Which Nut on Top, Which on Bottom

[Jimmy H NYC]

I am replacing the site glass on my Bryant 235A Natural Gas fired steam boiler, and I noticed that there are two different kinds of nuts (see photo). One is kind or smaller and rounder, and the other bigger and boxier. I don't remember which one was on top and which on bottom of the site glass. My sense is that it does not matter and they are basically the same. Am I right? (See photos) Thanks for your help!!!!

 

[Smooky]

It doesn't matter, they do the same thing.

 

[Sponsor]

 

[rjbphd]

Pair of nuts isn't the problem, most from using gasket without friction ring.