Installing ball valves

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frilaens

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I'm just about to replace various ball valves and have used Sikaflex to re-fix all the through hull fittings that I could easily remove. Some were, however, well and truly stuck so I decided to leave them alone. When I try to screw one of the new ball valves onto these the handle now operates in a different place than before and therefore cannot be screwed tight. My local chandlery recommended Loctite to fix these into place, but the disadvantage is that they will need heating for removal and I wonder if Loctite would be effective on larger diameter fittings. Anyone have any suggestions? Would PTFE tape or hemp be effective if the valves are not screwed in fully (do they need to be screwed on tight?) and the valves are in use often?

Andy
 
For water, use hemp and either the special "grease", or lead minium (the red paint used as primer on timber, or as anti-rust on iron/steel).
For oil, or diesel, use Teflon tape. Don't hesitate to be "generous".
This allow to place the handle wherever you want it, keeping the connection tight.

Good luck.

Paul
 
If possible use a backnut under the valve to lock 'the thread' after screwing the valve in as much as possible to the required position. This along with hemp and a jointing compound (water Hawk?) will stop the valve swing around during use. Idealy the backnut should be the same material as the hull fitting and valve though nylon/plastic should have the strength.
 
Firstly make sure you have got BRONZE ball valves - there are many on the market AND in chandleries that are Brass, which can dezinctify - pay the little extra and insist on Bronze. Fix with generous amounts of PTFE tape and you should be able to align the handles to suit and still be leakproof and tight.

dickh
I'd rather be sailing...
 
I had the same problems recently when changing the old gate valves on my boat for ball valves and did some searching on the forum on PTFE tape. If I remember rightly the consensus of opinion at the time was you can use normal PTFE up to 1 1/4" but bigger than that and it should be either hemp and bosswhite or the thicker PTFE tape used for gas fittings. The latter is what I used cos it required less skill to use (and I'm definitely not a plumber) and it appears to be a good tight fit but the boats not back in the water yet so can't say if it's the right choice.

Quite interesting posts on the subject to be found covering tapered and parallel threads - do a search for "Advice on BSP fittings"

HTH

Gavin
 
The handles on valves not ending up in the right place is a common occurence in my job, I'm a plumber!

I would use PTFE tape wound on to the male thread in the opposite direction of the thread. Be generous with the tape and use a little sealer to make sure. Fernox LSX is ideal, it is a sillicone which cures underwater. It's often known as "Plumber's get out of jail free!"

Don't use hemp. It's an ancient out moded product. Indeed, under the water and gas regulations It can only be used to seal backnuts.

Don't worry about the size of the pipe work. I've used PTFE on 100mm fittings which operate under 5 bar pressure.

Hope this helps.
 
Sikaflex.

I have used Sikaflex on the threads on some fittings where this problem occured.
Firstly I cleaned the threads with acetone and afterwards I allowed the Sikaflex to fully harden before launching.
The fittings can later be dismantled, but only with proper tools and quite much force.
 
I am not a plumber, but I agree with the above advice based on my experience of replacing ballvalves. Try to avoid any sealler and try to get a seal with the PTFE only. If you use sealer you will have a real problem to remove them next time, especially as in most boat cases there is little space to spin a wrench and no effective way of holding the skin fitting to stop it rotating.
 
Thanks

Thanks everyone for the replies. She goes in the water on Thursday evening so I hope it all goes OK.... I hadn't thought about locking nuts and I think there is enough room so I will try and get hold of them tomorrow. I'll go for the PTFE tape if I can get the nuts or Sikaflex if not. The ones I removed were installed with silicone gasket sealant, I think, and were tough but reasonable to remove.

Again, many thanks,

Andy
 
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