Jump to content
I Forge Iron

Flue size?

Recommended Posts

You can join two 6 inch sections at the seam and get 12 inch diameter. Circumference increases at the same rate as diameter.

However 2 separate 6 inch pipes are only 1/2 the area of a 12 inch pipe. It is the squared bit that causes this. When you double diameter you quadruple area.

The concept applies to square pipes too. If you have a square pipe with unit 1 sides, and put two next to each other you get a rectangle that has 2 units square inside, and a common double wall. If you take the side lengths and add them up, then you get 4 sides 2 units long with a contained area of 4 units square. When you make it a circle and throw pi in it gets confusing for no good reason for some people.

Hope this helps.


Link to comment
Share on other sites

  • 3 weeks later...

I'll pass on galvanized. Besides mine will sit right next to the fire so I'll stick with my cobbled together washer metal and use two pieces of stove pipe like Phil pointed out. I did manage to get the rest of the forge going and fired it up with some wood to test the blower and it all works. It sure isn't going to win any beauty or engineering contests but it works.

Link to comment
Share on other sites

If you use galvanized ducting and it burns off, it will only do it once. There is not a continueing problem. Plus the metal needs to be in the red hot range before it cooks off. I have never seen a coal forge flue get that hot. So what is the problem? I used corrucated galvinized tin 36in by 8ft to make mine. Rolled it into a circle and used sheet metal screws to fasten the overlap joint. The flue opening and hood are 10 gauge and painted with high temp paint. Plus I got it as salvage. Use the galvanized and don't worry about burnoff.

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

  • Create New...