Is is realistic to provide gaps of say, 60 mm for guides or limit stops to allow for thermal growth and and the same time design for seismic/wind load. Otherwise, if we limit the gap to say, 20 mm, we may need to put more bends, loops to meet the same requirement.

Is there any realistic limit to these gaps pipe diameterwise ?

regards,

sam

This sounds like the problems i have on relief lines.

The pipework expands like crazy during a fire event, which is operationally opposite to trying to hold it steady during a relief

I try to model the systems as accuratly as i can,
if particullar stresses are sensitive to a particular gap, i try to modify the design to eliminate this sensitivity.

Other wise, i designate the particular support with the gaps as a 'Special' which requires detailed design and site verification.

One thing i am aware of, is acceleration.
I am observant that the larger the gap and hence the farther the pipe is allowed to travel (due to non steady loading - wind/relief/earthquake?)
then the acceleration and hence momentum of the pipe starts to become critical.

I would think the answer to your problem is to use nominal support gaps only +/-2mm
and to not have the pipework in an unstable and unguided manner during the occasional event.

Then again, i have never done earthquake.

Gapped boxed guides for thermally displaced piping systems are common and in the scheme of things are more likely to provide needed restraint when required by an occasional load such as earthquake PSV etc.

They must be detailed and documented to assure conformance by construction. Limits of how wide a gap???... No real limit but inspection prior to start up is a necessity.

We often use large gaps especially on guides, but then it would also depend on the diameter of your pipe to a certain extent - a 100mm gap may not seem excessive for a 42" pipeline but then it might be extreme for an 8" pipeline.

When we have large gaps sometimes it is because a +Y support would be suitable for thermal growth, however some restraint is required for the seismic load case.

Also opening up support gaps can help reduce the loads on your pipe supports.

We tend to use a nominal guide gap of +/- 10mm then open up gaps as required around bends and loops.

Thanks to LufSir, TJN & Itchy for help.

regards,

sam

I always worry that a bolt or something will end up in the gap. An alternative is an Anvil (Grinnell) 1306 Limit Stop, but I have never tried one.

The limit stops work well but they are pricey.....

Also Lisega sells a device known as an Ebar which is a similiar gapped device.