Lubricating ball valves on through hulls

cindersailor said:
I would advise against soaking anything made of brass in hydrochloric acid (or indeed any type of strong acid). DZR is just brass with a few additions to limit dezincification. If you place a piece of brass in some hydrochloric acid it will fizz and the zinc will be dissolved away just leaving the copper.
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Nonsense. I have tested brass, bronze and DZR valves with a wide range of household products including hydrochloric acid, caustic soda and many others. Not one of them even stained any of the valves.
 
As others have said, the seal is effectively a solid lubricant, either PTFE or a similar plastic, and should need no lubrication. However, beware that if valves are stiff to operate it may be because the ball has pitted. Most older ball valves, even bronze ones, have a brass ball that is either chromium or nickel plated. Over time the plating flakes off as the brass pits beneath it. The almost inevitable result is that the stem sees more and more shear loading until it fractures, particularly since, also being brass in many cases, it suffers dezincification. I have photos of this kindly provided by a forum contributor but have yet to add it to my website.
 
Lubricating a ball valve with stainless ball and plastic seals is unnecessary and a waste of time. They should be 'exercised' regularly to keep them free.
If you're hauled out, it's worth checking that they actually open and close when the lever moves. Some have corrosion resistant ball and body but internal parts such as the operating spindle are made of inferior stuff. The operating handle is also prone to rot.
 
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Rogershaw said:
In the real world people and especially manufactures of AWB go for the cheapest solution rather then the correct engineering solution which makes maintenance easy.
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That doesn't answer my question. And it isn't just AWBs which use ordinary valves, the "premium" manufacturers do as well.
 
dunedin said:
Great photos and very helpful analysis. It is staggering that even people like Malo penny pinch on decent seacocks on a boat costing perhaps half a million Euros new
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Not necessarily penny pinching. They use what they use because they have been using them for decades without problems. When did you last hear of a Malo (or an HR) - or indeed any of the tens of thousands of European boats sink because of valve failure?
 
pvb said:
That doesn't answer my question. And it isn't just AWBs which use ordinary valves, the "premium" manufacturers do as well.
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Boats used to blake's type seacocks which could be serviced without disturbing the pipework but probably due to the cost of the blake's type seacock manufactures started to use bronze/DZR brass ball valves that could not be services without disturbing the pipe work maybe thinking the ball valves did not need servicing. It has also been spoken on the fora about some manufactures using brass ball valves and advising replacement after 5 years.

This sounds like alot of production builders run by accountants and not proper engineers.

When I built my boat I did use one piece ball valves in places mainly above the water line but slowly replacing then with 3 part valves as it makes checking and servicing so much easier.

Now that my answer what is yours to your question ?
 
Tranona said:
Not necessarily penny pinching. They use what they use because they have been using them for decades without problems. When did you last hear of a Malo (or an HR) - or indeed any of the tens of thousands of European boats sink because of valve failure?
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It may be the case that neither of these boat makes have sunk due to dezincification. However, I know that seacocks in both have been replaced due to serious dezincification in well under ten years of use. The many examples of dezincification that I have in my files have occurred across the board, all yacht types have been susceptible regardless of cost. There is an example of a seacock on a Malo on my website - it snapped when its owner leaned on the hose.

The MD of HR told us that he expected owners to replace their seacocks as part of normal maintenance. If you replaced a corroded or seized seacock at, say, seven years would you tell the boat builder? I certainly would not and I doubt that many would.
 
vyv_cox said:
It may be the case that neither of these boat makes have sunk due to dezincification. However, I know that seacocks in both have been replaced due to serious dezincification in well under ten years of use. The many examples of dezincification that I have in my files have occurred across the board, all yacht types have been susceptible regardless of cost. There is an example of a seacock on a Malo on my website - it snapped when its owner leaned on the hose.
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The possibility of dezincification is not in question - but as a %age of the hundreds of thousands in use, the number of failures is tiny, and the number of sinkings as a result even smaller. Brass valves are nothing new, neither did the RCD change anything. While you may find examples that fail in under 10 years - or even under the 5 year expectation in the RCD you will find a much greater number that last far longer than that. Life of such things is not predictable, so it is difficult to set a standard that will ensure there are no failures. as you have noted on many occasions, failure is often in the ball rather than the body, and the balls are generally the same irrespective of the material of the body. Equally, the body is under little stress in normal use and even severe dezinficiation may not affect the integrity of the fitting. As your example shows it only becomes apparent if the fitting is put under abnormal stress, or cut open after removal.
 
Sea cocks are unlikely to fail on an empty boat - it needs some external force to fracture them. It's recommended that you give them a clout with a lumphammer during the annual haulout (if you have one). I've never experienced a failure of the body but have had a couple where the internal spindle has rotted through.
 
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