My newly acquired 180, and the 2 holes already drilled, with Pics...

ya gasket inside nut on the out in my opinion.

 

Nut on the outside does not always work, nor does it need to be installed that way. I have two sumps plumbed in together where both bulkheads have the nut on the inside. It depends on the installation.

 

For the visual folks:



The gasket between the bulkhead flange and glass is what provides the seal. Now envision water on either side of the glass in that picture; either way there's a seal!

If the gasket is (incorrectly) installed between the nut and the glass, water can still find it's way past the threads of the nut, which then circumvents the gasket.

 

I vote for gasket on the inside, nut on the outside.

Makes the most sense, plus with what evolved noted, you don't have to worry about leaking out the threads.

 

Read the above again please. The gasket ALWAYS goes on the flanged side. In which case, it doesn't matter what side of the glass the flange/gasket is on; it will seal. Putting the gasket (incorrectly) on the nut side provides a leak path regardless.

 

Here's my last attempt at this; see the photo below. If you install the bulkhead correctly, it simply does not matter.

 

Nut out, gasket in is how I did my drilled tank.

If you have a dremel motor you can polish the knife edges on some of those chips. I did when I drilled my tank to reduce risk of crack propogation from a microfracture.

If no dremel, take a wet, low grit paper and hit those really good, IMO. Maybe overkill, but it made me feel better.

 

Exactly! I have (4) bulkheads with the nut out for my overflows and returns, and (2) bulkheads with the nut in where I tied two sumps together. If I remember, I will post a picture up later on. I did nut in as I did not have enough room with both nuts facing out. Putting the nuts in saved quite a few inches.

This is not a vote, nor a one way is better than the other; just keep the gasket on the opposite side from the nut

 

Good catch, I did miss that part. Thanks!

 

Thanks Evo., Marshall, et. al.,

I had understoo the concept about the gasket and all.