Seacocks Dilema

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aledlgriffith

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Having just received the surveyors report on our future yacht we decided to take the plunge to start sailing.

One of the essential items was the replacement of our broken gate valves. We decided on ball valves as the best replacement.

Because of the position of the seacocks (why do they put them in the worst possible places) and the need to turn the levers we will have to position these with the ball valve part way down the thread i.e. not completely tight.

My question is how do I seal them, I have had my suggetions, Sikaflex 291, PTFE tape and Loctite 243. I would like the option of taking these off in the future if necessary (does this rile out sikaflex).

Any advice/suggestions would be welcomed.

Many Thanks
 
If they are only going to be screwed partially onto the skin fitting then IMO you need to also fit back nuts so that they are firmly locked into position but make sure you have them screwed on by an adequate number of threads. Perhaps a bit of modification of the handles might not not be too bad an idea.

Almost any pipe jointing compound would then be able to seal the thread. A traditional white pipe jointing compound such as Boss white or Screwfix's own maybe.
I would not use ptfe tape, it is really intended for taper joints. Sikaflex will stick them together too soundly I suspect and Loctite 243 is primarily a medium strength thread locking compound
 
white jointing compound, fibre washers, with back up nuts, but I would be looking to modify the handles or a different valve/seacock arrangement.
 
A definitive answer is difficult without seeing the actual situation but if you can get the seacocks screwed down fully by modfying the handles then this is the way to go. Not fully tightening them and basically bodging it doesn't sound like a good plan. Contemplate the consequences of it failing. Why not run it by your surveyor?
Happy days
 
I don't agree with not screwing them right down, and I suspect you'll be thinking about it when you wake at night!

If it is jst a case of the handle fouling something, why not bend or cut the handle? I have had a similar problem on two of my seacocks, and modifying the handles got over it in both cases. Just a thought, as these valves turn very easily so a long 'lever' isn't always necessary.
 
Fernox LSX will seal the joint and not set solid. However, I agree with the advice regarding the use of locknuts and/or tightening right down.
 
We've just done this. The cooling water cock needs to end up aligned so that the lever is readily accessible, and doesn't foul the strainer. I used "back nuts" as recommended by Vic so that everything can be done up tight. In the event only one of the joints didn't end up fully tight but I used the back nuts anyway to lock all the joints tight. I also used Sikaflex 291, so it sounds like mine are probably never going to come undo - I'll cross that one when I come to it.
 
I assume you mean that the handle is now at the back of the fitting (Sod's Law) and unreachable by fingers with enough strength to turn it. I would endorse the backing nut idea, but also got to thinking about what is happening when the valve stops screwing onto the hull fitting. It is, after all bottoming out. If you were to use an angle grinder on the end of the hull fitting for half a thread, then the valve would turn another 180 degrees! Great care required, though!

Rob.
 
Second take on this. Rather than grind the hull fitting - with attendant problems of starting the thread, why not fit a shim/washer atop the hull fitting so that the valve bottoms out sooner? Only suggested in the instance of a straight thread. In the case of a taper thread, of course, this will not work. I still like the idea of backing nuts as well.
Rob
 
We've had the exact same issue. However there is a specific Loctite product for this that works very well. Both sides need to be metal (as in not plastic).
The product is 'LOCTITE 577 PIPE SEALANT' and comes in 50 ML and 250ML.
I think you will have ample supply with the 50 ml.
It seals off the thread and fixates the seacock in the desired position. It sets quite fast (minutes)

Arno
 
Thanks to everyone who has answered. Unfortunately, trying to modify the handles is not an option, the seacock is right next to the engine (would like to meet the original fitter!!) when screwed down the handle is at theback and so close to the engine that you cannot turn the handle. Back nut approach seems reasonable, just need to decide on the sealant.

Al
 
[ QUOTE ]
the handle is at theback and so close to the engine that you cannot turn the handle

[/ QUOTE ] Just a thought, perhaps a daft one or maybe the obvious, could you remove and refit the skin fitting so that when the valve is screwed on fully the handle is in a suitable position.
 
Its just too exciting to replace valves in-situ.
Get all the kit organised and get a lift out or a dry out to replace the gate valves. Gate valves are a menace because they come entirely to bits at the most unexpected moments.
Ball valves have to be considered carefully as they are often plated brass which is not a good marine material.
Looks like you have lots of bilge crawling fun ahead!!
 
[ QUOTE ]
Second take on this. Rather than grind the hull fitting - with attendant problems of starting the thread, why not fit a shim/washer atop the hull fitting so that the valve bottoms out sooner?

[/ QUOTE ]
Nice idea. It will reduce the length of thread engaged between the seacock and the skin fitting, though, but at least the seacock would be bottomed out.
 
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