Hi,

At our power plant the boiler feed pump uses ISO 32 and the drive motor uses ISO 68. Both units have sleeve bearings. Which is better for sleeve bearings, an AW oil or an R&O oil? Thanks for the info.

Penman39,
R&O oils are Rust and oxidation inhibiting oils. They are typically used in High-speed, low-load operation in enclosed gear sets and
sleeve bearing motors and turbines. They typically contain rust and oxidation inhibitors, antifoam and antiwear agents.

AW oils are AntiWear lubricants (typically fall into the EP, extreme pressure category) and are typically used in low speed, high load gearboxes and machine tool applications. AW and EP oils require thermally stable, sulfur-phosphorus additives or similar materials capable of producing a film that provides extreme pressure (EP) and antiscuffing protection under boundary lubrication conditions.
Most sleeve bearing machines are quite happy with a R&O oil. I can't think of any sleeve bearings, if properly designed, that would require an AW style oil...
I've delt with many boiler feed pumps, both motor driven and turbine driven, and I've never seen the motors or pumps use anything but a high grade turbine oil (R&O), but I'm not all knowing, so consult your vendor and a reputable lube company.

Ed,

Thanks for the reply. That confirms my thoughts. I also checked with my local LE rep. who concurs with your info. Muchas Gracias

Ed's explanation in very good. The only exception would be if the oil was dual use with some hydraulic function, such as a hydraulic servo valve control. Since your feedpump is motor driven, perhaps there is no such control in the system. I have seen some reservoirs where they also feed a hydraulic system that requires an AW additive for proper operation and wear of the hydraulic components. Otherwise, R&O is the way to go.

Rich Wurzbach
Maintenance Reliability Group
www.mrgcorp.com

It sounds like you have good advice.

We use R&O for these type applications. I believe the reason is because it is cheaper and we don't need AW.

One thing to beware if you use certain AW/EP additives it can create problems in presence of zinc (such as in brass slinger rings). I'm a little fuzzy on the details right now... maybe someone can refresh my memory on that problem.