Attaching bulkheads any silicone or just gasket?

[salth2owannabe]

Just drilled my tank today-
Do any of you place some silicone around the ext. threads of bulkheads or just use the single interior gasket?
Thanks for the help,

[latazyo]

just the gasket

I have never used silicone...some people use it, but I think its crazy

[zeusfc]

Just clarifying... the gasket goes inside the tank, but ONLY if the bulkhead thread is outside...

I've seen a standpipe with the bulkhead mounted the other way around, to get a better seal from the bulkhead to the standpipe, and the poor bloke had to strip his tank down, 'cos he'd put the gasket on the inside too!

[clevername]

DO the gaskets go in the water or outside?

Just restating the question

[JR719]

The "nut" goes on the outside and gasket inside.

[nursefry]

There should be no need for silicone at all. If it leaks then tighten a little bit til no leak. Gasket should be on the inside as others have said. Silicone will just make changes messy to deal with.

[medic29]

I've done it both ways and found adding a little silicone both on the threads and gasket helps make sure there is not a leak. I currently have a test tank set up and since it is a "test" tank I didn't use the silicone and I have a leak around the bulkhead. Tightening it just a little more is not always an option as you can accidently crack your glass by doing that.

Just for clarification....the bulkhead can be installed either way, threads in or out; the gasket always goes on the water side against the glass or side of the tank. I'm not sure why some think the threads always have to go on the outside.

I can't remember where I read it, but someone had suggested using silicone on the threads instead of teflon tape and I have had great success since doing this.

HTH

[DHyslop]

Silicone outgases as it cures--putting some anywhere on your bulkhead may cause pressure to build up and deform the gasket.

You should be just fine without silicone. You only need to hand-tighten bulkheads. If you have a leak take the bulkhead off and inspect it. Sometimes there's a molding line on the flange that needs to be sanded down and sometimes the gasket rubber has a crack in it. Regardless, usually taking the bulkhead out and reseating the gasket will fix the problem.

Dan

[BeanAnimal]

<a href=showthread.php?s=&postid=9447872#post9447872 target=_blank>Originally posted</a> by JR719
The "nut" goes on the outside and gasket inside.


Not exactly...

The GASKET ALWAYS GOES BETWEEN THE FLANGE AND THE TANK, NEVER BETWEEN THE NUT AND TANK!

The FLANGE can go inside or outside of the tank depending on your need (aesthetics, space, plumbing configuration, whatever).

You should NEVER need silicone to seal a bulkhead. That is what the gasket is for. If the gasket will not make a seal, then something else is wrong and you need to fix the problem, not reply on silicone to band-aid it.

[medic29]

I'll have to respectfully disagree, the gasket should go inside the tank. It can go next to the flange or the nut. I do see why it makes any difference as long as it seals against the glass.

Now I may be wrong about this. Bean, it seems we are usually stating the opposite on this issue. I'm more than willing to change my opinion if you could explain why you feel it needs to go against the flange part of the bulkhead.

If the threads are sealed and the nut holds the gasket against the glass and essentially seals it, there should not be a problem.

Maybe all is needed is an explanation.

Thanks

[Acrylics]

Water can seep through between the threads if you put the gasket on the nut side. If silicone is used on the threads, you are defeating the purpose of the threads. Also, once this silicone is cured, removal or tightening (if required) can be very problematic.
It is advised that one put the gasket between the flange and glass, it is also advised to put the nut on the outside, thus the flange & gasket on the inside. If the nut is on the inside, coralline growth on the threads can make removal/tightening problematic.
No one is saying it *can't* work any other way, just that they are designed to work in a specific way so should be used in the way it was designed.

James

[flyyyguy]

defintely flange side, unless you want to use a bunch of silicone to seal the threads

Also twisting the nut against the gasket will make it tend to twist and not seal

[BeanAnimal]

<a href=showthread.php?s=&postid=9449487#post9449487 target=_blank>Originally posted</a> by medic29
I'll have to respectfully disagree, the gasket should go inside the tank. It can go next to the flange or the nut. I do see why it makes any difference as long as it seals against the glass. You may disagree but then you would be wrong :)

Now I may be wrong about this. Bean, it seems we are usually stating the opposite on this issue. I'm more than willing to change my opinion if you could explain why you feel it needs to go against the flange part of the bulkhead.
Certainly. The GASKET seals the bulkhead between the tank and the flange. No water can get through this interface. If you put the gasket between the nut and tank, then water can seep through the threads. The gasket MUST go between the tank and the flange.

