Pipe Gate Design - Deflection

[rave426]

This is a simple project, but I want to have some data to back up my logic. I have not done a calculation like this is years, so I want to make sure I'm correct.

I am having to use 2" Schedule 40 piping for a pipe gate and I want to make sure that there wont be too much deflection.

Using one gate arm as an example:

1. Stake Piping will be placed in the ground about 6'
2. The gate arm will be welded on stake piping at about 4'above ground level and will span about 21'
3. A support arm will be welded on stake piping at aobut 1' above ground level and we welded at about 14' on the gate arm
4. Schedule 40 piping is about 3.65 lb/ft with 2.38" OD and 2.07" ID. Yield strength is about 60,000 psi.

I'm trying to ensure I'm not inducing too much stress/deflection due to the weight of the pipe.

Does anybody know a quick calculation for this?

Quick sketch below

 

[cvg]

the vertical member is the one I would be most worried about. it should be 4 or 5 inch diameter

 

[azcats]

It seems like the failure I most commonly see with these types of gate is the foundation. I think they are often not embedded deep enough.

And I agree that 2" 'seems' too light.