[SML] pipe grid question

[Bill Sapsis]

Richard

Your Clancy half clamps notwithstanding, my experience with pipe grids says that the weakest point is usually the hanging detailed, especially when the install was done by a non-theatrical company.  

threaded rod, especially the cheap stuff they use on grids, is pretty brittle.  It doesn’t like to bend or twits.  But that’s what happens to it when you add lights to the grid and then take them off.  

The detail at the ceiling usually resembles a sprinkler pipe installation.  C-clamp style beam clamps loading on one side of the bottom flange only.  Again, not happy with the load on/load off scenario.

Load rated full flange center pull beam clamps with chain or wire rope is the way to go.  A little flexibility in the grid is a good thing.  Oak tree -v- willow tree.

We typically use 45 lbs per linear ft of pipe to determine the load rating on fate grid.  this includes self weight. Personally,  I would never use those 200# RWL clamps on a pipe grid.  The full batten clamp has a rating of 750 #.  A much happier connection.

Zat help?

Bill 

bill at sapsis-rigging.com
http://www.sapsis-rigging.com
+1.267.278.4561   mobile

> On Oct 9, 2017, at 11:56 AM, Richard John Archer via Stagecraft <stagecraft at theatrical.net> wrote:
> 
> 
> University engineers are looking at the pipe grids in our spaces (not yet in the proscenium)  .   Seems like an odd time after 30 years in the building ….but…
> 
> Grids are all  kind of typical looking …..two way #40  1 1/2” pipe grid ,  cross grid connectors (so one direction of pipe below the other direction) ,  a bit over 4’ x 4’ spacing….beam clamps with 1/2” threaded rod seemingly  spaced appropriately  The problem is with the  pipe clamps….most appear to be JP Clancy   half pipe clamps (or other manufacturer? Clancy did Proscenium rigging).  Half pipe clamps only have a 200 # RWL  .  Why would anyone install these in a grid?  ….they just adequately  hold up the pipe weight.    Am I missing something here?    Was this some Cornell value engineering at it’s finest?  I’m sure original theatre consultants wouldn’t have spec’ed this (ARTEC) 
> 
> Needless to say, we’ve been hanging  up to maybe 200 fixtures in there for years.  Biggest flexible space is about 50 x 50. 
> 
> 
> 
> DickA
> TD, Cornell U 
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