porous blake's seacock?

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mistrilsir

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I've just been studying a Blake's seacock on my boat which is in the water - initial observation would suggest that water is 'weeping' through the body of the seacock. There is certainly some surface moisture. Has anybody any experience of these Blake's seacocks becoming porous due to dezincing, or am I reading more into this than I should?

Thanks all!
 
mistrilsir said:
I've just been studying a Blake's seacock on my boat which is in the water - initial observation would suggest that water is 'weeping' through the body of the seacock. There is certainly some surface moisture. Has anybody any experience of these Blake's seacocks becoming porous due to dezincing, or am I reading more into this than I should?

Thanks all!
Click to expand...

Condensation?
 
No. They do not dezincify because they are either bronze (very old) or DZR. Even dezincified brass does not become porous as the copper that is left is still solid - just weak so breaks easily.

Just clean the body, dry it and check it after a couple of days.
 
Agree, condensation is most likely. Do you have any other metal through-hull fittings? If they have the same it seems likely that the seawater, hence fitting temperature is colder than the cabin air, hence condensation.
 
Or, i not condensation, could it just be leaking slightly (i.e cone needs lapping in, or cone clamping bolts need tightening up slightly)?

I think if it (or any other brand skin fitting) were porous enough to let water through the metal body (rather than gaps between parts) you'd be in very serious danger of its catastrophic disintegration.
 
Other than the leakage or condensation advised above I am not aware of any other issues with these seacocks. Mine are 30 years old and certainly display some signs of corrosion but I doubt if they leak through the body.

Some ideas. The composition of these seacocks changed from bronze to DZR in about 1985, Blakes themselves do not know exactly when. Bronze components are made by a simple casting process, which in the case of this alloy does require a certain skill level. The molten metal is poured very steadily, as a 'crust' of solidified metal oxide forms around the stream. If this is ruptured it is possible for oxide to be incorporated into the casting. I have never heard of this in relation to Blakes products.

DZR is made by hot stamping of the brass. Casting defects are therefore ruled out but I guess it is theoretically possible for a crack to form in the body. Close inspection should show this up.

It seems much more likely to me that the leakage is due to a poor fit between the cone and body, which as has been said can be rectified by grinding the two in. If your seacocks are fitted with grease nipples it would be worth pumping some in to improve the sealing. If not, it is perfectly possible to remove the cone with the boat afloat, having a conical wood plug ready to replace it. I have done this and very little water entered the boat, easily sponged up. You can then grease the cone liberally and replace it. Do not bang the wooden cone in hard, it only requires a gentle push.

All this assumes that it is a genuine Blakes seacock. If not then dezincification could be present if it was made from brass.
 
vyv_cox said:
Bronze components are made by a simple casting process, which in the case of this alloy does require a certain skill level. The molten metal is poured very steadily, as a 'crust' of solidified metal oxide forms around the stream. If this is ruptured it is possible for oxide to be incorporated into the casting. I have never heard of this in relation to Blakes products.
Click to expand...

Perhaps unrelated to the OP's problem, but might be of interest:
On my Blake Baby toilet a minuscule leak occurred, right through the bronze material of the discharge pump top. This was after more than 20 years of service. No visible crack, so I do not think it was from frost damage. More likely an imperfection from the casting that took 20+ years to form a passage.
 
BabaYaga said:
Perhaps unrelated to the OP's problem, but might be of interest:
On my Blake Baby toilet a minuscule leak occurred, right through the bronze material of the discharge pump top. This was after more than 20 years of service. No visible crack, so I do not think it was from frost damage. More likely an imperfection from the casting that took 20+ years to form a passage.
Click to expand...

All good thoughts! I'll return to the boat and have a further study of the fitting - possible hip dislocation not withstanding!

thanks all.
 
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