Seacock failure

[AntarcticPilot]

Just had an "interesting" failure of the seacock on my engine raw water inlet. Opened it to start the engine; it apparently worked smoothly and easily (too easily?). Started the engine - no water. Checked the water pump - all ok. Investigated the seacock - handle and spindle both rotating smoothly. Opened up the strainer, which is the cylindrical type vertically over the seacock, and found that no matter what the position of the handle, the seacock remained closed. This is obvious in my case as you can see daylight through the strainer when it's open! But I probed with a long screwdriver to ensure it wasn't blocked by fouling. Apparently somehow the spindle has become detached from the ball.

The seacock is new; it was replaced last year by a reputable yard; but of course they don't make the seacocks!

I'm curious about the following:

1. How can the spindle become detached? After all, it worked fine when I closed the seacock!
2. How common is this failure mode?
3. How can it be avoided?

 

[vyv_cox]

Quite common. The ball is chromium or nickel plated brass, which pits, increasing friction enormously. The stem is brass, which dezincifies. The active part of the stem has a very small section, so it breaks easily.

There are photos at Brasses and bronzes

 

[LittleSister]

I have read on this forum various mentions of the possibility of the connection between the handle and the valve failing, such that it would be one of the first things I'd check if I experienced a lack of water coming in or out. I assumed, though, that this would be the result of years of corrosion, so I'm very surprised this would happen on a one year old seacock, and guess it might be the result of faulty manufacture.

It could be avoided by using Blakes seacocks, where you can see the top of the valve cone and hence whether it is turning - the handle fits on a tapered square that is actually an integral part of the cone. The disadvantage being that you can't poke straight through with a screwdriver or whatever (as you were intending) to clear an external blockage by weed, plastic bag or whatever, as the path through the seacock is angled.

If it were me in your position, I'd put it down to bad luck and replace with similar.

 

[jwilson]

Happened to me on launch a couple of years ago - a maybe 5-6 year old Italian bronze seacock with S/S handle on the engine inlet.

I started the engine, looked over the transom and saw water coming out of the exhaust, and motored away. 50 yards from the slip started to get steam out the exhaust, ran at fast tickover to a nearby pontoon to investigate. Took off the seacock and banged the conical bung in and it was obvious the handle to ball joint had failed. Went and bought new and fitted it. Replacing it whilst afloat was a slightly damp experience, but thanks to hybrid cure-underwater sealant it has never leaked since.

 

[lustyd]

A similar failure on mine led to me replacing all with TruDesign ones which have been much smoother in operation and cleaner/drier inside the boat since they don't create condensation and don't corrode

 

[rotrax]

Spindle sheared off on one of our boats. It was the heads outlet. The heads had been used before it was realised the outlet was not open.....................................

 

[James_Calvert]

A similar failure on mine led to me replacing all with TruDesign ones which have been much smoother in operation and cleaner/drier inside the boat since they don't create condensation and don't corrode

Is the True design spindle better?

 

[James_Calvert]

I confess I was reasonably happy with gatevalves, which were easy enough to take apart for annual inspection and lubrication. But a few years ago I replaced them with ball valves. No way of telling what state they are in. And now it seems a brand new one can fail...

Back to gatevalves next time then?

 

[AntarcticPilot]

I have read on this forum various mentions of the possibility of the connection between the handle and the valve failing, such that it would be one of the first things I'd check if I experienced a lack of water coming in or out. I assumed, though, that this would be the result of years of corrosion, so I'm very surprised this would happen on a one year old seacock, and guess it might be the result of faulty manufacture.

It could be avoided by using Blakes seacocks, where you can see the top of the valve cone and hence whether it is turning - the handle fits on a tapered square that is actually an integral part of the cone. The disadvantage being that you can't poke straight through with a screwdriver or whatever (as you were intending) to clear an external blockage by weed, plastic bag or whatever, as the path through the seacock is angled.

If it were me in your position, I'd put it down to bad luck and replace with similar.

I very much doubt if there's space for a Blake's seacock.

 

[justanothersailboat]

That corrosion and dezincification killed (EDIT - I should have said "might have killed") your seacock in ONE year is scary. And it could have failed stuck open. Are these the short-life domestic plumbing brass type, or a better grade?

James_Calvert - the trudesign spindle is glass reinforced nylon as far as I know. It's not easy to corrode. The ball doesn't either and it turns in Teflon, so it should avoid this failure mode. I don't hear anyone complaining about problems with trudesigns... fingers crossed... I just replaced my gate valves (with corroded stems...) with them.

