Brass or Bronze?

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John Hasler
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Re: Brass or Bronze?

Post by John Hasler » Tue Oct 10, 2017 1:42 pm

Carrdo writes:
> ...half of the materials seen there are brass.

Things made of bronze are often called brass, even by people who should know better. There are also anti-leaching brass alloys (I have no idea how well that works).

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10KPete
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Re: Brass or Bronze?

Post by 10KPete » Tue Oct 10, 2017 3:45 pm

The elephant is still in the room guys.

Is there and easy way to tell brass from bronze?

Chemistry?

Pete
Just tryin'

Wolfgang
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Re: Brass or Bronze?

Post by Wolfgang » Tue Oct 10, 2017 3:48 pm

As stated above, boiler bushings should not be made from mystery brass/bronze. If, in order to get the proper bronze for the job it is necessary to purchase a full length bar, so be it. This expense may be offset by offering say 1 foot lengths of the bar for sale to fellow club members, at a slight mark-up if you wish. Boiler bushings are NOT the place to scrimp on material costs!

Making boiler fittings from brass is much less problematic since deteriorated fittings may easily be replaced.

Threads... I'm of the firm opinion that boiler bushings should have standard inch or metric threads and NOT tapered pipe threads; but then I detest tapered pipe threads.:-)).
Wolfgang

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Re: Brass or Bronze?

Post by Wolfgang » Tue Oct 10, 2017 4:03 pm

10KPete wrote:The elephant is still in the room guys.

Is there and easy way to tell brass from bronze?

Chemistry?

Pete
Many moons ago I experimented with small crucibles of tin. Thus I propose the following test which I have not tried myself, but offer for your consideration.

Cut a 1/8" thick slice off a known bronze bar, and a similar slice off a brass bar. Place both on a fire brick close together but not touching, and heat them with an oxy-fuel flame until they melt.

Keep heating until a difference appears in the molten puddles.

Report your observations in this forum.

As I stated above I have not tried this, but I know that tin is quite a heat resistant metal. Even heated to over 1000 deg. Fahrenheit it remains a shiny liquid that appears like mercury, whereas the zinc will evaporate (sublime) at prolonged elevated temperatures.

So who's going to make a name for themselves by doing this test? If indeed successful we could name this test after you.

Wolfgang

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Carrdo
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Re: Brass or Bronze?

Post by Carrdo » Tue Oct 10, 2017 4:17 pm

Those fittings (all USA) which I reviewed on the internet are brass guys! They are all made from hex stock and not from imported UK bronze hex. And those suppliers know the difference between brass and bronze.

Pontiacguy1
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Re: Brass or Bronze?

Post by Pontiacguy1 » Tue Oct 10, 2017 4:29 pm

Brass is not a problem to use for fittings in my experience. Any problems or deterioration can be seen and the fittings simply replaced. Most of these will be brass, and will last longer than you care to imagine. I have many brass fittings on my locomotives, and most have been in service for almost 20 years or more. Only failures I've had were when something got hit and cracked or broke.

I think the point that everyone is trying to drive home is this: Don't use brass for anything that you are going to silver solder into your boiler like a bushing. If you use a piece of brass to make the fitting that screws into that bushing, then that's OK. Don't want brass fittings? Make them all yourself and then you'll know what you have.

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Fender
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Re: Brass or Bronze?

Post by Fender » Tue Oct 10, 2017 4:31 pm

There are many different alloys of both brass and bronze. In general, the more zinc there is, the more yellow the color. Since it is the zinc that causes the problem, any material that is yellow (vs. reddish) would likely be brass, and be avoided where dezincification would be an issue. Another way to tell the difference between bronze and brass is because bronze will have faint rings on its surface. Although I haven’t tried it, I expect A drop of sulfuric acid would react more strongly to an alloy with a high concentration of zinc (brass) than one with tin (bronze).
Dan Watson

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Carrdo
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Re: Brass or Bronze?

Post by Carrdo » Tue Oct 10, 2017 5:59 pm

Dan,

I don't want to be argumentative but it depends. I have both flat and round bars of bronze here which have the rings and then there are other pieces which don't. I guess it depends on how the material was finished or how old the material is (surface aging). I am posting a photo of a piece of quite old bronze round which I know is bronze (don't know what alloy it is) and it doesn't have any rings. Photos can be deceiving as well. The piece which I have is much more copper in colour that what is seen in the photo for some reason. It is really tricky to judge just by one's eyes alone.
Attachments
A Piece of Bronze Round Bar.jpg

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Builder01
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Re: Brass or Bronze?

Post by Builder01 » Tue Oct 10, 2017 6:04 pm

As for commercial fittings, yes, what you are saying is true. That's why I make just about all of these fittings myself, even the clean out plugs on my water gauge are bronze. I believe anything that touches live steam, should probably not be brass.

These commercial fittings, if and when there is a problem, can be unscrewed from the boiler and replaced (hopefully!) It is a good question though, why don't the commercial manufacturers make these items out of bronze?

David

rkcarguy
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Re: Brass or Bronze?

Post by rkcarguy » Tue Oct 10, 2017 7:01 pm

My first two jobs were in machine shops that often served the marine industry, bronze is more reddish in color and machines different. For instance, brass is a bit gummy while bronze "chips out" differently, like the difference between machining gummy aluminum and 7075 alloy.
Personally I think brass is ok, bronze threads strip easily and bronze fittings can crack. I've seen brass hold up better, for instance if a fitting is dropped or something hits it, brass will bend, bronze will break off at the threads.

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Fender
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Re: Brass or Bronze?

Post by Fender » Tue Oct 10, 2017 7:56 pm

Carrdo wrote:Dan,

I don't want to be argumentative but it depends. I have both flat and round bars of bronze here which have the rings and then there are other pieces which don't. I guess it depends on how the material was finished or how old the material is (surface aging). I am posting a photo of a piece of quite old bronze round which I know is bronze (don't know what alloy it is) and it doesn't have any rings. Photos can be deceiving as well. The piece which I have is much more copper in colour that what is seen in the photo for some reason. It is really tricky to judge just by one's eyes alone.
Carrdo,
I’m saying the color and presence or absence of rings are clues, but not definitive in determining the difference. As others have said, anything being silver soldered in should have a pedigree. But, if it is a light yellow color and machines easily it’s probably brass such as C360.
Dan Watson

John Hasler
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Re: Brass or Bronze?

Post by John Hasler » Wed Oct 11, 2017 11:12 am

Take a sample to a scrap dealer and ask him to check it with his XRF spectrometer. Alternatively, since the risk seems to be that chloride ions will leach out the zinc, boil a sample of each material in dilute sodium hypochlorite and then examine the samples for porosity.

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