Forge T Fitting and Brass Fittings Getting Hot on Burner

[Gee]

Hey everyone.  I am a newbie to the forging arena.  Been trying to learn how to build a forge.  Made my own and lit it up and it seems to burn well.  Only issue I am having is the burner tube and fittings heat up a bit.  Is this something that is dangerous and is my design flawed?  Any help would be appreciated.

 

Thanks.

[Irondragon Forge ClayWorks]

Welcome aboard Gee, I always 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, which is important to know for accurate answers on so many questions depend upon knowing where in the world you are located. You may be surprised how many members are close enough to lend a hand. Some of the other hints may help in flying under the moderators radar.

I'm sure the gas forge experts will be along to help with your question shortly. Who's plans did you follow when building the burners?

[ThomasPowers]

How long are those mixing tubes and are you getting burn back within them?

[Gee]

Thomas, my tubes are 8" long with a 1 3/4 overall diameter flare on the end and the T fitting on the other end.  Not sure about back burn...I just learned about that last night.  I will have to check to see if I am getting that...will let you know after I check this afternoon.  Because the burner is welded to the shell, it won't be as easy to see the back burn.  Maybe welding to the forge shell isn't a good idea?  Also because of welding to the shell there is a greater heat transfer to the tubes verses having a burner support holder??  Thoughts?

[ThomasPowers]

What's the diameter of the mixing tubes?   

The forge shell shouldn't be getting excessively hot so that's not a major problem.  Being able to change things out would be my major reason to have removable tubes.

Note that that design will suffer chimney effect heating after you turn the burners off, when did you measure the "hot" fittings?

I am NOT fond of vertical burner mounting for several reasons of which that is one.

[Gee]

Mixing tubes are 1" diameter.  I did just learn about chimney effect as well.  Didn't know about that until after my build.  I could modify and fix that though.  Hear is a picture of my burners.  I purchased these online.

Also, what is considered excessively hot for the forge shell?  Mine does get warm to the point it is too hot to touch.  Is this normal?

The fittings were hot after I had turned off the propane and began to disconnect the gas lines.  It may have been hot before that as well.  What I really need to do is another test this afternoon to answer these questions and then I will know for sure what is going on.  Let me do a test, take some pictures and get you the info you are asking for.  Any other things I should be testing for during this test??

[Irondragon Forge ClayWorks]

One thing I was going to ask was how far do the burner flares extend into the forge. One mistake I made when building our forge was to have the flare exposed to the interior and the burner did get rather hot as the flare heated up. It also developed a lot of scale on the flare which made it difficult to remove the burner. By backing the burner up so the flare was about a half inch into the refractory it eliminated the problem, now the burner gets warm (about the temp of a cup of coffee) while running but not so hot as to worry me. One way to stop or slow down the chimney effect is to plug the air inlets when you shut the forge down, another benefit to plugging the inlets it keeps the critters out of the burners. Last summer we didn't use the forge for a while and mud dobbers had built nests in it. Our burner is a different design with an air choke that I now close when shutting down.

 

[Gee]

My burner flares are flush with the 2" insulation inside.  So what you are saying is I would need to back those off so they are just inside the shell 1/2"?

[Irondragon Forge ClayWorks]

Correct, I think that will help. Here is a picture of our forge running.

[Frosty]

Welcome aboard Gee, glad to have you. 

I've regretted it every time I welded a burner to a forge but I still haven't learned and will have to cut my NARBs off when the time comes.

How many cubic inches is your forge interior? Two well tuned 1" burners should have enough output to bring around 1400 cu/in to welding temps provided it isn't too oddly shaped. 

What you're describing is mostly chimney effect, blocking them when you shut down will take care of that. They'll still heat up but not a lot. 

They're too deep in the forge, the output end of the flare should ONLY be  just inside the ceramic wool refractory, 1/2" is usually plenty. You just don't want flames coming back out of the burner ports. Yes?

One last note. We LOVE pics here and you're off to a good start so please let us see that baby HOT. 

Frosty The Lucky. 

[Gee]

Irondragon, thanks for the info.  Love the look of that forge too...Nice!!

[Gee]

Thanks for the welcome !  Learning a lot already!

I think I've already regretting welding the burners to the shell.  I think I may modify that if I can. 

Also, the chimney effect isn't good either.  I'm going to need to relocate my burners on the side coming in at an angle.  If I do this, is there a better angle than another?  Where should the flame be directed to...the bottom center or does it matter?  I will also have to modify the depth which means I have some work to do.

Cubic inches interior is around 1055 cubic inches on the most inside.  The shell itself is about 2373 cubic inches.  I have a 2" layer of UniTherm Ceramic Fiber Insulation #6 Density rated for 2300° F.  I have 2 fire bricks on the bottom.  I coated all that with Rutlands Dry Mix 211 Refractory Mortar rated at 2550° F.  Are these the right products I should be using or is there something I am missing or did wrong?

I just did a test and here are some pics.  I unhooked the front burner and plugged it...when I started it up it wasn't burning well.  Looked like half the flame of the back burner.  I thought I might have been running out of propane, but I think I was wrong on that because I burned the back burner for about 10 minutes.  As I burned, I felt the burner pipe and it started warming up at the welded connection to the shell.  The top stayed cool, but a few minutes later I felt the heat slowly working its way up the burner tube.  I also noticed what looked like tiny cracks in the burner tube...sprayed some soap water on it and saw a ring form around the base of the burner.  I shut off the propane right away.  I don't trust it now.  I get that feeling that something isn't right...ever get that feeling??

