Dezincified Blakes seacock? Advice on condition please.

[differentroads]

Hi. I have four Blakes seacocks which will be around 40 years old. All work fine, especially after regrinding the valves two years ago.
But after sharing a photo of them on a PBO forum thread, its been pointed out how pink one looks and that it might be badly dezincified (thanks ctva).
Here's the original photo plus another where the light shows that the valve isn't as alarmingly pink as the close up. But still rather pink and striated. I can't remember the look of the other valves but assume they'd be similar or I'd have been more alert to a potential serious problem.



I also serviced another Blakes that was only four years old. Haven't got a photo of the valve, but the colour of the body is noticeably more golden.
I'll be taking the boat out of the water next winter and will disassemble the seacocks and check the through-hull parts and bolts. In the meantime, any points and advice gladly welcomed

 

[LittleSister]

I had one that looked rather pink when I dismantled it, but when I when I lapped the cone a bit, and rubbed a couple of other parts of it with some emery cloth, it was clear from the change in colour that the dezincification was only a very thin layer at the surface.

 

[vyv_cox]

The pink looking one is not dezincification, it is bronze. What Americans call 'red brass'. Blakes changed over from bronze to DZR in about 1985, so your recent yellow looking one is DZR brass. See my website for lots more info.

 

[ctva]

Good to know.

 

[differentroads]

The pink looking one is not dezincification, it is bronze. What Americans call 'red brass'. Blakes changed over from bronze to DZR in about 1985, so your recent yellow looking one is DZR brass. See my website for lots more info.

Thanks for that reassurance. I think I panicked myself slightly by comparing photos in retrospect, not knowing that Blakes had changed to DZR brass
Your website is great, by the way. I've visited a fair few times over the past few years of my refit and really apprecited the depth of knowledge and experience you've taken time to share.

 

[pvb]

Your website is great, by the way. I've visited a fair few times over the past few years of my refit and really apprecited the depth of knowledge and experience you've taken time to share.

Vyv's website is an excellent resource for boaters, full of info and photographs. Great stuff!

 

[Poignard]

Has anyone here ever experienced a catastrophic failure (as opposed to a leak) of a traditional Blake's seacock due to de-zincification?

I mean the sort of failure where the seacock breaks up.

 

[Rappey]

Isnt something thats badly dezincified usually badly pitted too ?

 

[boatmike]

Has anyone here ever experienced a catastrophic failure (as opposed to a leak) of a traditional Blake's seacock due to de-zincification?

I mean the sort of failure where the seacock breaks up.

Very rare to see a blakes seacock really breaking down. vyv is absolutely right. Neither of the photos give rise for concern. What you are looking at is the plug. In other words the moving part. The fixed part attached to the hull is the part that would give concern if corroded. Clean up the part you see on the outside of the hull. If this is pitted or very "pink" replace it but its rare to see this on a blakes seacock. Lapping the plug to the housing with grinding paste should remove all surface discolouration then reassemble with waterproof grease. A tube of proper Blakes seacock grease is a wise investment. I have a tube I bought in 1976 and its still going strong!