Marelon ball valves open or closed

[lumphammer]

We are leaving our boat in the Villaine River for the winter (fresh-ish water). Following a conversation with a friend who had been told if the valves are closed when and the water freezes the expansion of the water in the ball valve could damage the body, I am wondering whether to leave them open would be a safer option? I know that the accepted advice is always to close them on leaving the boat, but as we have lived on board for the last 18 months with all the valves open all the time, I can't see that they are going to suddenly fail, especially as the boat will not be moving.

Am I right to be worried about ice damage to the valve?

PS: I don't need any advice about the rights or wrongs of leaving stop cocks open, thanks

 

[vyv_cox]

There is an example of what can happen here http://coxengineering.sharepoint.com/Pages/BrassandBronze.aspx. bottom picture. The question then is how do the the ductile/brittle properties of Marelon and brass differ and how cold is it going to be. Neither of which I can answer, although i do know that Marelon is known to fracture in a brittle mode.

 

[Billba]

Mine have the external blanking plug complete with 'O' ring which stows in the end of the moving part/handle. I am able to reach below the waterline and seal three of mine from the pontoon. Do ensure first that there is no antifoul or crud first and use the small lug to attach them to the boat to ensure they are not lost accidentally. When you do remove them refrain from any sideways pull if it is thinnish cord that is used as this will split the lug. Any deeper ones will be less likely to freeze but if you have the wet suit and mask and fancy that one last swim...... Do leave yourself a reminder to remove them before any activity next spring though. All of this will allow you to leave the cocks open and then if the water in the body of the cock was to freeze then it may pop the blanking plug which could be used as a tell tale when you return.

 

[MYStargazer]

Is it not possible to pump concentrated antifreeze down the pipe and into the valve? A little extravagant, of course, as much will dissipate into the water beneath the boat, but could enough get into the workings of the ball valve to prevent freezing?

 

[sarabande]

"MARELON®IS...

is the only synthetic material to be approved by the Marine U.L. Underwriters Laboratories) for use below the waterline and has passed the same stringent tests as bronze. It exceeds the ISO standards and is approved by the A.B.Y.C. (American Boat and Yacht Council). Marelon plumbing systems are corrosion and electrolysis resistant and will not freeze or become brittle with age or temperature extremes. "


and some pertinent discussion on Sailboatowners.com

http://forums.sbo.sailboatowners.com/printthread.php?t=123725

from

http://www.google.co.uk/url?sa=t&rc...61J3g9e4sOMy1Xg&bvm=bv.54176721,d.d2k&cad=rja

 

[KellysEye]

I would keep them closed, Marelon is a mix of nylon and GRP and is immensely strong, I doubt it would break given that the amount of water in the ball valve is tiny.

 

[rivonia]

The thing to do is to pump antifreeze through and the close the valve.

Good luck

 

[vyv_cox]

I would keep them closed, Marelon is a mix of nylon and GRP and is immensely strong, I doubt it would break given that the amount of water in the ball valve is tiny.

If you look at the link I posted above you will see a brass or bronze ball valve burst open by enclosed ice. The forum link posted by Sarabande includes a description of a Marelon one burst open in the same way.

 

[duncanmack]

When was the last time the Vilaine froze?

 

[Cloven]

I am based on the Vilaine and keep the boat in year round. I always leave the seacocks shut and have never had any problems. I do however out a bit of antifreeze down the pipes but I'm pretty sure its not really necessary, its just that I've always got a bit left over after winterising the engine.

We are leaving our boat in the Villaine River for the winter (fresh-ish water). Following a conversation with a friend who had been told if the valves are closed when and the water freezes the expansion of the water in the ball valve could damage the body, I am wondering whether to leave them open would be a safer option? I know that the accepted advice is always to close them on leaving the boat, but as we have lived on board for the last 18 months with all the valves open all the time, I can't see that they are going to suddenly fail, especially as the boat will not be moving.

Am I right to be worried about ice damage to the valve?

PS: I don't need any advice about the rights or wrongs of leaving stop cocks open, thanks

 

[steve_l]

With the boat in the water, unless the river freezes they should be ok left closed.
However, if there's a chance that the water will freeze and the valves are closed, they could burst.

This was a lesson I learnt after my first winter here with the boat. Had to lift the boat out again very quickly when it was craned in in the spring. Two 1in ball valves burst because I had forgotten to open them when the boat was craned out for winter.

You would be amazed at the power of ice!

 

[Billba]

Marelon claim "Marelon plumbing systems are corrosion and electrolysis resistant and will not freeze or become brittle with age or temperature extremes. "

Could Vyv expand on his statement that he knows that "it is known to fracture in brittle mode". Excuse thread drift but curious especially on the definition of brittle mode. I do recall some early examples of handles breaking when the valve was not correctly serviced.

Also both examples of fractured metal (assumed steve_l's were metal but it would be good to confirm) were whilst ashore and closed but with no lowest temperatures quoted. As we know outside air temperatures can hit some pretty impressive figures during cold snaps and I imagine be more persistent in Finland.