The FLANGE can go inside or outside of the tank It does not matter on a glass or acrylic tank. The flange/gasket/tank interface is what stops the water, no matter what side of the tank it is on.

If the threads are sealed and the nut holds the gasket against the glass and essentially seals it, there should not be a problem. The threads ARE NOT sealed. That is not how a bulkhead is designed to work. Trying to seal the threads is trying to use a bulkhead in a way it was not designed to be used. Trying to seal the threads is asking for problems and doing things the hard way.

Hope that helps :)

[medic29]

Okay, I'll accept this and admit my thinking is probably somewhat off and can understand it is most likely best to have the gasket next to the flange.

I do have to say that the bulkhead is "desigened" to make a watertight opening through a solid object. It doesn't matter whether or not the threads are on the inside or outside. If you look at bulkheads that are used in holding tanks or water jugs, etc, many times the threads are located on the inside.

So, all in all, gasket next to the flange.

[BeanAnimal]

Now for some more info:

If you have a tank that has an absorbant core (like a plywood tank) and if the HOLE in the tank is not sealed to protect that core...

Then you will want put the flange in the INSIDE of the tank. Putting the FLANGE on the outside of the tank will expose the core of the back panel to the tank water. Remember it is the gasket against the tank wall that makes the seal. If the gasket is on the outside of the tank, then the tank walls core is exposed to the water and will soak it up and leak or delaminate.

[BeanAnimal]

<a href=showthread.php?s=&postid=9449758#post9449758 target=_blank>Originally posted</a> by medic29
Okay, I'll accept this and admit my thinking is probably somewhat off and can understand it is most likely best to have the gasket next to the flange.

I do have to say that the bulkhead is "desigened" to make a watertight opening through a solid object. It doesn't matter whether or not the threads are on the inside or outside. If you look at bulkheads that are used in holding tanks or water jugs, etc, many times the threads are located on the inside.

So, all in all, gasket next to the flange.

Yes, that is exactly what I have been saying. It does not matter if the threads go inside or outside (except as I have noted above). And it is not "most likely best" it is required :D

[BeanAnimal]

<a href=showthread.php?s=&postid=9449639#post9449639 target=_blank>Originally posted</a> by Acrylics
It is advised that one put the gasket between the flange and glass, it is also advised to put the nut on the outside, thus the flange & gasket on the inside. If the nut is on the inside, coralline growth on the threads can make removal/tightening problematic.

James

And of course, as James points out... putting the NUT on the inside of the tank can cause its own problems.

[Acrylics]

<a href=showthread.php?s=&postid=9449758#post9449758 target=_blank>Originally posted</a> by medic29
I do have to say that the bulkhead is "desigened" to make a watertight opening through a solid object. It doesn't matter whether or not the threads are on the inside or outside. If you look at bulkheads that are used in holding tanks or water jugs, etc, many times the threads are located on the inside. I'd have to respectfully disagree :)
http://www.haywardindustrial.com/html/prods/prod.asp?TLDID=2&ProdID=26

Hayward specs out to have the nut on the outside, "Hayward Bulkhead Fittings have been designed so that only one person is needed to install it, not two. A special hex shape on the body end of the fitting allows it to be gripped from outside the tank while the nut is tightened".
Read the instructions with *any* of their bukhead fittings. The bulkheads are designed to be tightened from the outside. If you have a tank full of some chemical, you drain it to the bulkhead level. If the nut was on the inside, you'd have to get inside the tank to loosen the nut with chemicals still in the tank - not exactly a good idea :)
The aquarium industry is incidental to their main line of business, the fittings were designed with their primary customer base in mind.

James

[DrHank]

Has anyone used (and would there be any benefit to) a thin coating of plumbers silicone grease on the gasket prior to tightening?

[IMAGINEER]

hand tighten ? I see wrenches for them , but about how much torque spec on it?
J

[BeanAnimal]

The grease can cause the gasket to slip and deform. If you are having problems it may be worth a try.

Hand tighten then 1/4 to 1/2 turn with a bulkhead wrench. Too much and you will either crack the nut, cause the nut to jump threads, or deform the gasket.