Vinegar cleaning - what is it doing?

[Stig]

My new ss 26gallon is up and running. I wiped it out then added about 5 gallons of water and 3.5 of vinegar, heated it up till steaming, let it run for 20 min.
I had thought my garage would smell like pickles but really didnt smell much. I thought the vinegar was mixing with the steam and cleaning all parts of the pot and head? So i looked up the boil point of vinegar and google says 244 F which i of course did not reach.
So what exactly is going on? Is the steam taking some of the vinegar up and cleaning? or is just the steam doing the cleaning?

[Deplorable]

The boiling point of vinegar alone may be 244, but the BP of the combined solution is lower. You're running a weak acid solution to clean any machining oils and residual from the welding gases from the crevases.

Edit to add that you are also verifying any leaks in the joints.

[GreenEnvy22]

Yep as deplorable said, 244 may be pure vinegar boiling point, but a mixture like you made is much lower. Lots of vinegar would have evaporated and the acid in it will have cleaned off oils and other chemicals that may be in the vapour path.

[Stig]

Thanks for the confirmation. Got stuck in the numbers. Thankfully i'm finally leak free and ready to rock.

[contrahead]

So what exactly is going on? Is the steam taking some of the vinegar up and cleaning? or is just the steam doing the cleaning?

People around here often use muratic acid or a paste of tomato ketchup and salt to clean up the oxidization evident on the outside of their (copper) still parts. Usually though they can't see what's happening, on the inside surface of the copper pipe, coils, fittings or what have you. Acids will loosen and free-up oxidization on copper and silver; but then so will strong alkalies. Just drop some dirty pennies into kitchen grade ammonia overnight and see what happens.

-Ketchup is a pasty compound that holds vinegar (acetic acid) stable on the surface of copper, and salt crystals act as an abrasive. Together, when rubbed onto copper they make it shiny. Mustard as a substitute for ketchup should work as well.

- Brasso is an old, established metal polish intended for copper and silver. It uses the alkali base - ammonia as its main agent and silica as an abrasive. The formula also apparently uses small amounts of oxalic acid - a chelating agent (what that does – you can tell me some day).

- Star San is a commercial, foaming, self-adhering, sanitizing solution used to clean exactly the type of copper and stainless steel components, used for a common still. Its partial ingredients are phosphoric acid and dodecylbenzenesulfonic acid. Phosphoric acid of course has long been used for cleaning metals and has long been used by industry to pickel steel (forming a phosphate coat which can serve as a primer for a coat of lacquer or paint). Coke a Cola ® contains phosphoric acid and several “hacks” on the Internet might show Coke and aluminum foil being used to brighten up a chrome bumper or wheel hubcap. I've no idea what dodecylbenzenesulfonic acid is good for.

My impression is that: if your still is all stainless steel – then a vinegar run would be a waste of time (for counteracting oxidization inside). Nonetheless you should do it at least once to remove possible oils and soldering flux residues. One thing is certain however; when you cook vinegar properly, there will be no doubt in your mind about the stench. It will smell very toxic and will run you out of the house, so vent it to the outdoor air.