# Calculating Cantilever Pipe Weight Support

• screwbean
In summary, the conversation discusses calculating the weight a pipe can support in a cantilever situation for a crane application. The calculation is similar to that of a cantilever beam and the shape of the pipe determines the area moment of inertia. The thread also mentions the importance of defining failure criteria and conducting a proof load test. Ultimately, it is recommended to consult a professional crane manufacturer for safety and liability reasons.
screwbean
Hello the forum;
I am brand new here so I beg you indulgence.
How do I calculate the amount of weight a pipe will support if used in a cantilever cituation?

You would calculate it the same way you would do any cantilever beam calculation. The shape will dictate the area moment of inertia.

You will need to define what you consider for failure criteria.

Thank you Fred;
What I am trying to ditermine is will a certain size pipe be strong enough for a crane if the pipe is inserted into a hole in the slab and ground. I would dig a 12" hole 4' deep and use a pipe of 8 5/8" diameter with 1/2" wall thickness. The pipe is made of 60,000 psi material.
The pipe would extend above the floor 5'. The crane would be attached to the top of the pipe and act as a lever arm of 3' in length @90 degrees to the pipe, the load on the crane would be 3200#.

I don't want to pipe to deflect past it' elasticity point.
Thanks

Hi screwbean. From your post, this doesn't sound like homework, so I'll just give you the answer. Yes.

ok, just kidding. Why a 12" hole for an 8" pipe? bearings? This is a jib crane, right?

A 3500 pound load hanging off a horizontal arm (perpendicular to your 8", verticle pipe) and positioned 36" from the pipe centerline gives you a moment of 36x3500 = 126,000 inch pounds. This will produce a stress in the pipe of 5,140 psi. There's an additional axial load which I'll neglect because it isn't much. Deflection is around 0.072". I think you can also neglect column buckling in this case, just not enough load.

If I've interpreted your crane correctly, then you're well within design limits. But what's with that big hole your shoving this in? (I hate giving advice on the net when there's very little description or explanation of what this is used for. Kinda hard to ensure nothing's being overlooked.)

Oh - couple more things. Do a proof load on it just to make sure. If the maximum working load is 3500 pounds, put 1.5 times that much on it and make sure it doesn't break.

And if this is a commercial application, just forget everything and get a proper crane manufacturer to sell you one. You don't want to take the liability if it's going to be used by employees.

Gotcha. Q beat me to the post so I'll just say that from experience and gut feel (not to mention the numbers Q posted) that you'll be fine. I assumed you'll cut such a large hole because you're going to back fill with cement.

You're buckling load is very high so definitely no need to worry there.

Along the lines also of what Q mentioned, we have a lot of hoists and cranes in our facility. We assemble many of them. However, we get an outside company to come in and certify them. If this is for a commercial application, it would be definitely worth the money to do so as well.

## 1. How do I calculate the weight of a cantilever pipe?

To calculate the weight of a cantilever pipe, you will need to know the pipe's length, diameter, and material density. You can then use the formula W = π/4 * (D^2 - d^2) * L * ρ, where W is the weight, D is the outside diameter, d is the inside diameter, L is the length, and ρ is the material density. This will give you the weight in pounds (lbs).

## 2. What is the maximum weight a cantilever pipe can support?

The maximum weight a cantilever pipe can support will depend on several factors, including its length, diameter, material strength, and the distance between the support and the end of the pipe. To determine the maximum weight, you can use the formula W = (3 * E * I * L^3) / (4 * D), where W is the maximum weight, E is the material's modulus of elasticity, I is the moment of inertia, L is the length, and D is the distance between the support and the end of the pipe.

## 3. How do I know if a cantilever pipe needs additional support?

If you are planning to use a cantilever pipe for a specific application, it is essential to consider the weight it will be supporting. As a general rule, if the weight exceeds the maximum weight that the pipe can support, it will require additional support. You can also consult with a structural engineer for a more precise evaluation.

## 4. What is the effect of temperature on the weight support of a cantilever pipe?

The weight support of a cantilever pipe can be affected by temperature changes. As the temperature increases, the pipe's material may expand, causing it to become less rigid and reducing its weight support capacity. On the other hand, a decrease in temperature may cause the pipe to contract, making it more rigid and increasing its weight support capacity. It is essential to consider the potential effects of temperature when calculating the weight support of a cantilever pipe.

## 5. Are there any safety precautions I should take when using a cantilever pipe?

Yes, there are several safety precautions to consider when using a cantilever pipe. First, always make sure to use the appropriate size and type of pipe for your specific application. It is also crucial to regularly inspect the pipe for any signs of wear or damage. Additionally, always follow proper installation procedures and use additional support if needed. Lastly, consult with a professional engineer for any significant weight-bearing applications to ensure the safety and stability of the cantilever pipe.

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