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post #1 of 34 Old 12-02-2016 Thread Starter
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Brass thru-hulls?

Really? They, Jeanneau,used brass for thru-hulls back in 2000?
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post #2 of 34 Old 12-02-2016
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Re: Brass thru-hulls?

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Really? They, Jeanneau,used brass for thru-hulls back in 2000?
Absolutely ! Also Beneteau, Hanse, Bavaria, Dufour.

What makes you think they stopped this practice in 2000 ?

Take a look at a few articles on this page

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Re: Brass thru-hulls?

A decade ago we wanted to add a thru-hull and started trying to dig out details from basically all the suppliers in the US as to what their yellow thru-hulls were. And it turns out that "brass" and "bronze" overlap in alloys, so what one foundry calls "brass" is exactly the same as what another calls "bronze". And then at least one top name simply refuses to say what their "bronze" alloy actually is.

No, you should use brass on a boat, but yes, there are in fact "marine brass" alloys that can legitimately be used and called "bronze".

We gave up and went with genuine Marelon.
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post #4 of 34 Old 12-02-2016
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Re: Brass thru-hulls?

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No, you should use brass on a boat, but yes, there are in fact "marine brass" alloys that can legitimately be used and called "bronze".

We gave up and went with genuine Marelon.

Gentle disclaimer .... The metallurgy gets a little complicated so my opinions have been simplified for the purpose of this forum ....

This is incorrect , Brass is brass whether you call it plated brass, Naval bronze or admiraly bronze. These are largely marketing misnomers. True brass is defined by zinc content and the previously mentioned types have between 20% -39% zinc .... these are not bronze's

Various types of bronze's may have small amounts of zinc however the types preferred for marine use will have zero or close to it.

The issue with brasses is the "Dezincification" cause by galavaic corrosion. Think of it this way your "zincs" (anodes) are designed to waste by giving up electrons to more cathodic metals ..... Do you really want your brass thoughulls giving up electrons and wasting away like your zincs.

This whole brass throughull/seacock mess was caused by the CE standards stating that throughulls and seacocks should last 5 years. So what did Jeanneau, Beneteau et al do .... they bought the cheapest materials that would meet the standard

These same builders saved even more money in many cases by fitting NPT valves on NPS throughulls ... Shocking idiocy !

Suggest you Google "dezincification, brass seacocks, NPT, NPS" lot and lots of stuff from legitimate authorities on this issue. Also some terrific photos of this stupidity on Compass Marine website (a frequent poster here).

Just to get you started read one of Paul Stevens articles in Yachting Monthly

PS. I am a Certified Corrosion Analyst and I believe this is verging on criminal.
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Last edited by boatpoker; 12-02-2016 at 02:06 PM.
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post #5 of 34 Old 12-02-2016
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Re: Brass thru-hulls?

Boatpoker, the Blake seacock is a DZR brass that can be used for seacocks but I don't know of any other valve makers that use DZR brass for their valves. I was corrected by a metallurgist on saying all brass is a no go for the reason you sight.

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Re: Brass thru-hulls?

boatpoker-
I don't disagree with you, and don't need to google it. I went through all that and when the most respected names in the industry (US or otherwise) all played "he went that-a-away" like the three stooges used to, pointing to different names and alloys and contradicting each other AND metallurgy references, that's when I said **** this all, we're going plastic. Because a good glass filled nylon, kept below the waterline, will not take UV damage, will not corrode, will not de-zinc, and if it is in a place when gorillas and flying batteries can't land on it, it will be plenty sturdy enough. Not to mention cheaper.

Now, for you to suddenly reveal that a commercial mass-market boat builder would dare to cut corners and "build it to a price", that's just shocking. Really shocking. Next you'll be trying to convince me that they use stainless instead of titanium just to shave costs and keep the prices down. (We all know, stainless is shinier and shiny shiny pretty pretty is what really counts!)

I wonder, with online machine shops and CAD/CAM and all, what it would cost to either print or carve some truly durable titanium thru-hulls. You know, perfect xmas gifts for the racing, or fast cruising, set. And whether just any old titanium alloy would do?
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Re: Brass thru-hulls?

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Boatpoker, the Blake seacock is a DZR brass that can be used for seacocks but I don't know of any other valve makers that use DZR brass for their valves. I was corrected by a metallurgist on saying all brass is a no go for the reason you sight.

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DZR (DeZincification Resistant brass) is a better quality brass alloy witha lower zinc content than normal brass with a couple of other metals thrown in and will do the job but not for as long as a good quality bronze.

There is still a bit of a crap shoot even buying brand name bronze Groco who had a great product and reputation for decades screwed up badly some years ago when theY switched production to China and did not supervise closely enough ..... result a huge recall. Don't trust Chinese metallurgy

As to Marelon .... yes, I have no problem with sizes 1.5" and over but the smaller ones give me the creeps. In a survey I used to put my foot on seacocks and apply a little pressure as they are supposed to handle up to 500lbs. lateral force. Let me just say that I learned the hard way that the smaller Marelon units were not up to the 500lb. standard.

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post #8 of 34 Old 12-03-2016
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Re: Brass thru-hulls?

Bronze is a difficult material to pour (stringy), brass and stainless pour easily. No surprise manufacturers don't want to pour it.
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Re: Brass thru-hulls?

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...
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Re: Brass thru-hulls?

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Originally Posted by gonecrusin View Post
Bronze is a difficult material to pour (stringy), brass and stainless pour easily. No surprise manufacturers don't want to pour it.
Ditto ... 'gas' bubble pockets/blow-outs too, unless the inlet/outlet 'sprues' of the mold are engineered to 'perfect'. Most 'true' bronzes are very difficult to machine (re. threads, etc.). But that is all ancient metallurgy.

BRASSES THAT ARE NOT SUBJECT TO DE-ZINCING.
Just like true-bronzes that are formulated without tin such as NickelAluminum Bronze, there are various available forms of BRASS, with zinc, that are anti-de-zincable (DZR or DR) brasses that are alloyed with 'transitional metals' such as Tellurium, Selenium, Tantalum, Niobium, Arsenic, etc. that changes the entire molecular (grain) structure which in turn inactivates and prevents the de-zinc-ability of the brass. These formulations and 'sequences' were closely held proprietary secrets. Its going to take a very long time for asian foundries to recover them; hence, the current problem of zinc loss from asian produced DRZ brass. These DZR alloys were originally discovered/formulated in the ~1950s-1960s for critical navy, aerospace and chemical engineering applications. Their current usage is quite widespread, despite the almost total forced collapse of the US 'red metals' industry and other domestic 'foundry' activities.
Here's a brief technical explanation of how these 'de-zincing' BRASSES are formulated: http://www.jomarvalve.com/docs/lit-jv-dzr.pdf

Here's a bronze without tin and without the typical trace zinc that aids 'machinability' ... I worked for of the original discoverers of this alloy at that time as a student intern bench chemist (at Phila. Bronze & Brass Corp. / AMCO Metals): Alloy: C95500 Nickel Aluminum Bronze - Concast Metals

Last edited by RichH; 12-03-2016 at 10:44 AM.
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