Seacock (ballvalve) and Hosetail Sealant.

Habebty

Habebty

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I did ask this on another thread, and was curious to know what was best as a sealant when fitting saeacocks to skin fittings, and hosetails to seacocks?

I Sikaflexed the new bronze skin fittings in place and was going to use PTFE on the new DZR ballvalves and hosetails unless there is a more correct way of sealing the threads.

I know this kind of turns the whole thing into a bit of a Russian Roulette with ensuring the seaacock handles end up in the right place by fixing the skin fittings down first but clearances meant I had to tighten the skin fitting flange nut first before tightening the valve on to the skin fitting.

Why also the disparity between tapered and parallel threads?

cheers
 
I would use a lock nut to lfix the valve in the required position. No roulette of any nationality involved then!

Almost anything will seal the joint from Boss White and hemp onwards. I can remember when Sealastik ( sort of putty in a tube) was the most common sealant ... and it's lasted on my boat for over 30 years

I dont think I would use silicone though and PTFE tape is not best suited for parallel threads. Perfect on tapered threads but not parallel ones.
 
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mitiempo said:
If you are putting a valve on a through hull the threads will be mis-matched - straight on the through hull and tapered on the valve. They are made this way and this combination was never intended by the manufacturer.
Here is a great explanation of why it is not a good idea:http://www.pbase.com/mainecruising/seacock_primer
Click to expand...

I doubt if the valve will have a tapered thread! it will most likely be BSP
 
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mitiempo said:
I assumed he was in the UK as well - what I was not aware of is that your available ball valves are the opposite to those in North America and have parallel threads.
Click to expand...

I might be wrong but I think they have parallel threads.

I have not found any suggestion on the sites I have looked at that they have BSPT threads.

Not uncommon on plumbing to use tapered male thread into parallel female with loadsa ptfe tape!

I have some gate valves knocking about somewhere i'll look at those.
 
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I bought many ball valves in sizes from 1/4" fuel pipe to 2" cockpit drain when I refitted KS after purchase. All have parallel threads.

Pete
 
prv said:
I bought many ball valves in sizes from 1/4" fuel pipe to 2" cockpit drain when I refitted KS after purchase. All have parallel threads.

Pete
Click to expand...

I have a selection of ball valves and skin fittings bought for materials investigations. All have parallel threads. The only tapered plumbing fittings I am aware of in UK are the ones in radiators.

I usually use Sikaflex for the whole job, setting the skin fitting in the hull and sealing the threaded connections.
 
I can't recommend Loctite 577 highly enough.

Whilst trying to get 4 closely spaced seacocks on with PTFE and the handles lined up so they didn't foul each other, I slowly lost the will to live.

A phone call to our clubs Bosun regarding 'Help!' resulted in a trip to the local industrial estate to buy the 577.

Apply to threads, turn to desired position, leave for a couple of hours and then attach hoses etc. It cures when air is no longer present when squashed out, the bottle you buy is half full as the air inside stops it going off.
 
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