Thank you for your question. The threaded male end is 3/4" pipe thread which measures 1" in diameter. It is designed so a 1/2" pipe thread fitting can thread inside of it or a 3/4" pipe thread piece can thread over the outside of it.

The shank is pretty short. I don't have an exact measurement but it fits in my kettle with barely any threading exposed after the lock nut. My Kettle wall is 1.4mm thick. I'd say the usable length of the shank is something close to 1.75-2mm.

From the manufacturer's installation instructions: Unscrew (and remove everything...) Insert the larger threaded side of the bulkhead through the hole in your kettle from the outside. Replace the Red Gasket then the Stainless Washer and then thread the Lock Nut back on using wrenches or channel locks to tighten until snug. Summary: from inside of kettle to outside it's nut/washer/gasket/kettle-wall/bulkhead.

i mount the o ring and washer on the inside just like the picture

I install them in this order from the inside. Locknut-steel washer-rubber washer-kettle wall-outer threaded flange nut. No issues with leaks if your hole is the correct diameter.

Gasket and washer on the inside

Throw the washer away. It will leak if you use it. I believe I put the seal on the inside. Could not get it to stop leaking while using the washer.

(in order) washer gasket hole gasket washer...tighten! Lots!

Gasket and washer inside keep stuff out of hard to clean hole and use Teflon plumber tape to seal threads

Yes gasket on the outside nut and washer on the inside.

Have two of these on one of my kettles. Red silicone washer goes on the inside of kettle. I used the provided washer on the inside as well with a little keg lube so it doesn't misshape the gasket. Take it apart and clean it every few brews and replace the red gasket after a year regardless. So far haven't had any leaks installing it that way. Good fitting in my opinion.👍

I put the gasket then the washer then the nut on the inside of mash tun