So I have been given a load limit of 65 Pounds per Linear
Foot for a
grid ........... The
Grid is a 6ft square
grid supported by 1/2" steel rods at every junction but not secured to the walls at all. ......... the
grid is made out of standard 1.25" Schedule 40 pipe.
Got a couple of questions/points here.
First, standard loading per linear
foot recommended by
ESTA, and every rigging company and installer that I know of is 30 pounds per linear
foot.
Second: A
pipe grid that is not secured to the side walls and hung from rod is far against all good rigging practice unless substantial cross bracing is incorporated into the design.
Third: "Standard" pipe used in entertainment industry for hanging lights is 1 1/2" not 1 1/4".
Forth: 1 1/4" pipe is not rated to support 65 pounds per
foot on a 6'-0" span.
If this
pipe grid design is built and installed as you describe, there will be some serious
safety concerns and I for one, would refuse to work on or under it.
Oh, by the way, I've been designing and installing, rigging and pipe grids for over 30 years. I've installed over 100 pipe grids in schools TV studios, black boxes and
etc. so i do have some slight knowledge of the subject.
Here is an excerpt from InterAmerica one of the Nations' premier
pipe grid and tension
grid manufacturers and installers.
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Our standard
grid specification is based on a linear
foot live load of 30 pounds per
foot. Special considerations are required for heavier loads, especially
point loads. Examples of a heavy
point load might be a 250+ pound
speaker or TV
monitor
The standard
pipe grid consists of 1-1/2†schedule 40 steel pipe battens crossing at right angles. The upper
level of battens run
in one direction and is suspended from the building structure. The lower
level of battens is clamped perpendicular to the upper pipe battens. Our cross clamps are the heaviest duty found in the industry. Our clamps lock the crossing pipes together at a perfect 90 degrees.
For lateral stability, at least two ends of the
pipe grid should be attached to walls. This attachment can be a support shelf running the full width of the
grid along each wall, or individual wall flange brackets.
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