87944turbo

Does anybody know about annealing copper gaskets? I have been doing some research and it sounds like copper gaskets can be re-used, but they should be annealed to "soften" them before re-using them. I want to use these for my exhaust instead of the sealing rings.

From what I understand, the annealing process consists of heating the copper to a dull red and allowing it to cool. I have read that it should be allowed to air cool, but I have also read that it can be quenched and that the cooling process makes no difference, its the heating that matters???

Also, I know the melting point of copper is ~2000 DEG F, but what is the point where it becomes cherry red, I have heard about 800 DEG F? And can this be achieved with a propane torch, i have read that an Oxy/Acetylene torch can get too hot.

Frank@Work

Mark Evans showed in his program on Discovery that you can heat the copper gasket and cool it in water.

87944turbo

Do you know what he used to heat it? Propane is relatively cheap, but I don't know how hot it can get.

macnewma

If propane isn't enough, try MAPP. It is somewhere between the temps of propane and oxy-acet.

macnewma

Here is a quick guide to annealing copper gaskets. It is in regards to a head gasket though.
http://www.headgasket.com/preinstall.html

This website says not to anneal copper gaskets because a special oven is required:
http://www.scegaskets.com/techtips/engineprep.html

I have just reused mine asis. I guess I will clean it next time, but the pressure isn't nearly as intense for an exhaust gasket as it is for a head gasket, which is what all this refers to.

Trucho-951

annealing copper gaskets is important for high pressure hoses such as brake lines and fuel lines.

87944turbo

Max,

Can you tell me a little more about MAPP. Is it something that is readily available?

And do you think annealing is necessary for exhaust gaskets? To me, it just seems like a good preventative measure that might allow the gasket to form and make a better seal. I know that other commercially available copper exhuast gaskets are ~1/16" thick. So I can't imagine that they are subjected to that much pressure. But I really don't know what the maximum exhuast pressures for our cars would be ???

macnewma

MAPP gas is sold next to propane at the hardware store. It is usually in the yellow benzomatic bottle.

From my reading, propane is plenty hot for annealing and anything hotter is not advised. If you compare exhaust pressure to combustion pressure, they aren't in the same league...at least you hope they aren't.

I would just clean it and put it back in. I would guess you are more likely to screw it up than to improve the sealing.

87944turbo

Thanks for the vote of confidence Max!!

I really wasn't clear about this, but I am re-using one copper gasket and planning on fabricating the other two. I agree with you on the used one. I was just going to clean it up a bit. These questions were more directed toward the other two that I am going to make.

87944turbo

Did find this chart which I thought was interesting. Looks like Propane will get plenty hot. Of course these temps are based on the ability to supply the required ratio of oxygen, but still I am sure there is more than enough heat generated from a standard torch to reach 800F.

http://www.twi.co.uk/j32k/protected/band_3/jk49.html

Laust Pedersen

Typically the exhaust pressure is slightly more than the boost pressure and the combustion pressure is in the 1500-2000 psi range.
Also the typical EGT is about 1400 F, meaning that even the cooler exhaust flanges very likely at some point will exceed 800F (annealing the copper).

Laust

macnewma

Ha, I didn't mean it that way. It sounds like you know what you are doing much moreso than I do.

In the end, I think Laust is right on.

87944turbo

Thanks Laust, good information to know.