Seal/Sleeve Material problem

[DualPower]

Seal Bearing Sleeve

I have a requirement for a coated or solid sleeve to operate in seawater.
The sleeve will be fitted to a propeller drive shaft with 5 seals running on the outside diameter.

Sleeve duties,
Rotational speed - >600 RPM.
Seal - Shamban Variseal PTFE impregnated with graphite.
The sleeve will rotate submerged in seawater at pressures from 2 - 45 Bar.
When the sleeve is not rotating it will be submerged in seawater at pressures from 2 - 45 Bar, or on the surface subjected to salt spray.

Sleeve Surface Requirements,
Surface Finish - 0.05-0.1 ?m RA Plunge ground.
Material Contact Area Mr - 70%
Determined at a cut depth c=0.25 x RZ relative to the reference line of Cref 5% Mr.
Hardness - 65-70 RC Min

Can anyone advise on an appropriate sleeve material? Information on alternative seals that can operate in this environment would also be appreciated?

 

[kmurthy]

I have a similar situation. I am using 17-4 SST base material with Thin Dense Chrome plating. Thin Dense Chrome Plating will give us required hardness without deteriorating ground surface finish on the base material.
Check out to see if it works for you

 

[DualPower]

Thanks for the info, how many hours running did you get with the chrome plating as I have found this to fail in the past.

 

[sealguy]

You can not use standard hard chrome plating in rotary applications. The chrome will peel or crack and destroy the seals. You can use thin dense crome plating if the substrate is hard enough to suport the plating. A good substrate is 440C SS hardened to 44 Rockwell C. I have also found it necessary to polish the thin dense chrome, even though the platers say you do not have to. You can also use a ceramic sleeve, very good wear resistance at high pressures or high speeds. Used a lot in the pump industry.

There are alternative seals to the AV seals you mentioned. Your pressure is high and you did not mention the size (s). Have to be careful of your PV value as it will determine seal life. Let me know if you need help.