Good day all, Please I would like to know If its a good design practice to have REST SUPPORTS(+Y) on ALL alignments for large bore (e.g 68") pipes on the pipe rack?.
I am more concerned about the technical(workability)aspect of the system. (flexibility,rigidity,load distribution etc )
Thank you for your anticipated response.

IMO it is okay but you should consider occasional events(earthquake, wind, etc.). also check your local stress you will need pads.

Regards!

Not sure quite what you are asking here, but if you are suggesting supporting a 68" line on ALL bents of a pipe rack, the answer is ... look at the allowable span first and do check local stresses. You don't want a support every 6m on a 68" line, more like every 18m.

Hi caesarian,

In my opinion, the answer to your question depends mainly on the design of that piperack.The best thing to do would be to talk to your civil engineer who is in charge of designing the piperack especially when dealing with such huge loads.
I hope my answer is helpful to you.

Vapor or Liquid? In a 68" line, that's the difference between about 360 lbs/running foot and 1900 lbs/running foot!

but,there is important question,how to simulate the support?

Well, with lines that large, you don't want to neglect the movement due to radial expansion. I would model a rigid element from the centerline of the pipe, down to the OD and put your Y support there.

That will get you your globals loads and stresses. But, as was noted, you are likely going to need some kind of FEA to check the local stresses. A Pad may not be sufficient. You may need a full blown saddle, even if you have no insulation. Details....details....details! Don't forget 'em.

Talk to your civil, and agree a criteria. A possibility is to calculate the weight for a 18 meters span and place that load in the civil calcs every 12 or 6 meters, that is because you don’t know precisely how is going to be the distribution of loads. This criteria would be conservative.

Since you asked about rigidity and load distrubtion.....

My recommendation is to consider the stiffness of all of your support beams if they are not all the same.

My experience with large heavy lines and smaller support members is that the pipe will deflect as it pleases and the beam will deflect with it while the stiffer supports beams will carry the bulk of the loads.

The support contribution the smaller beam members will provide will be the pipe deflection times the support spring constant at the support point.

Good luck,

Also check for high local stresses at support locations.Formulas are available in Roarks.

For me a pipe resting on all the members of a pipe rack will simulate to a pipe simply resting on the ground if the support span is too small. On the other hand if the span is more it becomes a piping with descreate supports which we normaly analyse using caesar2. By providing pads or shoes we can get it supported only on the desired members alone. In the first case also practically it need not be resting on all the members, because of pipe body deflections caused by weight or expansions which can not be avoided in any temperature variations.
Another thing is the hammering effects which can transmit loads to the pipe rack structure with this large pipe diameter and depending on the type of fluid. Only a word of caution!!!.