Bronze Pipe Nipples

Feb 6, 1998
11,667
Canadian Sailcraft 36T Casco Bay, ME
All they say is that it is the same as their seacocks and galvanically compatible. Their seacocks, thru-hulls and other bronze is very, very resistant to corrosion. I have yet to have a Groco fitting suffer from any sort of galvanic degredation.

We know red brass is resistant to galvanic corrosion but has a much higher zinc content, about 15%, than does marine grade bronze so they technically are not galvanically compatible. Most pipe nipples you can buy at chandleries are red or yellow brass. While red is decent it's not ideal..
 

Ross

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Jun 15, 2004
14,693
Islander/Wayfairer 30 sail number 25 Perryville,Md.
I have always been amused by the confusion in naming copper alloys Naval bronze is by some definitions a brass. As best as I can learn if its primary alloying metal is zinc it should be called a brass. If zinc is a minor alloy and there are other metals used then it is a bronze. I would trust Groco or Buck Algonquin to get it right.
 

RAD

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Jun 3, 2004
2,330
Catalina 30 Bay Shore, N.Y.
My dock neighbor went through this last summer and he needed a 2" or 1-1/2" coupling,so I offered to get one at a big plumbing supply and could only find a brass one but believe or not one day shortly after the purchase I noticed in the plumbing section of West Marine they had bronze couplings so I told my neighbor and he bought it and changed out the brass one
 
Feb 6, 1998
11,667
Canadian Sailcraft 36T Casco Bay, ME
I have always been amuzed by the confusion in naming copper alloys Naval bronze is by some diffinitions a brass. As best as I can learn if its primary alloying metal is zinc it should be called a brass. If zinc is a minor alloy and there are other metals used then it is a bronze. I would trust Groco or Buck Algonquin to get it right.
For instance Manganese Bronze and Tobin Bronze are very high zinc content but are still considered a bronze?

This is why you see bronze prop shafts, usually made of tobin bronze & about 40% zinc, with dezincification and props, often made of manganese bronze, with dezincification. Nibral Nickel/bronze/aluminum has very little to no zinc but few sailboat props are made from Nibral and it is usually reserved for higher horsepower props. More expensive folders like Flex-O-Fold are made from Nibral but the standard Michigan Wheel "MP sailor props" are generally manganese bronze unless special ordered in nibral.
 
Oct 22, 2008
3,502
- Telstar 28 Buzzards Bay
The major problem is finding someone who stocks the bronze nipples at a reasonable price.:)
 
Feb 6, 1998
11,667
Canadian Sailcraft 36T Casco Bay, ME
The major problem is finding someone who stocks the bronze nipples at a reasonable price.:)
They can be ordered from any Groco dealer and the issue is NOT price. Cut a corner and mix brass and bronze and it could cost you a lot more than the price of a nipple!!:doh:;)

This is what can happen when mixing a brass hose barb and a bronze elbow. Note the pinkish dezincification of the brass where it broke..
 
Oct 22, 2008
3,502
- Telstar 28 Buzzards Bay
Maine—

You know I would never advocate mixing metals or cutting corners.
 

Ross

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Jun 15, 2004
14,693
Islander/Wayfairer 30 sail number 25 Perryville,Md.
Domestic plumbing often has chrome plated yellow brass nipples threaded into copper piping and if the water isn't neutral they come apart. I have picked the remains of the threads out of a female adapter. lift an end and unwind them like a piece of wire.
 
Sep 25, 2008
2,288
C30 Event Horizon Port Aransas
What happens to copper in sea water? Why is it not used more? Also I have a bunch of fittings on old seacocks that came in a box of parts, how do I tell if they are bronze or brass?
 
Oct 22, 2008
3,502
- Telstar 28 Buzzards Bay
If the copper is connected to more or less noble metals, it creates a galvanic cell and depending on the nobility of the metals involved, bad things happen. Aluminum and brasses are generally fairly low on the scale, bronze, passivated stainless steels, titanium are fairly high on the scale. :)
What happens to copper in sea water? Why is it not used more? Also I have a bunch of fittings on old seacocks that came in a box of parts, how do I tell if they are bronze or brass?
 
Oct 22, 2008
3,502
- Telstar 28 Buzzards Bay
Hose barbs on plastic or rubber hose isn't the problem. It is when metal-to-metal contact is present, like using a copper or brass pipe nipple with a bronze fitting. The fact that the two metals are in contact and one is more or less noble than the other is what causes the problem—especially if the fluid they're carrying is salt water.
Here are two identical hose barbs. I cleaned one up and left one how it came out.