

In addition, the output report for these flanges will show blank pages, as indicated below:

This has been logged under TFS-D263628, and will be allowed in a future version of the application.

Note: It is important to note that the calculations are embedded within the application. There are no mechanism available for adjusting or revising these hard coded calculations within AutoPIPE. Should you consider a modification to these calculations a valuable addition to AutoPIPE, kindly examine the existing IDEAs available here and cast your vote for those you support. If the IDEA has not yet been submitted, please feel free to post a new idea. These suggestions are forwarded directly to the development team and the Program Manager for their evaluation and feedback to you.

See Also

Flange Analysis

Bentley AutoPIPE