Jestersix

Threaded bulkheads are NOT NPT threaded?!

Vincerama2

Vincerama2

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I decided to replace the original bulkheads for the in/out drains in my AGA/Oceanic 180.

I bought some threaded bulkheads and discovered that the threads don't appear to be NPT !

ie; I can screw in a male x slip adapter (ie male threaded adapter for PVC pipe) and as you screw it in, it does NOT get tighter/waterproof.

Is this how they all are? I can't compare the originals because the original owner glued the threaded adapters into the old bulkheads (maybe this is why).

Is this typical? I tried teflon tape (maybe not enough) but I think I'm going to get some silicon to make sure it's sealed. This just seems odd that a bulkhead would not have NPT threading on it!

BTW, for those that don't know, all those PVC fittings we use, when you tighten them together, they get tighter because the threads are tapered so that they seal themselves. This bulkhead has threads like a nut and bolt, they don't get tighter.

V
 
No, every single bulkhead I have used in 30 years has had proprietary threads for their nut. Some are closer to NPT then others, but none are actually NPT :(
 
Only the nut that comes with the bulkhead will fit the threads on the outside of the bulkhead itself. Anything that you want to attach to the bulkhead needs to either slip inside or screw inside (depending on whether you bought a slip or threaded bulkhead).

I've never seen a bulkhead work any other way. I think they do this on purpose to keep us from making silly mistakes.
 
They do it due to proprietary threading from what I have been told by a few manufacturers. They patent the thread angle, etc. There is no reason not to connect to them and I have made quite a few adapters in my day for them. Its not hard.

When I tried to make produce a wrench for bulkheads I ran into a patent infringement on just about any style of configuration I could think of (angles, bites, etc). So frustrating.
 
No, I mean the INSIDE threads, not the nut threads. If they give you the nut, then that's no big deal, but I wanted to connect pipes to the bulkhead so it has threads on the INSIDE for conencting to other plumbing, and it's not tapered.

My question is, once the bulkhead is installed, how can the dry side not leak if the threads (not the outer nut thread) are not tapered?

Which is also weired because my male threaded adapter, which is tapered can easily screw in all the way.

I'm sure that both male and female threads must taper for a good seal.

V
 
I know male threads are tapered so as you screw it in, it's gets tighter as you mentioned. I would try to put more Teflon before silicon.

I don't know what kind of bulk head you are using but sometimes the abs ones are the funky ones. And I would be carful with the abs ones because some are thin and could split.
 
There has been a huge discussion on RC about PVC and teflon tape and paste. Spears does not recommend using either the teflon tape or paste but a product called 'Blue 75 Pipe sealant'. I have not found this product at Home Depot.

If you must use teflon tape or paste, use it correctly. Two to three wraps, applied clockwise and pulled tight. Don't over tighten. 1-2 turns after hand tight.

From their literature:
"Some “pipe dopes” and pastes contain chemicals that can produce stress cracking in plastics"

I'd stay away from the silicone used to seal glass aquariums. This is a case of 'More is not necessarily better'. A properly made up connection (see above) will not leak. For house plumbing these connections can handle 125psi or more. In our drain systems the pressure is almost zero. If that leaks, well, you did it wrong or the materials are defective.
 
sfsuphysics said:
Don't use teflon tape if you can avoid it. Use silicon based sealants (not those you use to seal cracks around windows)
Click to expand...
Could it cause a problem with our tanks? I figured this will still allow you to service the bulkhead and not have a hard time backing out an adapter or something.
 
Marc said:
Could it cause a problem with our tanks? I figured this will still allow you to service the bulkhead and not have a hard time backing out an adapter or something.
Click to expand...
As far as I know there is no chemical issue. Other sealants exist that allow you to "change your mind". The comment I made is due to two main reasons. 1) Potential for incorrect tightening, teflon tape is not really designed to seal (even though it does) the threads do the sealing, the tape allows you to tighten it good 2) PVC manufacturers do not recommend using it, now whether they mean under the pressurized conditions they expect their pipes to be under or in general sense I don't know but being as they make the stuff some leeway can be given to the ambiguity of it for now.

Now can you use teflon tape? Absolutely. Will something bad happen if you use teflon tape? probably not unless you're careless with it. Most people use it because they have it sitting around, or the guy at home depot told them that's the stuff to use
 
Interesting "Blue 75 Pipe Sealant" I'll look for it.

