1213 Corrosion 1

[ThirdString]

I'm trying to find out what effect elevated humidity will have on a smooth AISI 1213 shaft that is coated with hydraulic fluid. Previously, with lower humidity, the shaft does not visibly rust with a simple coat of hydraulic fluid. If we get up to 70-80% humidity (guessing at that number) for 10 days, will that somehow displace the hydraulic fluid?

 

[Goahead]

Would a black oxide coating, to help keep the hydraulic fluid in place, be compatible with your application?

http://www.welding-advisers.com/

 

[ThirdString]

From what I've read, a black oxide coating would work well. However, I first need to find out what I can about the effect of humidity with our current setup.

I have since learned that the shafts actually have grease applied before they are shipped to us. Previously there was not visible rust, but in recent shipments (which we believe had higher humidity) there is a uniform, thin layer of rust present.

With hydraulic fluid applied, I could see the rust forming, but with grease, from what I understand, it shouldn't form rust at all. I'm trying to find out what specific grease is being used.

 

[swall]

The first thing you need to do is contact a chemical supplier and get their recommendation on a petroleum based rust preventitive to protect the shafts during shipping and storage. Unless the "grease" is cosmoline, you can't be certain of its rust preventitive properties.

 

[kenvlach]

The hydraulic fluid is absorbing moisture from the air & causing rusting. Grease is far better, but the hydraulic fluid washed it off. Switch to a non-moisture absorbing hydraulic fluid ($) or add a corrosion inhibitor.

"Water condensed from entrained air in a hydraulic system causes rust if the metal surfaces are not properly protected. In some cases water reacts with chemicals in a hydraulic fluid to produce acids that cause corrosion. The acids attack and remove particles from metal surfaces allowing the affected surfaces to leak, and in some cases to seize. To prevent rust, hydraulic fluids use rust inhibitors that deposit a protective film on metal surfaces. The film is virtually impervious to water and completely prevents rust once the film is established throughout the hydraulic system. Rust inhibitors are tested according to the ASTM D 665 Rusting Test."
from

http://www.usace.army.mil/publications/eng-manuals/em1110-2-1424/c-4.pdf

 

[ThirdString]

kenvlach, That is great info for us! Thanks! Management will actually respond to that (I think). There is some testing to be done, but that gives us something to start with (ASTM D 665).

 

[unclesyd]

We are in in area of about the highest humidity around and here is the only thing that works with any reliability.
It Molykote Metal Protector or MMP Plus.

http://www.dowcorning.com/applicati...L2=&L3=&L4=&L5=&PG=00001059&Country=USA&req=M