Temporary forge muffle

[DanF]

I ordered a ht oven a couple months ago but it will be another 4 months before it arrives, so I need to get out the forge for heat treating until it gets here.
I was looking at temperatures that black iron pipe can withstand (for a muffle),and one site stated 1000*F.
Does that sound right or can I go a bit higher (1500-ish)?
Thanks

 

[Pinoy Knife]

i think the temp of 1000 degrees is probably very low..
black iron pipe is what i built my first forge out of... it was heavy duty gauge pipe but still..
i dont think heat treating temps would affect it at all .. forge welding temps either .. i may be wrong here but id use it as a baffle/muffle

 

[seanj]

I used a piece of iron pipe, ie schedule 40, as a muffler a while back. I don't recall the exact temperature I got to (I was just experimenting) but it was somewhere in the neighborhood of 1500 degrees F. It held up fine. I wouldn't want to use that particular piece of pipe afterwards for something critical, but I think you will be fine.

 

[weo]

Depending on how many times you plan on using it, you should be fine. A number of years ago I usedsome 1/4" walled square pipe for a similar task and it lasted quite a while, but the walls did gradually get thinner each time due to scale and burning.

 

[DanF]

I thought the 1000* sounded low and I thought I remembered old posts here using it. I ordered a piece of stainless so this will be very temporary, maybe 8-10 firings.
(If I had known the oven would take this long I would have ordered a different brand. ).
Thanks guys

 

[Bühlmann]

The 1000F ratings for malleable black iron piping is more for the joint fitting compounds and to ensure that the joints don't fail due to service temps. The actual melting point of malleable black iron is higher than the melting point of any knife steel that you may put into your forge.

 

[Stacy E. Apelt - Bladesmith]

You can use a piece of muffler pipe, but it won't last many HTs. The thicker the walls the longer it takes to burn out. Thicker walls also distribute the heat more evenly.

 

[DanF]

I ended up with two 8 inch by 2” i.d. black iron nipples with a threaded cap on one end at the back of the forge and a coupling joining the nipples together. The cap and nipple raised the pipe off the floor of the forge enough to get swirl under the muffle also. There is enough length that the muffle protrudes out the forge for a few inches.
The two test runs I performed today gave me very stable, and hold-able (is that a real word?), temps anywhere from 1000*F to 1650*F.
Historically, with this forge I have held temps up to 2100*F. The forge had more left but I never pushed it beyond that .