Hello!

I don’t quite understand what you mean by lifting one.

If it is what I understand in the picture below:

A total of 20 kilograms, plus a few kilograms of the square tube's own weight, 10cm from the midpoint of the load-bearing beam, and an expansion screw (above 8mm) on each ), the load-bearing capacity is sufficient.

If you are sensitive to end deformation, use a square tube with a size of 25x25x1 or above. The deformation does not exceed 10mm when bearing 10kg on one side. The larger and thicker the tube, the smaller the deformation.

You can also use rectangular tubes, such as 10x30, or 20x40, etc.

To sum up, it is safer to use 30x30x1.2 stainless steel square tube.