What would be the best way to go about removing hard scale from a locomotive boiler? Specifically mineral deposits such as lime and calcium. Obviously needle scaling is an option but only in parts where it will reach. Anybody have an idea?





Thanks,
Brian O

When re-building 464 we had an outfit come in that did baking soda blasting. It removed the scale, but didn't remove the Apexior coating except in a few spots. The big plus was the easy clean up. If I recall correctly the cost was about $4000. Probably more expensive than sandblasting, but we didn't have to worry about sand getting someplace we didn't want. They were able to do a fair job on the firebox and crown sheet, but they probably felt I was a pain because I kept having them go back in and do a better job. I seem to recall the company name was Geo-Strip.

Bead blaster. Have front and back open. Use a big fan at one end to create enough force to keep the stuff out of your face and nose! Try at the lowest air setting possible and go from there Hold the gun at least 1 foot from surface and keep it moving, don't want to create a weak spot. Did this on a 1918 engine and got good results.

You do not want to bead or sand blast the boiler interior. If there is a gamma magnitite coating then sand blast will remove it. Also the sand blast will leave a tooth to the metal and you do not want that either.

You may want to look into C02 blasting. This method uses pellitized C02 as the blast media. It will scale the boiler interior and not remove the black magnitite coating. Once the pellitized C02 cleans it simply turns back to gas and then the only clean up is the scale that was removed.

Don't let anyone talk you into acid washing the boiler interior. This will ruin your boiler.

After you have had the boiler media blasted you can use Terlyn system cleaner in your boiler. This will remove the scale in places where blasting can not reach. http://www.terlyn.com/

Do a google search for dryice or carbon dioxide blasting

Adam,
Why do you not want to bead or sand blast clean the boiler interior? What is a gamma magnitite coating?

The people who produce Apexior boiler coating recommend blast cleaning, before applying their product. I have had very good success using this method over the last 30 or so years

What other products are others using to coat the interior of their boiler?
Thanks,

As I stated above the sand blasting will take the smooth coating off of the metal and leave a tooth like sand paper. By using a beneficial blasting media you will take the scale off and not damage the metal. Sorry to use the word damage but in my opinion that is what it does. Also if a magnitite coating is there sand blasting will remove it.

Gamma magnitite is the black coating that forms on the boiler shell interior when the boiler water chemistry is correct. Here is some information copied and pasted.

Steam has the very important characteristic that at a specificelevated temperature it reacts with the iron ions on the boiler wall steel on the water side, to form a uniform layer of iron oxide (Fe3O4), known as magnetite. In a reducing atmosphere at temperatures above 100°C where the water acts as an oxidising agent,the electrochemical reaction takes place and a layer of magnetite is formed. This magnetite layer is a typically black, extremely thin adherent film that passivates the steel surface and therefore protects it from corrosion. The layer of magnetite is thus a desirable deposit in a steam boiler and in an ideal situation the water side of a boiler would be coated with just this thin film of magnetite. This is often achieved by using a boiler water treatment programme.

Adam,
Where did you copy and paste that info from, looks interesting and I would like to read more.

The only problem I have had with this natural coating you call magnitite is that it appears to me that scale readily attaches to it, when the water treatment is less than perfect. Where as the Apexior finish is more readily cleaned of scale with a stream of water during a normal boiler wash.

CO2 blasting in the confined space of a boiler must be done with proper ventilation or you may suffer the affects of oxygen deprevation.

Just do a google search for magnitite/boiler, you will find a lot to read.

Apexior is good stuff from what I have heard and read. How do you get it back around the backhead and mudlegs?

What's wrong with keeping your boiler chemistry correct? That is one of the most important items on boiler maintenance.

I have seen the inside of boilers that had good chemistry. When they were opened for inspection all the metal surfaces were gray black from magnitite, no scale. That is what I would like to see.

It will help your Internet search if you use the correct spelling: "magnetite" and not "magnitite". The only time looking for wrong spelling helps you is if you're searching eBay for someone who puts up for sale a "pennsilvannia raillroad steem wistle" or something similar. (Don't laugh, I know a guy who copped a royal prize of a locomotive whistle on eBay fairly cheaply because the seller couldn't spell worth a darn and my friend searched eBay under every possible mangling of the words.....)

The Apexior paint is a superior method to protect the boiler shell interior surfaces from the effects of less-than-perfect water treatments. You need to blast to white metal to properly prepare the surface to be painted. We have painted ALL the boilers we have restored in the last 25 years with Apexior. I have seen locomotive boiler interiors painted with Apexior in the 1950's where you could still see the brush strokes in the paint - such as CB&Q 4960 and the Y-6's scrapped in Roanoke in the late 1970's.
The boiler shell was painted and protected because it is much more expensive to repair than the firebox areas.