Let's cleanup that old boiler

[Glenn Brooks]

High pressure washer in through the steam dome and wash out plugs might do some good.

Glenn

[Bill Shields]

Steel boiler...steel tubes ....scale cleanout...be ready for leaks

[Gra2472]

Thanks for the suggestions guys. I think that I am going to go with a mild muriatic acid wash using coca-cola. I used a whole bottle of CLR with water and soaked it for 48 hours. It had some effect, but definitely did not break the crud loose as I had hoped. However, I had good results soaking my Chloe boiler in coca-cola a couple of years ago. I used cola and lemon juice, and the boiler came out like new. Of course, it did not have the baked on crud like this one. The boiler isn't too bad, the layer is only a 1/16 or less, so I think a coke might do the job. Heck I might even treat the old thing to a bit of rum, just to get it to relax (thats a joke).

[Harold_V]

Uhhh---there's no muriatic (hydrochloric acid) in Coke. It most likely contains citric acid--but it might also be phosphoric acid.

Salt and vinegar will also dissolve rust, as will molasses. I've used both methods with success. Don't know what they would do for other deposits, though.

H

[nabob]

coca-cola used to contain phosphoric acid ------probably still does. Bob

[ChipsAhoy]

Uhhh--- I dunno what's in it, but I remember our boy in school had to do an experiment. They put a nail in a jar of coca cola and in 3 days it was gone. Couldn't tell you what it was... but it worked. You just have to decide ifn' you want to have you boiler get cavaties!

[Greg_Lewis]

Here's from Snopes, a well-regarded fact-check site:
Coca-Cola contains less citric acid than does orange juice, and the concentration of phosphoric acid in Coke is far too small (a mere 11 to 13 grams per gallon of syrup, or about 0.20 to 0.30 per cent of the total formula) to dissolve a steak, a tooth, or a nail overnight. (Much of the item will dissolve eventually, but after a day or two you’ll still have most of the tooth, a whole nail, and one very soggy T-bone.)

https://www.snopes.com/fact-check/coca-cola-acids/

[Gra2472]

You guys are absolutely right, I misstated the muriatic acid component. I happened to be chatting with a friend of mine about it at the same time. I used coca cola once to clean the boiler in a Chloe without any side effects. I didn't leave it in there very long of course, just overnight. But it cleaned out the dusting of rust in the boiler with no ill effects.

What I am trying to remove is scale, with a small layer of rust underneath it on the metal surface. I came to this conclusion from a few small chips I got out if the last weekend. Mind you I am not a chemistry expert. I barely passed chemistry in college, that is why I graduated as a history major. If you want to talk about the history of the United States from the Colonial Period to the Reconstruction, of the origins of World War 2, I am your man. Chemistry, I gladly accept guidance from those with more knowledge.

Back to the boiler. My thinking, as flawed as it might be, was this. There is a thin layer of rust under the scale. The scale itself is very thin as well. I would say no more than the thickness of a piece of paper. So, I believe that coca-cola can remove or loosen the rust under the scale. So, if I can do that, then I can remove the scale when the coke dissolves (I think) the rust. Others have suggested, as did a good friend of mine, that I use muriatic acid. Since I am not terribly familiar with it, I wanted to try a, lets call it less invasive, method to remove the rust and scale. What do you guys think?

By the way, I am glad that you guys take the initiative to correct my error. That is one of the great things about this hobby. People jump in with all kinds of knowledge and create a massive repository.

[Gra2472]

Mr. Watson, what should the concentration of vinegar and the bicarbonate be in each solution? My chemistry classes have long faded away.

[Fender]

Mr. Watson, what should the concentration of vinegar and the bicarbonate be in each solution? My chemistry classes have long faded away.

Were it my boiler, I would try a 25% solution of white vinegar in the boiler, completely full. Gently heating the water will speed up the process. Afterwards, remove the washouts and flush vigorously.
I used sodium bicarbonate as an example, but any basic solution would work to neutralize the vinegar. In my area, the rainwater is somewhat acidic, with a pH around 4-5. I add a small amount of sodium hydroxide (lye/drain cleaner) on the order of well less than 1%, to boost the pH to about 10-11. That would be the ideal range for water in your steel boiler. Get some pH test strips like these to determine the correct amount of NaOH. Use caution when handling concentrated NaOH, but it is perfectly safe when diluted.

[Gra2472]

Thanks, I think that I will give the vinegar a try.

[Harold_V]

One thing to keep in mind. Sodium hydroxide has the potential to blind a person, something I learned when I splashed a drop of nitric acid into my right eye, many years ago. The drop of acid resulting in an almost instant destruction of the surface of the eye, in spite of the fact that I was very near a water source and immediately rinsed the eye. A trip to an ophthalmologist resulted in good news, however, with the admonition of my (apparent) good fortune. He told me that had that drop been sodium hydroxide, I would have lost the sight in that eye, as the human body can not resolve the damage that occurs, while it has the ability to neutralize acid, limiting damage.

Amazingly, the surface of my eyeball was lost, but it was regrown quickly, with no long term damage. The eye still works, and is the stronger of the two I have.

I gained a lot of respect for the potential threat of sodium hydroxide.

H