Batten Splices
ฝัง
- เผยแพร่เมื่อ 29 ก.ย. 2024
- In another round of "Why we do what we do", this video looks at why internal batten splices are preferred over threaded couplers. Drop any comments or questions below, and subscribe to see more!
[for entertainment purposes only]
What are your thoughts on internal batten splices with pressure plates and set screw, such as the Light Source Mega Batten Splice? Personally, it doesn’t seem secure to me because if the set screw isn’t sufficiently tight, the two pipes could pull apart. Your thoughts Ed?
Some of those splice plates are designed for use on moving battens, and are up to the task, but some are designed only for stationary pipe grid applications and should not be used on pipes that move. Read the manufacturer information carefully to know what your hardware is designed to do.
The only thing I would add is both failed as the internal is damaged and should not be reused, but the threaded coupler was a catastrophic failure and could cause the load the fall where the internal would keep the load in the air
That is a good note - implied but not explicitly stated. Thanks for pointing it out!
Suggests on making a 2-3 ft lifting bar with a safe working weight of 4,700lbs?
Can't answer this well without knowing the application and the design factor needed, but for that kind of load in such a short space, you most-likely will need to use an I-beam or some very hefty structural tube steel.
@@thechicagoflyhouseinc1865 No worries it is for working out lifting a 5,000lb chain with two swivel eye bolts and two hammock swing springs for 800lb ea wrapped around a steel plate while I stand on it. I put a 1/2" 30 long pipe inside a 1 1/2" 30" long pipe and capped the ends as a barbell.
Using internal coupler, the bend strength where batten segments meet is that of the internal coupler. If the coupler is same gauge pipe as batten, its bend strength is less than that of the batten, due to smaller diameter. Bend strength diagram would go something like: -------T------- (Top of the T is where the pipe is doubled). A suitably heavier gauge for the coupler would make its bend strength same or better than that of the batten: _____T_____
Using threaded connector, there are two potential points of failure rather than one: both threaded connections. Thread roots are severe stress concentration points; threads at the bottom will fail in shear, parting rather than bending. This is "off-label" use, they were never intended for this service. They are for plumbing pipes and conduits, which are always to be adequately supported with hangers, clips, brackets, stands.
Would love to see some tests with bolts all in-line at various orientation to see if that has any effect on strength.
100lbs difference around 3000lbs isn't a big difference to me. I suspect the test rig had a lot to do with that. I think a longer span would have far more representative results.
We were also limited by our testing equipment. I think that the internal coupler is drastically stronger than the threaded one, but we could not measure the forces that high.
What type of pipe are you using for the inner pipe? 1 1/4" schedule 40 steel? How big are the bolts and holes?
1-1/4" pipe doesn't fit like you want it to. It is a little more hassle to get the right pipe, which is actually not pipe. It is 1-9/16" DOM (drawn over mandrel) mechanical tube with a 3/16" wall. Our splices are 24" long, so 12" in each pipe, with holes for 3/8" bolts. Holes are spaced so they are 3" from each end of the splice and 3" from each end of the pipe (6" apart at the center of the splice). Holes are turned 90 degrees from each other where the two at the center of the splice both go the same way and the two at the ends of the splice go 90 degrees opposite. I believe that 2-3/8" long bolts with a narrow nylock nut gives the least protrusion. Bolts and nuts should be grade 5 and the nylon locking ring must be fully threaded.