Seacocks again! (sorry) perhaps for vyv cox

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emnick

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I need to change the heads seacock. Marine store are selling the size I need for about £47 (bronze). Is there a simple tway I can check that it is bronze and not a Chinese copy that says its bronze but isn't?

Or is there a trustworth seller on / near the east coast that sells them?

Thanks
 
Chemical analysis, or testing with a sparky thing.

I take it you are looking at ball valves rather than Blakes Seacocks?

Seamark Nunn t'other side of Ipswich have what you want ? No it would seem not

ASAP supplies mailorder ?
 
Last edited:
emnick said:
I need to change the heads seacock. Marine store are selling the size I need for about £47 (bronze). Is there a simple tway I can check that it is bronze and not a Chinese copy that says its bronze but isn't?

Or is there a trustworth seller on / near the east coast that sells them?

Thanks
Click to expand...

The only way you can differentiate without resorting to expensive analysis is by colour. I find this site quite useful. Americans call bronze 'red brass' with good reason, although why it couldn't be 'red bronze' is beyond me. C35300 and C34500 are leaded 60/40 brasses for comparison.

Take a known brass with you to check against the fitting. I suggest any new plumbing compression fitting would do, as this will certainly be 60/40 brass. DZR, Tonval, or any other 60/40 brass will be the same colour, leaded or not. You only have to watch out for 70/30 brass but components made from this are unlikely to be in chandleries, as it is used for extrusion, deep drawing, etc.
 
This is one for the metallurgists.
Could you test these different copper -based alloys by putting a drop of acid on them.
Presumanly copper would fizz away leaving the other components. True or false?
 
A few years ago I replaced all my gate valves with ball valves. They all still seem in good condition but with all the hoo-haa about brass valves thought I'd better check. They have a DIN number and rating which I think only relates to pressure rating. They are also marked CR16 (made in Italy), does this imply DZR?
 
SHUG said:
This is one for the metallurgists.
Could you test these different copper -based alloys by putting a drop of acid on them.
Presumanly copper would fizz away leaving the other components. True or false?
Click to expand...

I did an investigative piece for YM a few months ago, trying to find methods by which they could be differentiated. No acids readily available to the majority of us had any effect at all, along with many other household chemicals. Colour is the only way.

There is no easy way even for metallurgists. My colleagues and I have discussed it several times without reaching a simple conclusion.
 
The yard are removing a genuine Blakes complete seacock / through hull fitting next week. Perfect working condition, checked and serviced by the yard in August last year. Happy to sell it for 50% of the new cost. It's a toilet outlet size and we are removing it to reduce the number of deep bilge thru hull fittings and using another outlet instead. Based at Foxs.
 
SHUG said:
This is one for the metallurgists.
Could you test these different copper -based alloys by putting a drop of acid on them.
Presumanly copper would fizz away leaving the other components. True or false?
Click to expand...

False.

I am not aware of any simple chemical test that would distinguish brass from bronze. Presumably it can be done with a Metascope.

I'd not like to rely on appearance without a good deal of experience although I bet antique dealers have no difficulty.
 
vyv_cox said:
The only way you can differentiate without resorting to expensive analysis is by colour. I find this site quite useful. Americans call bronze 'red brass' with good reason, although why it couldn't be 'red bronze' is beyond me. C35300 and C34500 are leaded 60/40 brasses for comparison.

Take a known brass with you to check against the fitting. I suggest any new plumbing compression fitting would do, as this will certainly be 60/40 brass. DZR, Tonval, or any other 60/40 brass will be the same colour, leaded or not. You only have to watch out for 70/30 brass but components made from this are unlikely to be in chandleries, as it is used for extrusion, deep drawing, etc.
Click to expand...

Is the alloy C83600 a suitable underwater material please Vyv?
 
ean_p said:
Is the alloy C83600 a suitable underwater material please Vyv?
Click to expand...

Yes, it's 85/5/5/5, same as BS 1400 - LG2, widely used for underwater bronze fittings.

Interesting 30 year history of submersible pumps on offshore platforms. The best ones were in LG2, good but expensive. Some were made in aluminium bronze, also good but they can suffer from dealuminification (try that after a few beers) and are difficult to weld. A change to 316 stainless steel was made for cost savings. After a while several failed due to crevice corrosion in stagnant areas. A change was made to duplex stainless steel. These were also expensive, and eventually some crevice corrosion also occurred. So they have gone back to LG2, which is now cheaper than duplex anyway!

They are also marked CR16 (made in Italy), does this imply DZR?
Click to expand...

I cannot find this one. The DZR CR logo looks like this
IMG_2157.jpg
If the valve is plated it is unlikely to be DZR. Sorry, can't tell you any more but a photo might help.
 
Thanks for that info Vyv......as a fairly large cast fitting would the use of stainless bolts be ok for fixing it, or is there a better alternative please?
 
There have been several posts from people who have used stainless steel fixing bolts successfully but these mostly seem to be countersunk and well bedded in mastic. In this case I suppose that the contact with seawater would be minimal. The main problem I would anticipate in using them would be if they had domed or hex heads, particularly with an external strainer, where crevice and galvanic corrosion could be a problem.

Blakes seacocks are (were?) supplied with phosphor bronze bolts, which are strong and resist corrosion well. I have read recently that their cost is astonishing, £14 each I seem to remember. Silicon bronze might be a cheaper alternative and probably as good.
 
again many thanks for the insight Vyv.... the fixings are hex head stainless holding the fitting inside a steel tube(it's a bow thruster foot), as such, even though very well bedded in sikaflex, I think that I'll look and find some silicon or phosphor bronze bolts to suit. Thanks again.
 
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