Double threaded bulkhead leak issues

[b4tn]

All, am having some issues with a double threaded bulkhead micro leaking. When I first installed it I had no issues for 5 years but on re install it does not leak from the bulk head area but from the threads where the hose barb elbow threads in. I seem to have over tightened the fitting and split the bulkhead most likely because I used dope instead of tape over lubricating it. Its currently outer wrapped in teflon tape so the drip runs down the length of the hose back into the sump area instead of dripping on my floor and I have a new bulkhead arriving tomorrow. The question is whats the rule of thumb for tightening these types of fittings. Seems like you can get them pretty tight pretty easy splitting the bulk head, but not tight enough and they leak. Also, the outer bulkhead gasket in the pic is temporary, once I get the new bulkhead I will only be using the inner gasket.

 

[lolmatt]

Yes they can break easily with over tightening. Teflon tape 3 layers then some potable safe silicone grease will help prevent most leaks. You can grease the little gasket with that stuff too.

You can get actual pvc bulkheads (sch 80 I believe) that are much less likely to crack, but they require larger holes for the same size pipe. Imo use a slip thread (slip on the flange side) or even slip slip, dry fit your stand pipe, glue the outside (cut it out if you ever need to work on it and have a spare on hand).

 

[b4tn]

Yes they can break easily with over tightening. Teflon tape 3 layers then some potable safe silicone grease will help prevent most leaks. You can grease the little gasket with that stuff too.

You can get actual pvc bulkheads (sch 80 I believe) that are much less likely to crack, but they require larger holes for the same size pipe. Imo use a slip thread (slip on the flange side) or even slip slip, dry fit your stand pipe, glue the outside (cut it out if you ever need to work on it and have a spare on hand).

I did not think to use silicone grease, Just over top o the teflon tape? I already grease the gasket lightly.

I almost bought the slip fitting bulkhead to glue just because I know it would be more reliable but did not want to have to cut it out to remove.

 

[lolmatt]

Yeah just a little bit over the ttape on the threads. Gluing pvc is very easy, with an unfortunate side effect of having to wait for the glue to dry. Have you ever had properly glued pvc leak or fail? I have not, especially on a system carrying so little pressure (vs home plumbing).

 

[b4tn]

Yeah just a little bit over the ttape on the threads. Gluing pvc is very easy, with an unfortunate side effect of having to wait for the glue to dry. Have you ever had properly glued pvc leak or fail? I have not, especially on a system carrying so little pressure (vs home plumbing).

I have other places glued and never had issues with leaks. Thats why I would much rather glue the elbow in but I just dont want to have to cut it out if I want to change anything. Even though chances of changing something are slim to none lol

 

[lolmatt]

I have other places glued and never had issues with leaks. Thats why I would much rather glue the elbow in but I just dont want to have to cut it out if I want to change anything. Even though chances of changing something are slim to none lol

You can even glue a street elbow right in the bulkhead and save an inch of space between the wall if your stand will allow being so low profile.

 

[W1ngz]

i can't find the reference, the advice I took was to never use teflon tape for PVC because it increases the outward pressure on the fittings, and makes it more likely to split, particularly when it comes to the small imperfection sometimes created by the seam.

I always use this stuff, completely covering the threads on the female part.

https://www.homedepot.ca/product/oatey-1-oz-white-pipe-joint-compound/1000118480

 

[shred5]

i can't find the reference, the advice I took was to never use teflon tape for PVC because it increases the outward pressure on the fittings, and makes it more likely to split, particularly when it comes to the small imperfection sometimes created by the seam.

I always use this stuff, completely covering the threads on the female part.

https://www.homedepot.ca/product/oatey-1-oz-white-pipe-joint-compound/1000118480

Exactly.. I was always told do not use teflon tape on plastic threads always use plastic thread sealant like:

I have never had a thread leak with it.

 

[b4tn]

Exactly.. I was always told do not use teflon tape on plastic threads always use plastic thread sealant like:

I have never had a thread leak with it.

That is the stuff I used. The problem with it is that it really lubricates the fitting allowing it to be tightened very easily. Now, its very possible that I cracked the bulkhead during the move when I dissembled everything. But putting it all back together I removed the teflon tape that was previously on there, added the plasto stuff and installed it. After a couple days I noticed the drip (its a VERY slow drip). I removed everything and re installed with teflon tape this time and after a couple days it started dripping again thats when I noticed the crack.

 

[W1ngz]

Maybe I'm misunderstanding, there was joint compound and teflon tape on there when you took it apart? Or there was originally teflon tape and you removed it, in favor of PTFE joint compound?

