Thread: This forge, or that forge....

For heat treatment this is sometimes done to get a more even temperature and to protect the piece from direct flame. For forging I haven't seen it. The reason is that for forging, you want to get as much heat in the piece as quickly as possible (to prevent decarburization), not shield heat away. And if you need to reach welding temperatures, the thinwalled pipe would be hot enough to actually start burning away or melting.

Originally Posted by shooter74743

...a thin walled pipe that it would fit into. Supposedly the pipe keeps you from burning your piece, would this be true in your opinions?

For a coal or charcoal forge, this method does help keep the direct blast of air coming through the fuel (that contains that nasty oxidizing oxygen) from directly impinging on the material being heated. This reduces the amount of material lost to scale. I have used a piece of black iron pipe either capped on the far end or forged shut. I toss a small piece of charcoal or coal down in the bottom of the pipe so any heat will consume the local oxygen and create a reducing atmosphere inside the pipe. This equals less scale, plus when the pipe is glowing, I can see the work, especially critical if I'm trying to forge weld stuff. Obviously this doesn't work unless the pieces are smaller than the pipe diameter.

DO NOT ever use galvanized pipe for this, EVER.

Originally Posted by Mike Blue

For a coal or charcoal forge, this method does help keep the direct blast of air coming through the fuel (that contains that nasty oxidizing oxygen) from directly impinging on the material being heated. This reduces the amount of material lost to scale. I have used a piece of black iron pipe either capped on the far end or forged shut. I toss a small piece of charcoal or coal down in the bottom of the pipe so any heat will consume the local oxygen and create a reducing atmosphere inside the pipe. This equals less scale, plus when the pipe is glowing, I can see the work, especially critical if I'm trying to forge weld stuff. Obviously this doesn't work unless the pieces are smaller than the pipe diameter.

DO NOT ever use galvanized pipe for this, EVER.

But doesn't the pipe burn if you want to get your workpiece to welding temperature?

The pipe has to be treated like the coal, it's an item that will be consumed eventually. Standard black iron pipe will last a fair amount of time. Thin walled tubing will last a lot less.

Heat the pipe until it radiates an effective temperature into the center. I would also suggest not burying the pipe down in the fire just above the air blast but above a layer of hot coals and keep pulling it back up a little when it migrates downward so it is always buffered by some burning coals. If it lies in the direct air blast you will burn it up sooner.

Yes. Putting something close to the air inlet is an excellent way to burn a lot of fuel and not get much heat.
There shold be at least 2 or 3 inches of burning coal beneath the thing you're trying to heat.