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post #11 of 34 Old 12-03-2016
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Re: Brass thru-hulls?

Boatpoker-
For the main engine water intake, that's often someplace (like in the bottom of a laz) where someone or something might step on it. But for "that *damned thruhull" under the forward washbasin that you have to secure for the head intake"...Regardless of size, you might want it is extremely resistant to being found by a 500# gorilla. Or even a clever capuchin monkey.(G)
All these technical details of "newer" alloys are the reasons that I got allergic to hearing the terms "brass" and "bronze" in any marine setting. Even ten years ago, they were being tossed around and the big guys were insisting everything was a Trade Secret. Which doesn't really impress those of us who have seen things like analytical labs. Used to be a properly timed pizza and six-pack could get you a fast analysis of almost anything in any college chem lab. So...
Brass? Bronze? Might as well say the boat is made of "plastic" and the spars are made of "wood". They're all the same, and well-defined, too. Right? (G)
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post #12 of 34 Old 12-03-2016
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Re: Brass thru-hulls?

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Originally Posted by Maine Sail View Post
The big US manufacturers of seacocks & thru-hull fittings use 85-5-5-5 bronze almost exclusively. It has been the go-to bronze for seacocks as far back as the 1930's. I have many 85-5-5-5 seacocks out there beyond 50 years old. This list of manufacturers using 85-5-5-5 includes Groco, Apollo/Conbraco, Spartan, Buck-Algonquin and even defunct manufacturers such as Wilcocx-Crittenden... This is a far superior bronze than what the ISO/RCD builders use...
Yes, it was the go to. but do you know what 85 triple 5 means? the last 5 means it contains on average 5% Zn. the newer DZR alloys contain a lot less Zn. and there is not a set way of using the terms bronze or brass
Alloy Specifications Data Page

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post #13 of 34 Old 12-06-2016
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Re: Brass thru-hulls?

85 5 5 5 is better know as red brass, does anyone make a true bronze for seacocks? Props are aluminum brass with either magnesium or nickel, so a true bronze. Unless you have access to $13,000 Niton, how do you know?

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Re: Brass thru-hulls?

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Originally Posted by overbored View Post
Yes, it was the go to. but do you know what 85 triple 5 means? the last 5 means it contains on average 5% Zn.
I am well aware that 85-5-5-5 contains as much as 5% zinc. This alloy however is the most time tested and bullet-proof alloy that has been used for seacocks & thru-hull fittings. About 20 years ago Blake's (European brand) switched away from 85-5-5-5, what they built their reputation on, and went to DZR Brass. I have never once seen an older Blake's seacock dezinced nor have I seen a Spartan, Conbraco or 85-5-5-5 piece made by Groco dezinc. I have however seen newer Blake's and numerous "CR" DZR Brass seacocks dezinced and piles of standard yellow brass dezinced.

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Originally Posted by overbored View Post
the newer DZR alloys contain a lot less Zn.
No they don't. The DZR alloys used by European boat builders contain a LOT more zinc than American seacocks do....

The alloy most used by European boat builders, when they don't use straight brass and unfortunately many do use a standard 60/40 brass, is called DZR brass. DZR Brass/CW602N is 62% Cu - 0.7% Sn, 35.2% Zn & 2%Pb. The alloy has .7% tin added to aid in dezincification resistance... Resistance being the key word.. 85-5-5-5 has 5% Zn and 5% Sn (tin is what really aids in corrosion resistance) and DZR Brass has 35.2% Zn and only .7% Sn........


The European ISO/RCD essentially allowed or created this move to DZR brass by specifying that a 5 year service life is suitable. DZR brass is less costly and easier to machine thus the European boat builders love it. If it makes it beyond year five that is all they care about and all it takes to build a boat to meet the ISO/RCD federal laws..

DZR Brass is not more corrosion resistant than 85-5-5-5 bronze, especially not out in the real world... The most proven track record I know of, for any alloy used for seacocks or thru-hulls, is 85-5-5-5 and this is why companies such as Spartan, Groco, Buck Algonquin and Apollo/Conbraco still use it to this day for seacock and thru-hull material. This is most likely because DZR brass would not pass / meet the UL/ABYC corrosion requirements...


