Plan to fix PVC threaded joint leak

[wireform]

Wow, TIL! Thanks for the PVC Repair link! I have removed the Teflon tape from the threads. Just confirming my understanding, based on your comments & article, the reason for not using Teflon tap is that it may become easier to over-tighten when Teflon tape is present? The over-tightened state with pump's vibration may lead to cracks in union or deformation of O-rings, I presume? Thanks again guys.

The water is sealed with the O ring and the rest of the union is to keep both sides compressed to each other, keeping the O ring pressured.

 

[JamesW]

Teflon on the threads can crack the plastic nut by creating too much stress on the plastic.

Cracked Salt Cell Union - Advice/Confirmation

The union screw on my TCELL940-W split down the middle, and I have a few questions I'm hoping to get help with. Google says the replacement union is a Hayward GLX-Cell-Union - 2" union, but the pipe behind the salt cell is 3". Question 1: Does a 2-inch union (GLX-CELL-UNION) fit a Hayward...

www.troublefreepool.com

 

[ajw22]

Just confirming my understanding, based on your comments & article, the reason for not using Teflon tap is that it may become easier to over-tighten when Teflon tape is present?

Correct.

The over-tightened state with pump's vibration may lead to cracks in union or deformation of O-rings, I presume?

Yes. Unions should be hand tightened just enough to hold compression on its O-ring that forms the seal.

 

[PoolStored]

Teflon tape on non-union threaded connections can be easier to over-tighten. Overtightening, independent of vibration can lead to deformation of the conection.

On a union, is is the pressure of the threads that compress the o-ring. Teflon tape is used as a sealant. On a union, no sealant is necessary as the o-ring does that job.

 

[setsailsoon]

Two things that make union fittings hard to use and causes a lot of failures are dirty threads and using the wrong tool to tighten them. Large channel-lock type pliers can easily damage and over tighten the fitting. I've found easiest way to make these work well over and over again is:

• Clean the threads inside and out with a wet rag until all the dirt is removed. WD 40 can help as a cleaner if there's oily dirt.
• Clean the o-ring and make sure it's grove is pristine as well. Even small particles of dirt can cause a leak that won't stop 'till you clean it. No matter how tight you get it. Once you get it clean lube it with a small amount of soluble silicone lube. When you tighten if it's not lubed the o-ring can catch in the grove and become distorted. All surfaces need to slide.
• Use the right tool. A belt wrench is perfect. Use one like this that has gripping tread on the inside of the belt:

• Don't over-tighten. Snug is all you need.

I keep one of these handy to the equipment pad.

I hope this is helpful.

Chris

 

[PoolStored]

• Use the right tool. A belt wrench is perfect. Use one like this that has gripping tread on the inside of the belt:

A properly fitted union, with a proper, in good condition o-ring should be hand tightened.

If you do use this tool only use the strap wrench for an additional 1/16-turn of the nut.

https://www.spearsmfg.com/tech_updates/TECH-2-No.109_web.pdf

 

[phonedave]

Two things that make union fittings hard to use and causes a lot of failures are dirty threads and using the wrong tool to tighten them. Large channel-lock type pliers can easily damage and over tighten the fitting. I've found easiest way to make these work well over and over again is:

• Clean the threads inside and out with a wet rag until all the dirt is removed. WD 40 can help as a cleaner if there's oily dirt.
• Clean the o-ring and make sure it's grove is pristine as well. Even small particles of dirt can cause a leak that won't stop 'till you clean it. No matter how tight you get it. Once you get it clean lube it with a small amount of soluble silicone lube. When you tighten if it's not lubed the o-ring can catch in the grove and become distorted. All surfaces need to slide.
• Use the right tool. A belt wrench is perfect. Use one like this that has gripping tread on the inside of the belt:

View attachment 629815

• Don't over-tighten. Snug is all you need.

I keep one of these handy to the equipment pad.

I hope this is helpful.

Chris

You really only have to hand tighten them. If you problems getting them apart, then a wrench can help. I use a pipe wrench myself, because I happen to have large enough ones laying around.