This is a large clamp I built to pre-load 2" diameter brushed stainless steel hand rail tubes before welding. Normally when you weld the hand rail tube to the top of a stanchion, the hand rail tube will distort. If nothing is done to prevent or correct this, then when you are done you can sight down the tube and you will see that it looks lke a suspension bridge, and each stanchion is a tower.

I came up with this device so I could put a slight preload in the hand rail tube so after the weld contracted the tube would be straight. What's more, this thing ended up so strong that it can even bend the tubes straight after the fact.

You will also see my favorite way to hold the tube against the stanchion tops while tacking. A simple clamp is attached to the stanchion and stainless steel safety wire is used to cinch the tube down.

I have made adapters so this can also be used for 1-1/2" hand rail tube.