Segmental Furnace Lid made from Plastic Refractory Blu-Ram HS

Discussion in 'Furnaces and their construction' started by Melterskelter, May 21, 2020.

  1. Melterskelter

    Melterskelter Silver

    I am well into making a segmental oil-fired furnace lid for melting iron. I have found that melting iron in my furnaces has been pretty hard on the lids whether they were castable, IFB, or Satanite/Wool. THe castable held up best but also was quite thick and heavy and quite slow to heat up. It was also one-piece construction which I have learned invariably results in cracking and was the eventual cause of failure of that lid.

    I was recently at a commercial iron foundry located 60 miles from my home and was chatting with the owner as the crew was pouring ductile iron. I asked about the lining for the ladle which I felt must be subjected to pretty punishing conditions. He reported they were using Blu-Ram HS plastic (not castable) rammable refractory with good results. Inspection of some of the idle ladles confirmed no cracking and no penetration by iron despite many pours. I talked him into selling me a box of Blu-Ram to try for lid construction. Prior to my trip to the foundry, I had already begun making a mold for a segmental castable lid. But, since the performance of the Blu-Ram seemed so much better than what I would expect from castable, I decided to switch over to Blu-Ram. (Sorry if this sounds like a commercial---not so intended and I am sure other companies make competitive rammable plastic refractories.)

    I had no prior experience with plastic refractory products and there is very little that I could find on the Web about installation and firing of plastic refractories. So the video linked below I am submitting as an indication of the approach I took which may not be ideal. I hope anyone with more knowledge about this material will pipe up and make such corrections to omissions or misinformation as is needed. But my hope is that some information would be better than none for someone interested in using this or similar material. I am very hopeful this product will perform well---better than the castable I have used to date. In accordance to user instructions included in Mifco's user manual, I am going to coat the tiles periodically with Satanite (not stated by name in the manual and I may well be wrong in "figuring" the coating material they supply with their furnace is the same as or similar to Satanite.)

    So, FWIW here is a video made this afternoon:

    As time goes along I will post more about the details of construction and performance of this lid.

    Denis
     
  2. DavidF

    DavidF Administrator Staff Member Banner Member

    Pretty stiff stuff....
    I remember someone using it before, I just cant remember who... maybe Justin?
     
  3. Melterskelter

    Melterskelter Silver

    The stiffness is a plus, I think. If this lid proves to be durable, the next step is a segmental hotface for a 14 X 16 or 17 furnace. Being stiff, it will not need to be cast and vibrated into place. Rather, I would make a single-sided form/mold similar to the lid only larger and fire the segments in a 30 or 50 gal burn barrel using wood as fuel probably. For those segments I am thinking of making the segments have a radius convex on one side and concave on the other to help them register with each other. I will be adding 2 or 3 inches of wool to the lid and similarly wrap vertical segments with wool and then band it. I'll try to keep the vertical hotface segments as thin as I think I can get away with.

    I should mention this material is not all that expensive especially compared to castable. The 55# box was less than 45 dollars. So you could do an entire furnace with 1" walls for about 150 bucks. Castable would be comparable.

    Denis
     
    Last edited: May 21, 2020
  4. Al2O3

    Al2O3 Administrator Staff Member Banner Member

    Petee has some and built a forge for one of his buddies with it. The BluRam may very well be a good choice for iron service and metal contact but in general there's nothing magical about plastic refractories. They're just formulated for hand placement and ramming as opposed to vibe casting and/or gunning and most manufacturers have similar formulations available in any placement version.

    -Plastics stay where you put them without forms. Here's the BluRam data sheet. 171 lbs/ft3 is some dense stuff.

    http://corerefractorysys.com/images/BLU_RAM_HS.pdf

    Look forward to seeing your lid Denis. I toyed with the idea of rolling plastic refractory into very thin sheets (like 1/8-1/4" thick) for hot face. Plastics definitely have their place. Very popular for repairs and cupola maintenance.

    Best,
    Kelly
     
    Last edited: May 21, 2020
  5. Al2O3

    Al2O3 Administrator Staff Member Banner Member

    How many lbs of BluRam will be needed for the lid?

    Best,
    K
     
  6. Melterskelter

    Melterskelter Silver

    Just a little more than 30

    Denis
     
  7. Al2O3

    Al2O3 Administrator Staff Member Banner Member

    You're in that classic material trade-off zone of durability versus (low) mass.

