Why not use Silicon ?


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Old 07-12-16, 12:35 PM
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Why not use Silicon ?

I am just a DIY-er.... often I'd read instructions or watch a clip on youtube how to do something and then I follow the "procedure".
However, I do like to also learn why things are done in a particular way and so just last few days, when doing a new bath tub / shower setup and using several of Copper threaded connections, I wondered..... The technique is to put a Teflon tape on the thread and screw on the connection, but why nobody thought of finishing up with a bit of Silicon ??
Especially considering that those connections are behind a wall and hard to access in the future - I'd imagine that providing maximum security and prevent a failure of the connection would be critical.

I realize that threaded connection with tape or dope if done properly shouldn't ever leak but considering that it takes only 30 more seconds and is cheap - why not finish with a dab of Silicon ??

would there be any harm in doing so ?
 
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Old 07-12-16, 01:50 PM
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Silicone should never be used on plumbing connections, especially pipe threads. It won't harm the pipes, but it serves no purpose.
The most common misuse I see is on kitchen drain pipes. Someone thought it would help and it might or might not.

On pressurized water it's useless. That's what tape and dope are for.
 
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Old 07-12-16, 06:41 PM
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just to clarify...I didn't mean to put Silicone on the entire threads where the connection occurs but rather to "seal off" the final outer connection made between the male and female connectors.
Tape would still be used.

For me the idea came because of the "fear" and guessing if I am tightening the connection enough but not to the point of over-tightening and damaging the threads.
 
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Old 07-12-16, 06:52 PM
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Silicone isn't going to stop water that's under pressure, so putting silicone on the outside of a pipe connection is pretty pointless. The only time silicone should be used is where it's for a gasket type of application. Like under a faucet flange that has no rubber gasket or when installing a sink basket. Silicone has no place on supply lines.
 
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Old 07-12-16, 08:11 PM
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just to clarify...I didn't mean to put Silicone on the entire threads where the connection occurs but rather to "seal off" the final outer connection made between the male and female connectors.
Not to beat a dead horse but I understand. The sealing off is not necessary and won't work. Plumbers don't like to experiment, they like to install things as specified.

If you are not over tightening to the point of breaking something you are doing good. A taped and doped joint needs to be tight, but don't get carried away.
 
 

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