Over annealing copper fire tubes?

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ChooChooChris
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Over annealing copper fire tubes?

Post by ChooChooChris »

Not sure if I messed up here or not. I used a oven to heat to apx 900-1000 degrees (clean cycle) and left the tubes in the entire time. When they came out they had a powder of gray all over them. Unsure if it was from soot or if it is an oxide layer but it mostly comes off easily and very little discoloration relains after a light sanding.

Is there a worry about over annealing? A little bit of this discoloration remains where the tubes are being rolled in could this cause any future issues? Ideally I would acid bath them but don’t have the ability to do it so am just lightly sanding instead.
-Chris Srch---- Home track Tradewinds and Atlantic Railroad
ChooChooChris
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Re: Over annealing copper fire tubes?

Post by ChooChooChris »

This is how they look
68EB85AD-56A5-4D2B-96FA-49FB4CB7F1F9.jpeg
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-Chris Srch---- Home track Tradewinds and Atlantic Railroad
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Bill Shields
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Re: Over annealing copper fire tubes?

Post by Bill Shields »

Is normal...just clean and go.

When you over anneal cooper ...it melts into a puddle.
Too many things going on to bother listing them.
ChooChooChris
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Re: Over annealing copper fire tubes?

Post by ChooChooChris »

Guess I normally start working it before that powder has a chance to form (small scale stuff). Will a little missed grey that ends up in the joint cause any long term issues ? Did the best I could but short of an acid bath won’t get 100 percent ( see first photo first inch of pipe)
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Steggy
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Re: Over annealing copper fire tubes?

Post by Steggy »

Bill Shields wrote: Sun Oct 02, 2022 3:37 pmWhen you over anneal cooper ...it melts into a puddle.

...or turns into the metallic equivalent of a licorice stick. Gotta watch out when using an oxyacetylene torch to solder copper pipe. :o
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Harold_V
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Re: Over annealing copper fire tubes?

Post by Harold_V »

ChooChooChris wrote: Sun Oct 02, 2022 3:43 pm Will a little missed grey that ends up in the joint cause any long term issues ?
The gray you mention is oxidized copper. If you've fluxed properly, it shouldn't be an issue, but, if not, it could compromise a solder joint. Best scenario is to remove all oxides, inside and out, even for rolled tubes.
Did the best I could but short of an acid bath won’t get 100 percent ( see first photo first inch of pipe)
Copper will NOT dissolve in dilute sulfuric acid, but copper oxide readily does. It wouldn't be all that difficult to clean the tubes inside and out by placing them in a capped piece of PVC or ABS pipe filled with battery acid, readily available at many auto parts stores. They need not all be done at the same time, so a relatively small piece of pipe would suffice. Rinse them well with running water after they are removed from the acid. Wear gloves and eye protection.

H
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ChooChooChris
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Re: Over annealing copper fire tubes?

Post by ChooChooChris »

Harold_V wrote: Sun Oct 02, 2022 4:12 pm
ChooChooChris wrote: Sun Oct 02, 2022 3:43 pm Will a little missed grey that ends up in the joint cause any long term issues ?
The gray you mention is oxidized copper. If you've fluxed properly, it shouldn't be an issue, but, if not, it could compromise a solder joint. Best scenario is to remove all oxides, inside and out, even for rolled tubes.
Did the best I could but short of an acid bath won’t get 100 percent ( see first photo first inch of pipe)
Copper will NOT dissolve in dilute sulfuric acid, but copper oxide readily does. It wouldn't be all that difficult to clean the tubes inside and out by placing them in a capped piece of PVC or ABS pipe filled with battery acid, readily available at many auto parts stores. They need not all be done at the same time, so a relatively small piece of pipe would suffice. Rinse them well with running water after they are removed from the acid. Wear gloves and eye protection.

H

It is a rolled joint. No solder involved just a tight squeeze. .75 od .62 id hole is .757 expanding Id of copper to .64 which if my math is correct is a 10 percent thinning of the material which every book says is “correct” for copper
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Bill Shields
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Re: Over annealing copper fire tubes?

Post by Bill Shields »

As said earlier...do not worry about it.

You are good...
Too many things going on to bother listing them.
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Re: Over annealing copper fire tubes?

Post by Marty_Knox »

Why did you anneal them? You don't need to anneal if you are installing tubes with a roller.
ChooChooChris
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Re: Over annealing copper fire tubes?

Post by ChooChooChris »

Marty_Knox wrote: Sun Oct 02, 2022 5:46 pm Why did you anneal them? You don't need to anneal if you are installing tubes with a roller.
The first tube I did was not annealed and reaulted in surface cracking and lots of copper flakes that kept jamming up the roller . Hope I didn’t make a mistake doing that.
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Bill Shields
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Re: Over annealing copper fire tubes?

Post by Bill Shields »

You are ok.

I prefer to roll annealed tubes, but both ways will work if you have experience.
Too many things going on to bother listing them.
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Re: Over annealing copper fire tubes?

Post by Marty_Knox »

ChooChooChris wrote: Sun Oct 02, 2022 5:56 pm
Marty_Knox wrote: Sun Oct 02, 2022 5:46 pm Why did you anneal them? You don't need to anneal if you are installing tubes with a roller.
The first tube I did was not annealed and reaulted in surface cracking and lots of copper flakes that kept jamming up the roller . Hope I didn’t make a mistake doing that.
What were you using as a lubricant? You shouldn't roll tubes dry. Just about any oil or grease will work, even Crisco.
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