    Best,
    Kelly
     
  8. Petee716

    Petee716 Silver Banner Member

    Yup that's the stuff I used. I had pretty much the same performance with as in Denis' video. It becomes much more pliable as you work it and it becomes surprisingly cooperative. Spritzing with water brings it to life as well in case it gets a bit dried out in the box or you need to to be a little pastier in order to fill cracks. But once you start pounding it it moves really nice. The brickie I got it from told me that they finish the surface with a courier's comb as opposed to a smooth trowel. One of the other things he said was that when you patch with it you can ram the stuff in and just put your furnace right into service without the drying out period as you'd need with castable.
    The forge Kelly referred to above has seen a good amount of service with no cracks. I coated it with one of the HeatStop products. For the body of the forge I rammed the material with a 1" dowel into a 1" wide cavity 12" deep and 10"x12" square. It was basically a box form with a core. I would not do this again because it was way more work than it needed to be. It was really a job for castable but it's what I had at the time. (He was going to make it out of a propane tank with kaowool but my compulsiveness and ego wouldn't let him). The Blu-ram was a good fit for the doors though which was a flat open mold.
    I've also used it to make plinths of different heights for use with different sized crucibles. No problems.
    As far as I can tell, you're doing it right!

    Pete
     
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  9. Melterskelter

    Melterskelter Silver

    One odd thought recently flashed through my mind related to the easy-patching characteristics of Blu-Ram. I suppose it is not likely, but could the segments fuse with heating once I assemble the pre-fired segments. That would be a disappointment if they did since freedom of movement and relatively small size to prevent destructive cracking is the driving force behind the segmental design. I suspect I am imagining trouble that won’t occur.

    Denis
     
  10. rocco

    rocco Silver

    Maybe put a sheet a paper between the segments the first time you bring it up to full heat, even it that does not prevent the pieces from fusing together, it might at least create a controlled weak zone where the cracks are more likely to form.
     
  11. Melterskelter

    Melterskelter Silver

    Yes, that would seem like a good plan with no downside. I really think I am imagining a problem with fusion of segments that does not exist. But, can't hurt to ask as there are a lot of knowledgeable people on this forum.

    Presently, I have all the segments cast that I will need. And, much to my amazement, they fit and support themselves in a dome-like shape. Well, there is the matter of that small take-up-the-measuring-error "keystone" piece. Don't ask me how, but I laid out the form about .08 radians too narrow so that there was a cumulative error requiring casting a "keystone." To be honest, I did not expect to hit it dead on with the 5 pieces fitting perfectly. But this was a a larger error than anticipated. In the end, it does not matter and the larger under-size error is easier to compensate for than would an error of .008 radians.

    Here are a couple pics of the initial layup of the segments with no fettling of the tiles.

    The form I used is to the left and you can see the added divider welded in to make the keystone. A couple comments: The uncovered sheet metal does scale quite a bit as it is subjected to 1500 degrees of heat for an hour plus the cool down. Painting a very thin coating of Satanite onto the metal was very protective. It needed to be reapplied each firing. I put brown paper into the mold as a release agent every time except once when I tried a couple of layers of newsprint. The brown paper worked much much better. I had a hard time getting the newsprint tile out of the mold as it seemed to stick. There was no sticking with the brown paper from the shopping bag.
    BluRam Lid (4).JPG
    Another view of the layup reusing the metal shell from my failed wool/Satanite lid. I think I could stand on the dome and it would support me just fine in that it really wedges itself firmly together. I'll clean up the casting flash a bit and then add 2 or 3 inches of wool. I will coat the flame side of each tile with a thin coat of Satanite to improve flame/atmosphere resistance of the tiles. BluRam Lid (1).JPG

    Here are a couple pics of the failed lid which held up reasonably well. Long, large batch melts were especially hard on the lid as any defect that occurred had a long time to progress in a single melt. Shorter melts allowed me to reapply Satanite to flaked areas and I think I would have got a lot more short (70 to 90 minute) melts out of it. Also, better design of the lid shell would have allowed the wool/Satanite lid to be more durable.

    BluRam Lid (2).JPG BluRam Lid (3).JPG

    One nice thing about reusing the metal shell is that all the lifting and support bits can be reused saving a day or more of welding and fitting.

    I may be able to light a fire under this thing in a couple days. Likely could light it tomorrow, but there is sand to mull and pack.

    I used just a little over half the BluRam box (55 pounds full) in making the lid tiles.
    I probably will paint Satanite onto the face of the wool that will lay on the tiles. Not sure this is needed, but there will be leaks of flame through the cracks in the tiles. I have found that the wool and steel tolerate static flame contact pretty well (in other words dead-end gentle flow.) It is the rapid passage of a stream of flame tangentially passing over the wool that causes breakdown. So, the Satanite is likely not needed. But it is so easy and would add a measure of insurance, so I will do it.

