Seacocks ... sealing with?

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rszemeti

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Hi,

I am just fitting new seacocks to the heads (lovely job .. not.) when re-fitting the skin fittings, what's a good sealant to use? Just regular Sikaflex caulk, or some silicone or ??

And the seacock to the skin fitting ... PTFE tape or?
 
I just use Sikaflex. Leave overnight and do the final tightening up after it has set. Obviously, don't allow it to turn when tightening.

I've generally used PTFE between the fittings, but last time used Sikaflex there too. Just tightened straight up as no option to tighten later without it turning.
 
I'd use PU40 to seal between skin fitting and hull. I don't go for the 'nip up after curing' technique as you risk unseating the joint which could cause a leak. PTFE tape has always worked for me between skin fitting and sea cock. Use minimum of 3 turns.
 
Polysulphide is the proper stuff. Sikaflex 291 is an adhesive and if the skin fitting needs replacing (it's a service item these days, not an annual one, but nevertheless its a service item), the skin fitting and adhesive can only be removed mechanically.
 
ghostlymoron said:
I'd use PU40 to seal between skin fitting and hull. I don't go for the 'nip up after curing' technique as you risk unseating the joint which could cause a leak. PTFE tape has always worked for me between skin fitting and sea cock. Use minimum of 3 turns.
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Agree with PU40 and don't retighten the skin fitting after it has set. I also just use PU40 in the threads to joint the skin fitting to the ball valve - allows you to orientate the valve to get the handle angle convenient. If I ever have to change the valve I'll just cut off the skin fitting and change the lot again. It's faster and easier than messing about
 
jwilson said:
Agree with PU40 and don't retighten the skin fitting after it has set. I also just use PU40 in the threads to joint the skin fitting to the ball valve - allows you to orientate the valve to get the handle angle convenient. If I ever have to change the valve I'll just cut off the skin fitting and change the lot again. It's faster and easier than messing about
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Yep. The only reason to 'service' the actual through hull skin fitting, is if you think it is corroded. Taking it out doesn't tell you a lot more, so if you think it needs coming out, it needs coming out to change. So cut it out and be done.

Real bronze or decent plastic ones don't cost a lot more than DZR in the first place, so buy a good one, put it in with PU40, tighten it all the way down, don't re-tighten and enjoy 20+ years of happiness.
 
Motor_Sailor said:
Real bronze or decent plastic ones don't cost a lot more than DZR in the first place, so buy a good one, put it in with PU40, tighten it all the way down, don't re-tighten and enjoy 20+ years of happiness.
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I am struggling to find a bronze valve that has a bronze ball in it. They are available in USA but not generally in EU. Whereas DZR ones are the same throughout. Look at brass and bronze on my website for examples of what can happen.
 
vyv_cox said:
I am struggling to find a bronze valve that has a bronze ball in it. They are available in USA but not generally in EU. Whereas DZR ones are the same throughout. Look at brass and bronze on my website for examples of what can happen.
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I wrote: "The only reason to 'service' the actual through hull skin fitting", so no problems with balls of dissimilar metals. The valves you attach are another mater.
 
I tend too use what I already have in stock so at the moment it would be butyl tape or PU 40 type of sealant if I had to go and buy something.
 
Right, the consensus seems to be on PU40 then, I'll use that.

I've gone for bronze "Maestrini" fittings and vlaves from ASAP Supplies, it's a plastic hull, but I'll bond them anyway, to be sure.

I did notice that the fittings have two "pegs" near the outlet, presumably to stick a big screwdriver in to hold onto it and prevent it rotating ... is it required to remove these pegs after fitting? I could see they might help stuff get clogged.
 
rszemeti said:
... is it required to remove these pegs after fitting? I could see they might help stuff get clogged.
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I've always left them.

But your comments about 'bonding' have opened another very large can labelled 'WORMS'.
At the very least, it's an unnecessary complication.
 
rszemeti said:
I did notice that the fittings have two "pegs" near the outlet, presumably to stick a big screwdriver in to hold onto it and prevent it rotating ... is it required to remove these pegs after fitting? I could see they might help stuff get clogged.
Click to expand...

The 'pegs', or lugs, are for a step wrench to hold the fitting in place. Step wrenches are hard to get in Europe for some reason. I got one made to fit my skin fittings with a M24 head for holding the skin fitting in place when tightening. It makes the job easy. Using a big screwdriver or file or similar to hold the skin fitting in place is rarely successful, which is maybe why quite a few posters are reluctant to tighten up.
 
rszemeti said:
Right, the consensus seems to be on PU40 then, I'll use that.

I've gone for bronze "Maestrini" fittings and vlaves from ASAP Supplies, it's a plastic hull, but I'll bond them anyway, to be sure.

I did notice that the fittings have two "pegs" near the outlet, presumably to stick a big screwdriver in to hold onto it and prevent it rotating ... is it required to remove these pegs after fitting? I could see they might help stuff get clogged.
Click to expand...

I assembled all at the same time while 'wet' to avoid any risk of disturbing the skin fitting joint later. I found an old gate hinge in the boat yard + mole grips to shove up the 'ole, engage with the lugs and prevent the skin fitting from rotating. I'd recommend finding or making something strong for this purpose before you start the job.
 
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