Seacocks replacement

Koeketiene

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At what age should you replace bronze seacocks?
We've had the boat for 11 years now, previous owner for 3 years (no replacement in his ownership either).
Apart from occasionally greasing them (maybe every other year - if I can remember to do it), I've never really done anything to them - adopting an 'if it isn't broken, don't fix it' attitude.
Boat really hasn't been out of the water for any length of time since 2010 (pontoon berth in winter, mooring in summer).

As we're now in the final stages for the big 'off' in a year or two I was wondering whether to leave them be or whether it would be wiser/necessary to replace them.

What does the panel think?
 

Nigelb

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Agree, if they are definitely bronze and valve is in good order, then no reason to replace them. Assume you have checked makers marks and no pinkish discolouration on external flange etc.
 

Heckler

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At what age should you replace bronze seacocks?
We've had the boat for 11 years now, previous owner for 3 years (no replacement in his ownership either).
Apart from occasionally greasing them (maybe every other year - if I can remember to do it), I've never really done anything to them - adopting an 'if it isn't broken, don't fix it' attitude.
Boat really hasn't been out of the water for any length of time since 2010 (pontoon berth in winter, mooring in summer).

As we're now in the final stages for the big 'off' in a year or two I was wondering whether to leave them be or whether it would be wiser/necessary to replace them.

What does the panel think?
If you are greasing them then they are the old fashioned taper plug ones? They dont dezincify,?
S
 

LittleSister

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If you are greasing them then they are the old fashioned taper plug ones? They dont dezincify,?
S

I'm not sure that's true. I was a bit alarmed that the cone of my Blakes bronze(?) seacock, about 30 to 35 years old, looked distinctly pinkish. Fortunately when I cleaned it up with grinding paste it showed this was solely in the extreme surface layer - there's a good bit of solid metal to go. But it appears to me that it shows that it can dezincify, albeit that mine has done so very little in that time.
 

macd

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I'm not sure that's true. I was a bit alarmed that the cone of my Blakes bronze(?) seacock, about 30 to 35 years old, looked distinctly pinkish. Fortunately when I cleaned it up with grinding paste it showed this was solely in the extreme surface layer - there's a good bit of solid metal to go. But it appears to me that it shows that it can dezincify, albeit that mine has done so very little in that time.

I'm sure you're right. As has been written many times, Blakes seacocks have not been bronze for many decades, but DZR brass. DZR can dezincify, albeit much more slowly than ordinary brass. No-one seems to know quite when the change of alloy occurred (even the estimable Vyv Cox), although something like 40 years ago may be a reasonable guess.

Assuming the OP's seacocks are indeed Blakes, and they appear in good working order, I'd suggest he do no more than maintain them and check for signs of significant pinkness periodically. As you write, superficial pinkness on the cone need not be cause for alarm. Any weakness in the parts is obviously more likely to be exposed by a stiff action in the valve, whether caused by excessive tightness on the clamp bolts, lack of grease, or poor cone seating.

I have known a couple of nuts holding Blakes through-hulls to completely fail through dezincifiction, although my suspicion was that these were non-original parts. Unfortunately there was no way to tell from their crumbly remains whether this was the case.

There's a current thread running about actual seacock failures, which may make reassuring reading for the OP.
 

yerffoeg

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If you are planning a long trip and havn't been out of the water for a while, then it might be a good idea to haul out and look at the hull, prop, rudder etc. As others have said, give the external aspect of the seacocks a gentle scrape with a knife and look for pink dezincification and softness of the metal. If there is only a minor degree, leave the seacocks and check them again in a few years.
 

Koeketiene

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Thank you for all the replies so far.

I've been led to believe that the seacocks are still original (boat 1984 vintage).
Have contacted the yard that built her to find out what make/material they are.

Can't see any obvious signs of dezincifiction but will take a closer look when we are alongside this winter.
 

vyv_cox

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My boat was also built in 1984. This is about the date on which Blakes seacock materials changed over from bronze to DZR, although I believe there was a period during which the cone and body were made in two different copper alloys. The cones in mine have a pink/red appearance when withdrawn but I do not think this is evidence of dangerous dezincification, simply a very thin layer of enriched copper. It disappears on grinding in.
 

ex-Gladys

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My boat was also built in 1984. This is about the date on which Blakes seacock materials changed over from bronze to DZR, although I believe there was a period during which the cone and body were made in two different copper alloys. The cones in mine have a pink/red appearance when withdrawn but I do not think this is evidence of dangerous dezincification, simply a very thin layer of enriched copper. It disappears on grinding in.

Mine is 1981and the heads seacocks are Blake and show no issues.
 

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