Quote:
Originally Posted by overbored View Post
and there is not a set way of using the terms bronze or brass
Alloy Specifications Data Page
85-5-5-5 has many names that get applied to it such as leaded gunmetal, ounce metal, bearing bronze, leaded red brass, tinned bronze etc. but there is no question about its durability in the marine environment. You could not pay me to install DZR on my own boat.

Sometimes we can learn from industry and large classification societies. A look at the shipping classification societies such as DNV (Det Norske Veritas) is but one source. The classification rules for big cargo ships says that a zinc content greater than 30% is not approved for seawater systems. Under DNV classification rules DZR brass "CR" marked seacock or valve or thru-hull/skin fitting would be disallowed but an 85-5-5-5 alloy would be fine.

Under ABS classification (American Bureau of Shipping) no alloy can contain any more than 15% zinc. DZR Brass fails this classification society too but 85-5-5-5 passes.

Under UL1121 any alloy containing more than 15% zinc must undergo an additional "10-Day Moist Ammonia-Air Stress Cracking Test". At the end of this test there; " shall show no evidence of cracking or delamination when examined using 25X magnification".. I've not known of any DZR product to pass UL 1121.

The problem, and where all this nonsense started, was the ISO/RCD:

"ISO/RCD:
Through-hull fittings for water shall be corrosion resistant, defined as material used for a fitting which, within a service time of five years, does not display any defect that will impair tightness, strength or function."


While DZR is certainly much better than standard yellow brass, what far too many European builders slap into boats, it is NOT 85-5-5-5 in terms of corrosion resistance..

Thanks but I will stick with a proven time tested alloy for my seacocks, and that would be 85-5-5-5....
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post #15 of 34 Old 12-06-2016
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Re: Brass thru-hulls?

I don't know the chem composition or maker of my thru hull or ball valves in some cases. Do I worry? What are the signs of impending failure? The ball valves are neither loose nor tight.

Should I consider replacing all or some of them in the Spring?
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Re: Brass thru-hulls?

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I don't know the chem composition or maker of my thru hull or ball valves in some cases. Do I worry? What are the signs of impending failure? The ball valves are neither loose nor tight.

Should I consider replacing all or some of them in the Spring?
It should be embossed or etched into the body. Usually it is just part of the casting. If it says DZR then yes I would replace it. Keep in mind the parts are only supposed to have a service life of five years. So some will fail before that some after.

The EU standard has been a disaster, and it's a stupid way Tom save a trivial amount of money. But the series builders can shave a grand of the cost of a boat from the factory.

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Re: Brass thru-hulls?

WOW replace all the thru hulls and ball valves each 5 years? For real???? YIKES
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post #18 of 34 Old 12-08-2016
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Re: Brass thru-hulls?

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Originally Posted by SanderO View Post
WOW replace all the thru hulls and ball valves each 5 years? For real???? YIKES
I'm not sure that is exactly what the certification standard means. While this seems to be a genuine quality problem, I believe the majority far outlive 5 years. I'm just not sure that majority is high enough. After the 5 years certification window, you become the test pilot.

I'm hoping to begin a swap out to Groco this spring. Don't think I stand a chance of getting to them all, but will start with those furthest beneath the waterline.


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Re: Brass thru-hulls?

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I'm not sure that is exactly what the certification standard means. While this seems to be a genuine quality problem, I believe the majority far outlive 5 years. I'm just not sure that majority is high enough. After the 5 years certification window, you become the test pilot.

I'm hoping to begin a swap out to Groco this spring. Don't think I stand a chance of getting to them all, but will start with those furthest beneath the waterline.
In a perfect world they will not fail the day they pass the five year limit but a little galvanic or stray current action can make them fail very quickly (possibly weeks/hours respectively). Good quality bronze may take years or decades to be affected by the same current

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Re: Brass thru-hulls?

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Originally Posted by Minnewaska View Post
I'm not sure that is exactly what the certification standard means. While this seems to be a genuine quality problem, I believe the majority far outlive 5 years. I'm just not sure that majority is high enough. After the 5 years certification window, you become the test pilot.

I'm hoping to begin a swap out to Groco this spring. Don't think I stand a chance of getting to them all, but will start with those furthest beneath the waterline.
That'll be a big job Minne, some of the seacocks on the Beneteau built boats are tough to get to. I would bring rum and leave my sawza and sledge hammer at home. Good luck.
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