Normally, the NPT tapered pipes are great, they get tight as you screw in the fitting and I'm confident of the seal. These bulkheads though, I can screw the make adapters in all the way until the bottom with no tightening.

These are ABS bulkheads from "Bulk Reef Supply", and I trust them on selling aquarium correct plumbing. I've asked them a question via email, but have not had a reply.

For the inside tank side, it's OK if it leaks a touch, since it will hold a Durso standpipe and/or the return pipe, so any leakage is into the tank or into the return pipe. However, for the connection beneath the tank, obviously a leak would not be good.

If I can find that blue 75 stuff, I'll use that, otherwise marine goop or something that is not permanent, but can seal the threads.

I've screwed in the male adapter into another female threaded pipe and it tightens, (plus I think all the pvc adapters at HD/Lowes are all NPT threaded) so the issue is the bulkheads.

I bought these bulkheads to replace the originals which have chewed up threads and older gaskets. Unfortunately, the original owner used some sort of blue cement or something (maybe this is why?) to permanently connect some fittings into the bulkheads.

If I find the blue 75 stuff, I'll post where I found it.

V
 
What bulkhead was it? The good schedule 80 ones from Bulk Reef Supply have been
properly tapered, and worked well for me.
Was the male thread -> slip good quality? Schedule 80?
Could just be bad luck with a manufacturing issue?

My opinion will remain : Use lots of silicone!
It lubricates, so easy to tighten.
It stop leaks, and you do not have to over tighten.
It allows you to take things apart later.
Plenty of data showing it is fish safe, and is usually labeled as such.
Easy to get the right type at the local hardware store.
Make sure to let it dry well though.

There might be better sealants for certain tasks, but the combination above is hard to beat.
 
Message overlap. Looks like you answered my first question.
Warning : I have had one of the cheaper ABS bulkheads from BRS crack.
(I over tightened it because it was leaking .... )

My suggestion : Return it, and buy the good schedule 80 ones.
 
why didn't you use slip connectors then glue them on the outgoing side?

I'm as cheap as cheap can be, but I've learned that spending $5-10 more on a new bulkhead is well worth the cost considering I've NEVER had to take them apart. And if I did need to get at the pipe for some reason, cut the pipe then spend a buck on a coupler to glue them back together.

(I say this as I currently have slip fittings that aren't even glued... but that tank should be coming down within a month or two so no worries about all the drips... I have cups to collect the drippings :D)
 
I didn't use slip x slip because I wanted to be flexible in the plumbing if I decided to change anything. Also, the tank came with fpt x fpt, so I was going to reuse them, then changed my mind. I had no idea if abs or pvc bulkheads were better.

I bought some "Rectorseal 5" which is pipe thread sealant suitable for potable water. I'll use that.

I just gotta put this stupid thing together and if there are flaw, I'll just have to adapt ... as long as the flaws don't include leaking.

Any local stores sell bulkheads? I ordered mine online.

V
 
sfsuphysics said:
As far as I know there is no chemical issue. Other sealants exist that allow you to "change your mind". The comment I made is due to two main reasons. 1) Potential for incorrect tightening, teflon tape is not really designed to seal (even though it does) the threads do the sealing, the tape allows you to tighten it good 2) PVC manufacturers do not recommend using it, now whether they mean under the pressurized conditions they expect their pipes to be under or in general sense I don't know but being as they make the stuff some leeway can be given to the ambiguity of it for now.

Now can you use teflon tape? Absolutely. Will something bad happen if you use teflon tape? probably not unless you're careless with it. Most people use it because they have it sitting around, or the guy at home depot told them that's the stuff to use
Click to expand...

aqua-nut said:
There has been a huge discussion on RC about PVC and teflon tape and paste. Spears does not recommend using either the teflon tape or paste but a product called 'Blue 75 Pipe sealant'. I have not found this product at Home Depot.

If you must use teflon tape or paste, use it correctly. Two to three wraps, applied clockwise and pulled tight. Don't over tighten. 1-2 turns after hand tight.

From their literature:
"Some “pipe dopes” and pastes contain chemicals that can produce stress cracking in plastics"

I'd stay away from the silicone used to seal glass aquariums. This is a case of 'More is not necessarily better'. A properly made up connection (see above) will not leak. For house plumbing these connections can handle 125psi or more. In our drain systems the pressure is almost zero. If that leaks, well, you did it wrong or the materials are defective.
Click to expand...

You two should watch SPEARS video.

Please note they do not suggest pipe dope and why
Also please note the two products they do recommend
:D

 
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