 

[John the kiwi]

With many ball valves you can drill a (small)hole in the body of the valve that will drain the cavity formed when the valve is closed.
This effectively creates a "double block and bleed" valve.
When the valve is open the hole is blocked off but when closed not only is the cavity drained, but any leakage past the seals is apparent.
Common concept in industry. This would of course provide frost protection as well.
If you want to be really flash, drill and tap the hole into the cavity and fit a tiny ball valve that you use as either as a tell-tail or to drain the cavity prior to lay-up.
Cheers

 

[vyv_cox]

Could Vyv expand on his statement that he knows that "it is known to fracture in brittle mode". Excuse thread drift but curious especially on the definition of brittle mode. I do recall some early examples of handles breaking when the valve was not correctly serviced.

Also both examples of fractured metal (assumed steve_l's were metal but it would be good to confirm) were whilst ashore and closed but with no lowest temperatures quoted. As we know outside air temperatures can hit some pretty impressive figures during cold snaps and I imagine be more persistent in Finland.

This photo shows a failed Marelon valve handle. I have to assume that the body is made from the same material. The fracture is very clearly brittle, i.e. no necking, no plastic deformation and even a somewhat crystalline appearance. This one is from Maine Sailing's website, in which he has tested Marelon valves to failure at far less than the specified loads. One of the characteristics of brittle fractures in metals is that they occur within the elastic region of the stress-strain curve, i.e. before yielding takes place. Plastics do not follow quite the same rules as metals but I think the same general rules are applicable.

The fractured brass/bronze ball valve shown on my website is one of two that failed in this way on the south coast of UK last winter.

 

[Billba]

Thanks Vyv, much as expected with the handle problem. I would point out in fairness that the picture is a ball valve which could be used as a seacock but is not a current design of combined seacock that I believe is being spoken of and also nothing to do with ice damage.

http://www.google.co.uk/aclk?sa=l&a...arelon-Plastic-Seacocks.html?referrer=froogle

Here is another irrelevant but interesting stuctural failure that I suspect you have already seen

http://www.youtube.com/watch?v=YzKb0rm56Zk&feature=youtu.be

Most things will break if you don't give appropriate respect.

 

[vyv_cox]

I was answering your question about brittle fracture, not making any comment regarding the design of the valve. The plastic in the Marelon valve, and of the brass skin fitting in your video link, failed in brittle mode. Very few well-designed and manufactured engineering components are brittle for exactly the reasons that can be seen here - they fail catastrophically in overload, particularly under impact.

 

[steve_l]

Also both examples of fractured metal (assumed steve_l's were metal but it would be good to confirm) were whilst ashore and closed but with no lowest temperatures quoted. As we know outside air temperatures can hit some pretty impressive figures during cold snaps and I imagine be more persistent in Finland.

Correct, mine were metal (marine brass - not subject to de-zincification) and boat was ashore.
Lowest temperature maybe about -30C but certainly at least -15C for extended periods.
But anyway, when water freezes it needs 4% more volume. Even a small amount must expand and if there isn't space for that expansion then "bang" goes the valve...

 

[thalassa]

But anyway, when water freezes it needs 4% more volume. Even a small amount must expand and if there isn't space for that expansion then "bang" goes the valve...

I seem to remember it is more like 9 % expansion.
I had installed new brass ball valves, but after two years, the Galley Slave couldn't open or close the valves anymore, although we had worked them on each visit to the boat. And so I did look at the 'plastic' ones, and fitted Trudesign ones. It is a commercial video, and a bit of an unscientific freezing test, but still interesting.

She's (still..) delighted. Let us hope it stays that way. As Vyv's photo shows, the handle can be an issue, also with this make..

 

[steve_l]

I seem to remember it is more like 9 % expansion.

Oops, yes, you are right.
The "4" comes from the max density of water at +4C.
Seems my brain is playing tricks with me tonight, or maybe it's just old age creeping up on me

 

[NormanS]

We are leaving our boat in the Villaine River for the winter (fresh-ish water). Following a conversation with a friend who had been told if the valves are closed when and the water freezes the expansion of the water in the ball valve could damage the body, I am wondering whether to leave them open would be a safer option? I know that the accepted advice is always to close them on leaving the boat, but as we have lived on board for the last 18 months with all the valves open all the time, I can't see that they are going to suddenly fail, especially as the boat will not be moving.

Am I right to be worried about ice damage to the valve?

PS: I don't need any advice about the rights or wrongs of leaving stop cocks open, thanks

If the river doesn't freeze, the valve, or seacock, will be alright closed. If it is left open, and you have no heating in the boat, the pipework may be subjected to sub-zero temperatures, and may burst. If the pipework bursts, you will wish that the seacock was closed.

Some years ago, several boats in the Caley canal had "unfortunate experiences" caused by seacocks being left open. The pipes froze, split, and when they thawed, there was nothing to prevent the water coming in.