Now click on Analysis type and select Modal from the drop down menu. You will get the following window as shown in Fig. 3. ⬇️
* You will get four input spreadsheets as lumped masses, snubbers, control parameters and advanced.
* Click on Control parameters and it will open the window shown in Fig. 4.
* Change the frequency cut off to your desired frequency based on your project specification. If you need to arrest all frequencies below 5 Hz and set that value as 5.
* Now select the static load case for which you want to extract the natural frequencies. Normally it is advisable to select the operating temperature case.
* Click on Control parameters and it will open the window shown in Fig. 4.
* Change the frequency cut off to your desired frequency based on your project specification. If you need to arrest all frequencies below 5 Hz and set that value as 5.
* Now select the static load case for which you want to extract the natural frequencies. Normally it is advisable to select the operating temperature case.
*Now you are set for analysis, So click on the run button similar to what you do for static analysis. The analysis will extract all the natural frequencies which the piping system will experience below your cut off frequency values. Fig. 5 shows such a typical modal run screen.
* After analysis run is complete the output screen will open. Select Natural frequencies to check the extracted natural frequencies of the system. Most of the time we check the animation view to get a feel of the actual vibration process. So select Natural frequencies and then click on animation button as shown in Fig. 6.
*In the animation view check how the system is experiencing vibration. Accordingly provide supporting. Normally guide and line stop supports with zero gaps will be required to arrest the vibration frequencies. Accordingly provide supporting. Sometimes hold down supports will be required.
* As soon as you will provide guide and line stop supports the system will become more rigid and expansion stresses will increase. So each time you change some support type you have to perform static analysis and make the system safe from all consideration and then proceed to dynamic module.
* As soon as you will provide guide and line stop supports the system will become more rigid and expansion stresses will increase. So each time you change some support type you have to perform static analysis and make the system safe from all consideration and then proceed to dynamic module.
Surge(Water Hammer) Protection System-Water hammer
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