1" TC ferrule hole size

[Maltose]

I'm having 1" TC ferrules welded onto my brewhouse vessels:
http://www.brewershardware.com/1-Tri-Clover-Ferrule-Long.html

How big should the hole be that I punch out to have these welded in?

 

[Junkster]

I would say give it to the weldor and let him do it to get the fit that works for his approach and any finishing work he may do.

 

[Malric]

I recently did 1.5" tc long ferrules and used a 1.5" step bit. I was freaking out, but it end up fine.

 

[Airplanedoc]

Mark where you want the ferrule and let the gut welding it cut the hole himself. He will be much happier