Welding steam table pans together to make a single pan leads to inevitable questions

[Logan Cabin]

Working to upgrade last years homemade evaporator. Old filing cabinet with four 12X16 steam table pans set in the arch. Last year we were able to get near 10 GPH evap rate when we were really cooking. We would ladle sap from back to front, which was time consuming to say the least. Have dropped the pans off with a cousin to have them welded together. Here come the questions.

We plan to connect them using SS tubing in an alternating pattern to allow flow between pans. It will also allow me to reverse the pans to slow mineral build up. Looking at 1" tubing connected as close to the bottom of the pans as is practical.

Next, welding the pans at the joints along the top to create a more airtight seal. Used the stove gasket along the outer edges last year. Don't see any obvious issues with the first two steps.

Third step has the big question. We talked about using some flat stock to weld along the outside of the pans to help stabilize & hold them together (the pans taper, so they would still fit in the firebox with this). Since dropping the pans off, it has occurred to me that this may lead to warping, as the flat stock will be exposed in the fire and not cooled by the sap as the pans are.

Possible solution? The pans have a 3/4" (min.) lip around them. What about welding steel square tubing to the underside of the pan lips? Seems like that would give us a good strong joint that would rest on the stove gasket. Would lift the pans out of the box a little, but I could adjust the firebox accordingly. Would the square stock need to be SS to be welded to the pans?

Thanks for all the input on this site. This has been a tremendous resource!

[RileySugarbush]

That is an interesting idea. If you have the top lip welded and a tube near the bottom I think it would be stable. Even better if you put a tube on each side. Plug one if you want to limit flow to a zig zag. Watch out for differential expansion. The lip will be hot and the tubes at boiling point. The whole assembly may bow up in the middle.

[Ausable]

Logan - Would an angle iron rectangle work? With the four pans edges resting on the inside lip on the angle iron and the other lip facing upward. Might not have to weld the pan edges to the angle iron frame. Have any of the stainless pans warped yet? If not might work provided the alternate connections dosen't keep them from laying straight. Ha - You would have a Flow-Through and the whole pan set up would be like a drop flue with all that pan surface exposed to heat. At the almost syrup end (lol - in this case might be the maple sugar end) you would need a drawoff valve. -- Just some thoughts -- Very interesting.

[Jec]

anything you decide to weld to it has to be stainless. You can't weld 2 different metals to each other.

[Ausable]

Whoops! Logan - I was just looking at the pictures on deckers007 and see You have too - Impressive - --gotta looks at it some more and see if it has interconnected pans

[rookie]

anything you decide to weld to it has to be stainless. You can't weld 2 different metals to each other.
beg to differ, my best friend is the manager of a large welding company and he says not a problem, you can weld mild steel to stainless with 309 rod and a stick welder, not brass to stainless though.

[lpakiz]

What if you used 2 tubes instead of one to connect each pan to the next? Just plug one. This will be very strong, as long as you also weld the lips together. No problem to weld mild to SS with regular MIG wire (Bead will rust, tho) Or SS to Mild with SS wire or regular MIG wire. It actually makes a VERY nice bead....

[Jec]

Oh now I know!

[Logan Cabin]

Ausable,

Don't think the pans warped last year (they're only 12x16, 6" deep). I ran sap probably 3-4 inches deep, which I know is deeper than what most run on a purpose built pan, but as you mention, these seem to act as a drop-flue so I gain some heated area along the sides. I had just screwed some flat stock to the top of the file cabinet to get a consistent straight surface to set the pans on, and THAT warped some!

Draw off valve may be next year, I'll just be happy to not ladle anymore! At my scale, we ladle out the final pan, then refrigerate the near syrup and finish/bottle inside on the stove. This year bought a turkey deep fryer, the pot (5 or 6 gallon) has a drain valve for grease so we'll be able to fill bottles directly from that. Also think we can use the pot & propane burner to pre-heat sap.

I do like the suggestions of using a pair of tubes to connect each pan. By closing them off, I assume everyone means to weld a cover over one end. That would allow sap to fill the tube to protect it from heat. And then keep the original zig-zag tube connections open.

[Ausable]

Michael - I use a steam table pan to finish on. My Grandson (The Welder) welded or brazed (I'm not a welder) a standard thread pipe stub on the pan and I screwed a valve onto that for drawoff -- works good for taking a sample for my hydrometer cup. Could do the same on your last pan of your evaporator for drawoff. Save Your skimmer - they always come in handy. ----another Mike - lol-----

[Logan Cabin]

Update on the welding of the steam table pans. They used SS angle stock and welded them together along the outside of the pans. Since the pans are stamped, the bottom of the pan is considerably thinner so they had difficulty getting clean welds on the tubes used to connect the pans. Picked them up Thursday and barely had time to get the evaporator set up for teaching the syrup class Saturday. Wanted to have a boil going for the class, and as soon as I put sap in noticed a small leak at one of the tube joints. Went ahead & boiled anyway, kind of like ignoring the dashboard warning lights on a car!

So, any advice on fixing a leak on a really ugly weld? I've seen in other threads folks soldering copper to SS. Is it possible to use the silver solder to fix a small leak, or do I need to find someone local who can work on SS?

Teaching the class was a blast, had a beautiful sunny day and ended up boiling off about 40 gallons, have five gallons sweetened to start the next batch with.

[Ecnerwal]

You can solder with lead-free solder - the problem with fixing a hole in an ugly weld is going to be getting the area you need to solder clean enough to solder. You'll probably need to grind out crummy weld, and with thin metal you may grind right through the pan instead...

Physically clean (grind it out - wirebrush or scotchbrite if not starting from a crummy weld) chemically clean (flux) don't overheat == nice solder joints.

Probably would have been better to solder the tubes in in the first place, IMHO. I've seen a few things welded to syrup pans that are simply horrid (I guess I expect the sort of sanitary weld job that brewing and dairy equipment has...and a decent soldering job sure beats a lumpy black weld on a jagged hole in my book.)

[Logan Cabin]

It's definitely ugly, I can only guess how hard it will be to pinpoint exactly where the hole is. Maybe a bright light?

There's always a price for free work, oh well! My cousin's husband is an exec at a large grain processing firm and they've got guys who well lots of SS. I'm sure the thin gauge had a lot to do with it. Good news is that he gave me a stainless pan he'd salvaged out of an old DQ a few years ago. It was for a salad bar and had copper refrigerant lines under foam insulation. Cleaned that off and had a 12"X32" six inch deep pan with a nice lip around it. Built a small block arch for it & it worked great today.


You can solder with lead-free solder - the problem with fixing a hole in an ugly weld is going to be getting the area you need to solder clean enough to solder. You'll probably need to grind out crummy weld, and with thin metal you may grind right through the pan instead...

Physically clean (grind it out - wirebrush or scotchbrite if not starting from a crummy weld) chemically clean (flux) don't overheat == nice solder joints.

Probably would have been better to solder the tubes in in the first place, IMHO. I've seen a few things welded to syrup pans that are simply horrid (I guess I expect the sort of sanitary weld job that brewing and dairy equipment has...and a decent soldering job sure beats a lumpy black weld on a jagged hole in my book.)