Our group is working on restoring a small 2-6-2, and we are in the process of disassembly.

The boiler is in good shape, but has a considerable amount of scale on the shell inside.
We have been using a needle gun to remove it, but it is a slow, time consuming process.

Has anyone used any better method of scale removal they might be willing to share with us? It would be greatly appreciated!

Sincerely,
Bruce Pierce
Mid-South Rail Heritage Foundation

http://www.midsouthrail.org
brucepierce@frankelectro.com

I have used three methods, none are perfect.

Chemical (Acid) cleaning: The boiler is filled with acid laced water and the water is circulated for a period of time and then flushed. This is best done by a 3rd party. You have to have a leak free boiler for this and of the tube are out it is probably not going to work. Once the acid is out a really good flush is in order. Something like a firehose. You need to make sure you dispose of the spent acid properly.

Needle Scaling: This takes forever, however is pretty safe and can be done in house. Little risk compared to the other methods. No real disposal issues.

Sandblasting: This is a little quicker. More danger to this process. Make sure everything outside of the boiler is protected. Sand is not good for much of the moving parts of the locomotive. Proper disposal of the sand could be an issue.

With all jobs make sure you follow instructions, wear proper personal protective equipment, and dispose of waste properly.

Tom Gears
Wilmington, DE

> Our group is working on restoring a small
> 2-6-2, and we are in the process of
> disassembly.

> The boiler is in good shape, but has a
> considerable amount of scale on the shell
> inside.
> We have been using a needle gun to remove
> it, but it is a slow, time consuming
> process.

> Has anyone used any better method of scale
> removal they might be willing to share with
> us? It would be greatly appreciated!

> Sincerely,
> Bruce Pierce
> Mid-South Rail Heritage Foundation


tom@forgottendelaware.com

When we de-scaled the 3751 we weighed all the methods. Citing what Tom has already added we decided to use a method that would not leave spent media (sand) in and around the boiler. Also we did not like the idea of sand blasting as this would remove the beneficial gamma magnetite layer already built up on the inside of the boiler. Secondly sand would leave a very toothy surface which we thought would promote further corrosion. Sand will also remove some metal and this was not an option.

The method we used was pellitized C02. We contracted with a media blasting company which employed this method. Basically this is a self contained unit on a large truck that pellitizes C02 and blasts it through a hose much like a sand blast rig. The result was that the media once used disappeared leaving only scale to be swept and the magnetite layer was still intact.
The magnetite layer is the gray black that you see form on the metal interior surface.

Another method and one that probably should be used anyway after the assessable areas have been cleaned is a boiler wash. I would not acid wash a riveted boiler though rather I would contact Bill Bondie at Iron Horse water treatment and ask about his system cleaner program. You will not be able to clean the areas around the firebox mud legs and backhead and to do this you will need some type of treatment program.

> When we de-scaled the 3751 we weighed all
> the methods. Citing what Tom has already
> added we decided to use a method that would
> not leave spent media (sand) in and around
> the boiler. Also we did not like the idea of
> sand blasting as this would remove the
> beneficial gamma magnetite layer already
> built up on the inside of the boiler.
> Secondly sand would leave a very toothy
> surface which we thought would promote
> further corrosion. Sand will also remove
> some metal and this was not an option.

> The method we used was pellitized C02. We
> contracted with a media blasting company
> which employed this method. Basically this
> is a self contained unit on a large truck
> that pellitizes C02 and blasts it through a
> hose much like a sand blast rig. The result
> was that the media once used disappeared
> leaving only scale to be swept and the
> magnetite layer was still intact.
> The magnetite layer is the gray black that
> you see form on the metal interior surface.

> Another method and one that probably should
> be used anyway after the assessable areas
> have been cleaned is a boiler wash. I would
> not acid wash a riveted boiler though rather
> I would contact Bill Bondie at Iron Horse
> water treatment and ask about his system
> cleaner program. You will not be able to
> clean the areas around the firebox mud legs
> and backhead and to do this you will need
> some type of treatment program.

How did the CO2 process compare in price to sandblasting? It might be a better choice for the outside of a boiler (paint prep), since we're leary of sand near bearings, if the cost is reasonable.


kevinmccabe@avenew.com

When we cleaned the Quincy #2's boiler during the FRA Form 4 inspection, we first needle-gunned all the heavy scale we could find, then used a wire brush wheel on braces and the staybolts we could reach. We tarped and covered all the running gear and sand blasted the inside of the barrel to get the surface really clean, followed by a thorough washing with a firehose to get rid of all the sand. Once the barrel was completely clean and dry, the surface was coated with Apexior to prevent water from sitting around the braces and on the bottom of the barrel.

One thing about the Apexior, it cannot be applied to heat-transfer surfaces such as the firebox or tubes. A breathing mask must also be used when applying the Apexior.

Good luck!
Johnathon

http://www.ncry.org

johnathon_kruger@hotmail.com

Kevin,
We did both interior and exterior of the boiler for that reason, sand in the machinery. Sorry I cannot quote any costs as we talked the company into a donation for the job. I will have to go through our archives to search for a company name as well. This was however a nationwide company.

> The magnetite layer is the gray black that
> you see form on the metal interior surface.

This is a very stable oxide and good for metal protection. When you sandblast to grey you are leaving a very reactive surface that must go thru the oxidation steps again to form a stable oxide.

lamontdc@adelphia.net

Call Rick Musser or Kelly Anderson at Strasburg railroad at (717) 687-7522 or 8421. They can provide you with expert advise on scale removal from steam locomotive boilers and proper water treatment once you get the engine operable. They have also honed the fine art of water treatment to a high degree and test it daily. Some of the best steam guys around and the condition of their boilers backs this up. They are a bit on expensive side but it is worth it in the long run.

> Our group is working on restoring a small
> 2-6-2, and we are in the process of
> disassembly.

> The boiler is in good shape, but has a
> considerable amount of scale on the shell
> inside.
> We have been using a needle gun to remove
> it, but it is a slow, time consuming
> process.

> Has anyone used any better method of scale
> removal they might be willing to share with
> us? It would be greatly appreciated!

> Sincerely,
> Bruce Pierce
> Mid-South Rail Heritage Foundation

> Our group is working on restoring a small
> 2-6-2, and we are in the process of
> disassembly.

> The boiler is in good shape, but has a
> considerable amount of scale on the shell
> inside.
> We have been using a needle gun to remove
> it, but it is a slow, time consuming
> process.

> Has anyone used any better method of scale
> removal they might be willing to share with
> us? It would be greatly appreciated!

At the Huckleberry Railroad we have used a company that uses baking soda as the blast medium. It is much easier to clean up after, and the baking soda breaks down so that if it does get somewhere you don't want it isn't as abrasive. We had the interior of 464's boiler blasted about 3 years ago, If I remember correctly the cost was aboyt $3000 - $3500. The baking soda removed the scale but left most of the Apexior, so we only had to touch it up.


Martyhuck@aol.com