A question about the construction of a molten salt furnace

rallyx99 said:
Nick: thanks for the video! It's great to see your setup. Why did you decide to use a blower instead of venturis?

Matthew: do you have a similar setup?

Do any of you guys have a good source of 316L tube? My local place wants $1100 for a 20' piece of 5". I'm not really complaining about the price, I'm complaining about the quantity!

Maybe we could forget the tube altogether and use a square/rectangular tank? Would we need to use stainless, or is there another material that would work? Nickel alloys? Ceramics? Titanium? ...surely they don't always use tubes in industrial applications?...
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The nickel alloys like Hastalloy or Monel woud probably work, but the price of those and a welder qualified to cap the bottom would be out of sight costly.



The key to finding supplies and or good prices on supplies is to use the telephone.

Use the yellow pages to find every place within range, then call and ask for "price and availability"
When they ask who it's for; you are a "cash customer"

For every place that will only sell a whole length, there is another that cuts and sells pieces; with the possibly of a short piece on the remainder rack they want to get rid of.
 
Yeah I have both an auber and an Omega cn76030. The Omega is the buy once cry once deal, but the Auber works quite well and is less than a tenth of the price. The manual sucks though.:foot::D A bit of time studying Omegas website would do you a lot of good here, as they have a lot of technical and scientific info on process control. You can also call and speak to an engineer who designs these systems, as Omega has always been very helpful for me when I am designing such things. That is the best way for you to learn how to deal with the control side of the equation as these guys deal with it day in, day out, and design multi-million dollar systems that have to keep a QC level that is insane, as opposed to a hack like me. :eek::D

As for the tube I bought 6 feet of 304L stainless tube way back when and still have 4 feet of it. Looking back on it I would go with regular heavy wall tube, schedule 80 or better. At temperature 304L and 316L don't offer much more durability than plain old carbon. Now 310 would probably be a huge upgrade, but the price reflects. Tim Zowada recommends regular and now so does Kevin Cashen. At the amount of useage that a full time bladesmith uses them it should last you many years, now if you were running the pots 24 hours a day 7 days a week like, say, some aerospace companies then the extra expense would probably be worth it. As Nick said the real key is the weld. Find someone who is a qualified pipe welder to weld it up for you and make sure you explain what you need. Stick works just dandy, possibly better than TIG, as long as the welder knows what he is doing.
 
So does wire feed on stainless.
Stainless is actually a lot of fun to weld because of the purity and consistence relative to A36 (reg'lr mild steel). I always feel like I'm cheating, since it's comparatively easy to make a pretty, strong weld. There is a bit of a learning curve with TIG, but it would sure be great if everyone started with torch O/A welding, because then you can actually see how the heat source, puddle, and material to be welded are actually interacting, plus then you're halfway to being a decent TIG welder.

Sorry, I'm like a puppy with a bone when someone mentions Tig on stainless. :)
 
elementfe said:
So does wire feed on stainless.
Stainless is actually a lot of fun to weld because of the purity and consistence relative to A36 (reg'lr mild steel). I always feel like I'm cheating, since it's comparatively easy to make a pretty, strong weld. There is a bit of a learning curve with TIG, but it would sure be great if everyone started with torch O/A welding, because then you can actually see how the heat source, puddle, and material to be welded are actually interacting, plus then you're halfway to being a decent TIG welder.

Sorry, I'm like a puppy with a bone when someone mentions Tig on stainless. :)
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You can wire feed stainless. You just need the right wire and set up. I welded up my tubes with 316l stick rods. The navy trained me to weld so I'm pretty confident on my welds. TIG would have been cleaner and more precise but would have taken a lot more time. I had two tubes 5" in diameter welded up in less than an hour with the stick method. Would have taken a lot longer with TIG and I was using my employers machine so time was critical. All materials were mine and I had permission to use the welder I just needed to be done before our night shift ended.
 
Hey jimmyseymour,

Did you set up any kind of gas purge on the inside of the tube while you were welding it from the outside?
 
If You want keep the inside clean (and should) simply rig a tube split in and tape the opening. the argon will leak down trough the joint until is welded providing adequate shielding athmosphere, and then it will pool there.
there is no need of too much gas, but it's easy to eyeball...you'll see immediatly flowering if the shielding is not enough and regulate accordingly
 
No. I just ground a bevel like I was trained to do and welded it. You are going to have to replace the tube eventually and should replace it long before the weld, or tube ever has a chance to fail. Remember you tube is not the most important piece in this puzzle. Make it adequate and your good to go, over engineer it if you can afford it. After having mine for some time I think the tapered rods providing a escape path for the hot gases is one of the most important things to get. Some guys don't even use stainless for their tubes. They just have a schedule where they replace the tubes before it ever becomes an issue.

rallyx99 said:
Hey jimmyseymour,

Did you set up any kind of gas purge on the inside of the tube while you were welding it from the outside?
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