 

[redfishbluefish]

It's been said, No telfon tape on plastic/PVC threaded pipe!

If the bulkhead is cracked, replace it and only use pipe dope (for plastic pipe) to make the seal.

 

[b4tn]

Maybe I'm misunderstanding, there was joint compound and teflon tape on there when you took it apart? Or there was originally teflon tape and you removed it, in favor of PTFE joint compound?

Joint was leak free for 5 years using teflon tape. I moved and had to disassemble and re assemble at the new house. As mentioned above everyone says to not use teflon tape so when I re assembled I used plasto stick pipe dope. Thats when it started leaking. I think the pipe dope allowed me to over tighten it causing a crack. I took it all apart and re installed with teflon tape since it didnt leak before and thats when I found that the bulkhead was cracked.

It's been said, No telfon tape on plastic/PVC threaded pipe!

If the bulkhead is cracked, replace it and only use pipe dope (for plastic pipe) to make the seal.

I may have cracked the bulkhead taking it apart. I will try again with the pipe dope when the new bulkhead arrives.

 

[shred5]

That is the stuff I used. The problem with it is that it really lubricates the fitting allowing it to be tightened very easily. Now, its very possible that I cracked the bulkhead during the move when I dissembled everything. But putting it all back together I removed the teflon tape that was previously on there, added the plasto stuff and installed it. After a couple days I noticed the drip (its a VERY slow drip). I removed everything and re installed with teflon tape this time and after a couple days it started dripping again thats when I noticed the crack.

First of all a bulkhead is not supposed to be super tight.. There is a gasket.. You hand tighten and then do about a 1/4 turn or the gasket can leak or worse you crack the glass... Some just hand tighten..

Forget it you are talking about the fitting and not the bulkhead.. Sorry got lost.

Never had that issue with , maybe put a little more on...

 

[saltyhog]

I suspect the bulkhead didn't crack but may have deteriorated a little over time and didn't seal because of that. If I tear down or move and the bulkhead is more than a year old, I always replace it. They just don't cost that much and a leak or the stress of concern about a leak just isn't worth it to me.

Every plumber I've talked to says to never use tape in pvc to pvc threaded joints. PVC male to metal female is ok to use tape from what I was told.

 

[ca1ore]

I have found that the threads on typical ABS bulkheads are a bit looser ( they lack the taper) than on standard schedule 40 pvc fittings. It’s pretty easy to prove this to yourself by threading in a male fitting without any tape or paste on the threads. You can usually get them to bottom out without much effort. All to say, a larger amount of thread sealant is often needed. These bulkheads are also quit easy to crack, so the recommendation to NOT use tape in this case particularly is wise. I don’t personally use threaded bulkheads anymore, preferring slip/welded. ABS bulkheads are cheap. Plus you’d probably be well served getting rid of those barbed elbows - they are about the worst piece of plumbing for friction losses.

 

[shred5]

I have found that the threads on typical ABS bulkheads are a bit looser ( they lack the taper) than on standard schedule 40 pvc fittings. It’s pretty easy to prove this to yourself by threading in a male fitting without any tape or paste on the threads. You can usually get them to bottom out without much effort. All to say, a larger amount of thread sealant is often needed. These bulkheads are also quit easy to crack, so the recommendation to NOT use tape in this case particularly is wise. I don’t personally use threaded bulkheads anymore, preferring slip/welded. ABS bulkheads are cheap. Plus you’d probably be well served getting rid of those barbed elbows - they are about the worst piece of plumbing for friction losses.

Do you use ABS to PVC transition cement? I was told i should.

I did on my last build but never did before.

 

[ca1ore]

I never have. The standard pvc solvent has always sufficed.

 

[link81]

i use tape all the time on plastic joints. never had an issue. The threaded connections do not need to be that tight though. jenerally i can get by with hand tight, occasionally it needs a little "oof" with a wrench, but never very much. Same with the bulkhead itself, lube it up with a little water, hand tighten, and watch for leaks. if it drips, give it a 1/16 turn or so with a wrench.

you can, and you will crack plastic fittings easily with too much torque.

 

[b4tn]

So far so good. I used the dope and just went hand tight plus a small nudge. No leaks so far. Knocking on wood

 

[Abe K]

I just had my leak alarm go off under my tank and noticed a drip from the bulkhead fitting. I guess I will need to drain the tank to make repairs. I am afraid of trying to tighten it as the fitting has not leaked in over 4 years. Are these fittings anything special or can I pick one up in Home Depot or Lowe’s. Looks like schedule 3/4” 40 piping to me. Any advice is much appreciated.