Wrong size pipe problems

[dpak]

So the chorus teacher, on someone else's advice, bought a lot of schedule 40 water pipes to make a grid to hold lights (he had a connection that could get the pipes cheap). The thought was to have them on a base plate on the stage and attach them to the pipes hanging above the stage, then use cheeseboros to attach some horizontal pipes. The problem (or at least one of them) is that the pipes are 2.25 inches in diameter and not 2 inches. None of the cheeseboros he bought fit, and only my c clamps will fit around the pipe. Is possible (and advisable) to make8 hojmemade cheeseboros out of c clamps? Or are there other options to connect the pipes? Or is he just out of luck and money?

 

[Jay T]

Not advisable to home make anything. The most likely reason pipes are wrong size is because plumbing is sized off of Inside Diameter, therefor when you want a 2" OD you order 1 1/2" ID.

 

[Footer]

So they bought 2" sch 40 black iron pipe instead of 1-1/2 sch 40. That is actually a good thing at that 2" is stronger. Give these guys a call, I'm sure they can set you up with the proper sized clamp.

https://scaffoldexpress.com/collections/tube-and-clamp-scaffolding

Thats about as far as I feel comfortable going here. It sounds like this rig might have some other faults that no one is thinking about. If in doubt, pull the plug.

 

[Luke82]

Remember, cast iron cheeseboros and scaffolding clamps are NOT rated for overhead suspension or lifting. Only use pipe grid clamps rated by the manufacturer for a pipe grid application.

 

[dpak]

Quick update - he's able to get the pipe replaced with 1.5 inch pipe (he has a buddy who works for a pipe company). After talking it over, he's thankfully decided against the horizontal pipes. The pipes screw into metal bases which will be attached to a 2x2 sheet of 3/4 inch plywood. They will be attached to a hanging pipe with the cheeseboros.

Thank you for the replies!

 

[cbrandt]

Are the tops getting attached or tied off at all?

 

[dpak]

The vertical pipes reach just a few inches higher than the hanging pipe, so they will be attached to it with cheeseboro clamps.

 

[Footer]

Quick update - he's able to get the pipe replaced with 1.5 inch pipe (he has a buddy who works for a pipe company). After talking it over, he's thankfully decided against the horizontal pipes. The pipes screw into metal bases which will be attached to a 2x2 sheet of 3/4 inch plywood. They will be attached to a hanging pipe with the cheeseboros.

Thank you for the replies!

Hopefully the metal bases look more like this....

And not this...

 

[Van]

As Kyle said above, cast floor flanges, are not meant to be used in rigging, and while cheeseburgers are not "ANSI Approved for Overhead Lifting" it is a commonly accepted practice to use them for temporary rigging of cross pipes on Pipe Grids; I would also argue that in this particular case they are NOT being used as an Overhead lifting device but rather as horizontal stabilization hardware.

Liability is a thing, but, if the boom is supported on the floor both vertically and horizontally (tied to the floor with an accepted boom base <NOT a scd40 pipe flange> and the scaffolding clamp <cheeseburger> is ONLY being used to stabilize the top, by attaching it to a load rated, stabilized Pipe grid, AND the potential horizontal loads to be imparted on the pipe grid by the boom do not exceed it's rated load capacity, my PERSONAL belief is that the application of a cheeseburger would be acceptable. The proper, approved, hardware for supporting the top of a pipe is this.

Oh, and yeah Years ago I did a similar thing where I ordered a ton, well, a 'Lift' of 2" pipe, only to find out that pipe is rated by ID rather than OD. If you want 2" OD <1.9" actually> you have to order 1.5" pipe.

 

[David Ashton]

Pipe is measured by it's internal diameter. Tube is measured by it's outside diameter. This is a common problem which I resolved by making a clamp which fits a variety of sizes and also square tube. Very useful on country tours.

 

[Malabaristo]

As Kyle said above, cast floor flanges, are not meant to be used in rigging, and while cheeseburgers are not "ANSI Approved for Overhead Lifting" it is a commonly accepted practice to use them for temporary rigging of cross pipes on Pipe Grids; I would also argue that in this particular case they are NOT being used as an Overhead lifting device but rather as horizontal stabilization hardware.

And not only that, but any use in a pipe grid is going to be pretty darn similar to the type of scaffolding applications they were designed for, and there is engineering data readily available that could easily be used/adapted to help you determine whether a particular application is safe. Not everything that exists above people's heads needs to be "rated for overhead lifting". It's important to know what does fall into that category and it's not bad to err on the side of over-caution if you're not 100% sure, but it's also important to know what doesn't need to meet that standard.

 

[kicknargel]

And pipe is not really measured by inside diameter either (1.5 sch 40 is 1.610" internal and 1.9" external), but some nominal or legacy dimension. See also 2x4. It's just knowledge you gotta build up.

Just checking on a point Van made: are the "pipes hanging above the stage" that will stabilize these new booms securely fixed and rigid in all directions, or able to move / swing around? Must be rigid for this to work at all.

