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Old 07-03-2012, 19:43   #31
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Re: Near disaster with brass used in below waterline plumbing

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Originally Posted by Nicholson58 View Post
The part on the left appears to be brass as well. Its like archeology. Its hard to know without provenance. BTW, the cast barbs can be hard to seal (right picture). I chuck them in a drill or lathe and use a file to make them smooth and sharp. At least file off the casting parting lines.
The part on the left is brass that is why it says BRASS above it...

I agree about cast brass being hard to seal. I do a similar routine if I can't get the cast brass machined male adapters...
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Old 07-03-2012, 19:57   #32
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Re: Near Disaster with Brass Used in Below Waterline Plumbing

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Originally Posted by s/v Jedi View Post
Before replacing anything, research the Groco flanged adapters. Search CF for the posts by MaineSail on the subject.

Replace everything.

ciao!
Nick.
Flange adapters are the way to go. I used them when I replaced all my thru hulls. Very strong, very easy fix. Highly recomended.
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Old 07-03-2012, 21:10   #33
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Re: Near Disaster with Brass Used in Below Waterline Plumbing

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Originally Posted by s/v Jedi View Post
Before replacing anything, research the Groco flanged adapters. Search CF for the posts by MaineSail on the subject.

Replace everything.

ciao!
Nick.
Yes better then just a plain thruhull, especially the thread crush. But they are still weaker then a full seacock when it comes to getting knocked off, or if the valve gets stuck and pressure it applied. As well there are no drain/grease holes, unless special order. Especially important in the great white north on the hard.


eg
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Old 07-03-2012, 23:34   #34
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Re: Near Disaster with Brass Used in Below Waterline Plumbing

It amazes me that chandleries sell brass valves for seacocks. And the worry is, somebody must be buying, or they wouldn't keep stocking them.
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Old 08-03-2012, 04:48   #35
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Re: Near Disaster with Brass Used in Below Waterline Plumbing

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Originally Posted by delmarrey View Post
Yes better then just a plain thruhull, especially the thread crush. But they are still weaker then a full seacock when it comes to getting knocked off, or if the valve gets stuck and pressure it applied. As well there are no drain/grease holes, unless special order. Especially important in the great white north on the hard.


eg
What is this statement based on? Which full seacocks are you comparing to? Some are thicker, and some are not. I have both physically tested these and made measurements of wall thickness compared to many "off the shelf" seacocks and don't find weakness to be of any issue.

If you've load tested these against other seacocks please let us know your findings?

Even in the smallest size flanged adapter, 3/4", the minimal wall thickness, at the threads, is twice that of the next size up 1" bronze thru-hull and there are millions of boats out there with nothing more than a valve on a thru-hull. At the thru-hull to flange section even the smallest 3/4" flanged adapter has a 2.75 times thicker wall than the next LARGER size 1" thru-hull fitting. You then thread a thru-hull into this area and make it even stronger.

While not ideal the number of boats that have sunk because someone tried to turn a handle is quite small on bronze thru-hull/valve installs.

I know for a fact that a 3/4" valve threaded onto a 3/4" thru-hull will handle over 400 pounds of side load when loaded at the male adapter. I don't know too many folks that can apply 400 pounds of force to open a handle. This represents the weakest bronze fittings, a valve & thur-hull, that qualifies as a "seacock" by the ABYC definition.. While it does not meet the ABYC H-27 standard for strength it is still requires over 400 pounds of force to break one. The smallest flanged adapter is, at a minimum, twice as thick, at it's smallest & thinnest point, than the wall of a 1" bronze thru-hull.....

A 3/4" valve on a 3/4" thru-hull is the weakest installation you can make other than the same set up in Marelon. In Marelon a 3/4" valve on a 3/4" thru-hull fails at under 200 pounds but in bronze it is slightly over 400 pounds...

I have never heard of a single failure of a flanged adapter and you'd be hard pressed to apply more than 100 pounds pressure when turning a handle. If you've heard of a flanged adapter failure myself, others and I'm sure Groco would love to hear about it....
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Old 08-03-2012, 07:00   #36
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Re: Near Disaster with Brass Used in Below Waterline Plumbing

I'm sorry I don't have a bunch of junk parts laying around to take pictures of with pointy arrows, labels and stuff. But I have been in the valve industry for several years and have learned what strong is, when it comes to valves.

And I'm not just talking about twisting handles, but stuff moving around in the storage areas where valves exist, or in wet bilges like on fishers. In a rough sea these things can take a beating with gear moving around. And in time, where after corrosion may have set in, that sharp little corner and them sheet metal handles are less durable. I see nothing wrong with the flanged adaptors for standard coastal use but I'm just saying..............

Personally! I'd rather have something a little more dependable. The rest of ya can cheap out if ya want. Not to mention how high up an adaptor sets the valve off of the hull. I don't have that much room on my vessel with shallow bilges and all. And when your measuring them wall thicknesses, don't forget to subtract that double thread depth (with another sharp corner).

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Old 08-03-2012, 20:04   #37
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Re: Near Disaster with Brass Used in Below Waterline Plumbing

A few months ago we discovered a stainless hose connection below the waterline. BIG connector. Pulled it, and it looked like swiss cheese! Stainless plumbing also doesn't belong below the waterline.
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Old 08-03-2012, 20:50   #38
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Re: Near Disaster with Brass Used in Below Waterline Plumbing

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Originally Posted by delmarrey View Post
And in time, where after CORROSION may have set in, that sharp little corner and them sheet metal handles are less durable.
It's the concern about potentially unseen corrosion somewhere in a dark corner in the bilge that bothers me, a bit more so than ultimate bending strength and thickness of the metal parts. Although more strength will always be good (appreciate seeing some figures by Maine Sail).

So I have opted for synthetic valves (not full seacock). Not ideal, but it just makes me feel better that they will never corrode.

I took note of the problems reported with Marelon - sticky ball valve, and handles breaking off. Based on Boracay's recommendation, I contacted Tru Design in New Zealand, where they manufacture marine valves similar to and in competition with Marelon. They assured me they had taken note of the problems reported with Marelon and had therefore chosen synthetic materials to ensure no sticky ball valve, and designed sturdier handles. I replaced all my valves with Tru Design valves.

In respect of the option of bronze flanged adapters, I do like the fact that they allow you to remove and replace/service the valve without chopping out the through-hull itself. In January I had to remove a couple of 2" bronze through-hulls, and after spending time trying to extract them neatly, I eventually resorted to grinder, hacksaw blades and chisels. So I like to avoid removing a through-hull where I can.
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Old 08-03-2012, 23:58   #39
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Re: Near Disaster with Brass Used in Below Waterline Plumbing

cures are:
1 never marry brass to metals higher up the galvanic scale - particularly bronze, in my experience, too
2 connect each metal item (e.g. THFs, portholes...) to your boat's CGP to earth them all and eliminate corrosion - see Nigel Calders handbook for details. make sure its Common to your other bits like engine, prop shaft...to eliminate voltage differentials which are the foundation of galvanic corrosion.
btw i am currently replacing brass fastenings on my bronze portholes with s/s. as salt got on the brass/bronze join it stripped the zinc from the brass - obviously.
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Old 09-03-2012, 04:05   #40
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Re: Near Disaster with Brass Used in Below Waterline Plumbing

Get rid of those metal through hulls and valves and fit marelon.
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