    Denis
     
  12. Petee716

    Petee716 Silver Banner Member

    I sent a text and your assembly picture above to my friend who is a professional installer. He said your design is exactly correct and as long as the sections were cured separately they will remain dry stacked and will not fuse.

    Pete
     
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  13. Melterskelter

    Melterskelter Silver

    Here is a bit more on the build. The lid is ready for fire (I hope).

    Here is a tour of the metal parts of the lid as they secure the tiles and support the chimney.


    Lid Stuffed (2).JPG
    One nice thing about using wool is that it is pretty forgiving on the cutting and stuffing. BTW, a sharp serrated knife cuts wool nicely. So, I just eyeball the spot it needs to go, make an approximate cut, and if its close, its good enough. I did paint some Satanite on the exposed edge of the wool where the chimney meets the lid. Without Satanite, that wool would melt away in an hour or two of firing.
    Lid Stuffed (1).JPG
    I previously painted some Satanite around the base of the chimeny as prior leakage there is hard on the sheet metal and the Satanite protects it pretty well.

    Lid Stuffed (3).JPG
    The chimney/muffler makes a good tight fit. I will spray rigidizer on the wool when I get to the foundry tomorrow.

    Denis
     
    Last edited: May 25, 2020
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  14. Melterskelter

    Melterskelter Silver

    I am finally running my lid. I am 90 mins int a 65 pound melt and expect to pour in 30 mins approx. one thing I notice about the lid is it has stabilized at 350F where the furnace side walls are 580. I’m interested to examine it tomorrow. So far peaking at the lid when opened lols just fine. Fingers crossed. Also pouring into new wider mold that allows a 4-gate side runner.

    Denis
     
  15. 350F?, that's about perfect to bake a loaf of bread while the furnace is running if you had a metal box to sit on top. Hope it goes well, that extra effort pays off with better efficiency and a longer life/less maintenance.
     
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  16. Melterskelter

    Melterskelter Silver

    You nicely summarized my hopes. My wife makes a wonderful dill bread. Hmmmm, warm bread and honey mid-melt. Sounds wonderful. ;-)

    The lid performed very well. I did lie down on the ground to look up at it---but not for long as it was still probably 800 to 1000 degrees on its under surface. It looked to be free of any cracks other than the built-in ones. There was no spalling. So, after 2 hours only it looks very encouraging. I'll feel more like declaring it a usable design after 10 to 20 more melts. If it holds up without requiring significant maintenance I'll feel the time was well-spent. I am definitely thinking of lining my to-be-built furnace with as thin a segmental layer of Blu-Ram as I think I can get away with and then two or preferably three inches of wool.

    Denis
     
  17. Melterskelter

    Melterskelter Silver

    I went out to the foundry and took a look at the lid. It does look like it came through with flying colors. Not that that is saying all that much as one firing does not mean much. But, then again, it did not fall in a heap---not an impossible outcome either.

    Below you see the surface of the refractory segments. Wedged into the recess between the segments and the steel ring that form the lower part of the steel shell and provides a ledge for the segments is wool that I painted on the fire side with Satanite. I left the very bottom surface of the wool and steel raw so that it would not heat-fuse to the top of the furnace. The seal held in the combustion gases perfectly---there was no leakage. Leakage would not matter in a way except that it allows extreme local heating of the steel and fairly rapid scaling and loss.

    The heat pattern on the lid is interesting. In my furnace the fuel enters more or less parallel to the lid support on the right side of this pic and swirls around and exits. You can more or less see the nautilus-like pattern on the lid. After first firing.JPG

    I don't think the lid needs any tweaking at this point. My plan is to monitor the Satanite on the segments carefully. When it seems to start flaking off or thinning, I will paint on another thin coat.

    Hope to be firing again in a few days once I get the sand mulled and a mold packed and a weather window. Unsettled weather is forecast after tomorrow.

    Denis
     
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  18. It's a first class effort, it should last a good long while and be easily maintainable too!, you can clearly see the clockwise direction of the flame wash as it spirals out the hole. Getting a good seal is a major achievement in itself, I plan to grind a few spots off and lap mine in with silicon carbide when I get a spare moment. Also I have heard of people baking bread in the furnace with the residual heat, this might be a good way to make "Tank" loaf.

    breads-milk.jpg
     
    Last edited: May 30, 2020 at 1:47 AM
  19. Melterskelter

    Melterskelter Silver

    Thanks for the kind words!

    Do you have a similar segmental lid? Pics?

    Denis
     
  20. Not even close, mine is cast in place refractory which sits on top of a furnace height extension, so the original fit is lost now. A bit of lapping with silicon carbide grit should ensure a close fit.
     

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