sway brace or rigid strut/stop - how to choose ?

For vertical gravity load, we use spring hanger & rigid rod hanger/support based on the allowable vertcal thermal movement of the attached node.

For horizontal wind/seismic/2-phase flow shock load,do we use sway brace & rigid strut/stop based on the allowable horizontal thermal movement of the attached node ?

regards,

sam

I would say that you should use stops if your systems thermal movements allow you to do it. I would block the line as much as possible taking care of thermal displacement, restraints reactions and nozzles reactions.
In the case of 2-phase flow we talk about vibration, which can be reduce increasing the use of Y supports, guides and stops. The point is that sometimes in a straight section of the system you can not put stops due to the thermal displacement, there is when you need to install something that gives the line the possibility to move due to the thermal grow but to stop during a sudden movement. A sway brace is use to mitigate vibration by the mean of allowing the thermal grow and adding a preset load to the system that will oppose the vibration.

When we talk about wind and earthquake one can install a snubber that will not include a preset load but will give the line the freedom to move and during a sudden violent movement will block and act as an stop.

snubbers do NOT work for wind loads. Seldom is the piping system moved quickly enough to "lock up"

Sirs,

Thanks to both of you for the response to the query.

Luf-Sir is right that hydraulic or mechanical snubbers are mainly employed to counter steam/water hammer or seismic loads, which are of transient nature of short duration. Wind load, although occasional, does not fall in that catagory. Apart from sway brace,rigid strut/stop & snubber, visco dampers can also be used, if FEA software has provision for applying the same.

regards,

sambhu