730 Old Boiler Dissection

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Re: 730 Old Boiler Dissection

Post by ccvstmr » Sun Oct 27, 2019 9:17 am

What's Next?

In examining the old boiler, one item showed up that so far can't be explained. There's this tan'ish colored scale/residue on the inside of the boiler. In fact, inside the ENTIRE boiler with the exception of the crown sheet. With the rapid generation of steam and water boiling over the crown sheet, wouldn't expect any scale or sediment to form there. However, why is there scale at the top of the boiler barrel? Anyone?

The residue appears to be evenly coating the entire boiler barrel surface. Here's a photo of the cut up boiler half after the front/rear flue sheets and flues were cut off...


Once the boiler was cut open, cleaning/descaling methods took an elevated level of importance. Evaluated several types of solutions. Some just for curiosity sake...even though those would never be used in boiler cleaning practice. For these tests, used several of the flues from the cut-up boiler half and set those in a bucket/container with the solution for some period of time. There was no agitation or liquid circulation. This was simply a static test to see what transpired.

Test #1: 15% sulfuric acid used for pickling copper boilers. Sample flue was left in the drum for 2.0 hours...bottom 6-8 inches of the flue only. Results: the diluted acid removed the built up scale.

Sulfuric acid after 2 hours.jpg

Test #2: Haymaker/Oatey descaling solution for tankless water heaters. This is supposedly a citrus acid solution. Sample flue was left in the solution for 2.0 hours. Results: some scale removal was observed at the end of the flue starting at the flue cut. Perhaps more time and agitation would be needed for improved results.

Haymaker citrus acid 2 hours.jpg

Test #3: Muriatic acid from Menards which contains a 34% hydrochloric acid. Sample flue was left in the solution for 1.5 hours. CAUTION: not only was the solution "fuming" in the cool air outside...more fumes were created as soon as the flue was exposed to the liquid. Results: no doubt, the acid cleaned the scale off completely. Just for giggles, put a piece of cold rolled steel in the bucket too. Didn't seem to affect the steel at all.

Muriatic acid 1.5 hours.jpg

Test #4: CLR from Menards...undiluted from the bottle. Sample flue was left in the solution for 1.5 hours. Results: left one side of the flue undisturbed. Didn't really see any cleaning (nor were acid cleaning results like above expected). Here again, more time and agitation (circulating solution) would improve results.

CLR 1.5 hours.jpg

However, on the flip side of the flue, used a cloth to easily wipe off the scale/residue. However, wiping or any other form of physical agitation would not be possible in a "working" boiler.

CLR after 1.5 hours wiped off.jpg

Was going to try another flue in a 30% vinegar cleaning solution, but couldn't find this on the store shelves...even though it was listed in the websites. Vinegar is acetic acid. Stopped looking for readily available cleaners at this point.

Will the old boiler be cleaned for display purposes? No, but might pour some kind of liquid plastic in the water legs to prevent sediment from coming loose. The rest of the boiler might get some kind of clear coat...after the boiler shell edges are cut/ground and deburred...and the boiler half mounted on a display board.

Some comments for the Chaski community...1st: NO WAY will I be pouring "aggressive acids" in a new boiler for cleaning purposes! Forget that. More to the point, what kind of descaling/cleaning solutions do other live steamers use? What material? How long? Your method/procedure? Anything else?

Boiler cleaning lines are open... Carl B.
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Re: 730 Old Boiler Dissection

Post by Fender » Sun Oct 27, 2019 12:43 pm

Might be interesting to compare how well the scaled-up tubes are (or aren't) cleaned by the descaler, the CLR or the LSB in boiling hot water (?)
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Re: 730 Old Boiler Dissection

Post by rkcarguy » Tue Oct 29, 2019 10:24 am

I've used Muriatic acid to remove piston aluminum from otherwise good condition cylinders, and it will eat away the aluminum as well as remove rust and scale without *seemingly* affecting the base metal.
The heat exchanger place used a mixture of salt and vinegar to clean copper exchangers for repairs, but it did seem to eat the copper away. I used a car battery and some jumper cables and effectively copper plated a steel part in the cleaning tank just for giggles during lunch one day.

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Re: 730 Old Boiler Dissection

Post by Harold_V » Tue Oct 29, 2019 4:07 pm

Muriatic (HCl---hydrochloric acid) dissolves steel (iron). It's just not dissolved as quickly as aluminum or zinc.

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