Anyways, here are the pics I was able to take.  Thoughts anyone??

 

 

 

[Gee]

Also, I was running the burners at around 5 psi...does that sound about right or does it vary??

[Frosty]

Forget the pressure gage it varies so widely any suggestion is pretty meaningless. Judging by the look of the flame turn it up a little at a time and see how it performs. 

Chimney effect just is, even a little aluminum foil will block it enough it won't damage the propane hose. 

1055cu/in isn't too small for all that burner it should get SCREAMING hot. You can always turn the psi down it it's too hot. 

I'd just use it as is for now, you're going to need to rebuild it before long anyway. Next time NO MORTAR or CEMENT even if it says refractory on the package! Mortars and cements are designed to stick brick and such together NOT survive flame contact. 

When you rebuild it is  good time to reorient the burners so they aren't aimed directly at the far side. A little angle allows the flame to swirl in the chamber and not develop back pressure which inhibits burner performance. Swirl also helps even the temperature in the forge. 

Also, rather than laying a couple brick in the forge for a floor you can lay a piece of ceramic blanket with the edges feathered to make a smooth transition to the sides and cover it with castable refractory to make a floor. Fire brick is a serious heat sink and has about the same insulating qualities as an equal thickness of limestone. It takes a lot of propane to get hot and a lot to keep it hot. 1/2" of hard castable refractory is plenty tough but is backed with an insulation layer 1" thicker than the rest of the forge.

Your forge will also be more efficient and hotter with more closed ends. The subject of baffle closures in forges is discussed at length already. 

There are build discussions in the Forges 101 section here. 

Frosty The Lucky. 

 

[Irondragon Forge ClayWorks]

As you can see the refractory mortar is already cracking and flaking off exposing some insulation on the opening. It looks like the fiber blanket was not rigidized, which will be a health hazard with micro fibers floating in the air. I would wear a good mask and chip all the mortar out, rigidize the fiber blanket and put in a coat of Kast-O-Lite 30 or Satanite refractory then a coat of Plistix 900F wash.

[Gee]

Ok guys, after reading what has been said, here is what I plan to do.  Please tell me if this is a good idea or bad idea.

1 - I  am going to relocate my burners.  Cut off the existing ones and patch up the holes.

2 - Create new holes for burners using a 2" burner sleeve this time that will hold my burner in place.  Locate burners on an angle directed towards the far edge of the forge bottom/side.

3 - Remove firebrick base and remove mortar from insulation.

4 - Reinstall insulation.  Place another piece of insulation for the bottom of the forge and feather in the sides.

5 - Coat insulation with Kast-O-Lite 30.  How thick should the coat be?  1 coat? 2 Coats? More?

6 - 1/2 thick bottom layer of Kast-O-Lite for the bottom of forge.

7 - Coat of Plistix 900F Wash.  How thick of coat? 1 Coat? 2 Coats? More?

8 - Light it up and watch it get hot and start swinging the hammer!

 

Anything I missed here, please let me know.  Is this the right direction for me to go to have what will WORK?

 

Thanks.

[Gee]

Working on my burners.  How does the flame look?  It seems hard to light....

[Frosty]

Your rebuild plan sounds okay. Have you rigidized the blanket? If not you need to rigidize it. 

Remember to butter BEFORE you apply the next coat of anything. Stritz it with water to butter it or things won't bond properly.

I like 1/2" Kastolite for the forge floor, it's going to be supporting the weight of your work plus the mechanical erosion from inserting and removing work. Yes? Most guys like 3/8" or a little less for the walls/sides and ceiling. It's what I'll try on my next forge.

Apply Plistex mixed to about the consistency of latex wall paint. Butter the liner and paint it on. Just cover everything, too thin is much better than too thick. Let it dry, butter and paint on another coat. A couple three coats is probably plenty though a few more won't hurt. Just don't get carried away.

Uh. . . did you change the camera setting between pic 1 and 2 AGAIN? If so stop doing that! Use the setting you used for pic 2 or you'll never get an accurate evaluation. I'm not going to offer an opinion if you do that again.

It's still burning rich. But it WILL burn differently IN THE FORGE. Tuning a burner in a vise is good IF you're going to use it in a vise. You'll have to tune it again in the forge, you're wasting your time and increasing the odds of getting it wrong enough you'll have to start over with a new mig tip.

Frosty The Lucky. 

[Gee]

Frosty,

Sorry about the camera shots.  I did not change the settings.  I used my phone to take the pics and it adjusts itself based on the lighting.  I'll try to do a better job next time.  

As for the insulation...what are you referring to when you say to "butter" it with water?  What is that process exactly?  What should I be looking for?  Just moistening the insulation?  Please elaborate if you would.

Point taken on the burners...I'll tune them up in the forge when I am ready.

[Irondragon Forge ClayWorks]

Yes buttering involves spritzing clean water on the insulation to moisten it.

[Gee]

Is it a bad idea to use a form when applying Kast o lite to my insulation?  I am going for a 1/2 thick layer.  Thoughts?  Experience?

[Frosty]

No need to apologize about cell phone camera exposure, I was just feeling grouchy and I succumb to frustration easily when grouchy.

Nothing wrong with using a form, it looks pretty darn nice from here. How'd you get the Kastolite to release from the stove pipe? 

Frosty The Lucky.

[Gee]

Frosty,

I haven’t applied the Kast o Lite yet. Will I have issues removing the form?  I can cut it out...it’s just HVAC vent piping.  Wondering if I will have problems ruining the Kast o Lite application if I do it this way....