question on new still design

[tauren58]

I am converting an old stainless steel pool filter into a pot still. I have a question about leaving a crevice in the boiler that will be hard to clean. this unit comes apart in the middle and is held together with a clamp and rubber gasket. My plan is to weld the top and bottom together at the flange in the middle. here is an example of what it looks like. when we weld the flange in the middle, there will be a crevice around the body that will be hard to clean after runs. I plan to have an opening at the top large enough to reach in and scrub with a brush. But is it okay to have a crevice in a boiler or is that a no no for cleaning? I plan to only run liquid wash, without solids.

I have scoured the forums but could not find an answer to my question. Thanks

no plastic parts on mine.

[Setsumi]

weld it and run it. no worries. that is my opinion.

[SomethingObscure]

I am converting an old stainless steel pool filter into a pot still. I have a question about leaving a crevice in the boiler that will be hard to clean. this unit comes apart in the middle and is held together with a clamp and rubber gasket.

I'm sure someone more knowledgeable than me will correct me if I'm wrong, but why go to the effort and expense of welding the middle join and creating a large opening at the top. Wrap the seal in PTFE tape and used the original clamp. You pot still will be super easy to clear if it splits.in 2. After all it sealed when it was a filter.

Plus you need to back purge with argon to ensure you won't get porosity (I think that's the right word) on the inside of the weld. I understand that rusting can be an issue if you don't, especially in an acid environment.

Another benefit is you'll be able to use bolt on bulkhead fittings saving on more welding.

Cheers SomethingObscure

[Saltbush Bill]

I think it will be ok .....boilers rarely need more than a rinse after use......if anything does get scorched its usually on the bottom.....not half way up the side.

[Danespirit]

Well, if you plan on TIG welding it, do it with purging gas.
That eliminates the ugly black oxidation you get otherwise.
It will be perfectly fine afterward.
If you plan on going electric be aware of the placement of the heating element.
Set it in a way so you won't get an uncovered element when the still is only partly filled.

[Demy]

No problem for center welding. Being able to access the interior would be a very useful option: loading, unloading, cleaning, repairs etc ... I used an inverted stainless steel bowl in my kettles, sealed with Teflon tape and held with clamps. Things get a little complicated with the construction but it's worth it. Another option is to use a large tri-clamp on one side with a cap. Consider the situation, the construction and even which column you want to use on that kettle because if you bring the keg to be welded it is convenient for it to be welded all at once. In any case, that keg has great potential, great idea!
Add one more thing: I don't know how those filters are made, so it may already have a large opening in the bottom to remove the internal components (I guess) so you could use it upside down.

[Deplorable]

That looks big enough for a manway and a 4 inch column on top. How big is that?

[tauren58]

Hey guys, thanks for the responses.

SomethingObscure - good suggestion and I considered that. It would make cleaning it much easier. The reason I am choosing to weld it shut is that my wash will go up to or maybe past the joint and i want it liquid tight. What sealed it as a pool filter was a rubber ring and I don't want to use that. And yes, we are TIG welding the unit and will use gas. I am putting a stainless steel head on the top with a 7 inch diameter mouth to pour my wash in and be able to reach my arm in to clean. Plus that will make for my boiler head where my copper worm will connect too and a hole for a thermometer.

Setsumi and Saltbush Bill - I was thinking I would not have worry about cleaning it with being welded, thanks for the confirmation.

Danespirit - yep, doing the TIG weld. I plan to use propane burner underneath. Good tip on the purging gas!

Demy - thanks. My 7" diameter head on top will work for getting my arm in with a brush if I need to. Turns out this piece was already made into a roughshod still once so the all the guts and such have been removed and its been cleaned.

Deplorable - Not sure the size yet, i need to fill up and see, but i figure its ~25 gals. What is a manway with 4" inch column? Interested to know.

This will be my first build, well partial since it was used as a still once before, but we are modifying it. My first still was my grandpa's old copper still but it was made with lead solder so its now a show piece. my long-term goal is to make box shaped copper still out of sheet copper, but have lots more reading to do for that!

[3illmesmart]

If you are worried, just cut 1 or both flanges off, problem gone.

[Deplorable]

A manway is an opening with a hinged lid.
https://www.glaciertanks.com/non-pressu ... press.html

A four inch column would be the diameter of the "riser"(in the case of a pot still) of "column" (on a reflux still) off the top of the still.
That picture might be deceiving me but it looks like that would be big enough across the top to put a 8 or 10 inch manway for filling and cleaning,
a 2" ferrule to add a agitator, and run a 4 inch ferrule in the center to mount your column.

[tauren58]

Thanks for the link, I’ll check that out!