A Question for all the Pipefitters

[The Gentleman Sawyer]

Whats the best sealant to use when joining straight pipe fittings? For example, a seacock to a thru hull or shaft log to a cutlass bearing housing.
Thanks,
Ken

[Jim Ledger]

Pipe Dope (the blue stuff) over teflon tape. AFAIK

[The Bigfella]

I'd put the first one on dry and use epoxy on the second one - although that may vary depending on the boat - the second one that is.

[The Gentleman Sawyer]

Thanks for the replies. I think I'll try Loctite 565, based on advice from their technical department.

Ken

[The Bigfella]

I don't think you need or want sealant on that first application. There's no pressure involved and its important to be able to get the fittings apart again without damaging the hull.

As for the shaft log / cutlass bearing.... there's as many variations on that theme as you care to mention. The last two I've done were totally different - and one of them replaced yet another type.

My last one is PVC pipe - epoxy / fibreglass cloth-wrapped and epoxied into a timber shaft log. The one before was fibrous material (can't recall the name) epoxy glued into a bronze casting..... replacing a rubber bush.

[pipefitter]

http://www.rectorseal2.com/files/214/trublu.jpg

Below is what I typically use for just about everything.

http://www.rectorseal.com/files/215/no5-special.jpg

[The Bigfella]

.... on thru-hull fittings? Why?

[Tylerdurden]

I used to run into a lot of straight pipe on dry cleaning machines and the standard impregnated hemp cordage would not stand up to the perchloroethylene. I started using waxed sail twine with a dose of Rector seal 5.. Just wrap the threads with twine starting at the end and work your way back one turn per thread and then dope it liberally.
Depending on the size of pipe you are using would mean some trial an error for the right twine.
Locktite made a TFE based cord for straight pipe but it didn't sell well so they dropped it. I bought what was left from a plumbing supplier but I don't have any more.
I wonder if the Brits have a similar product as they loved straight pipe.
I sure as hell didn't.:p

[The Gentleman Sawyer]

.... on thru-hull fittings? Why?

I'm referring to sealing the threaded connection between the thru hull fitting and the seacock. These threads are straight, not tapered. I've always been taught tapered threads don't need sealant and the reason one should apply tape or sealant is for lubrication of the threads so the joint can be tightened properly - not for "sealing" the joint. And yes, the boat is English although I believe pretty much all thru hull threads and seacock inlet threads are straight.

Ken

[peter radclyffe]

ptfe tape

[Plumbtex]

I'll second the vote for tru blu on top of teflon tape. The tru blu is plenty good for sealing on it's own the teflon tape seems to make disassembly easier.
Disclaimer: my experience is as a plumber and not boat related

[John B]

Here's another one then.
brass male thread into plastic female thread. Thread tape isn't enough to put any 'weight' on the connection ie , its too easy a fit with no interference .
What sealant would be best for that?
I have red silcone gasket maker, sikaflex, mastic, epoxy. I'll buy other if needed.

I also have hemp and some graphite but I'm wary of using hemp into a plastic fitting.

[The Bigfella]

Smoke the hemp and all your cares will waft away

[Plumbtex]

I won't screw metal into plastic - too often cracks the plastic. I would instead use a plastic nipple or metal coupling to change the transition ensuring that plastic was screwed into metal instead of vice versa

[Tylerdurden]

Here's another one then.
brass male thread into plastic female thread. Thread tape isn't enough to put any 'weight' on the connection ie , its too easy a fit with no interference .
What sealant would be best for that?
I have red silcone gasket maker, sikaflex, mastic, epoxy. I'll buy other if needed.

I also have hemp and some graphite but I'm wary of using hemp into a plastic fitting.

TFE then rector seal 5. Use caution with torque. Skip the above mentions products. Use of TFE is so one can break the connection down the road.