Threaded vs Slip Fittings for Plumbing a tank

[CJ Monty]

Dumb question why use slip fittings for the expensive pieces such as union, gate valves, or union ball valve. My understating when glued it is pretty much impossible to get the pipe out. Seems like it worth while buying male adapters for under a buck a piece to be able to reuse 20+$ fittings. Also if you use threaded at the end of the run pipe it acts as a union.

I understand threaded fittings reduce the amount of pressure the piping can take by about half but reef plumbing is considered low pressure.

 

[Joekovar]

One thing to remember with threaded vs slip is that it's possible to over tighten threaded fittings which will cause the fitting to crack eventually and not only leak, but leak a lot and suddenly.

 

[ThePlummer]

Threaded fittings are 'mechanical' in nature, and everything mechanical WILL eventually fail. Slip fittings are 'solvent welded' (the plastic is actually melted and creates a permanent bond. Usually, if you need to reuse the fittings, just cut the pipe that's glued into them and leave enough hub depth to engage into another coupling and take right off again.

 

[Greg Goby]

I can think of a few things, granted I have pretty limited experience.

If you tighten say, a 90 degree threaded fitting all the way onto a piece of pipe, will it necessarily be pointing the proper direction when it is fully seated?

When I have played around with dry fitting threaded pieces I have accidentally tightened them enough where I couldn't loosen them by hand again. I am thinking that once these fittings are in place on a tank and get some salt creep inside them, they won't come undone easily at all down the road, especially in cramped quarters where you may not have the best leverage.

It would be a headache to get everything put together and realize that the threaded fittings are just not water proof enough. Then you would have to use thread sealer (permanent bond), teflon tape (not designed for PVC and unsightly), or redo plumbing with slip fittings and PVC cement.

 

[RocketEngineer]

Because $20 valves are pocket change compared to the $200 pump, $800 controller, or $1200 in lighting. I don’t know about everyone else but I plan my plumbing out so I only have to assemble it once. The next time I need to change out the plumbing, it’s because I’m going to a different tank. JMO

 

[DSEKULA]

There's no reason to take your plumbing apart if you plan well, slip fittings are the better long term hold. I'm a little curious why you would take fittings apart often enough that $20 will break the project?

 

[CJ Monty]

I can think of a few things, granted I have pretty limited experience.

If you tighten say, a 90 degree threaded fitting all the way onto a piece of pipe, will it necessarily be pointing the proper direction when it is fully seated?

When I have played around with dry fitting threaded pieces I have accidentally tightened them enough where I couldn't loosen them by hand again. I am thinking that once these fittings are in place on a tank and get some salt creep inside them, they won't come undone easily at all down the road, especially in cramped quarters where you may not have the best leverage.

It would be a headache to get everything put together and realize that the threaded fittings are just not water proof enough. Then you would have to use thread sealer (permanent bond), teflon tape (not designed for PVC and unsightly), or redo plumbing with slip fittings and PVC cement.

Yeah you have to tighten the fitting all the way when dry fitting and the cement the pipe in the direction it should face.

Your point about salt creep and where the thread fitting is a great point. I can see a union behind the tank instead of a thread fitting. Even then a thread union might be the best of both worlds.

Why do you say teflon tape is not designed for PVC? I have used it in the past with no issues.

 

[CJ Monty]

Because $20 valves are pocket change compared to the $200 pump, $800 controller, or $1200 in lighting. I don’t know about everyone else but I plan my plumbing out so I only have to assemble it once. The next time I need to change out the plumbing, it’s because I’m going to a different tank. JMO

I agree relative to other cost in the hobby its nothing. But I would like to keep as much in my pocket plus it seems wasteful to just throw it away. I am going to a new tank. I used a threaded gate valve on my old one. Now I do not need to buy another one.

 

[CJ Monty]

There's no reason to take your plumbing apart if you plan well, slip fittings are the better long term hold. I'm a little curious why you would take fittings apart often enough that $20 will break the project?

If they are better long term than that is great reason to use them. I was not aware there was a better long term type. $20 will not break the project at all. It is about planning to reuse as much as you can.

 

[DSEKULA]

If they are better long term than that is great reason to use them. I was not aware there was a better long term type. $20 will not break the project at all. It is about planning to reuse as much as you can.

I suppose, I guess I just consider my tank more of a permanent fixture so by association so is the plumbing. I won't reuse it because I never plan on moving the tank . I guess if that's not your situation and you plan on moving or something the logic makes sense but I've never plumbed anything with the intent of moving it later.

 

[Crustaceon]

I slip fit and glue everything. Pvc plumbing is cheap and leaks are expensive.

 

[samnaz]

I’m not concerned with reusing $20 fittings. Never even crossed my mind when I plumbed my tank. I want leak free, easily accessible, easily removable if need be. Slip fittings only, and lots of unions. Unions are worlds different than threaded fittings if you ask me, if nothing else unions are just 10x easier. And at 4 bucks each it’s more than worth it, maybe even cheaper than some sch80 threaded fittings. I’m all for pinching pennies but not when it comes to Leak free plumbing and Piece of mind.

 

[JoshH]

Dumb question why use slip fittings for the expensive pieces such as union, gate valves, or union ball valve. My understating when glued it is pretty much impossible to get the pipe out. Seems like it worth while buying male adapters for under a buck a piece to be able to reuse 20+$ fittings. Also if you use threaded at the end of the run pipe it acts as a union.

