I can't seem to find an explanation on the reason that most people put their burner tubes into their cylindrical forges at an angle as opposed to straight up and down. I'm sure this has been discussed before, but I can't seem to find threads on the subject.

It seems like you would want your burners pointed straight at your work piece and, in the case of a forge lined with coated Kaowool, pointed at your fire bricks instead of the Kaowool (even if it is coated with ITC) so that it will last longer.

What is the proper angle and why? I've seen some straight up and down (0 degrees), some at a slight angle, some at around 45 degrees and others at 90 degrees.

In square forges, they always have the burners in the top pointing right at the bottom of the forge. Why would it be different for cylindrical?

Just another reminder of how we are missing Frosty, (get well soon please we all miss you and look forward to your return)

I have very little experience to call on with gas forges, I have a Swan forge and yes the burners are straight down hit the base and spread the heat, I have built temporary square chambered gas forges and found that it was better to feed the burners in from a side angled position than vertical, vertical caused numerous problems.

Round chambers I am experimenting with at the moment, but I would think that offsetting the burners from the centre line would create more of a vortex effect, thus spreading the heat more evenly around the chamber

Thats my opinion for what it is worth, no doubt others will have their views and correct me if I am wrong in my assumptions.

Frosty was the resident expert on this subject, Get well brother you are missed.

Yep! Angle creates a vortex that makes for a more even heat.

One other question: I made an assumption in my original post that may not be correct - Does the flame blowing right on the Kaowool (assuming a coating of ITC-100) eventually cause that area to break down? If so, would it be worth the trade-off to blow on the firebrick at the sacrifice of heat distribution?

There is no sacrifice. Angled twards the brick creates a swirl effect for more even heating.
Ken

Propane is capable of a bit over 3000F, which is (likely) higher than your wool or firebrick is rated for. This temperature is difficult to achieve due to losses though.

Vortex makes more even heating, hot spots are desirable by some people. For a vortex calculate the tangent entry for the insulated diameter. If you prefer hot spots choose where you want them.

ITC and similar coatings stabilize the wool and reduce air born particles as well and offering potential IR reflection for higher heat. These coatings also offer some protection to the wool against flux damage and can tolerate higher temperatures.

Frosty could answer better is right. We all miss his knowledge. Hopefully he will be back with us soon.

Phil

Looks like Grant (Nakedanvil) has some insights into this topic. I just found this in a different post:

I think that two forges might be a good idea. Even with a shelf, if you are forge welding a lot, the flux goes everywhere. There is a mini-tornado in there you know. Especially for forge welding, don't point the burners at the work, come in tangent and heat the lining, you'll be much happier I guarantee it! With the burners pointed at the work it's easier to burn the work and it's harder to see when the part gets to just the right temperature.
__________________
Grant Sarver
"Bigamy is having one wife too many!
Well, I guess monogamy is too"!

-emphasis added

There is no sacrifice. Angled twards the brick creates a swirl effect for more even heating.
Ken

So if I understand what you are saying, it sounds like you still point the flame at the brick, just angled, right?

I'm brand new here, So I'll jump right in. based on what you guys have said, The spiral angle seems better. I plan on making a 2- in -1 forge/foundry setup, so angled burners seem ideal for both. 

On 10/31/2009 at 3:14 PM, brucegodlesky said:

Yep! Angle creates a vortex that makes for a more even heat.

Actually not. The angle creates swirl for more even heat, and longer hang-time, before the gases exit the forge. It takes passage through a reducing chamber, such as a funnel, to create vortical flow.

1 hour ago, Ernest_U said:

I'm brand new here,

Welcome aboard, I suggest reading this to get the best out of the forum.  READ THIS FIRST  It is full of tips like editing your profile to show your location and many others.