Can I use iron pipe as frame for a gas evaporator?

[jdircksen]

Thinking about next year --
I want to build a frame so I can use 6 gas burners to boil on 3 full size steam pans. Eventually I can ditch the steam pans and get a similarly sized pan from Silver Creek that is 18x34 (almost a perfect fit).

Questions:

Would iron pipe work to make the frame instead of welded angle iron? Any thoughts on pipe diameter?
How much of a lip do I need for the edges of the pan to sit on?
The fittings on the corners will be taller than the pipe (rails) so I'll plan on using arch/rail gasket to fill that void.
Does the pan need any support in the middle or just around the edges?


Some photos I've collected over time to help visualize this idea:
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[In da bush]

Myself personally,I would go with 1.5"x1.5"x1/4" angle iron,it’s easy to get and easy enough to weld it together in short order. I would also have cross member of the same dimension angle iron to support your pans.
If you have a pile of pipe kicking around then I suppose that’s a different story,but angle would be my #1 choice all day long,personally.
Good luck

[SyncroScott]

Here are a few of my thoughts, hope they help!

1. Would iron pipe work to make the frame instead of welded angle iron? Any thoughts on pipe diameter?
Sure, why not?! My few steam table pans I use for various things have a 1/2" lip on them so I would go with something with a O.D. of 1" at most, at least for those parts supporting the pans.

2. How much of a lip do I need for the edges of the pan to sit on?
I think most pans have about a 1/2" lip/rim so if they are supported from the top then I'd personally try to support the entire lip of the pan.

3. The fittings on the corners will be taller than the pipe (rails) so I'll plan on using arch/rail gasket to fill that void.
Sounds like that could work.

4. Does the pan need any support in the middle or just around the edges?
No need for support in the middle in my experience. The pans are made to be supported only by that rim and made to hold more weight than the 1" or 2" of boiling sap will weigh; just think of a buffet table with a pan piled high with bacon and sausage! LOL.

Having said all that, keep in mind that IDEALLY (and ideals are hard to achieve in real life of course and you may already know all of this anyway), the heat should be concentrated on the very bottom of the pans to prevent scorching. When I started with steam table pans on a fry burner and two-burner Colman camp stove, I had issues with the sap scorching on the sides and turning my syrup pretty dark and having an off-taste. Some of the darker color also comes from boiling in batches as is done with multiple steam pans anyway.

Given that, I quickly moved to a system where I could support the pans from the BOTTOM and was able to shield the heat from escaping around to the sides. That also greatly increased the efficiency since I wasn't loosing precious heat to anywhere but where it really counted. To do that since it is tough given the radius of the corners, I made an angle iron frame which had the angle "upside down" (for lack of a better term) where the horizontal leg held the weight and the vertical leg was a lip that kept the pan in place.

Good luck!

[jdircksen]

Thanks guys. I found someone who can build a stand out of angle iron for a decent price, so I'm heading that route. I realize 1-1/2" angle is logical, but is that overkill? 5 gallons of water is 40lbs and the weight of the steam pans isn't much. I may see if 1-1/4" angle is cheaper, or maybe even 1".

I was planning to have the steam pans rest on top of the stand, not drop them down into it. That way the heat is focused on the bottom and not the sides where it might scorch the sap.

I've been looking at different pictures of arches and it seems like the lip on the top is about 1". So I imagine that outer 1" of the pan that is sitting on the rail will not get direct heat. Right?

[SyncroScott]

A great source of angle steel in the dimensions you are specifying is old "harvard" bed frames. I have found them free or dirt cheap and they are plenty strong enough.

Also, given they are pretty mild steel, if you have a a sawzall or angle grinder and 3 or 4 pound hammer, you can cut and bend it to your hearts content. If you can drill it easily too then you can attach pieces with metal screws and/or small bolts...no welding necessary! :-)

[jdircksen]

Back with an update on the stand I'm building. I had someone weld a frame with 1-1/4 angle to fit a 2x3 pan.
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Then he welded some flat steel together to give me a surface to rest 3 full size steam pans. I went that route because I don't always have enough sap to keep a 2x3 pan working. So I can customize the size of my boil based on the number of pans I use. In the future I can remove the top and have a 2x3 pan.
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Lots more to do. I'm going to shield all 4 sides at least 12" from the top. The burner setup is next on the to-do list. Planning for 6x 40,000Btu water heater burners. That'll give me 80,000Btu per pan where my gas cooktop was giving 21,000Btu per pan and didn't have any way to trap the heat.

[DRoseum]

This is looking very similar to what I built last year. I did the same thing regarding a larger flat pan and ability to step down to steam pans. Set my burners up to be individually controlled. Used U-burners and wrapped firebrick all around it. Overall it worked great and I think your setup is looking great and you will be very happy with it!

https://www.sugartree.run/2019/03/custom-hobby-maple-syrup-evaporator.html

[jdircksen]

Pretty sure I hold the record for slowest progress on a build. But I finally got the water heater burners attached to the natural gas line. The grill igniters don't work as well as I'd like, but they eventually worked and I got all 6 burners to light. There's plenty of heat for the 3 steam table pans this year. Maybe next year I'll get a 2x3 pan, but it really depends on how much sap I plan to collect.

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[DRoseum]

Looks great! Should make for a fun season for you!

[Sugarmaker]

That arch and burner set up looks good! Should be able to boil sap like crazy! And you can add or delete pans. Shield the valve handles they may get very warm? Keep on boiling!
Regards,
Chris

[jdircksen]

I don't know if this is going to work, but here is a video of my setup running:
https://www.facebook.com/12415472/videos/10115163765629045/?multi_permalinks=1321977237973177&notif_id=1578837736298328&notif_t=feedback_reaction_generic

It's really hot. Once I put my pans on top, the heat caused the flat steel to warp. I'm not sure if I want to add a bolt in that spot since the heat will just find the next weakest point. It got 2" of water boiling in 10-15 minutes and the steam looked good. But I might be looking for smaller burners because these produce a little too much heat.