Pictures / drawings / sketches would help a lot.

 

[dpak]

I've attached a few pictures. It might be hard to see, but each pipe is attached to a hanging pipe near the top. The guy who put it together showed me the math on the load on the cheeseboros for the the horizontal pipes and it feels solid to me. We both tried moving it and it would require a LOT of force to make it move in any direction. Even with all of the movers going, the pipes don't shake. It is temporary, and I don't know if I would use something like this for a theatrical production. If we were to do this again, any suggestions on how to make it even better? It looks like we might need to get different metal bases.
Thanks for all the responses!

 

[avkid]

I've attached a few pictures. It might be hard to see, but each pipe is attached to a hanging pipe near the top. The guy who put it together showed me the math on the load on the cheeseboros for the the horizontal pipes and it feels solid to me. We both tried moving it and it would require a LOT of force to make it move in any direction. Even with all of the movers going, the pipes don't shake. It is temporary, and I don't know if I would use something like this for a theatrical production. If we were to do this again, any suggestions on how to make it even better? It looks like we might need to get different metal bases.
Thanks for all the responses!

You definitely need real bases.
https://entfab.com/products/ultimate-theater-base-plate

 

[almorton]

If your uprights aren't threaded then a tank trap could work better.

Tank Trap

 

[egilson1]

Keep in mind that ALL cheesborough style clamps are rated for horizontal loading only, and not vertical. This is because in a vertical loading situation the holding force is determined by the torque of the nut holding the clamp closed.

BUT, in this application there is almost zero vertical load on the clamp, as the vertical pipie is working as a compression member and taking most of the vertical load. Cast fittings should not be used and as well as threaded fittings. There are some good options out there that are purpose design for this style of application.

 

[Malabaristo]

Keep in mind that ALL cheesborough style clamps are rated for horizontal loading only, and not vertical. This is because in a vertical loading situation the holding force is determined by the torque of the nut holding the clamp closed.

Please clarify what you mean by horizontal vs. vertical loading... in this case, don't the cross-pipes that the fixtures are hanging from present a vertical load on the clamps? If so, that would also describe the forces on all of the horizontal pipes used to support work platforms with tube & coupler scaffolding. You are correct that the clamp/coupler's resistance to sliding down the vertical pipe is determined by the torque of the nut, but that's why they have torque specs in order to ensure an appropriate amount of clamping pressure. It sounds weird to say they're not rated for the exact application they were originally designed for, so I feel like I'm misunderstanding what you're describing.

 

[egilson1]

Please clarify what you mean by horizontal vs. vertical loading... in this case, don't the cross-pipes that the fixtures are hanging from present a vertical load on the clamps? If so, that would also describe the forces on all of the horizontal pipes used to support work platforms with tube & coupler scaffolding. You are correct that the clamp/coupler's resistance to sliding down the vertical pipe is determined by the torque of the nut, but that's why they have torque specs in order to ensure an appropriate amount of clamping pressure. It sounds weird to say they're not rated for the exact application they were originally designed for, so I feel like I'm misunderstanding what you're describing.

You in fact understand correctly. And they don't come with torque specs. For instance the Light Source specifically calls out that their clamps are rated for loading in a horizontal plane only (EG a pipe grid where both pipes are horizontal). The original scaffold clamp which we refer to as a cheeseboro are actually not rated at all due to being cast and not forged. If you want to kill some time (hours) search through OSHA scaffold regulations or manufactures documentation and try to find a torque requirement for scaffold clamps. if you find one, please share it here, as I never have. And I've killed many many hours searching.

 

[Malabaristo]

You in fact understand correctly. And they don't come with torque specs. For instance the Light Source specifically calls out that their clamps are rated for loading in a horizontal plane only (EG a pipe grid where both pipes are horizontal). The original scaffold clamp which we refer to as a cheeseboro are actually not rated at all due to being cast and not forged. If you want to kill some time (hours) search through OSHA scaffold regulations or manufactures documentation and try to find a torque requirement for scaffold clamps. if you find one, please share it here, as I never have. And I've killed many many hours searching.

I know I found a tube & coupler scaffold design guide that had a variety ratings several years ago when looking into it for a scenic design, but I'm not finding that exact guide now from a quick search. I did find info from this vendor that has torque values and slip ratings for their drop-forged products. I also grabbed one of my swivel couplers and it does, at least, claim to meet the same BS EN-74 standard referenced there. So... there may be cast couplers that don't have any rating or meet any standard, but there definitely is a standard that at least some couplers live up to (or claim to meet). Pretty sure I bought these from some generic, online scaffolding supply company that happened to be cheap, so I didn't exactly go out of my way to find special ones either.

I will admit that I don't actually use a torque wrench when assembling these, but 40-60nM is a wide enough range that I feel reasonably comfortable judging by feel. I also don't use them anywhere remotely close to a situation where you could get 10kN on a single clamp and exceed their minimum slip rating.