Sea Cocks -- PTFE Tape vs Caulk and Oakum

[Dockhead]

Any opinions on this?


Moody used caulk and oakum, but I always heard PTFE tape was better.


Which is it?

[Neziak]

Loctite 572 or 577 is my go to these days. Seals every time vs ptfe tape and takes a fraction of the time.

[Pete7]

I used PTFE tape, the thick stuff rather than the very thin type of old, to seal this Trudesign valve to the original bronze seacock. It didn't work. May have been my application but never had a problem with PTFE before, or perhaps it was using the thick stuff.

I have since been recommended this stuff instead and as soon as I can get the boat out of the water will have another go.

https://www.clesse.co.uk/product/cle...ant-50ml-tube/

Pete

[slug]

Originally Posted by Neziak

Loctite 572 or 577 is my go to these days. Seals every time vs ptfe tape and takes a fraction of the time.

Yah, loctite is industry standard

https://www.new-line.com/nldocs/reso...o_It_Right.pdf

I prefer Loktite pipe sealant with PTFE

I think it’s called 565

Easier to disassemble in hard to access installations

I

[Cowpoos]

Originally Posted by Dockhead

Any opinions on this?


Moody used caulk and oakum, but I always heard PTFE tape was better.


Which is it?


Attachment 213098

I don't really want to play the devil's advocate here, but that metal your new seacocks are made of looks like Brass and not bronze?? If brass it has a much higher zinc content which will make your seacocks an anode to a point.

Very happy to be corrected in this case.

[chris95040]

Originally Posted by Cowpoos

I don't really want to play the devil's advocate here, but that metal your new seacocks are made of looks like Brass and not bronze?? If brass it has a much higher zinc content which will make your seacocks an anode to a point.

Very happy to be corrected in this case.

I don’t think you know what ‘devil’s advocate’ means.

OP, after repeated attempts to make my home boiler leak free I’ve given up on Teflon tape. The PTFE pastes they make seem to do a far better job (at least with the miserable threads on Home Depot steel pipe.)

Ive heard that teflon tape isn’t really trying to seal anything, it’s reducing friction so you can snug up tapered pipe threads to the point where they don’t leak. I don’t know if your seacock threads are tapered pipe threads or not. If not, I think you need some sort of thread sealant.

[SVHarmonie]

When people are talking about "Loctite" they are not referring to the first Loctite brand product people think about, the thread locking compound, but one of the pipe sealing compounds.

A proper seacock has straight threads, NOT tapered ones like standard pipe. "Teflon tape" does not provide enough "bulk" to reliably seal non-tapered threads. You need some type of "pipe dope" to fill the gaps and make a good reliable seal.

You certainly would NOT want to use a polyurethane caulk, unless you were 100% sure your worst enemy was the person who had to next disassemble it.

[s/v Jedi]

You guys talk of seacocks but your pictures only show thru-hull fittings with some ball valves screwed on top

Pro’s use both: PTFE tape first, then add PTFE paste... RectorSeal in particular.

[HopCar]

Originally Posted by Cowpoos

I don't really want to play the devil's advocate here, but that metal your new seacocks are made of looks like Brass and not bronze?? If brass it has a much higher zinc content which will make your seacocks an anode to a point.

Very happy to be corrected in this case.

He is in Europe where it is common to use DZR Brass for underwater parts. DZR brass meets European standards but it is not as good as bronze. It is better than regular yellow brass. I can’t say for sure that’s what he is using but it kind of looks like it.

Just to throw it out there, my favorite thread sealant is Leak Lock. You can use it on water, fuel or gas fittings.

[Cowpoos]

Originally Posted by chris95040

I don’t think you know what ‘devil’s advocate’ means.

I may not? But you did understand what I was saying.

[Cowpoos]

Originally Posted by HopCar

He is in Europe where it is common to use DZR Brass for underwater parts. DZR brass meets European standards but it is not as good as bronze. It is better than regular yellow brass. I can’t say for sure that’s what he is using but it kind of looks like it.

Just to throw it out there, my favorite thread sealant is Leak Lock. You can use it on water, fuel or gas fittings.

Thanks, didn't know about the use of DZR bass in Europe. Is there a way to tell it apart from normal brass?

[Wotname]

Originally Posted by Dockhead

Any opinions on this?


Moody used caulk and oakum, but I always heard PTFE tape was better.


Which is it?


Attachment 213098

Would Moody use the best or the cheapest?

I have never heard that PTFE tape was better than anything but perhaps you have a better source of PTFE tape opinion.

Threaded pipe joints in the oil/gas industry usually specify a thread sealant (i.e. not tape) relevant to the liquid enclosed.

Back in the day, hemp (oakum) and white lead paint was the goto pipe thread sealant for water applications. Messy but effective. I can't say that it has been improved on although I wonder what paint could be used today.

In reality, sealing a sea cock thread is a low tech application i.e. low pressure and sea water so while it is important to get 100% right, don't overthink it IMO.

[RGN]

I agree with SV Jedi, RectorSeal (Known as Rectum seal in the trades) is the stuff to use and you can find it anyplace. Do Not use caulking compound from a tube!

[HopCar]

Originally Posted by Cowpoos

Thanks, didn't know about the use of DZR bass in Europe. Is there a way to tell it apart from normal brass?

It should be marked DZR, CR, or DR on it. It is yellowish and it looks like it machines nicer than bronze.

[Emmalina]

Hemp and paste is my sealant on everything. You can even make adjustments as it expands over time. Teflon is ok on small stuff .