What size and shape of steel tubing is needed for a belay bar on a slackline?

In summary, the Expert says that they need a certain size of tubing, and that a sliding pulley would be a great idea. They would also like to have a pulley to keep the belay loop over the person walking on the slackline.
  • #1
josephd
2
1
I am trying to complete a project and have to properly size some steel tubing. The project is a belay bar for a slackline we have in the yard.

I have 2 poles that are set in the ground 21' apart and a slackline runs between them. We want to run a steel tube beam, permanently attached to the posts, that will act as structure to attach a belay line to the kids in case they fall off.

Ive attached a sketch of the set-up. The belay line will attach around the tube and to a harness the kids wear.

I'm figuring the max load at 500lbs and max fall distance at 18". I'm not sure I've given all the info needed but I do appreciate any help.

My question is what size tubing do we need and what shape would work best?

steel tube.jpg
 
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  • #2
Thread closed temporarily for Moderation...
 
  • #3
Thread re-opened.

Welcome to the PF. We try to be careful about allowing discussions of potentially dangerous activities, so the Mentors needed to discuss your thread a bit before it could be re-opened.

Can you say a bit about your mechanical background? From your sketch, it looks like you at least have training in drafting, and maybe more.

How are you planning on securing and bracing the two end poles? Are you going to have a sliding pulley on the belay bar, to make it easier to keep the belay loop over the person walking on the slackline? What is the ground like under the slackline? Concrete, grass, sand?
 
  • #4
Thanks for the reply.
So, a bit about my background: I have a Bachelor of Architecture Degree that hasn't been used for 15 years. ;)
I have experience in construction and welding, but not expertise.

The two poles are in the ground 6'-6" and are old telephone poles. They are currently not braced at all and the slackline is being used.
The ground under has a built up bed of pea gravel approx 8" deep.
A pulley sounds like a great idea. I would like to have some sort of pulley to aid the belay staying over the person.

Right now my kids and friends are using the line I'm just trying to reduce the chance of injury.
 

1. What is the purpose of sizing steel tubes?

The purpose of sizing steel tubes is to ensure that they have the correct dimensions and tolerances for their intended use. This ensures that they can be easily connected and used in various applications, such as construction, transportation, and manufacturing.

2. How is steel tube sizing determined?

Steel tube sizing is determined through a combination of calculations, measurements, and industry standards. The most common method is to measure the outer diameter, wall thickness, and length of the tube, and then compare it to the appropriate sizing chart or standard.

3. What factors affect the sizing of steel tubes?

There are several factors that can affect the sizing of steel tubes, including the intended use, environmental conditions, material composition, and manufacturing process. These factors can influence the dimensions and tolerances needed for the tube to perform its function effectively.

4. Are there different sizing standards for steel tubes?

Yes, there are various sizing standards for steel tubes, depending on the industry and country. Some common standards include the American National Standards Institute (ANSI), International Organization for Standardization (ISO), and American Society for Testing and Materials (ASTM).

5. Can steel tubes be resized after manufacturing?

In most cases, steel tubes cannot be resized after manufacturing. However, some specialized processes, such as cold drawing and sizing, can be used to produce tubes with precise dimensions and tolerances. It is important to consult with a qualified engineer or manufacturer for specific sizing requirements.

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