SEACOCKS - what sealant to use?

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bonny

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Hi,
I'm re-fitting all my fittings having replaced all my skin fittings due to a number of cracked nuts.
(See earlier post - check your nuts)

Fitting the skin fittings to hull - no problem - Sikoflex.

What sealant should I use on the threads to connect the elbows, seacocks, tails etc?
The originals seemed to have some form of setting sealant.

The problem is that in order to get the taps, bends etc pointing the correct way, the fittings could be upto one turn short of fully tightened. If a non-setting sealant is used, I feel things may move, especially when opening/closing the sea-cocks.
 
You have a choice in my opinion. 1-. slacken the skin fittings and assemble the pipe work , then tighten up the skin fitting nut.

2-.file the skin fitting thread down until the angle that you want is acheived.

regarding sealer I use Red Stag "B" which is for course surfaces as I find that Stag "A" if a bit fine for this sort of work.

ps, in the first method it requires removal of all the old sealant.
 
Yes, alignment is not a problem if you assemble the valves and tails before locking in the skin fittings. Should not need sealant on the threads. I use a polysulphide for hull sealing, but others use Sikaflex. Don't think it makes much difference from a sealing point of view, but Sika is also an adhesive.
 
I have used hawkwhite which is a plumbers thread sealant along with a backnut to 'lock' the fitting in place. For the skin fittings themselves I now prefer Arbomast BR which is a non setting sealant. This allows the easy removal of the fitting in the future.
 
Thanks for some of the suggestions but...
My problem is not what sealant to use for the skin fittings (fitting to hull), as I said I will use Sikaflex for them.

I have 11 skin fittings to fit. Many require a right angle bend immediately on the skin fitting, then the ball valve, then a hose tail.

1. Yes, I can more or less align the skin fitting such that the bend point the right way.
Unfortunately it is not possible to get a spanner in to tighten the nut (because the nut is recessed in an inner hull lining) only a box spanner will fit, so this must be tightened before anything is fitted to the skin fitting.

2. Fitting the ball valve after the bend such that the lever can be operated without fouling on something means that it is impossible to be fully threaded on.

3. Fitting the hose tail is no problem, this can be fully threaded.

My problem still stands. The threads MUST be sealed or they will leak and because they can't be fully tightened, I need a setting compound rather than a non-setting.

I have considered PTFE tape but this would be fiddly to get tight in the correct orientation.

The original installation used some sort of setting (not brittle) compound which worked fine, I just don't know what it was.

Unfortunately some of the joints will be on the sea-side of the ball valves, so once the boat is back in the water, they cannot be re-done without an expensive lift-out.

Boathook.
Is Hawkwhite a setting compound, or is it like Bosswhite which basically doesn't set for years?
 
Thread Sealant

I have used Loctite 577 with great success in this very application,
it hardens up in less than a minute but can be broken if needs must.
Lots of info on Loctite site. I use it on diesel fittings too.
 
Unfortunately it is not possible to get a spanner in to tighten the nut (because the nut is recessed in an inner hull lining) only a box spanner will fit
Click to expand...

Might be worth making up a special tool - start with a suitably-sized socket or box spanner, but grind enough of it away so that it can be fitted in place, (making it 'C' shaped from above) , with a piece of steel strip welded onto it for tightening. That way, you could do the angled connectors up tight, then align them and tighten down the nuts. You might even be able to adapt a ring spanner.
 
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Depends on access and size but what about a bath tap open C adjustable spanner, I got one from wickes to do the taps at home but would also do seacocks.
 
Maybe not NP threads but you probably do have tapered and straight threads.

The nut on the through hull is not the best solution. Through bolts are stronger.

Here is one of the better solutions from Groco.
 
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Use loctite 572 its a slow curing thread sealant with a medium disassembly strength giving you time to adjust fittings. I have used it on many commercial vessel when the same problem arises to align fittings and is hasn't failed me yet, above or below the water line.
 
mitiempo said:
Maybe not NP threads but you probably do have tapered and straight threads.

The nut on the through hull is not the best solution. Through bolts are stronger.

Here is one of the better solutions from Groco.
Click to expand...

Yes almost certainly British pipe thread (BSP)
Yes it comes tapered or parallel.
(a common plumbing practice is to use a parallel female thread on a tapered male thread )

Parallel-parallel joints ought to tighten on to a joint washer of some sort as the seal is ( best ) not made on the thread.

The skin fitting and the valves probably both have parallel threads but no provision to tighten onto a joint washer.

I would use a jointing compound on the threads but lock the two together with a back nut so that the valve can be positioned however it it is required and firmly secured in that position.

Hose tails could well have parallel threads and a shoulder to accommodate a joint washer.
 
mitiempo said:
In North America the through hull is straight threads but most valves I have seen are tapered.
Click to expand...

hence the IBVF adaptor in your diagram. I cant say I have seen those before, but why the triangular flange?

Most ( but not all) the valves listed by a popular supplier in the UK appear to have parallel threads.
 
mitiempo said:
The triangular flange receives three flat head machine screws from the outside of the hull, well countersunk of course. See below.

http://www.pbase.com/mainecruising/replacing_thruhulls
Click to expand...

Got it!

A bit better than
403106.jpg
 
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