Silicone bulkheads - gasket or not
 

I'm in the process of installing some gaskets and I want to be 100% sure they will not leak so I will be sealing them with silicone. Should I just use silicone for the seal or should I also install the gasket?

If you use silicone with a rubber gasket it will just act as a lubricant to help squeeze the rubber out when tightened. Just use one or the other, but not the two together.

Also, if your going to use silicone. Let it cure a bit before tightening the fitting. :)

I would put silicone on both sides and along the threads and then tighten it up, wouldn't worry about letting it cure unless you want to be able to take it apart again easy. if you let it cure that mean one side won't bond fully and thus the possibility of a leak at some point maybe.

Steve

I put a thin film on both sides of the gasket, yes it probably helped in sealing but does seem to make the gasket want to slide out even when tightening slightly. Bit on the threads will help lock the nut.

Putting a thin seal of silicone on the gasket is just a set up for leaks down the line. The silicone will wear, as it is apt to do, forming channels between the glass and the gasket.

how about putting the gasket on normally and then siliconing around the bulkhead?

Cheers,
Aquaman

Ive never siliconed a bulkhead.But when I use it on an engine,I run a good sized constant bead.Tighten up the bolt untill its just pushing into the silicone,then let dry.After it dries I tighten up the bolt.This way the silicone works as a gasket.Dont see why it wouldn't work the same on a tank.So far on a tank Ive found the gaskets work well enough alone.

I would suggest using the gasket (on the inside of the glass), tightening the threaded nut and then using a thin bead of silicone around the gasket just as a precaution. This has worked fine for me.

I had a hell of a time getting the bulkheads drip-free when I plumbed my 120, but I finally got it to work with no silicone.
My first try around, I used the gasket on the inside and silicone on the outside.. Drip drip dip.
Second time, silicone on both sides.. Drips!

The third time, I forewent the silicone and just used one gasket and tightened the hell out of it.. Drip!

Finally, I hand-tightened in, but only about as strong as I could do with my left hand (being right handed).. Not a single drip in six months..

Though I see a drip forming in my drain line plumbing... I think the next time I do this, I'll splurge and use PVC primer before cementing!

Dont use silicone.
If the fitting does leak,now or eventually...its a nightmare to prep for another seal..let alone even getting the nut back off.

90% of bulkhead leaks are just from the gasket being dryfitted.
Wet the gasket before tightening, making sure the gasket is on the "wet" side of the wall.

If you want to make absolutley sure it wont ever leak, place a rubber gasket on the wet and dry side, with an additional cork gasket after the rubber on the nut side.
WET both rubber gaskets prior to assembly.
Youd almost have to try to make that combination leak.

The only time silicone should be used, is if the hole was done poorly, and chipped out more than half the gasket width on the wet side.

Marc.