I won't bore you with the history.  Just to say that I have a male PVC thread that I want to put a brass female-female extender (which it should have been in the 1st place) and make it permanent.  I'm thinking of smearing some silicone onto the threads and letting it set after screwing on the brass.  The threads on the PVC have had a corroded fitting on it and look like they wouldn't take much torque to break.  So I want something I can do one time and know it won't leak.  I'm pretty good at using the teflon tape but I just don't want to screw with it this time.

 

So, is that a good way to go or what advice better?

 

Rgds.

You can get threadlock at HomePro, should do the trick. Or just wrap PTFE on the male thread, coat in glue and wind on the female fitting.

 

I take it there's no spare pipe behind the male threaded PVC fitting?

Agreed the above, PTFE tape on the male thread, don't skimp - and if the joint exposed to sunlight, paint it with vinyl/acrylic paint.

16 minutes ago, grollies said:

You can get threadlock at HomePro, should do the trick. Or just wrap PTFE on the male thread, coat in glue and wind on the female fitting.

 

I take it there's no spare pipe behind the male threaded PVC fitting?

It's in the bathroom wall.  The wizard that hooked up the basin faucet attached the hose directly to that - no stop valve.  I have had to replace all most all my original drains and faucets due to corrosion.  They just crumble and fall apart when I try to unscrew something.  

 

Are you saying silicone is not a good idea?

 

Silicone is crap, it just makes sealed edges look good for a while. As a waterproofing solution, on threads, no.

Must have been the same superstar that did our shower. Water feed is the same male PVC thread sticking out of the wall.

Not sure of availability here but the product is first class

 

 

https://www.tradecounterdirect.com/product/virgin-white-ptfe-thread-paste_size-120ml.html

If it's going to be permanent, there is nothing that binds together like epoxy.

I wouldn't use silicone, I would use RTV.  It's a form a gasket compound sold mainly at auto supply stores.  Also, the male fitting in the wall has a shoulder on it.  .  First I would wrap the male fitting with tape.  I would then get an "O" ring that fits over the treads and sit it against the shoulder.  I would smear the RTV into the treads of the female brass fitting, let it set for a few minutes and then screw the fittings together. When I built my house I used transition fittings at all of the places where metal connected to PVC, but I still use the "O" ring.crew them together,

17 hours ago, sappersrest said:

Not sure of availability here but the product is first class

 

 

https://www.tradecounterdirect.com/product/virgin-white-ptfe-thread-paste_size-120ml.html

Agreed excellent stuff and best overall product for the job, trouble is, as you say not available here?

3 hours ago, wayned said:

I wouldn't use silicone, I would use RTV.  It's a form a gasket compound sold mainly at auto supply stores.  Also, the male fitting in the wall has a shoulder on it.  .  First I would wrap the male fitting with tape.  I would then get an "O" ring that fits over the treads and sit it against the shoulder.  I would smear the RTV into the treads of the female brass fitting, let it set for a few minutes and then screw the fittings together. When I built my house I used transition fittings at all of the places where metal connected to PVC, but I still use the "O" ring.crew them together,

That's probably the best answer.

Thanks all for the advice.  It turns out I need to return to square-1 as I could not get the stop valve to fit behind the sink.  The only way it would fit would leave the valve in one position or the other but unable to turn it.  Aagh.

 

In testing, I didn't use anything and just finger tightened the fittings.  To my surprise, they didn't leak a drop.  Makes me wonder if over tightening has caused some of my previous frustrations.  (?)

 

BTW:  I liked the "O" ring idea but the threads of the female connectors run short of butting up to the male shoulder so that wouldn't have worked with the kit I have.

 

Cheers.

Just to add a caveat to an earlier post.

 

Make sure that fittings are compatible, i.e. don't screw a parallel thread to a tapered thread.

Just to add a caveat to an earlier post.
 
Make sure that fittings are compatible, i.e. don't screw a parallel thread to a tapered thread.

I second that, a common mistake !

I also wonder if this is available in LOS


This is the real deal, sort of liquid PTFE, just need to make sure that the joints are dry and allow sufficient drying time.

Used this for many years in my previous life as someone who worked for a living !

39 minutes ago, bankruatsteve said:

I could not get the stop valve to fit behind the sink.  The only way it would fit would leave the valve in one position or the other but unable to turn it.  Aagh.

Are you saying the male threads are too far within the wall? I had to use a short brass extension on 1 of our sinks (female threads on both sides).

Out of all our bathrooms plumbing only one was somewhat close to flush with finished tile. Went through a lot of different stop valves to get good seals & a decent finished look.

1 minute ago, r136dg said:

Are you saying the male threads are too far within the wall? I had to use a short brass extension on 1 of our sinks (female threads on both sides).

Out of all our bathrooms plumbing only one was somewhat close to flush with finished tile. Went through a lot of different stop valves to get good seals & a decent finished look.

No, the female connector has less thread than the male so it just won't screw in far enough to contact the shoulder.

 

I also had several of the situation you describe and used brass extenders successfully. What really blows my mind is where some of the plumbing points were positioned in the wall.  Most were simply left at the point the rough-in left them and no thought as to how they would hook up to something.

10 minutes ago, bankruatsteve said:

no thought as to how they would hook up to something.

I've had the same problems over the years with my house also. When I finally get the problem solved I go in the bathroon and look in the mirror and yell at the architect, general contractor, plumber or electrician responsible, ME!

9 minutes ago, wayned said:

I've had the same problems over the years with my house also. When I finally get the problem solved I go in the bathroon and look in the mirror and yell at the architect, general contractor, plumber or electrician responsible, ME!

Same here.  I should have been there but I wasn't.  Our first builder assured us that he had worked on lots of "western" style homes but it took several months to realize he was clueless and fired him.  Then two more came and left before I finally realized I need to take things on myself.  Even so, I ended up re-doing many things.  Traps were left to the side for all the sinks because they had no idea what they were for.  Small leaks were left to drip because it wasn't too bad.  Just crazy stuff.