Unfortunately Trudesigns are also really tall and quite bulky.

 

[wrr]

I had a similar experience with failure of the stem of a "bronze"seacock after two years. While the body was bronze, examination showed that the ball was chromed brass, the stem was brass and the handle was plated steel. Perhaps I should have wired a bulb to it as an anchor light! The all bronze replacement with a plastic ball has lasted more than 10 years.

 

[lustyd]

Is the True design spindle better?

There's no metal to corrode and cause friction so I guess yes it's better but not necessarily because of the spindle itself.

 

[vyv_cox]

I confess I was reasonably happy with gatevalves, which were easy enough to take apart for annual inspection and lubrication. But a few years ago I replaced them with ball valves. No way of telling what state they are in. And now it seems a brand new one can fail...

Back to gatevalves next time then?

The stem on a gate valve is even smaller than its cousin on a ball valve. The slide tends to foul up, friction increases ten-fold, the stem dezincifies and snaps and the valve fails closed. Doesn't usually fail open as the stem is in compression when closing.

 

[AntarcticPilot]

That corrosion and dezincification killed your seacock in ONE year is scary. And it could have failed stuck open. Are these the short-life domestic plumbing brass type, or a better grade?

James_Calvert - the trudesign spindle is glass reinforced nylon as far as I know. It's not easy to corrode. The ball doesn't either and it turns in Teflon, so it should avoid this failure mode. I don't hear anyone complaining about problems with trudesigns... fingers crossed... I just replaced my gate valves (with corroded stems...) with them.

Unfortunately Trudesigns are also really tall and quite bulky.

At the moment I have no evidence of why the seacock failed; it could have been a manufacturing fault. There is no sign of corrosion externally, and both handle and spindle are clean and in good condition externally. No inspection I could have done would have detected a problem.

 

[James_Calvert]

The stem on a gate valve is even smaller than its cousin on a ball valve. The slide tends to foul up, friction increases ten-fold, the stem dezincifies and snaps and the valve fails closed. Doesn't usually fail open as the stem is in compression when closing.

Thanks, that's a bit reassuring. With maintenance, my gatevalves opened and closed easily so the stem didn't get much stress. I was aware that the thread inside the gates seemed weak though...

 

[tjbrace]

My heads inlet had the same symptoms last season. Replaced the ball valve during layup, the broken one was original in 1991.
Ball was seized and the shaft sheared.

 

[Plum]

Just had an "interesting" failure of the seacock on my engine raw water inlet. Opened it to start the engine; it apparently worked smoothly and easily (too easily?). Started the engine - no water. Checked the water pump - all ok. Investigated the seacock - handle and spindle both rotating smoothly. Opened up the strainer, which is the cylindrical type vertically over the seacock, and found that no matter what the position of the handle, the seacock remained closed. This is obvious in my case as you can see daylight through the strainer when it's open! But I probed with a long screwdriver to ensure it wasn't blocked by fouling. Apparently somehow the spindle has become detached from the ball.

The seacock is new; it was replaced last year by a reputable yard; but of course they don't make the seacocks!

I'm curious about the following:

1. How can the spindle become detached? After all, it worked fine when I closed the seacock!
2. How common is this failure mode?
3. How can it be avoided?

some (cheap?) ball valves have very little engagement of the spindle into the recess in the side of the ball. I had one that although had not yet failed completely, the ball only turned 45 degrees when the handle rotated 90 degrees. Huge backlash.

 

[Halo]

I replaced my brass seacocks with bronze after they suffered de zincifification a few years later I replaced the bronze ones after the balls failed because they were brass, no way to fit true design so I used stainless 316. 8 years on they are working well- really easily turned. So despite the potential for crevice corrosion I think they are the best option for me and potentially others
Something to bear in mind when you replace

 

[Snowgoose-1]

I

I replaced my brass seacocks with bronze after they suffered de zincifification a few years later I replaced the bronze ones after the balls failed because they were brass, no way to fit true design so I used stainless 316. 8 years on they are working well- really easily turned. So despite the potential for crevice corrosion I think they are the best option for me and potentially others
Something to bear in mind when you replace

Interesting.
Lots of other stainless fittings that are under water.
Guessing that the stainless seacocks attached to bronze skin fitting ?

 

[MoodySabre]

Mine failed in the open position as did the heads inlet. At least I could continue using the boat until the end of season. Both were old. I reckon yours was faulty to have gone that quickly.