I understand threaded fittings reduce the amount of pressure the piping can take by about half but reef plumbing is considered low pressure.

No such thing as a dumb question. Both threaded and slip fittings have there place in your plumbing setup depending on what you want to achieve as well as your skill level plumbing wise. Ideally you want to use slip whenever possible and install unions for future additions or alterations. However they are not for every situation. I used threaded bulkheads for my closed loop and I'll say right now if I had have used slip fittings I would have been SCREWED! A couple of the bulkheads had to be reseated a couple of times until they were good to go and if they were glued I'd be buying a few new bulkheads.

My MRC pump comes with threaded outlets on both ends so need to use those there as well. I use threaded gate valves and use thread to slip fittings that go into unions after that. The trick to using threaded fittings is using Teflon paste and not tightening the fittings all the way down as it's not needed.

Then you would have to use thread sealer (permanent bond)

Thread Sealant (Teflon Paste) is not a permanent bond

 

[Greg Goby]

No such thing as a dumb question. Both threaded and slip fittings have there place in your plumbing setup depending on what you want to achieve as well as your skill level plumbing wise. Ideally you want to use slip whenever possible and install unions for future additions or alterations. However they are not for every situation. I used threaded bulkheads for my closed loop and I'll say right now if I had have used slip fittings I would have been SCREWED! A couple of the bulkheads had to be reseated a couple of times until they were good to go and if they were glued I'd be buying a few new bulkheads.

My MRC pump comes with threaded outlets on both ends so need to use those there as well. I use threaded gate valves and use thread to slip fittings that go into unions after that. The trick to using threaded fittings is using Teflon paste and not tightening the fittings all the way down as it's not needed.



Thread Sealant (Teflon Paste) is not a permanent bond

You're right, I stand corrected. I'm all slip here and admittedly inexperienced as I warned

 

[JoshH]

You're right, I stand corrected. I'm all slip here and admittedly inexperienced as I warned

Just making sure everyone is on the same page that's all

Nothing wrong with going all slip Either, just would like people to understand threaded fittings aren't as terrible as some make them out to be.

 

[KStatefan]

Why do you say teflon tape is not designed for PVC? I have used it in the past with no issues.

It is not recommended to use by many of the fitting manufacturers

From the Lassco fitting website

The "Do's and Don'ts" of Assembling Threaded Plastic Fittings

Today, there are millions of miles of plastic piping with threaded fittings, providing reliable, leak-free service. However, a tiny percentage of those threaded plastic fittings may leak or break. The reason for this is improper assembly of threaded joints.


Here are some of the Do's and Don'ts of PVC joint assembly:

• Don't over-tighten joints by giving them "one more turn to be sure."Do finger tighten plus one or two turns - No More.
• Don't wrap Teflon tape or Teflon paste or pipe dope to add bulk to or to lubricate the joint. Do use a sealant for threaded joints.
• Don't use "stronger" Schedule 80 threaded fittings on the assumption that they may solve the problem of splitting through over-tightening.
• Do use only Schedule 40 threaded fittings with Schedule 40 pipe and fittings.
• Don't over-tighten.
• Do finger tighten plus one or two turns.

 

[JoshH]

Why do you say teflon tape is not designed for PVC? I have used it in the past with no issues.

As @KStatefan mentioned above, it's not generally recommended by manufacturers. However you can use it with care. The issue with tape is that it very easy to use too much and cause splitting or leaks. If you are careful with it and use just enough theres nothing wrong with using it. I've used it successfully in the past as well and it's definitely a case of "Less is more" when installing it. Paste is generally much easier to use and get right, especially for a novice plumber.

 

[ThePlummer]

As @KStatefan mentioned above, it's not generally recommended by manufacturers. However you can use it with care. The issue with tape is that it very easy to use too much and cause splitting or leaks. If you are careful with it and use just enough theres nothing wrong with using it. I've used it successfully in the past as well and it's definitely a case of "Less is more" when installing it. Paste is generally much easier to use and get right, especially for a novice plumber.

You are correct. The reality is that teflon tape was never designed to be a sealant in the first place. What it was designed for was a lubricant to the threads to allow a deeper engagement on the threads, than not having any lubricant.

In days past, a product called 'Leather Lock' was the go to pipe dope. It actually has ground leather in the paste. I've used it for years, and it works very well. On metal fittings, ferrous and non ferrous, I put three wraps of teflon tape on the threads, then add a dab of the brand name ' Mega Loc' (a version of leather lock). I get the best of both worlds, I get the lubricating feature of the teflon, so I get a much deeper engagement of threads (which is a mechanical feature of holding back liquid), and I get the benefits of a non hardening sealant too.

Now on plastic threads, I do use teflon tape, but again, very sparingly, and most of the time I don't need the sealant, but it can't hurt. I've even used it with gasoline and it works well.

One thing, and the probably won't apply to this hobby but may help folks who do their own plumbing. If you are transitioning from metal to plastic ALWAYS make the male threads plastic, and the metal female. If you try to thread a female plastic onto metal, you run a huge risk of overtightening and splitting the plastic. If you overtighten the other way, the male threads just compress and get tighter and tighter, without the ability to split.

 

[JoshH]

Mega Loc

My go to for any of my tank plumbing needs as well A really good product!

 

[ThePlummer]

My go to for any of my tank plumbing needs as well A really good product!

Did you ever smell the leather smell from it? It's actually ground leather...