Trapeze Supports
Trapeze Supports
(OP)
Which is better and why.
Back to back channels?
"W" i-beams? Why would a spec not allow "W" shapes?
Thanks for your replies!
Back to back channels?
"W" i-beams? Why would a spec not allow "W" shapes?
Thanks for your replies!





RE: Trapeze Supports
I would use 1-C where possible, keeping in mind that any axial displacement of the pipe above would tend to twist them useless, and a W section for a heavier load.
I've NEVER seen a spec that prohibited W shapes for pipe supports. Probably a mistake. Ask for a variation.
BigInch
-born in the trenches.
http://virtualpipeline.spaces.msn.com
RE: Trapeze Supports
Big inch...you are not a structural engineer, are you ?
The use of a single channel or "C" in a trapeze support in not recommended because you are not loading the member properly. Twisting (shear) is induced in the single C when loaded in this manner
Back-to-back channels are always preferred because the load is applied to the composite member properly and only bending is induced.
-MJC
RE: Trapeze Supports
Anyway getting back to the "C"s .... If vertical loads were small, such that eccentric loading on the C causes only minimal torsion, and axial pipe loads are minimal to nonexistant, as I would be the case if using a swinging support since they don't resist any to begin with, I would not see anything wrong with using a C. Try specing a back to back C on an offshore platform and the maintenance and operation department will schedule you for some open heart surgury.
And I also note that it is really very difficult to avoid torsion or eccentric bending in some form or another when loading a C in any manner, so are you saying that Cs should always come back to back? I say, check it, feel it, smell it. If it works, use it.
BigInch
-born in the trenches.
http://virtualpipeline.spaces.msn.com
RE: Trapeze Supports
RE: Trapeze Supports
BigInch
-born in the trenches.
http://virtualpipeline.spaces.msn.com
RE: Trapeze Supports
The suport system you use should be suited to what your supporting in terms of load, convience of mounting etc.
For pipes I see no point in welding 2 channels back to back
unless its just a one off support somewhere as Big Inch stated its just extra fabrication cost.
For supporting long running pipes there must be off the shelf systems you can purchase similar to the site I found
here:- ht
Further if you use back to back channel which in reality is an "I" beam then they will see a bending load "only" if the supporting threaded rods are mounted evenly about the neutral axis ie you need 4 threaded rods to prevent a torsional load on a back to back channel or "I" beam unless
you decide to put threaded blocks in line with the neutral axis of the "I" beams or back to back channel but again think of the cost.
regards
desertfox
RE: Trapeze Supports
In light of the discussion thus far, I thought I would mention that the ASME B31 Pressure Piping Codes require that the pipe supports comply with the requirements of MSS SP-58. This being the case, it would be prudent to look at a good pipe support manufacturer's catalog to see what MSS SP-58 pipe supports look like. E.G., I don't think you are going to see unistrut in MSS SP-58.
Just a thought.
Regards, John.
RE: Trapeze Supports
BigInch
-born in the trenches.
http://virtualpipeline.spaces.msn.com