Implementation of Seismic Stops in Piping Systems

[Mehr_1139]

Because of the snubbers malfunctions and time consuming and costly inspections required for them, the use of “seismic stops” has been taken into account to reduce the piping vibrations . These stops usually have 3-4 centimeter of gaps and are designed in a way to be as effective as snubbers in controlling seismic motions.
If anyone knows any reference for designing the seismic stops, please let me know.

 

[MJCronin]

You are talking about two different issues here ...

You mention "piping vibrations" which are operational vibrations, as I understand, and "Seismic Stops" which become significant during earthquakes.

As I understand, Seismic stops are simply rigid supports with (relatively) large gaps.

Developing design loads for these stops can be done through a detailed Stress analysis using a computer program such a CAESAR-II.

To perform the analysis, you must know details such as the piping materials, configuration, design temperature etc, etc ...and locations where seismic stops can be located.

You must know something about the specific earthquake that you are evaluating.

Oh ..... another point .... Establishing the seismic gap that you are interested in is a bit difficult. The gap must be large enough so that the stop does not touch the pipe as the system heats up.

And ..... it must not be so small so that it does not restrain the pipe during the seismic event...

And that is why I hate the mandated use of seismic stops .... They are an invention of SATAN ....or perhaps an evil MBA ...

This is certainly NOT the kind of problem that I would dump on a NEWBIE mechanical engineer ....



MJCronin
Sr. Process Engineer

 

[KevinNZ]

Have read of B31E. There are simple design rules in this code for low hazard lines that do not require detailed stress analysis.